The product from the burning of a combination of carbonaceous materials.

Endpoint summary

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

between 19 May 2010 and 30 July 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant guideline study.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Objective of study:

toxicokinetics

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity in Rodents)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, France.
- Age at study initiation: 6 - 8 weeks
- Weight at study initiation: males 151.4 g and 181.1 g, females 131.9 g and 151.6 g
- Fasting period before study: -
- Housing: 5 rats of one sex per cage
- Individual metabolism cages: no
- Diet (e.g. ad libitum): RM1 (E)-SQC SDS/DIETEX feed
- Water (e.g. ad libitum): available ad libitum in polycarbonate bottles with a stainless steel nipple
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24°C
- Humidity (%): relative humidity between 45% and 65%
- Air changes (per hr): approximately 10 times
- Photoperiod (hrs dark / hrs light): 12 hours light and 12 hours darkness with light on at 7.30 a.m.

IN-LIFE DATES: From: May 19, 2010 To: Jul. 30, 2010

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

1%

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Ash was weighed in a brown glass flask previously tarred. The vehicle was added. The suspension was ground using a homogeniser without agitation until homogenisation was completed. Samples were taken under magnetic stirring. The test item formulations were prepared daily before administration.

VEHICLE
- Justification for use and choice of vehicle (if other than water): homogeneity of dosing suspensions
- Concentration in vehicle: 0, 50, 100 or 200 mg/ml
- Amount of vehicle (if gavage): 10 ml/kg
- Lot/batch no. (if required): SIGMA-Aldrich, Batch No. 044K0101, Expiry date: Oct 2010

HOMOGENEITY AND STABILITY OF TEST MATERIAL: based on chemical analysis of Pb, Cr and Cd; dosing suspension prepared daily immediately before dosing

Duration and frequency of treatment / exposure:

Once daily for 28 days.

Remarks:

Doses / Concentrations:
0, 500, 1000 or 2000 mg/kg bw/day

No. of animals per sex per dose / concentration:

2

Control animals:

other: 1% carboxymethyl cellulose

Positive control reference chemical:

-

Details on study design:

- Dose selection rationale: A dose range-finding study.

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled : blood
- Time and frequency of sampling: Day 1: predose, 1 h and 6 h; Day 14: predose; Day 28: predose, 1 h and 6 h.

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled (delete / add / specify): urine, faeces, tissues, cage washes, bile

Type:

absorption

Details on absorption:

Blood Pb concentrations showed dose-dependent increases and modest accumulation during the Study. Cr concentrations showed at most only very slight increases and virtually no accumulation. Cd concentrations were not affected by the treatment. Blood concentrations reflected the concentrations of Pb, Cr and Cd in Ash.

Transfer type:

other: gastrointestinal tract/blood

Observation:

slight transfer

Metabolites identified:

no

See Figures 3, 6, and 9 in Appendix E of the Study Report.

Conclusions:

Interpretation of result: low bioaccumulation potential based on study results. Systemic bioavailability of heavy metals (Pb, Cr, Cd) from Ash is very low. Blood concentrations reflected the concentrations of Pb, Cr and Cd in Ash.

Executive summary:

Concentration of 3 indicator metals (Cr, Cd, Pb) in blood were analysed in 2 male and 2 female satellite animals on study days 1, 14 and 28. Samples were taken from the same animals predose, 1h and 6h after dosing; on study day 14 only predose. Blood Pb concentrations showed dose-dependent increases and modest accumulation during the study so that the predose values on day 28 were about 1, 1, 2.5 and 4.5 µg/l in males and 1, 2, 4 and 7.5 µg/l in females at dose-levels of 0, 500, 1000 and 2000 mg/kg/day, respectively. Cr concentrations showed at most only very slight increases and virtually no accumulation. Cd concentrations were not affected by the treatment.

Reference 2

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant, non-guideline experimental investigation. Study published in scientific, peer reviewed journal.

Reason / purpose for cross-reference:

reference to other study

Objective of study:

toxicokinetics

Principles of method if other than guideline:

Rats were exposed to CFA (coal fly ash) aerosol 7 h per day 5 days per week for 1 month. Aluminum concentrations in lungs were analysed at the end of exposure period or at 6 or 10 months after exposure.

GLP compliance:

no

Radiolabelling:

no

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

No data

Route of administration:

inhalation: aerosol

Vehicle:

other: air

Details on exposure:

Mass median aerodynamic diameter 3.0 um, geometric standard deviation 1.8

Duration and frequency of treatment / exposure:

7 h/day, 5 days/week for 1 month, total exposure time 147 h

Remarks:

Doses / Concentrations:
10.4 mg/m3

No. of animals per sex per dose / concentration:

5-7

Control animals:

yes

Positive control reference chemical:

No

Details on study design:

Exposure system described in Tanaka et al., J. UOEH 1983; 5:423-431 and Tanaka & Akiyama, Ann. Occup. Hyg. 1984; 28:157-162. Fly ash aerosol concentration was monitored continuously by a light-scattering method and was adjusted automatically by the on-off control of the screw feeder. The mass concentration of fly ash aerosol was measured gravimetrically at daily intervals.

Details on dosing and sampling:

Just after exposure, 6 month and 10 month after exposure.

Statistics:

No data

Type:

distribution

Results:

Al concentration in lungs was increased in exposed animals and the decrease was slow.

Details on distribution in tissues:

Al concentration in lungs was increased in exposed animals and the decrease was slow (Table 3). Al concentrations in liver, kidney, spleen and blood were not increased.

Transfer type:

other: lungs/blood, liver, kidneys, spleen

Observation:

no transfer detectable

Metabolites identified:

no

Conclusions:

Interpretation of results: low bioaccumulation potential based on study results Systemic bioavailability of metals from Ash is very low.
Systemic bioavailability of metals from Ash is very low.

Executive summary:

Wistar male rats were exposed to coal fly ash aerosols at average exposure concentration of 10.4 mg/m3 for 7 hr/day, 5 days/week for 1 month. Some rats were sacrificed just after the exposure, while others were kept for 6 or 10 months clearance time before sacrifice. There were no differences in body weight gain between fly ash exposure groups and controls, and the weights of lung, liver, kidney and spleen were not affected by the treatment. In histopathology, no adverse alterations were observed in lungs or lymph nodes. The burden of fly ash was estimated by the measurement of aluminum contents in rat organs. Aluminum concentrations in lungs of exposure groups were much higher than those of controls. No apparent deposition of fly ash was observed in the liver, kidneys, spleen, and blood, but lung burdens of up to about 0.7 mg of fly ash were found. The apparent deposition fraction was 5.1% after the 1-month exposure. The clearance rate of fly ash derived aluminum deposited in rat lungs may be very slow.

Reference 3

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant, non-guideline experimental investigation. Study published in scientific, peer reviewed journal.

Objective of study:

absorption

bioaccessibility (or bioavailability)

distribution

excretion

toxicokinetics

Principles of method if other than guideline:

Male Syrian golden hamsters were exposed to neutron-activated coal fly ash for a single 95 min exposure period in a nose-only exposure system. Radionuclides 60Co, 46Sc and 59Fe were selected as preferable fly ash tracers. Animals were serially killed over a period from 15 min to 99 days for the analysis of the tracers using g-ray spectrometry.

