Fatty acids, tallow, zinc salts

Endpoint summary

Description of key information

Hazard assessment is conducted by means of read-across from surrogates.

Oral:

NOAEL (OECD 408, rat): 13.3 mg Zn/kg bw/day (RA from CAS 7440-66-6)

NOAEL (OECD 408, rat): 53.5 mg Zn/kg bw/day (RA from CAS 7733-02-0)

NOAEL (OECD 408, mouse): 104 mg Zn/kg bw/day (RA from CAS 7733-02-0)

Inhalation

NOAEL (guinea pig, 5d): 2.2 mg Zn/m³ (RA from CAS 1314-13-2, ultra fine)

Human data:

The oral NOAEL of 0.83 mg Zn/kg bw/day (recalculated from the NOAEL of 50 mg Zn/day for a 60 kg human being) was used as the starting point for deriving DNELs for worker and general population. NOAELs for zinc exposure via the dermal or inhalatory route were estimated by taking into account the bioavailability of zinc via the different exposure routes (for details see the Chemical Safety Assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 in the technical Dossier (see IUCLID section 13)). By molecular weight correction, these data are read across to Fatty acids, tallow, zinc salts.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

8.3 mg/kg bw/day

Study duration:

chronic

Species:

other: human

Quality of whole database:

The available information comprises adequate, reliable and consistent studies from surrogate substances with similar intrinsic properties. Read-across is justified based on common physiological active moieties (refer to endpoint discussion for further details). The studies are sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.6, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.

Justification for data waiving:

other:

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Deviations:

not applicable

Principles of method if other than guideline:

Guinea pigs were exposed by nose-only exposure at 3h/d for 6 d to ZnO ultrafine particles and examined at 24, 48 and 72 h postexposure for functional and morphological changes in the lungs.

GLP compliance:

no

Limit test:

no

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Wilmington, Mass.)
- Weight at study initiation: 260 -300 g
- Housing: Four animals per suspended stainless-steel cage
- Diet : Feed (Agway, Syracuse, N.Y.), ad libitum
- Water: Distilled water, ad libitum
- Acclimation period: Five days


ENVIRONMENTAL CONDITIONS
- Temperature: 23 °C
- Humidity: 50 %

Route of administration:

inhalation

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Mean particle size expressed as projected area diameter = 0.05 µm, sg 2.0.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Rectangular stainless-steel chamber with a trapezoidal plenum consisted of three chambers- inlet, exposure and exhaust chambers.
- Method of holding animals in test chamber: Plexiglass animal holders
- System of generating particulates/aerosols: Zinc turnings were heated to 480 °C in a crucible and the zinc vapours were carried by argon gas flow. The vapours react with oxygen to yield ultrafine particles upon condensation.
- Temperature, humidity, pressure in air chamber: Temperature = 25 - 28 °C, humidity = 43-49 %
- Method of particle size determination: Piezoelectric crystal, TSI model 3030

TEST ATMOSPHERE
- Brief description of analytical method used: ZnO concentrations were determined by total aerosol collection on Millipore GSWP 47-mm filters. Gravimetric analysis was done on a Cahn electrobalance Model 21. Chemical analysis consisted of atomic absorption spectrometry and electron spectroscopy for chemical analysis.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Atomic absorption spectrometry and electron spectroscopy

Duration of treatment / exposure:

6 d

Frequency of treatment:

3 h/d

Remarks:

Doses / Concentrations:
4.6 ± 2.7 mg/m3
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
5.3 ± 2.9 mg/m3
Basis:
analytical conc.

No. of animals per sex per dose:

38 (for 4.6 ± 2.7 mg/m3 exposure),
35 (for 5.3 ± 2.9 mg/m3 exposure)
18 & 35 (control)

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: Based on the recommended threshold limit value (TLV).

Positive control:

None

Observations and examinations performed and frequency:

BODY WEIGHT: Yes


OTHER: Physiological measurements - Measurements were done at 1, 24, 48, or 72 h after the end of sixth exposure for the treated animals and at 1 and 48 h postexposure for control animals. The following pulmonary function parameters were measured in the anesthesised, tracheostomised animals: ventilation, dynamic compliance, flow resistance, vital capacity, inspiratory capacity, total lung capacity and single breath diffusing capacity for carbon monoxide.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, lungs of exposed animals were examined.
HISTOPATHOLOGY: Yes, lungs of exposed animals were examined for microscopic lesions.