GLP compliance:

no

Radiolabelling:

yes

Remarks:

Neutron activation

Species:

hamster, Syrian

Strain:

other: Outbred LAK:LVG

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Lakeview Laboratories
- Age at study initiation: 5 months
- Weight at study initiation: 120-130 g
- Fasting period before study: No
- Housing: Not described
- Individual metabolism cages: yes/no Not described
- Diet (e.g. ad libitum): Not described
- Water (e.g. ad libitum): Not described
- Acclimation period: Not described

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Not described
- Humidity (%): Not described
- Air changes (per hr): Not described
- Photoperiod (hrs dark / hrs light): Not described

IN-LIFE DATES: From: To: Not described

Route of administration:

inhalation: aerosol

Vehicle:

other: air

Details on exposure:

TYPE OF INHALATION EXPOSURE: nose only

GENERATION OF TEST ATMOSPHERE / CHAMPER DESCRIPTION
- Exposure apparatus: 20 liter aerosol exposure chamber (Wehner et al., 1977) was constructed of Lucite with exposure ports for nose-only exposures arranged in 7 tiers, each containing 10 exposure ports.
- Method of holding animals in test chamber: Animals were placed in soft-drink bottles that had bottom and part of the top removed so that the nose of animals were close to the open tops of the bottles. The bottles were inserted through neoprene stoppers into the ports of the exposure chamber. The animals were maintained in this position by wadding pushed against their posteriors, and by neoprene stoppers taped to the bottoms of, and sealing, the bottles.
- Source and rate of air: Not described
- Method of conditioning air: Not described
- System of generating particulates/aerosols: Wright Dust Free Mechanism (Wright, 1950) followed by cyclone elutriator for removal of particles larger than 10 µm aerodynamic equivalent diameter (AED).
- Composition of vehicle (if applicable): -
- Concentration of test material in vehicle (if applicable): Respirable aerosol concentration (mean ± SD) 470 ± 39 µg/l
- Method of particle size determination: Andersen cascade impactor (Andersen, 1966)
- Treatment of exhaust air: Not described

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: Activity mean aerodynamic diameter (AMAD) (mean ± SD) 3.5 ± 0.33 µm, geometric SD 2.8 ± 0.045
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): Activity mean aerodynamic diameter (AMAD) (mean ± SD) 3.5 ± 0.33 µm, geometric SD 2.8 ± 0.045

Duration and frequency of treatment / exposure:

A single exposure for 95 min.

Remarks:

Doses / Concentrations:
Respirable aerosol concentration (mean ± SD) 470 ± 39 µg/l.

No. of animals per sex per dose / concentration:

6 males per time point.

Control animals:

yes, concurrent no treatment

Positive control reference chemical:

No

Details on study design:

- Dose selection rationale: Not applicable

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: urine, feces, lungs (including mediastinal tissue), liver, kidneys, head, gastrointestinal tract, skinned and decapitated carcass, pelt
- Time and frequency of sampling: 15 min, 1day, 3, 7, 14, 24, 51 and 99 days after exposure

10 unexposed control hamsters were killed 2 or 102 days after the exposure of test animals.

The tracers were analyzed using gamma-ray spectrometry

METABOLITE CHARACTERISATION STUDIES: Not applicable

TREATMENT FOR CLEAVAGE OF CONJUGATES (if applicable): Not applicable

Statistics:

Not described.

Preliminary studies:

No

Type:

distribution

Results:

Only 60Co showed some distribution.

Type:

absorption

Results:

The tracers were detected in lungs, liver, gastrointestinal tract, carcass and head.

Type:

excretion

Results:

The leached Co was excreted in urine and the most urinary Co excretion took place within the first few days after exposure.

Details on absorption:

The tracers were detected in lungs, liver, gastrointestinal tract, carcass and head already 15 min after exposure, but amounts in kidney were very low (Table 4.).

Details on distribution in tissues:

Listing of the 6 individual 15 min lung burden analysis samples indicate that the tracers 46Sc and 59Fe behave similarly remaining together and represent fly ash particles rather than leached radionuclides (Table 5.). The lower values of 60Co suggest that this metal leaches selectively from the fly ash deposited in the deep lung translocating primarily to the head, pelt, kidneys, liver and the carcass (Table 4.).

The estimated initial lung burden of fly ash was 63.2 ± 8.3 µg, which is about 2.3% of the estimated amount of 2.7 mg fly ash inhaled during the exposure period of 95 min.

Considerable quantities of fly ash were detected in the gastrointestinal tract up to 3 days after exposure. These ´values are likely to represent fly ash originally deposited in the respiratory tract and subsequently translocated by mucociliary clearance mechanisms to the GI tract, and externally deposited fly ash translocated to the GI tract by grooming (licking and swallowing) of the animals after exposure.

Transfer type:

other: lung/other tissues, urine, feces

Observation:

distinct transfer

Remarks:

for Co

Transfer type:

other: lung/other tissues, urine, feces

Observation:

slight transfer

Remarks:

for Sc and Fe

Details on excretion:

The leached Co was excreted in urine and the most urinary Co excretion took place within the first few days after exposure (Table 4.).

At 99 days postexposure the mean lung burden of fly ash particles had decreased to about 10% of its initial value. It can be estimated that near-complete clearance and/or translocation of fly ash from the lung would take about 200 days. The estimated initial lung burden is 63.2 ± 8.3 µg.

Toxicokinetic parameters:

half-life 1st: Fly ash particles from the airways 2.6 ± 3.2 days (mean ± SD)

Toxicokinetic parameters:

half-life 2nd: Fly ash particles from alveolar deposition 34.5 ± 28.7 days (mean ± SD)

Metabolites identified:

no

Conclusions:

Interpretation of results: low bioaccumulation potential based on study results
Radionuclide tracers 46Sc and 59Fe proved to be good markers for the coal fly ash particulates. On the other hand, 60Co selectively leached from fly ash deposited in lungs, was translocated to other sites and excreted in the urine. Most of the urinary Co exposure took place within the first few days after the exposure. About 2.3% of the inhaled fly as was initially retained in the respiratory tract. The estimated biological half-lives of fly ash were 2.6 and 34.5 days for the airways and alveolar deposits, respectively. After 99 days the mean lung fly ash burden had decreased to about 10% of its initial value.

Executive summary:

Male Syrian golden hamsters were exposed to neutron-activated coal fly ash for a single 95 min exposure period in a nose-only exposure system. Radionuclides⁶⁰Co,⁴⁶Sc and⁵⁹Fe were selected as preferable fly ash tracers. Animals were serially killed over a period from 15 min to 99 days for the analysis of the tracers using gamma-ray spectrometry. Radionuclide tracers⁴⁶Sc and⁵⁹Fe were used as markers for the coal fly ash particulates. On the other hand,⁶⁰Co selectively leached from fly ash deposited in lungs, was translocated to other sites and excreted in the urine. Most of the urinary Co exposure took place within the first few days after the exposure. About 2.3% of the inhaled fly as was initially retained in the respiratory tract. The estimated biological half-lives of fly ash were 2.6 and 34.5 days for the airways and alveolar deposits, respectively. After 99 days the mean lung fly ash burden had decreased to about 10% of its initial value.

Reference 4

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant, non-guideline experimental investigation. Study published in scientific, peer reviewed journal.

Objective of study:

bioaccessibility (or bioavailability)

Principles of method if other than guideline:

Fly ash from two fuels (coal and coal 95% + shredded tires 5%) were evaluated for trace metal solubility in simulated human lung and gut fluids (SLF and SGF, respectively) to estimate bioaccessibility.

GLP compliance:

no

Radiolabelling:

no

Details on test animals or test system and environmental conditions:

No animals used.

Duration and frequency of treatment / exposure:

6 d

Details on study design:

Triplicate 1-g subsamples of fly ash were continually mixed by rotation in 30-mL capped polypropylene vials containing 20 mL of either SGF or SLF, giving a liquid/solid ratio of 20:1. Parallel blank tests were also carried out (in duplicate) to allow for background subtraction of elemental concentrations in the leachates. Temperature was held at 37°C using a hybridization oven.

The leachates and solid residues were separated by vacuum filtration through a 0.4 µm cellulose nitrate membrane. After pH measurement, the leachates were acidified with 3 vol. % concentrated, analytical grade nitric acid to ensure the elemental constituents remained in solution. The acidified leachates were retained for analysis. This procedure was also carried out on the solutions from the parallel blank experiments.

Type:

other: Dissolution

Results:

Only a proportion of the total metal concentrations in either fly ash was soluble, and hence bioaccessible.

Details on absorption:

Not applicable.

Details on distribution in tissues:

Not applicable.

Details on excretion:

Not applicable.

Metabolites identified:

no

The accuracy for most of the elements in the QC was greater than 95%. The RSD (relative standard deviation) values for each element in each sample analyzed, determined by the ICP-MS as a measure of the deviation of the individual elemental count rate from the mean triplicate result, were less than 5%.

Solubility of metals in simulated biofluids

 

In SLF, solubilities of toxic metals from the fractionated CDF with total digests (mg/g) were: Al 0.36% (110 mg/g), Cr(III) 0.08% (1.3 mg/g), Cu 33% (0.9 mg/g), Ni 53% (1.7mg/g), Pb 9% (1.0 mg/g), Th 0.05% (0.02 mg/g), U 6.7% (0.03 mg/g), and Zn 78% (3.9 mg/g). No detectable solubility of V was found (0.6 mg/g). With the same total digests, solubilities of toxic metals from the fractionated CDF in SGF were higher: Al 9.1%, Cr 7.7%, Cu 78%, Ni 53%, Pb 40%, Sr 29%, Th 10% U 33%, V 67%, and Zn 77%. Solubility of these metals from bulk CDF and TDF in SGF were: Al 6.9%, Cr 5.3%, Cu 78%, Ni 47.1%, Pb 19%, Sr 28.6%, Th 5%, U 67%, V 31%, and Zn 74%.

 

In relation to international inhalation limits for the hazardous metals present in CDF, the most restrictive was for Pb at 0.0005 mg/m³ set by the Australian National Environmental Protection (Ambient Air Quality) Measure (NEPM). The mass of fractionated CDF that could be inhaled ranged from 0.5 (total Pb) to 6 mg/m³ (bioaccessible Pb). However, the NEPM (which is due to be introduced in 2005) also provides maximum concentration for generic particulate matter with an aerodynamic diameter of 10 µm or less (averaged over 1 day) at only 50 µg/m³. Hence, the fractionated CDF is over 100 times more restrictive as a particulate than as a source of bioaccessible metals.

There was a substantial shift in the risk ranking for bioaccessible metals in fractionated CDF between SLF and SGF due to differential solubilities in those media (table). Lead, Cu, and Zn were the highest risks in SLF while Al, Ni, and Pb were ranked in SGF. In either media, Cr was much more restrictive when it was assumed to be in the Cr VI form as distinct from Cr III. In an acidic environment, such as the gut, most of the Cr would be reduced to the less toxic form Cr III. Analysis indicated that the levels of Cr were very low or undetectable (<50 ng/g) in all media. That is, most of the metal in the leachates was present in the Cr III form. The Cr III form is 500 times less restrictive as an inhaled metal and considered innocuous when ingested.

 

There was no substantial change in the relative risk of metals between the fractionated and bulk samples of CDF in SGF (Tables 2b and 3a).

 

Depending upon likely exposures, the gut leachate values may be considered hazardous. As little as 10 mg of the fly ash consumed per day exceeds the limit for Al (based on the bioaccessible concentrations). This ignores the contributions of adverse effects (potentially synergistic) from any of the other toxic metals, notably bioaccessible Ni and Pb, that will further restrict the ingestion of fly ash as their implied limits are also at levels typically less than 100 mg per day. Less than 1 mg of CDF is required to exceed the limit based on total Al concentrations.

 

The large variation in leachability of the different metals observed in both types of simulated biofluids is most likely the result of partitioning of the metals among different types of solid phases. A number of studies have shown that several metals exhibit distinct preference for oxide, sulfate, or silicate particles rather than a uniform distribution across all fly ash particles (e.g., ref 38). Therefore, a mineralogical study of the material used here is currently being conducted to better understand the leaching mechanism.

 

Varying solid-to-liquid ratios have been shown to affect bioaccessibility in some cases (39). The ratios used in our study are comparatively high and hence may tend to reduce apparent bioaccessibility. A future study to evaluate the effect of solid-to-liquid ratio on Al, Ni, and Pb solubility from fly ash may be appropriate.

 

The normal adult male active breathing rate is assumed to be 1.2 m³/h (based on a reference man value of 2400 m³/2000 h working year (18)). This value over-estimates the weighted average rate that would apply if females and

children as well as periods of lower activity were included. Hence this estimate is precautionary. From this, the inhalation limit of 0.5 mg/m³(total Pb) or 6 mg/m³(bioaccessible Pb) converts to a maximum daily intake limit of 14 or 170 mg of ash assuming continuous exposure. Given that the implied threshold for ingestion is only 1 or 10 mg per day (based on total or bioaccessible Al), it is apparent that the ingestion exposure route is at least approximately 15-20 times more limiting than the inhalation route for fly ash metals based on the results of this study.

Conclusions:

Interpretation of results: low bioaccumulation potential based on study results
The proportion of bioaccessible to total metal ranged from zero (V) to 80% (Zn) for coal-derived ash in SLF and from 2 (Th) to 100% (Cu) for tire-derived fly ash in SGF. On the basis of total concentrations, the metals closest to exceeding limits based on international regulations for inhalation were Cr, Pb, and Al. In most cases only a proportion of the total metal concentrations in either fly ash was soluble, and hence bioaccessible, in either biofluid. When considering the regulatory limits for inhalation of particulates, none of the metal concentrations measured were as hazardous as the fly ash particulates themselves. On the basis of the international ingestion regulations for Al, the maximum mass of fly ash that could be ingested is only 1 mg per day (10 mg based on bioaccessibility). Therefore it was assessed that the ingestion exposure route is at least approximately 15-20 times more limiting than the inhalation route for fly ash metals.

Executive summary:

Power plant fly ash from two fuels, coal and a mixture of coal and shredded tires, were evaluated for trace metal solubility in simulated human lung and gut fluids (SLF and SGF, respectively) to estimate bioaccessibility. The proportion of bioaccessible to total metal ranged from zero (V) to 80% (Zn) for coal-derived ash in SLF and from 2 (Th) to 100% (Cu) for tire-derived fly ash in SGF. The tire derived ash contained much more Zn. However, Zn ranked only 5th of the various toxic metals in SGF compared with international regulations for ingestion. On the basis of total concentrations, the metals closest to exceeding limits based on international regulations for inhalation were Cr, Pb, and Al. On dissolution in SLF, the most limiting metals were Pb, Cu, and Zn. For metals exposed to SGF there was no relative change in the top metal, Al, before and after dissolution but the second-ranked metal shifted from Pb to Ni. In most cases only a proportion of the total metal concentrations in either fly ash was soluble, and hence bioaccessible, in either biofluid. When considering the regulatory limits for inhalation of particulates, none of the metal concentrations measured were as hazardous as the fly ash particulates themselves. However, on the basis of the international ingestion regulations for Al, the maximum mass of fly ash that could be ingested is only 1 mg per day (10 mg based on bioaccessibility). It is possible that such a small mass could be consumed by exposed individuals or groups. Given that the implied threshold for ingestion is only 1 or 10 mg per day (based on total or bioaccessible Al), it is apparent that the ingestion exposure route is at least approximately 15-20 times more limiting than the inhalation route for fly ash metals based on the results of this study.

Reference 5

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant, non-guideline experimental investigation. Study published in scientific, peer reviewed journal.

Objective of study:

bioaccessibility (or bioavailability)

Principles of method if other than guideline:

Occupational health risks of using power plant bottom ash and fly ash were assessed based on chemical analyses of the ashes and extractability of metals from the ashes to artificial sweat and gastric fluid.

GLP compliance:

no

Radiolabelling:

no

Details on test animals or test system and environmental conditions:

No animals were used.

Details on exposure:

No animals were used.

Duration and frequency of treatment / exposure:

Not applicable.

Remarks:

Doses / Concentrations:
Not applicable.

No. of animals per sex per dose / concentration:

Not applicable.

Control animals:

no

Details on study design:

Artificial sweat was prepared by dissolving 5 g NaCl, 1 g lactic acid, and 1 g urea in 1 L of deionized water and adjusting the pH to a value of 6.47 with ammonia. Artificial gastric fluid was prepared by dissolving 60.06 g glycine in 2 L of deionized water and adjusting the pH to a value of 1.51 with HCl. The extraction was carried out in polypropylene bottles by shaking 1 g of ash on a dry weight (d.w.) basis with 100 mL of the extract (i.e., artificial sweat or artificial gastric fluid) for 1 h by end-over-end mixing at 37°C. Thus, the liquid-to-solid ratio was L/S 100 L/kg. To minimize possible chemical and/or microbiological changes in the ash during the extraction procedure, extraction was carried out by using an undried ash sample instead of a dried sample. After extraction, the extract was separated from the solid residue (i.e., the undissolved ash) by filtration through a 0.45 μm membrane filter. The pH of the extract was then measured, and the metal concentrations were determined using inductively coupled plasma optical emission spectrometer (ICP-OES).

Preliminary studies:

Not applicable.

Type:

other: dissolution

Results:

Concentrations of heavy metals were clearly higher in the artificial gastric fluid extracts than in artificial sweat.

Details on absorption:

Not applicable.

Details on distribution in tissues:

Not applicable.

Details on excretion:

Not applicable.

Metabolites identified:

no

Details on metabolites:

Not applicable.

Bioaccessibility (or Bioavailability) testing results:

Not applicable.