Other examinations:

Epithelial permeability: Permeability of the lower respiratory epithelium to macromolecules was assessed in five animals at 1 and 24 h after exposure. Results were expressed as the concentration of horseradish peroxidase in plasma 30 min after instillation.

Morphologic examination: Five animals were sacrificed at 1, 24, 48, or 72 h after exposure for morphologic examination of the respiratory tract under transmission electron microscope.

DNA synthesis: In epithelial cells of the bronchi and terminal bronchioles, DNA synthesis was studied by calculating the [3H]thymidine labelling index of the cells on autoradiographs. Minimum 1000 nuclei were examined and labelling index was expressed as the no. of labelled nuclei per 1000 nuclei examined.

Statistics:

Statistical analysis was done by analysis of variance and additional comparisons were done by the method of Scheffe.

Clinical signs:

not examined

Mortality:

not examined

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

BODY WEIGHT AND WEIGHT GAIN: No significant difference was observed in body weight between treated and control animals.


ORGAN WEIGHTS: Elevated lung weights due to inflammation were observed and were not returned to normal by 72 h.


GROSS PATHOLOGY: The lungs of treated animals appeared normal, but some failed to collapse when the chest was opened.


HISTOPATHOLOGY: NON-NEOPLASTIC: Inflammation of the proximal portion of the alveolar ducts and adjacent alveoli was observed. The lesions were characterised by interstitial thickening, increased pulmonary macrophages and neutrophils in adjacent airspaces and alveolar squamous epithelium was replaced with cuboidal cells (type 2 pneumocytes).

OTHER FINDINGS: Physiological measurements - Vital capacity, functional residual capacity, alveolar volume and single breath diffusing capacity for carbon monoxide were decreased and did not return to normal values by 72 h. Increase in flow resistance, decrease in compliance and total lung capacity were returned to normal values by 72 h.
Epithelial permeability - No significant effect was observed in the epithelial permeability to horseradish peroxidase.
DNA synthesis - [3H]Thymidine labelling of bronchiolar epithelial cell nuclei was increased for 48 h.

Dose descriptor:

conc. level:

Effect level:

ca. 4.6 mg/m³ air (analytical)

Sex:

male

Basis for effect level:

other: Decreased Vital capacity, functional residual capacity, alveolar volume and single breath diffusing capacity for carbon monoxide and elevated lung weights due to inflammation

Critical effects observed:

not specified

Table 2: Ventilation and lung mechanics

Time post exposure (h)	Control	ZnO
	1 and 48	1	24	48	72
No. of animals	18	8	9	9	8
Body weight (g)	288 ± 8	292 ± 8	294 ± 9	294 ± 11	294 ± 13
Respiratory frequency (breaths/min)	67 ± 8	63 ± 8	66 ± 11	65 ± 9	56 ± 5*
Tidal volume (mL)	1.7 ± 0.1	1.8 ± 0.1	1.8 ± 0.2	1.8 ± 0.2	1.8 ± 0.2
Flow resistance (cm H2O/mL/sec)	0.31 ± 0.08	0.50 ± 0.13*	0.41 ± 0.10*	0.30 ± 0.07	0.34 ± 0.09
Compliance (mL/cm H2O)	0.28 ± 0.06	0.20 ± 0.09*	0.20 ± 0.06*	0.22 ± 0.05*	0.25 ± 0.08

Note: Values are mean ± SD. All values were from anesthesised, tracheostomatised spontaneously breathing Guinea pigs.

* p < 0.05.

Table 3: Alveolar duct inflammation in Guinea Pigs exposed six times to 5.3 mg/m3 of ultrafine ZnO

Hours following sixth exposure	Exposure
	Control gases	ZnO
1	0/5	5/5
24	0/5	4/4
48	0/5	3/5
72	0/5	3/5

Conclusions:

Under the test conditions, vital capacity, functional residual capacity, alveolar volume and single breath diffusing capacity for carbon monoxide were decreased and did not return to normal values by 72 h.

Executive summary:

A study was conducted in guinea pigs to evaluate the potential of ultrafine zinc oxide particles for changes in the functional and morphological changes in the lungs.