Characteristics of the ashes

 

Both ashes were strongly alkaline (pH 10.4–10.5). TOC and LOI values were very low for bottom ash (< 0.5 g/kg d.w. and <0.5 % d.w., respectively). In case of fly ash, these results were higher (140 g/kg d.w. and 15.6 ± 0.3% d.w., respectively). Dry matter content was 94.0% for fly ash and 71.1% for bottom ash. No particles of a diameter range between 0.5 and 16.0 mm existed in the fly ash, whereas these particles accounted for approximately 81.1 weight percent (wt%) of the bottom ash. The fly ash consists of small particles with a diameter of less than 0.5 mm.

 

Both ashes contained silicate minerals such as microcline [K(AlSi3O8)] and quartz (SiO2), and their abundances in the ashes were relatively similar. However, hematite (Fe2O3), which is an oxide mineral, and dolomite (CaMg(CO3)2), which is a carbonate mineral, only existed in the fly ash and bottom ash, respectively.

 

Except for the total concentration of PAH in the fly ash (23 mg/kg d.w.), which exceeded the limit value for an agent used in covered earth construction, the other total concentrations in the ashes were less than the statutory Finnish limit values for both covered and paved structures.

 

The extractable concentrations of DOC, heavy metals, fluoride, sulfate, and chloride in the ashes and the limit values for the extractable concentrations of these compounds in earth construction agents used for covered and paved structures. Except for V, the extractable concentrations of all other compounds in the fly ash were more than those in the bottom ash.

Except for the extractable concentrations of Mo and Se in the fly ash, which exceeded the limit value for agents used in covered earth constructions, the other extractable concentrations in the ashes were lower than the statutory Finnish limit values for use in both covered and paved structures.

 

Extractability to artificial gastric fluid and sweat

 

All the heavy metals in this study were extractable in the artificial and gastric fluids. Except for Zn, the extractable concentrations of heavy metals in the artificial gastric fluid were clearly more than those in the artificial sweat fluid (see Table 4). The highest extractable concentrations in the artificial sweat fluid were observed for Ba, which were 16.9 mg/kg (d.w.) and 25.1 mg/kg (d.w.) for the bottom ash and fly ash, respectively. The highest extractable concentrations in the artificial gastric fluid also were observed for Ba, which were 86.6 mg/kg (d.w.) and 446 mg/kg (d.w.) for the bottom ash and fly ash, respectively. In addition, the extractability of Zn in both ashes, and the extractability of Cu, As, V, and Pb for the fly ash were relatively high in the artificial gastric fluid. These results are reasonable considering that the pH of the gastric fluid was extremely acidic both before (i.e., pH 1.49 for both ashes) and after (i.e., pH 1.62 for the bottom ash and 1.79 for the fly ash) extraction. However, for the fly ash, the extractable concentration of Mo was slightly more in the artificial sweat (6.9 mg/kg; d.w.) than that in the artificial gastric fluid (5.2 mg/kg; d.w.). For the fly ash, the pH of the artificial gastric fluid was extremely acidic both before (pH 1.49) and after (pH 1.79) extraction, whereas the pH of the artificial sweat fluid was slightly alkaline before (pH 6.50) and after extraction (pH 8.81). The higher extractable concentration of Mo in the artificial sweat is reasonable, because Mo is able to form oxyanions, which means that its extractability clearly increases from acidic pH values to neutral and alkaline conditions. Although the highest extractable concentration of Se also occurs in strongly alkaline conditions, the extractability of Se for the fly ash was practically the same in the artificial sweat (3.7 mg/kg; d.w.) and gastric (3.9 mg/kg; d.w.) fluids.

 

The extraction recovery (R) values (%) for the metals, which were determined as the ratio of the metal concentration extracted with artificial sweat and gastric fluids (Table 4) to the total metal concentration in the ash (Table 1), varied between 2.9% (V) and 71.2% (Se) in the artificial sweat fluid and between 11.4% (V) and 94.1% (Cd) in the artificial gastric fluid.

Conclusions:

Interpretation of results: low bioaccumulation potential based on study results
Extraction of the heavy metals to artificial sweat and gastric fluids was higher from fly ash than from bottom ash. The only exception was Zn, which concentration was same in the artificial gastric fluid extracts of both fly and bottom ashes. In the artificial gastric fluid fly ash extract, concentrations of all the determined metals, with the exception of Sb were above the detection limits. The highest extractable concentrations were observed for Ba in all cases. Generally, the concentrations of heavy metals were clearly higher in the artificial gastric fluid extracts than in artificial sweat indicating that most of the heavy metals studied are soluble in this very acidic body fluid. Additionally, having smaller particle size, the dusty fly ash enters inhalation and oral routes easily.

Executive summary:

As a case study, the potential to use bottom ash and fly ash from a large-sized (120 MW) bubbling fluidized bed boiler (BFB) at the power plant of a fluting board mill were assessed to determine their suitability for use as an earth construction agent. In addition, the extractability of heavy metals in the ashes was determined using artificial sweat and gastric fluids to assess the potential occupational risk from ash handling.

Extraction of heavy metals in artificial gastric fluid was higher than to artificial sweat due to very acidic pH. Additionally, heavy metal concentrations were higher in smaller particle size fly ash extracts than in bottom ash extracts. Because of the high extractability of certain heavy metals in fly ash by using an artificial gastric fluid, e.g., Ba (446 mg/kg; d.w.; 60.2%), V (65.6 mg/kg; d.w.; 69.2%), Zn (100 mg/kg; d.w.; 36.4%), Cu (38.3 mg/kg; d.w.; 38.5%), and As (36.7 mg/kg; d.w.; 78.3%), the careful handling of this ash residue is recommended to prevent the ingestion and penetration of ash particles across the human gastrointestinal tract.

Reference 6

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Published in 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant, non-guideline experimental investigation.

Reason / purpose for cross-reference:

reference to same study

Objective of study:

distribution

Principles of method if other than guideline:

Pastures and hay production areas for sheep treated with electrofilter ash from coal power plants were experimentally cultivated and effects on sheep health and breeding were studied. Levels of heavy metals (Pb, Cd, Cu and As) in muscle, liver and kidney, and levels of radionuclides (K-40 and Cs-137) in bones, muscle, lungs and kidney of the sheep were analyzed.

GLP compliance:

no

Radiolabelling:

no

Species:

sheep

Strain:

other: Local Slovenian sheep breed

Sex:

male/female

Route of administration:

other: Via feed (grass), feeding on control pasture and electrofilter ash treated pasture

Duration and frequency of treatment / exposure:

Via feed for 1 or 2 years

Remarks:

Doses / Concentrations:
Grass from control pasture and electrofilter ash treated pasture.

No. of animals per sex per dose / concentration:

Groups of 20 ewes were maintained on pastures for one year after which two ewes from each group were euthanized for analysis. The rest of the ewes were mated and the body weight development of the offspring was monitored for 75 days. At the end of the second year three ewes from each group were euthanized and analyzed.

Control animals:

yes, concurrent vehicle

Positive control reference chemical:

No

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: muscle, liver, kidney, bone
- Time and frequency of sampling: 1 year, 2 years
- Method type(s) for identification (e.g. GC-FID, GC-MS, HPLC-DAD, HPLC-MS-MS, HPLC-UV, Liquid scintillation counting, NMR, TLC): Analyses carried out according to AOAC 1995 (Official methods of analysis of the AOAC, 16th edition, AOAC, Washington, D.C.

Statistics:

No data on methods

Type:

distribution

Results:

All the metal levels (Pb, Cd Cu, As,K-40, Cs-137) were below administrative reference values.

Details on absorption:

Not applicable

Details on distribution in tissues:

Levels of metals (Table 6.) and radionuclides (Table 7.) in tissues of sheep maintained on electrofilter ash treated pasture were mainly lower than those of sheep maintained on control pasture. All the levels were below administrative reference values.

Transfer type:

other: gastrointestinal tract/muscle, liver kidneys

Observation:

no transfer detectable

Details on excretion:

Not applicable

Metabolites identified:

no

Details on metabolites:

Not applicable

Bioaccessibility (or Bioavailability) testing results:

Not applicable.

Conclusions:

Interpretation of results: no bioaccumulation potential based on study results
No elevated concentrations of heavy metals (Pb, Cd, Cu, As),or radionuclides (K-40 or Cs-137) were found in tissues of sheep maintained on electrofilter ash treated pasture.