Male Hartley Guinea pigs were used in the study. Exposure was given by nose only for 3 h/d for 6 d. Dose selection was based on the recommended threshold limit value (TLV). 38 animals were exposed to 4.6 ± 2.7 mg/m³ ZnO concentration and evaluated for pulmonary function tests at 1, 24, 48 and 72 h postexposure. 35 animals were exposed to 5.3 ± 2.9 mg/m³ ZnO concentration and evaluated for morphology of respiratory tract, lower respiratory epithelial permeability to macromolecules and DNA synthesis in the epithelial cells of bronchi and terminal bronchioles. Statistical analysis was done by analysis of variance and additional comparisons were done by the method of Scheffe.  

Increase in flow resistance, decrease in compliance and total lung capacity were returned to normal values by 72 h. [3H]Thymidine labelling of bronchiolar epithelial cell nuclei was increased for 48 h. Inflammation of the proximal portion of the alveolar ducts and adjacent alveoli was observed. Elevated lung weights due to inflammation were observed and were not returned to normal by 72 h.  

Under the test conditions, vital capacity, functional residual capacity, alveolar volume and single breath diffusing capacity for carbon monoxide were decreased and did not return to normal values by 72 h.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

22 mg/m³

Study duration:

subacute

Species:

guinea pig

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from surrogate substances. Read-across is justified based on common physiological active moieties (refer to endpoint discussion for further details).

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: inhalation

Remarks:

other: 5 d repeated exposure study

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.

Justification for data waiving:

other:

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Guinea pigs were exposed by nose only 3h/d for 5 d to ZnO ultrafine particles and examined after 1, 2, 3, 4 and 5 d post-exposure for functional changes and extent of damage in the lungs.

GLP compliance:

not specified

Limit test:

no

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Wilmington, Mass
- Weight at study initiation: 240-300 g
- Housing: Animals were housed 4/cage
- Diet: Ad libitum, Charles River Guinea Pig Formula
- Water: Ad libitum
- Maintenance: According to guidelines of Division of Comparative Medicine at MIT, which is accredited by the American Association for Accreditation of Laboratory Animal Care (AALAC)
- Others: Observed in quarantine for 5 d for any externally detectable evidence of pulmonary disease before exposure to test material


ENVIRONMENTAL CONDITIONS
- Temperature: 23 °C
- Humidity: 30-50 %

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: no data

Remarks on MMAD:

MMAD / GSD: 0.05 µm/2.0

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Dynamic animal exposure chamber
- System of generating particulates/aerosols: Zinc turnings were heated at 480 °C in a crucible, and the zinc vapours were carried by a flow of argon gas to be contacted by purified air downstream in the furnace. The vapours react with oxygen to yield ultrafine zinc oxide particles upon condensation.
- Method of particle size determination: Test material aerosol was collected on pre-coated carbon grids using Thermosystem Model 3100 electrostatic precipitator and examined (400 to 600 particles) and photographed in a Philips 300 electron microscope
- Particle size distribution: Piezoelectric crystal TSI Model 3030


TEST ATMOSPHERE
- Analytical method used: Test material concentration was determined using Millipore GSWQ 47 mm filters for total aerosol collection and weighing of the filters on a Cahn electrobalance Model 21. Chemical analysis consisted of Atomic absorption spectrometry and electron spectroscopy used for chemical analysis (ESCA)
- Samples taken from breathing zone: Yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Measured by aerosol collection on Millipore GSWQ 47 mm filters, followed by weighing on a Cahn electrobalance Model 21

Duration of treatment / exposure:

3 h/d for 5 d

Frequency of treatment:

Daily

Remarks:

Doses / Concentrations:
Experiment I: 7 mg/m3 (For details see Table 1 under 'Any other information on materials and methods incl. tables')
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
Experiment II: 2.7 mg/m3 (For details see Table 1 under 'Any other information on materials and methods incl. tables')
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
Experiment III: Single high-peak exposure at 34 mg/m3 , and terminated exposure (For details see Table 1 under 'Any other information on materials and methods incl. tables')
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
Experiment IV: Single high-peak exposure: 25 mg/m3 and continuing exposure at: 4-8 mg/m3 (For details see Table 1 under 'Any other information on materials and methods incl. tables')
Basis:
analytical conc.