Executive summary:

Pastures and hay production areas for sheep were experimentally cultivated with electrofilter ash. Potential effects on health and breeding of sheep maintained on these pastures were studied. Ash deposits were spread out in dumping areas in the depth of 2-4 meters followed by several months of watering and compression to stabilize the ground. The second phase included conveying, spreading, compression and preparation of earth deposit at the depth of 0.5 meters, seeding of grass and corresponding one year maintenance to make the pasture suitable for grazing and production of hay for winter nutrition. Experimental and control groups of 10 older ewes and 10 one year old ewes were grazing on the pasture cultivated with electrofilter ash or ordinary pastures in the surrounding area, respectively. Health condition, body weight, hematology, clinical chemistry and reproductive performance were monitored during the study. Animals from each group were slaughtered after one or two years and hematological, clinical chemistry, gross pathological, histopathological and analytical chemistry analyses were carried out. Levels of heavy metals (Table 6.) and radionuclides (Table 7.) in tissues of sheep maintained on electrofilter ash treated pasture were mainly lower than those of sheep maintained on control pasture. All the levels were below administrative reference values. The significant difference was not observed in the health status, the studied parameters or the reproductive performance between the experimental and the control animals.

Reference 7

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant, non-guideline experimental investigation.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Objective of study:

bioaccessibility (or bioavailability)

Principles of method if other than guideline:

The concentrations of inhalable dusts (n = 64); metals Al (n = 32), As (n = 32), Pb (n = 31), Cd (n = 32), Mn (n = 32), Se (n = 31), Be (n = 32), and Th (n = 32); and respirable crystalline silica (n = 15) were measured in workers’ breathing zones and in stationary sampling points during maintenance and ash removal tasks. Exposure via hands was assessed with hand washing tests. Whole-body exposure was assessed with skin collectors in back and chest of the workers. Finally, biomonitoring samples were taken from urine to assess total exposure. These measurements were carried out on the plants including inside and outside boilers with participation of 35 male workers.

GLP compliance:

no

Radiolabelling:

no

Details on exposure:

Workers were exposed to ash and also to other materials and chemicals (originating from activities such as grinding, welding, demolition of walls etc.) during ash removals and various maintenance tasks inside the power plant components.

Details on study design:

Exposure of power plant workers to harmful chemicals of ash was monitored during different work tasks inside the power plant components by chemical analysis of air samples in the working zones, skin patches, hand washings as well as blood and urine samples of workers. Three power plants using mainly coal, but also to some extent sawdust and some other fuels, and their workers were included in the study.

Type:

excretion

Results:

Concentrations of aluminum, manganese, mercury, arsenic and selenium in the urine of exposed workers were all clearly below the reference values.

Type:

absorption

Results:

Only modestly increased lead concentrations in blood. Blood cadmium concentrations (mean 7 nmol/l) were below the reference value for non-exposed persons (18 nmol/l).

Details on absorption:

Only modestly increased lead concentrations in blood. Blood cadmium concentrations (mean 7 nmol/l) were below the reference value for non-exposed persons (18 nmol/l).

Details on distribution in tissues:

Not applicable.

Transfer type:

other: occupational routes of exposure/blood

Observation:

slight transfer

Details on excretion:

Concentrations of aluminum, manganese, mercury, arsenic and selenium in the urine of exposed workers were all clearly below the reference values.

Metabolites identified:

no

Bioaccessibility (or Bioavailability) testing results:

Only modestly increased lead concentrations in blood. Blood cadmium concentrations (mean 7 nmol/l) were below the reference value for non-exposed persons (18 nmol/l).

Although workers used protective gloves metals (arsenic, cadmium, nickel, lead) were detected in their hands. Smaller concentrations of these metals were also detected in whole body samples. Protective clothing protected the body skin more efficiently than gloves.

With regard to total exposures only modestly increased lead concentrations were observed in blood samples of exposed workers. The average blood lead concentration of workers (0.11 μmol/l = 22.8 µg/l) was only slightly higher than the reference value for non-exposed persons (including pregnant women) (0.09 μmol/l = 18.6 µg/l) as set by the Finnish Institute of Occupational Health, and therefore not likely to be associated with adverse health effects. Blood cadmium concentrations (mean 7 nmol/l) were below the reference value for non-exposed persons (18 nmol/l). Similarly, concentrations of aluminum, manganese, mercury, arsenic and selenium in the urine of exposed workers were all clearly below the reference values.

Based on the results the use of powered air respirators with ABEK+P3 cartridges and face masks as the minimum requirement for people who have to work inside coal-fired power plant boilers is recommended. During work tasks outside the boilers, the use of P3-class respirators is recommended. Workers should also use over-the-wrist long protective gloves, and pay more attention to their personal hygiene in order to avoid hand and body exposure to metals. In addition, workers should also properly maintain and clean their personal respirators, mask, gloves and clothes to minimize exposures to chemical agents.

Conclusions:

Interpretation of results: low bioaccumulation potential based on study results
Biomonitoring samples indicated that total exposures to lead, cadmium, aluminum, manganese, mercury, arsenic and selenium were low.

Executive summary:

Exposure of power plant workers to harmful chemicals of ash was monitored during different work tasks (e.g. demolition of walls, washing of boilers and reparation of electric filters) inside the power plant components. Three power plants using mainly coal, but also to some extent sawdust and some other fuels. Biomonitoring samples indicated that total exposures to lead, cadmium, aluminum, manganese, mercury, arsenic and selenium were low.

The use of powered air respirators with ABEK+P3 cartridges and face masks as the minimum requirement for people who have to work inside coal-fired power plant boilers is recommended. During work tasks outside the boilers, the use of P3-class respirators is recommended. Workers should also use over-the-wrist long protective gloves, and pay more attention to their personal hygiene in order to avoid hand and body exposure to metals.

Reference 8

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

supporting study

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant, non-guideline experimental investigation. Study published in scientific, peer reviewed journal.

Reason / purpose for cross-reference:

reference to same study

Objective of study:

excretion

Principles of method if other than guideline:

Analysis of Al, As, Ba, Be, Cd, Co, Cu, Cr, Fe, Mn, Mo, Ni, Pb, Sb, Se, Th, U, and Zn from whole-body and hand-washing samples. Biomonitoring urine samples included Al, Pb, Mn, As, Se, Cd, Be, Th and Hg.

GLP compliance:

no

Radiolabelling:

no

Details on exposure:

Exposure of ash removal workers and maintenance workers to metals (24 male workers with an average age of 37 and standard deviation of 11 years) during their tasks inside the boilers.

Details on study design:

Eight biomass-fired power plants (BMPP) were sampled twice during annual ash removal and maintenance periods.

Nitrile gloves were used during sample preparation. Background concentrations of metals of samplers (oil, wipes, and whole-body dermal patches) were tested. Zero samples were used in every sample series to assess any possible metal contaminations of samples. All the worker samples were collected in “clean” industrial environments (worker restrooms) to avoid any possible metal contamination via airborne dust. The samples were stored and transported to the laboratory in sealed, metal-free (polystyrene) containers.

Workers’ urine biomonitoring: Contamination of urine samples was avoided by proper washing guidance prior sampling. The urine samples were collected in acid washed plastic sample containers before the working week started, after two days without working (Al); immediately after workdays (Pb, Mn, As, Se, Cd, Be, Th); and the following morning before workdays (Hg). ICP-MS was used the urine Pb (n = 23), Mn (n = 24), Cd (n = 23), Hg (n = 14), Be (n = 14), Th (n = 21), and Se (n = 21) analysis. AAS (graphite furnace) was used in urine aluminium (n = 21) analysis, and liquid chromatography, atomic fluorescence detector, and columns (Supelguard Disvovery C18, 2 cm x 4.9 mm, 5um, and Disvovery C18, 15cm x 4.6 mm, 5 um, Supelco) in the urine arsenic (As3+ and As5+) analysis (n = 21). The urinary results of Pb, Mn, Cd, Hg, Be, Th, and As were corrected with the specific gravity of each urine sample measured by refractometer to reduce the variability of the urinary metal results. The urinary results of Al, Pb, Mn, As, and Se were referred to reference values (U-Al= < 0.6 μmol/l; U-Pb = < 1.7 μg/l; U-Mn = < 10 nmol/l; U-As = < 30 μmol/l; and U-Se = < 0.07 mg/g creatinine) of these which are based on statistical (95th percentile) examination of a reference population (Finns who are not exposed to the chemical at work).