No. of animals per sex per dose:

5-8 animals in each experiment (For details on number of animals in each experiment - see Table 1 under 'Any other information on materials and methods incl. tables')

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: Based on the previous acute exposure study at 8 mg/m3 for 3 h and repeated dose study for 3h/d, 6 d exposure at 5 mg/m3: the following doses were selected: (a) 7 mg/m3 for 5 d : to address the time course of alterations of pulmonary function, (b) 2.7 mg/m3 for 5 d: to determine effects at lower concentration and (c) Two peak experiments (25-34 mg/m3): to address the effects of occasional peak exposure of test material during chronic low-level exposures

Positive control:

None

Observations and examinations performed and frequency:

OTHER: PULMONARY FUNCTION MEASUREMENT
- Number of animals: 5-8 animals
- Time schedule for examination: After 1, 2, 3, 4 and 5 exposure periods (3 h)
- Anesthetic used for examination: Yes (ketamine hydrochloride and xylazine - 100 mg/kg 1M and 15 mg/kg 1M, respectively)
- Pulmonary function parameters checked: ventilation, dynamic compliance, flow resistance, vital capacity (VC) and inspiratory capacity (IC), total lung capacity (TLC), Functional residual capacity (FRC) and residual volume (RV), single-breath diffusing capacity for carbon monoxide (CO) ( DLco) and apparent alveolar volume (VA)

Sacrifice and pathology:

None

Other examinations:

LUNG WEIGHT:
- Time schedule for examinations: After the last functional measurement
- Brief description of method: The chest was opened and the lungs were removed after exsanguination of animals. The heart and mediastinal tissues were dissected to measure the wet-lung weight. Dry-lung weight recording were obtained by drying the lungs at 45 °C for 48 h, followed by keeping in desiccator for 24 h.

Statistics:

Analysis of variance (ANOVA) was used to compare the means of variables across all exposure groups with the pooled control data. Significant differences (p = 0.05) among group means were analysed for group differences by applying Dunnett's multiple range test. Correlations between variables were computed using StatView 512+©

Clinical signs:

not examined

Mortality:

not examined

Body weight and weight changes:

not examined

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Details on results:

ORGAN WEIGHTS: Extent of pulmonary damage was measured by:

- Wet-lung weight/Body weight ratio: (see Figure 6 )
(a) Experiment I (7 mg/m3): Ratio increased about 10 % on Day 2 and 29 % by Day 5
(b) Experiment II (2.7 mg/m3): No significant increase
(c) Experiment III (single high-peak exposure (34 mg/m3) with terminated exposure: Ratio increased 30 %, 49 %, 45 % and 19 % on Days 2-5 respectively
(d) Experiment IV (single high-peak exposure (25 mg/m3) with continued exposure at 4-8 mg/m3: No change on day of peak (Day 1), but increased about 45 %, 50 % -60 % on Days 2 and 3-5 respectively

- Wet-lung weight/Dry-lung weight ratio: (see Figure 6)
(a) Experiment I (7 mg/m3): Increased significantly only on Day 4
(b) Experiment II (2.7 mg/m3): No significant increase
(c) Experiment III (single high-peak exposure (34 mg/m3) with terminated exposure: Ratio increased 8 % on Day 2-4 and then decreased on Day 5
(d) Experiment IV (single high-peak exposure (25 mg/m3) with continued exposure at 4-8 mg/m3: Ratio increased by 10 % on Day 2 and remained constant till Day 5


OTHER FINDINGS: PULMONARY FUNCTION MEASUREMENT

- Tidal volume, respiratory frequency, airway resistance or compliance:
(a) Experiment I (7 mg/m3): No alterations
(c) Experiment III (single high-peak exposure (34 mg/m3) with terminated exposure and (d) Experimnet IV (single high-peak exposure (25 mg/m3)(with continued exposure at 4-8 mg/m3: Increased airway resistance and decreased compliance was observed at both peak exposures (see Figure 5)

- Lung volumes (TLC, VC, FRC and RV): Significant decrease below control was observed
(a) Experiment I (7 mg/m3): VC and TLC decreased -22 % and -18 %; No change in FRC and RV was observed (see Figure 1A)
(b) Experiment II (2.7 mg/m3): No change in lung volume (see Figure 2A)
(c) Experiment III (single high-peak exposure (34 mg/m3) with terminated exposure: TLC decreased -15 %, -22 %, -24 %, -17 %, on Days 2-5 respectively; VC decreased -17 %, -28 %, -25 % and 19 %, on Days 2-5 respectively; No change in FRC and RV was observed (see Figure 3A).
(d) Experiment IV (single high-peak exposure (25 mg/m3) with continued exposure at 4-8 mg/m3: TLC decreased -10 %, -32 %, -34 %, -28 % and -28 % on Days 1-5 respectively; VC also decreased in similar way; FRC decreased -17 %, -27% and -20 % on Days 2-4 respectively. No difference on Day 5; RV reduced -20 %, -30 %, -20 % and -10 % on Days 2-5 respectively (see Figure 4A)