Statistics:

Statistical analyses:
- The average concentration and standard deviations of urine lead, lead in the air, lead on hands, and lead in whole body samples
- Squares of Pearson’s correlations coefficient between urine lead, air lead, lead on hands, and whole-bodies were measured and the Pearson’s correlations coefficient.
- The effect of protection from gloves in glove groups of long leather gloves, short leather gloves, and other gloves.
- The effect of protection of coveralls and hoods, coveralls without a hood and open coveralls.
- Average concentrations (±SD) urinary excretions of Al, Cd, Pb, Mn, As, and Se in worker groups who were using respirators (TM = Turbo Mask and FF = disposable filtering half mask) with filters TM3-A2B2E2K2-P; TM3-P and FF-P3; TM2-P and FF-P2; or did not use any respirators.

Type:

excretion

Results:

The workers’ urine metal concentrations exceeded the reference values of non-exposed population in several of the samples.

Details on absorption:

Not applicable.

Details on distribution in tissues:

Not applicable.

Details on excretion:

The workers’ urine metal concentrations exceeded the reference values of non-exposed population in several of the samples (figure 3). The average concentrations varied as follows: 0.2 - 0.6 µmol/l Al, 0.4 - 2.7 µg/l Pb, 6 - 8 nmol/l Mn, 14 - 19 nmol/l As, 0.02 - 0.05 mg/g creatine Se, 2 - 4 nmol/l Cd, 5 - 8 nmol/l Hg, 3 - 4 nmol/l Be, and 0.0001 nmol/l Th.

The effect of personal protection equipment to the metal concentrations was 2.3 - 4.4 times for Pb and 3 times for Al in the urine analyses.

Metabolites identified:

no

Bioaccessibility (or Bioavailability) testing results:

Not applicable.

The measured metal concentrations correlated with the measured concentrations of metals in the workplace air (Jumpponen et. al. 2014). The correlation was found to be best for Pb.

Conclusions:

Interpretation of results: low bioaccumulation potential based on study results
Exposure to metals during ash removal and maintenance was likely in biomass fired power plants without proper personal protection. Exposure to metals was highest in power plants using recycled fuel. The measured metal concentrations correlated with the concentrations of metals in the workplace air. Use of long leather gloves, coverall suit with hood and powered air respirator with TM3-A2B2E2K2-P filter decreased the workers’ exposure.

Executive summary:

Exposure of workers to metals was studied during the maintenance and the ash removal tasks in the annual shut-down of eight biomass-fired power plants. Whole-body samples and hand-washing method were used for dermal exposure assessment, and biomonitoring of metals in urine for total exposure assessment. In recycled fuel-fired power plants, workers’ excretions of Al, Pb, and Mn exceeded the reference values of non-exposed population in 33%, 100%, and 50% of samples, respectively. The fact that the workers’ urinary excretions of metals exceeded the reference values proved intake of metals during these work tasks. Average urine excretions of Al, Cd, Pb, and Se were smallest in workers using respirators with the TM3-A2B2E2K2-P class filters, compared to usage or no usage of other respirators. Average urine excretions of Pb were highest (3.5 μg/l) when respirators were not used, and its concentration exceeded clearly its reference value (U-Pb = < 1.7 μg/l). Biomonitoring of blood Pb would be the most recommendable way to assess the total Pb exposure of workers, because it has lower contamination risk and lower background variation then urine Pb. It is recommended that biomass-fired power plant workers, especially those who work inside the power plant boilers or superheaters, should routinely use powered air respirators with TM3-A2B2E2K2-P cartridges, and hooded one-piece coveralls and over-wrist long leather protective gloves.

Reference 9

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Study period 10 Dec 1950 - 14 Apr 1954 (main study 3 years for 6 cows followed by an off-dose period of 4 months for 3 cows)

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Doctoral dissertation. Scientific publication with well-documented data.

Reason / purpose for cross-reference:

reference to same study

Objective of study:

bioaccessibility (or bioavailability)

Principles of method if other than guideline:

Fertility study in grazing cows.

GLP compliance:

no

Radiolabelling:

no

Species:

cattle

Strain:

other: Schwarzbunte Niederungsrasse

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Oldenburg, Germany (a region without no known fly ash residues from coal combustion)
- Age at study initiation: 2.75 - 6.75 years
- Weight at study initiation: 535 - 710 kg
- Housing: Cattle pen and grazinge
- Diet (e.g. ad libitum): fodder root vegetables, hay and straw (ad libitum) supplemented with mash and fortified fodder.
At arrival a careful clinical examination was carried out for all animals. All animals were in good nutritional state and showed no symptoms of illness.

ENVIRONMENTAL CONDITIONS
All animals were kept on farm without contact to other cattle.
The cattle pen was kept clean, dry and ventilated with fresh air.

IN-LIFE DATES:
Exposure period: From: 10 Dec 1950 To: 15 Dec 1953
Off-dose observation period: From: 16 Dec 1953 To: 14 Apr 1954

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Remarks:

(Test material mixed with feed.)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The test substance was mixed with the feed.
Animals were fed twice a day using individual boxes to assure the complete intake of the individual portions.

DIET PREPARATION
In the high dose group, the fly ash was mixed with soaked fodder beed and mash, to improve the taste and to ascertain the daily intake of the high amounts of fly ash. On pasture the fly ash was mixed with grass cuts.

Duration and frequency of treatment / exposure:

Exposure period: 3 years
Frequency of treatment: Twice a day

Remarks:

Doses / Concentrations:
300 g / animal / day (about 0.43 g/kg bw/day [assuming an average body weight of 700 kg])
Basis nominal conc. (fed to the animals of group 1 and group 2)
1500 - 1800 g / animal / day (about 2.1-2.6 g/kg bw/day)
Basis nominal conc. (fed to the animals of group 3)
Basis nominal conc. (resulting from calculated amounts of coal fly ash precipitation to the grazing land in the experimental geographic area and the daily intake of the grazing test animals.)

No. of animals per sex per dose / concentration:

9 cows were divided into 3 groups (3 animals/group):
Group 1 (animal # 1-3): served as concurrent no treatment control animals during the first two years and received 300 g fly ash/day/animal (about 0.43 g/kg bw/day) during the 3rd year of the experiment
Group 2 (animal # 4-6): 300 g fly ash/day/animal (about 0.43g/kg bw/day) during the first and second year of the experiment, during the 3rd year no treatment.
Group 3 (animal # 7-9): 1500 - 1800 g fly ash/day/animal (about 2.1-2.6 g/kg bw/day) during all 3 years of the experiment

Control animals:

other: yes, concurrent no treatment (for the first two years of the exposure period)

Positive control reference chemical:

No

Details on study design:

From milk and blood samples, dry residue, ash, Mg, CaO and P2O5 were analysed.
pH, Glucose, Protein, Dry residue, CaO, MgO and P2O5 were analysed from urine samples.
Liver and bone samples of all animals were analysed for concentrations of arsenic, manganese, lead, iron, copper, zinc and cobalt. Bones were also analysed for CaO and P2O5.
All the analyses were performed for the following groups: controls, 300 g fly ash / day /animal, and 1500 - 1800 g fly ash / day /animal (n = 3).

Details on dosing and sampling:

Milk, blood, urine and faeces samples for chemical analyses were taken on December 10th, 1952.
Trace element (arsenic, manganese, lead, iron, copper, zinc and cobalt) analysis of liver and bone samples were performed at the end of the experiment.

Statistics:

not applicable (n=3)

Type:

absorption

Results:

Low gastrointestinal absorption potential.

Type:

excretion

Results:

Dose-dependent increase in concentrations of Ash, SiO2, Al2O3, Fe2O3, MgO, CaO, SO3, P2O5 in faeces representing unabsorbed constituents of CFA. After two years no changes in chemical parameters in milk or urine were found.

Type:

other: bioaccessibility

Results:

No increase in concentrations of constituents of CFA in blood, bones or liver.

Details on excretion:

Dose-dependent increase in concentrations of Ash, SiO2, Al2O3, Fe2O3, MgO, CaO, SO3, P2O5 in faeces reflects the unabsorbed constituents of fly ash and suggests low gastrointestinal absorption potential of these constituents of fly ash. After two years no changes in chemical parameters in milk or urine were found.