- DLco and VA: Significant decrease below control was observed
(a) Experiment I (7 mg/m3): Only a slight increase was observed on the Day 1 of exposure (see Figure 1B)
(b) Experiment II (2.7 mg/m3): No change in DLco was observed (see Figure 2B)
(c) Experiment III (single high-peak exposure (34 mg/m3) with terminated exposure: VA decreased significantly by -10 % on Day 3; DLco decreased -40 %, -50 % and -25 % on Days 2, 3 and 5 respectively (see Figure 3B).
(d) Experiment IV (single high-peak exposure (25 mg/m3) with continued exposure at 4-8 mg/m3: VA only decreased on Day 3; DLco decreased -60 %, -40 %, -30 %, 25 % and -25 % on Days 1-5 respectively (see Figure 4B)

Dose descriptor:

NOAEL

Effect level:

2.7 mg/m³ air (analytical)

Sex:

male

Basis for effect level:

other: All measured parameters equivalant to 2.2 mg Zn/m³ air

Dose descriptor:

other: decreased lung volume

Effect level:

7 mg/m³ air (analytical)

Sex:

male

Basis for effect level:

other: Other: Pulmonary function measurement

Dose descriptor:

other: decrease of Lung volumes and diffusing capacity at peaks occurs rapidly and to a greater extent

Effect level:

25 - 34 mg/m³ air (analytical)

Sex:

male

Basis for effect level:

other: Pulmonary function measurement

Dose descriptor:

other: Pulmonary damage

Effect level:

7 mg/m³ air (analytical)

Sex:

male

Basis for effect level:

other: Wet-lung weight/Body weight ratio and Wet-lung weight/Dry-lung weight ratio

Dose descriptor:

other: Increased pulmonary damage at peak concentrations

Effect level:

25 - 34 mg/m³ air (analytical)

Sex:

male

Basis for effect level:

other: Wet-lung weight/Body weight ratio and Wet-lung weight/Dry-lung weight ratio

Critical effects observed:

not specified

Correlation analysis: Significant associations exists between TLC and DLco with the ratio of wet-lung weight to body weight (r = 0.93 and r = 0.70, respectively). A correlation also exists between the change in DLco and that of TLC ( r = 0.73). (see Figure 7). Association of decreased of lung volumes and DLco with the ratio of wet-lung weight to body weight indicates presence of pulmonary oedema.

Remarks on results on extent of pulmonary damage: The increased wet-lung weight to body weight ratios on peak exposures indicate high dose of ZnO given within a short period of time was more effective in inducing lung damage than an equivalent dose given over a longer period.

Remarks on results on Pulmonary function measurement: Nonpeak exposures induced gradual decreases in TLC and VC and diffusing capacity, whereas, in peak exposures, the changes occurred very rapidly.

Conclusions:

Under the test conditions, Exposures to 2.7 mg/ m3, using the same 3 hr/ day, 5 day time frame, did not alter any parameters measured.

Executive summary:

An inhalation study was conducted to evaluate the low-level exposures together with occasional intense exposures of ultrafine test material particles in guinea pigs.

 

5-8 Male Hartley Guinea pigs in each experimental group were given an exposure to different concentrations of test material, by nose-only for 3 h/d for 5 consecutive days. The animals were then evaluated for pulmonary function tests and extent of pulmonary damage after 1, 2, 3, 4 and 5 d post-exposure.

An exposure at concentration of 7 mg/m3 produced a gradual decrease in total lung capacity and vital capacity over the course of the exposure period. The carbon monoxide (CO) diffusing capacity (DLco) dropped abruptly to 30% below control levels on Day 4. Wet-lung weight/body weight ratios and wet-lung/ dry-lung weight ratios increased, indicating the presence of edema. Exposures to 2.7 mg/ m3, using the same 3 hr/ day, 5 day time frame, did not alter any parameters measured.

In two experiments a single high peak of test material (25-34 mg/m3) occurred with or without continued exposure. In both, lung volumes were decreased abruptly and to a greater extent than when peaks were absent. Continued exposure caused greater decrements in TLC and V C as well as decrements in FR C and RV than were observed when exposure was stopped. Peak exposures reduced DLco to 45%-60% below control. These values rose to 25%-30% below control with or without continued exposure. Increased airway resistance and decreased compliance were also observed at both peak exposures.