Metabolites identified:

not specified

Bioaccessibility (or Bioavailability) testing results:

Oral administration of coal fly ash did not affect the concentrations of arsenic, manganese, lead, iron, copper, zinc and cobalt in liver or bones nor the concentrations of CaO and P2O5 in bones.

Table 1 Chemical analysis on coal combustion fly ash (Scholven)

Component	Laboratory A (51 samples)		Laboratory B*	Laboratory C*
	Mean (%)	Range (%)	(%)	(%)
Ignition loss	10.01	3.89-20.60	11,76	8.93
SiO2	41.59	36.41-47.39	44.7	38.5
Al2O3	21.72	14.04-31.50	20.6	20.0
Fe2O3	14.25	6.33-21.96	9.47	14.9
MgO	2.67	0.93-4.12	2.49	2.3
CaO	4.84	2.47-10.03	6.72	5.3
SO3	1.19	0.46-2.82	0.64	1.0
P2O5	0.53	0.12-1.31	0.18	0.51
CuO	0.0075*	-	0.0069	0.0085
ZnO	-	-	0.0078	0.040
PbO	0.0011*	-	<0.0009	0.0014
MnO	-	-	-	0.15
CoO	-	-	-	0.0011
F	-	-	-	0.008
B2O3	-	-	-	0.0021
As2O3	0.0012*	-	0.0012	0.0013
Sulphite S	-	-	0.0012	-

*only 1 sample analysed

Table 2 Analysis of milk samples collected at the end of the second year.Mean values (%) determined by two different laboratories.

Animal number	Treatment group	Dry residue	Ash	CaO	Mg	P2O5
1	control	12.9	0.74	0.172	0.0144	0.212
2	control	15.8	0.89	0.267	0.0222	0.276
3	control	10.3	0.71	0.136	0.0155	0.185
4	300 g fly ash / day /animal	11.2	0.78	0.173	0.0170	0.235
5	300 g fly ash / day /animal	14.7	0.82	0.197	0.0194	0.299
6	300 g fly ash / day /animal	14.1	0.71	0.152	0.0204	0.159
7	1500 - 1800 g fly ash / day /animal	15.3	0.69	0.161	0.0161	0.220
8	1500 - 1800 g fly ash / day /animal	14.1	0.73	0.155	0.0144	0.213
9	1500 - 1800 g fly ash/ day /animal	10.3	0.73	0.151	0.0153	0.224

 

Table 3 Analysis of blood samples collected at the end of the second year.Mean values (%) determined by two different laboratories.

Animal number	Treatment group	Dry residue	Ash	CaO	MgO	P2O5	Fe2O3
1	control	19.2	1.37	0.0127	0.0058	0.0374	0.0534
2	control	19.9	1.03	0.0110	0.0060	0.0380	0.0544
3	control	18.7	1.15	0.0116	0.0061	0.0371	0.0435
4	300 g fly ash / day /animal	19.5	1.22	0.0133	0.0062	0.0396	0.0502
5	300 g fly ash / day /animal	19.2	1.36	0.0094	0.0077	0.0333	0.0572
6	300 g fly ash / day /animal	19.6	1.13	0.0101	0.0068	0.0350	0.0430
7	1500 - 1800 g fly ash / day /animal	20.3	1.16	0.0105	0.0071	0.0359	0.0480
8	1500 - 1800 g fly ash / day /animal	18.3	0.98	0.0112	0.0062	0.0362	0.0489
9	1500 - 1800 g fly ash / day /animal	19.3	1.12	0.0116	0.0077	0.0345	0.0547

 

Table 4 Analysis of urine samples collected at the end of the second year.Mean values (%) determined by two different laboratories.

 

Animal number	Treatment group	pH	Glucose	Protein	Dry residue	CaO	MgO^a	P2O5
1	control	8.14	neg.	neg.	6.84	0.0055	0.0170	0.0027
2	control	8.20	neg.	neg.	5.18	0.0018	0.0221	0.0024
3	control	8.18	neg.	neg.	5.41	0.0011	0.0261	0.0016
4	300 g fly ash / day /animal	8.36	neg.	neg.	5.33	0.0066	0.0090	0.0013
5	300 g fly ash / day /animal	8.26	neg.	neg.	4.53	0.00097	0.0080	0.0014
6	300 g fly ash / day /animal	8.34	neg.	neg.	5.11	0.0043	0.0302	0.0031
7	1500 - 1800 g fly ash / day /animal	8.08	neg.	neg.	3.85	0.0084	0.0100	0.0013
8	1500 - 1800 g fly ash / day /animal	8.40	neg.	neg.	6.33	0.0041	0.0357	0.0022
9	1500 - 1800 g fly ash / day /animal	8.38	neg.	neg.	5.80	0.0233	0.0411	0.0025

^aMgO was only analysed only by one laboratorium

 

Table 5 Analysis of faeces collected at the end of the second year.Mean values (% of fresh weight) determined by two different laboratories.

 

Animal number	Treatment group	Ash	SiO2	Al2O3	Fe2O3	MgO^a	CaO	SO3	P2O5
1	control	2.77	1.51	0.119	0.066	0.118	0.270	0.057	0.183
2	control	2.23	1.11	0.086	0.054	0.150	0.250	0.044	0.164
3	control	2.28	1.13	0.091	0.062	0.111	0.259	0.052	0.167
4	300 g fly ash / day /animal	2.68	1.32	0.296	0.142	0.131	0.255	0.054	0.190
5	300 g fly ash / day /animal	2.36	1.17	0.240	0.148	0.111	0.240	0.054	0.170
6	300 g fly ash / day /animal	2.98	1.55	0.431	0.201	0.131	0.350	0.077	0.270
7	1500 - 1800 g fly ash / day /animal	4.81	2.49	0.716	0.615	0.286	0.372	0.107	0.182
8	1500 - 1800 g fly ash / day /animal	6.21	2.84	0.827	0.643	0.352	0.477	0.135	0.246
9	1500 - 1800 g fly ash / day /animal	4.76	2.31	0.644	0.506	0.288	0.492	0.105	0.208

^aMgO was analysed only by one laboratory

 

Conclusions:

Interpretation of results: no bioaccumulation potential based on study results
Chemical analyses showed low oral bioavailability of the analysed constituents of coal fly ash. Oral administration of coal fly ash did not affect the concentrations of arsenic, manganese, lead, iron, copper, zinc and cobalt in liver or bones nor the concentrations of CaO and P2O5 in bones. Dose-dependent increase in concentrations of Ash, SiO2, Al2O3, Fe2O3, MgO, CaO, SO3, P2O5 in faeces reflects the unabsorbed constituents of fly ash and suggests low gastrointestinal absorption potential of these constituents of fly ash.

Executive summary:

Groups of 3 milking cows were exposed daily to coal fly ash mixed with fodder at 0, 300 or 1500-1800 g/day (equivalent with about 0, 430 or 2100-2600 mg/kg bw/day) for 3 years in a non-GLP study. (After 2 years the control group and the low dose group were switched.) Chemical analyses of milk, excreta and tissues were performed. After two years no changes in chemical parameters in milk, blood, urine, liver or bone were found. Instead, oral administration of fly ash for 2 years dose-dependently affected the analysed variables of faeces. Dose-dependent increase in concentrations of the analysed variables reflects the unabsorbed constituents of fly ash and suggests low gastrointestinal absorption potential of these constituents of fly ash. As a conclusion, chemical analyses showed low oral bioavailability of As, Mn, Pb, Fe, Cu, Zn and Co from fly coal ash.

Description of key information

Leaching and dissolution studies with Ash indicated low leachability of metals from Ash. In accordance with these findings toxicokinetic data indicate that even at high doses the systemic exposure to metals Pb, Cd, and Cr from Ash or to Al from CFA is negligible and clearly below levels causing toxic effects. Also biomonitoring of power plant workers during ash removal and maintenance tasks indicated low systemic bioavailability of metals.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Additional information

Leaching and dissolution studies carried out in vitro can be used to estimate the theoretically bioavailable fraction of potentially harmful substances of Ash by measuring their extractability to different solvents (Välimäki I. (2010), Water solubility.leaching test.002). When homogenized Ash was leached in the two phase extraction with ultraclean water for 6 + 8 h barium was the most leachable metal (11.5% of the concentration present in Ash was leached into the cumulative eluate). The other metals leached only to a minor extent as follows: selenium 3.53%, molybdenum 2.04%, lead 0.36% and zinc 0.03%. Concentrations of cadmium, cobalt, chromium, copper, mercury, nickel, antimony, tin and vanadium in the eluate were below the quantitation limits. Of these compounds selenium, molybdenum, zink, cobalt, chromium3+, copper, nickel and to some extent vanadium are essential trace elements and normally present in the body (Tokar et al., 2013). They are present in Ash at so low concentrations that they are unlikely to have toxicological significance. Barium is a relatively abundant alkaline earth metal that is commonly found in plants and animal tissues, and even at high amounts in some foods, such as Brazil nuts, pecans and seafood. The amounts of barium from these sources do not usually cause health concern, and occupational exposure primarily occurs during mining and manufacturing activities (Tokar et al., 2013). Also the concentrations and leachability of mercury, antimony and tin are so low that they are not considered toxicologically relevant.

In the extraction test for of ammonium acetate soluble elements the most soluble metal was calcium followed by magnesium, silicon, potassium, sodium, aluminum, phosphorus and iron (Välimäki I. (2010), Water solubility.acetate extraction.003). The best extracted trace metals were zinc and copper while lead, nickel, arsenic and cadmium were less extracted.

The observed low leachability of metals from Ash is also in agreement with results of the dissolution studies of Twinings et al. (2005, Basic toxicokinetics.005), which indicated that only a proportion of total metal concentrations in fly ash a was soluble and thus bioavailable in simulated human lung and gut fluids. Furthermore, with regard to the regulatory limits for inhalation of particulates, none of the metal concentrations measured were as hazardous as the fly ash particulates themselves. Overall, the metals were more soluble to the simulated gut fluid than to the simulated lung fluid. Similarly, Manskinen et al. (2012, Basic toxicokinetics.006) reported that heavy metals were more extractable to the artificial gastric fluid that to the artificial sweat. These data suggest that oral exposure to ash is likely to result in higher systemic exposure than inhalation or dermal exposure. Accordingly, observations of Matsuno et al. (1986, Basic toxicokinetics.002) suggested low bioavailability of metals after inhalation of CFA. They studied deposition of CFA after inhalation exposure for 28 days by determining aluminum levels in different organs, and found increased levels only in lungs, but not in liver, kidney, spleen or blood.

In accordance with the outcome of leaching and dissolution studies the toxicokinetic analyses carried out during the 28-day oral toxicity study indicate very low or negligible oral bioavailability of potentially toxic metals from Ash. Of the selected indicator heavy metals of Ash (Pb, Cd, Cr) only Pb showed modest accumulation in terms of slightly increased blood concentration during the course of the 28-day oral toxicity study even after exceptionally high daily doses of Ash (up to 2000 mg/kg bw/day; limit dose for repeated dose toxicity studies is 1000 mg/kg bw/day!). Blood Pb concentrations did not reach toxic levels. At the highest dose level of 2000 mg/kg bw/day (equivalent with 0.36 mg Pb/kg bw/day) the blood lead concentrations were only 5-13 µg/l on day 28 of the study. These concentrations are almost an order of magnitude lower than the lowest blood levels in humans associated with the well-characterized adverse effects of lead (Goyer, 1996; Bellinger, 2005), and well below the reference value for non-exposed persons, including pregnant women (18.6 µg/l). Dosing of Ash did not affect the blood Cd levels at all and they did not increase in the course of the study. The values ranged from below the detection limit (0.008 µg/l) to 0.337 µg/l. These levels are also well below the reference limits for non-exposed humans (0.562 µg/l [5 nmol/l] for non-smokers and 2.023 µg/l [18 nmol/l] for smokers) (Finnish Institute of Occupational Health, 2015). For Cr there was a weak trend for dependence of blood concentration on dose at the end of the study only, but no accumulation. At 2000 mg/kg/day the blood Cr concentrations on day 28 of the study were 0.9-1.41 µg/l, and the highest measured Cr concentration during the study was 2.25µg/l. According to the Agency for Toxic Substances and Disease Registry (ATSDR, 2015) the normal blood chromium concentrations are 20-30 µg/l. The results imply that the oral bioavailability of Pb, Cd and Cr from Ash is very low and that it is not possible to administer Ash to rats at so high doses that blood concentrations of these metals would reach toxic levels. The measured blood concentrations also reflected the outcome of the leaching test, which indicated that only 0.36% of Pb in Ash was dissolved in the cumulative eluate, and that leached concentrations of both Cd and Cr were below the quantitation limit (<0.42% and < 0.16%, respectively) (Välimäki I. (2010), Water solubility.leaching test.002).

Two supporting studies also suggest negligible oral bioavailability of potentially toxic metals from Ash. Concentrations of Pb, Cd, Cu and As in muscle, liver and kidney of sheep maintained for one year on pastures treated with electrofilter ash from coal power plants were not increased (Pestevsek et al., 2000: Toxicity to reproduction.001). Similarly, concentrations of As, Mn, Pb, Fe, Cu, Zn or Co in liver or bone of milking cows were not increased after oral exposure to coal fly ash at doses up to about 2100 mg/kg bw/day for 2 years (Herrmann, 1955: Toxicity to reproduction.009).

Inhalation exposure of rats to CFA at the concentration of 10.4 mg/m3 for 7 h per day, 5 days per week for one month indicated that the systemic bioavailability of aluminum from CFA is very low (Matsuno et al., 1986: Basic toxicokinetics.002). Samples were analysed at the end of the exposure period and after recovery of 6 or 10 months, and elevated aluminum concentrations were observed only in lungs, but not in liver, kidneys, spleen or blood.

Overall, the toxicokinetic data indicate that the systemic exposure to metals Pb, Cd, and Cr from Ash or to Al from CFA is negligible and clearly below levels causing toxic effects. The results also imply that it is not possible to administer Ash to rats at so high doses that the blood concentrations of these metals would reach toxic levels.

Biomonitoring studies on exposure of power plant workers to harmful chemicals of ash during ash removal and maintenance tasks indicated also low systemic bioavailability (Jumpponen M. et al., 2014: Basic toxicokinetics.008). Modestly increased Pb concentrations were observed in blood samples of exposed workers. The average blood Pb concentration of workers (0.11 μmol/l = 22.8 µg/l) was only slightly higher than the reference value for non-exposed persons (including pregnant women) (0.09 μmol/l = 18.6 µg/l), and therefore not likely to be associated with adverse health effects. Blood cadmium concentrations (7.0 nmol/l = 0.787 µg/l) were below the reference value for non-exposed persons (18 nmol/l = 2.023 µg/l). Similarly, concentrations of aluminum, manganese, mercury, arsenic and selenium in urine of the exposed workers were all below the reference values for non-exposed persons.

Biomonitoring of ash removal and maintenance workers from power plants using different types of biomass fuel (pellet, peat, wood or recycled fuel) who variably used personal protection equipment (ranging from no respirator at all to respirators with efficient filters and variable degree of protective clothing) revealed increased urinary excretion of Pb, Mn and As above the reference values of non-exposed population (Finnish Institute of Occupational Health, 2015) in 17%, 33% and 50% of the workers (Jumpponen et al., 2015: Basic toxicokinetics.009). However, the median excretions did not exceed the reference values. The highest excretions were in workers of recycled fuel-fired power plants. As expected, the proper use of respirators and protective gloves and clothes decreased the exposure of workers.

REFERENCES

Agency for Toxic Substances and Disease Registry (ATSDR) 2015. Environmental Health and Medicine Education. Chromium Toxicity. Clinical Assessment – Laboratory Tests.http://www.atsdr.cdc.gov/csem/csem.asp?csem=10&po=12(accessed Aug. 9, 2015)

Bellinger DC. Teratogen update: lead and pregnancy. Birth Defects Res A Clin Mol Teratol. 2005; 73(6):409-20.

Finnish Institute of Occupational Health (2015). Biomonitoring of exposure to chemicals. Guideline for specimen collection. 44 p.http://www.ttl.fi/en/work_environment/biomonitoring/Documents/BM-Guideline.pdf(accessed Oct. 12, 2015).

Goyer RA. Results of lead research: prenatal exposure and neurological consequences. Environ Health Perspect. 1996; 104(10):1050-4.

Tokar E.J., Boyd W.A., Freedman J.H., Waalkes M.P. Toxic effects of metals. In: Klaassen C.D. (ed.) Casarett & Doull’s Toxicology. The Basic Science of Poisons. 8thedition. 2013. McGraw Hill Education.