 

Under the test conditions, the short peaks occurring during normal low-level exposures can induce rapid pulmonary functional changes and greater extent of pulmonary damage and oedema.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

22 mg/m³

Study duration:

subacute

Species:

guinea pig

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from surrogate substances. Read-across is justified based on common physiological active moieties (refer to endpoint discussion for further details).

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

As no repeated dose toxicity data are available for fatty acids, tallow, zinc salts or for the analogue substances fatty acids, zinc salts, a read-across to soluble and slightly soluble zinc substances is made in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5.

It is assumed that after intake of fatty acids, tallow, zinc salts are changed (at least in part) to ionic zinc and that only ionic zinc is determining biological activities. Further justification is given within the CSR chapter 5 and the read-across justification.

The read-across approach and conclusion are in accordance to conclusions on repeated dose toxicity in the EU RAR on the structural analogue Zinc stearate (CAS# 91051-01-3, CAS# 557-05-1) Part II – Human Health. EUR 21168 EN: “No data were provided on the repeated dose toxicity of zinc distearate. Data on other zinc compounds have been used, based on the assumption that after intake the biological activities of the zinc compounds are determined by the zinc cation."

Inorganic zinc salts:

Non-human information

The repeated dose toxicity of water soluble zinc sulphate and zinc monoglycerolate has been examined in a total of 3 subchronic oral feeding studies (Maiata et al., 1981; Edwards and Buckley, 1995). Due to the different dosing regimens, the lowest NOAEL was determined to be 31.5 mg/kg bw/day of zinc monoglycerolate which equals a total zinc exposure of approximate 13 mg/kg bw/day. The zinc NOAEL derived from the feeding studies with zinc sulphate was determined to be 104 mg Zn/kg bw/day in mice and approximately 53.5 mg/kg bw/day in rats. At higher doses the most important effects in the rats were the development of hypocupremia, and significant changes in the pancreas (i.e., focal acinar degeneration and necrosis) and a decreased number of pigmented macrophages in spleen.

No longer term inhalation studies allowing to derive a robust NOEL for the inhalatory exposure of the respective zinc compounds has been identified. In a short term 3-day inhalation study with guinea pigs, a concentration of 2.3 mg ultrafine ZnO/m³ (3 hours/day) resulted in changes in neutrophils and activities of lactate dehydrogenase and alkaline phosphatase in the pulmonary fluid. At higher concentrations increased protein concentration, neutrophils, and enzyme activities in lung lavage fluids were seen, together with significant centriacinar inflammation of the pulmonary tissue (Conner et al., 1986). Inhalatory doses of 2.7 mg ultrafine ZnO/m³ for 5 days 3h/day did not alter the lung function parameters in guinea pigs, but at 5 and 7 mg ultrafine ZnO/m³ exposure according to a similar pattern, a gradual decrease in total lung capacity, vital capacity and reduction of the carbon monoxide diffusing capacity was seen in combination with inflammatory changes and edema (Lam et al., 1988). The relevance of the findings in studies with ultra-fine zinc oxide fumes is unclear with respect to commercial grade zinc oxide, as the latter is of much larger particle size and can have different toxicological characteristics.

Human information

Upon supplementing men and women with 150 mg Zn/day (as zinc sulphate capsules), women appeared to be more sensitive than men to the effects of high zinc intake: clinical signs such as headache, nausea and gastric discomfort were more frequent among women and women but not men had decreased activities of serum ceruloplasmin and ESOD (Samman and Roberts, 1987, 1988). In some earlier oral studies in which humans were supplemented with moderately high amounts of zinc (50 mg Zn/day), a reduction in ESOD activity was also observed and again women appeared to be more sensitive to this effect (Fischer et al., 1984; Yadrick et al., 1989). Hence, a reduction in ESOD was thought to be a sensitive indicator of copper status. However, in more recent and more sophisticated studies by Davis et al., (2000) and Milne et al., (2001) using the same dose level, ESOD was only marginally reduced (without a correlation with changes in copper balance), while findings on more specific copper deprivation signs (decreased serum ceruloplasmin and platelet cytochrome c oxidase) indicated that a sub-optimal intake of zinc was more effective than a moderately high intake of zinc in inducing changes associated with a decreased copper status in postmenopausal women. Given this, and the degree of the observed ESOD reduction in comparison to the natural variability in its activity, the zinc-induced decrease in ESOD activity is considered to have marginal biological significance, if any and also because it may not have been caused by an interference with copper metabolism as deep tissue SOD increases as a function of zinc exposure was observed.

Overall, it can be concluded that from studies in which humans were supplemented with zinc (as zinc gluconate), that women are more sensitive to the effects of high zinc intake and that a dose of 50 mg Zn/day is the human NOAEL. This equals a daily exposure of 0.83 mg/kg bw. At the LOAEL of 150 mg Zn/day, clinical signs and indications for disturbance of copper homeostasis have been observed.

The oral NOAEL of 0.83 mg Zn/kg bw/day (recalculated from the NOAEL of 50 mg Zn/day for a 60 kg human being) was used as the starting point for deriving DNELs for worker and general population. NOAELs for zinc exposure via the dermal or inhalatory route were estimated by taking into account the bioavailability of zinc via the different exposure routes (for details see section 5.1 of the Chemical Safety Assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006) in the technical dossier (IUCLID section 13)). By molecular weight correction, these data are read across to fatty acids, tallow, zinc salts.

References:

Davis CD, Milne DB and Nielsen FH (2000). Changes in dietary zinc and copper affect zinc- status indicators of postmenopausal women, notably, extracellular superoxide dismutase and amyloid precursor proteins. Am. J. Clin.Nutr. 71, 781-788.

Fischer PWF, Giroux A and L’Abbé MR (1984). Effect of zinc supplementation on copper status in adult man. Am.J. Clin. Nutr. 40, 743-746.

Milne DB, Davis CD and Nielsen FH (2001). Low dietary zinc alters indices of copper function and status in postmenopausal women. Nutr. 17, 701-708.

Samman S and Roberts DCK (1987). The effect of zinc supplements on plasma zinc and copper levels and the reported symptoms in healthy volunteers. Med. J. Australia 146, 246-249.

Samman S and Roberts DCK (1988). The effect of zinc supplements on lipoproteins and copper status Atherosclerosis 70, 247-252.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:

No study was selected since the oral NOAEL of 50 mg Zn/day, which is used as the starting point for deriving DNELs for worker is based on human experience and data following chronic exposure to zinc through food supplementation. The NOAEL of 8.3 mg fatty acids, tallow, zinc salts/kg bw/day is the recalculated value for a 60 kg human being and the average zinc content of 10% for fatty acids, tallow, zinc salts.

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:

The selected study is the most adequate and reliable animal study with the lowest dose descriptor. The NOAEC of 2.2 mg ultra fine Zn/m³ was converted into a NOAEC of 22 mg/m³ for fatty acids, tallow, zinc salts assuming an average zinc content of 10%. However, this dose descriptor was not taken into account for DNEL derivation, since the relevance of the findings in studies with ultra-fine zinc oxide fumes is unclear in respect to commercial grade zinc oxide and thus for fatty acids, tallow, zinc salts, as the latter are of much larger particle size and can have different toxicological characteristics.

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:

The selected study is the most adequate and reliable study with the lowest dose descriptor. The NOAEC of 2.2 mg ultra fine Zn/m³ was converted into a NOAEC of 22 mg/m³ for fatty acids, tallow, zinc salts assuming an average zinc content of 10%.  However, this dose descriptor was not taken into account for DNEL derivation, since the relevance of the findings in studies with ultra-fine zinc oxide fumes is unclear in respect to commercial grade zinc oxide and thus for fatty acids, tallow, zinc salts, as the latter are of much larger particle size and can have different toxicological characteristics.

Repeated dose toxicity: inhalation - systemic effects (target organ) respiratory: lung

Justification for classification or non-classification

There is no evidence for intrinsic toxic properties relevant to humans. Data on other zinc compounds have been used, as it is assumed that after intake fatty acids, tallow, zinc salts, are changed (at least in part) to ionic zinc and that only ionic zinc is determining biological activities. Zinc is essential for human growth and development, neurological functions and immunocompetence. The main clinical manifestations of zinc deficiency are growth retardation, delay in sexual maturation or increased susceptibility to infections (SCF, 2003). Health specialists recommend supplementing the diet with zinc in case human diet is zinc deficient. The maximum allowable daily intake has been established to be 50 mg zinc per day. Hence fatty acids, tallow, zinc salts, do not meet the classification criteria according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.