Formaldehyde

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Methods used is related to US EPA, but with major deriviations (regarding time etc.)

GLP compliance:

no

Specific details on test material used for the study:

reagent grade

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

24 ± 1°C

Details on test conditions:

TEST SYSTEM
- Test vessel: 4 L transparent chemostat incubator
- Type of flow-through: variable speed-pump, dilution rate 0.25/d

GROWTH MEDIUM
- Standard medium used: described in US EPA bottle technique, except NaNO3, K2HPO4 and EDTA were reduced to 12.75 mg/L, 0.52 mg/L and 30 µg/L, respectively

OTHER TEST CONDITIONS
- Light intensity and quality: 65 µEm-2s-1

EFFECT PARAMETERS MEASURED : growth rate, dissolved oxygen production

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

4.249 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2.627 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: dissolved oxygen production

A median effectice concentration of 6.494 mg/L is cited from Krebs F (1991) Deutsche Gewässerkundliche Mitteilungen 35, 161 -170

Validity criteria fulfilled:

no

Conclusions:

The test item is acutely harmful to aquatic green algae

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

calculation (if not (Q)SAR)

Remarks:

experiemntal EC50 values from author's previous publications (see references) were used for statistical NOEC and EC10 estimation

Adequacy of study:

supporting study

Study period:

2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Qualifier:

no guideline required

Principles of method if other than guideline:

108 sets of raw data including aldehydes, nitriles, anilines, chlorophenols, benzenes, alkanes, alcohols, polycyclic aromatic hydrocarbons, and pesticides from the author’s previous works (Chen et al.,2006; Yeh and Chen, 2006; Tsai and Chen, 2007)

Calculation of EC10: best fit approach, Experimental data were fitted into three different dose response models, i.e., probit, logit, and Weibull. The best-fit model was determined based on the minimum Chi^2 values

Calculation of NOEC: One-tail Dunnett's procedure

GLP compliance:

no

Specific details on test material used for the study:

Purity: reagent grade

Analytical monitoring:

yes

Remarks:

measurement of test concentrations was conducted in previous work (Tsai and Chem, 2007).

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Water media type:

freshwater

Total exposure duration:

48 h

Details on test conditions:

- Test vessels: 300 ml BOD without headspace
- Test type: closed
- Endpoints: Dissolved oxygen (DO) production, algal growth rate (GR), and the net production of algal cell density (final cell density initial cell density, biopopulation)

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1.06 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

same for growth rate and biopopulation (biomass)

Remarks on result:

not measured/tested

Remarks:

calculated from acute values

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

0.801 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Remarks on result:

not measured/tested

Remarks:

calculated from acute values

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2.55 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Correlation (ACR) between acute and chronic values for ractive substances (mean (95 % CI)):

ACR (EC50/NOEC) = 3.53 (2.05 -5.00)

ACR (EC50/EC10) = 4.49 (2.94 -6.04)

 

Conclusions:

NOEC and EC50 values could be estimated from EC50 values with good accuracies.

Executive summary:

Based on previous published experimental acute data of the author, chronic values were estimated statistically via best fit approach (EC10) and NOEC values were calculated via one-tail Dunett procedure for 108 substances in total with respect to different endpoints (biomass, growth rate and oxygen production). The ratio between acute and estimated chronic vales (ACR) was calculated for the different substance classes. The chronic values could be estimated with good accuracies.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Although the study is performed according to OECD Guideline 201 (1981), and national/international standards, only few data are presented in the study, so that validity criteria cannot fully be verified. Furthermore, no analytical monitoring was performed; methanol content of the test substance is not given. However, these deficiencies do not invalidate the study.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

ISO 8692 (1989; DIN 38412 L9 and EN 28692), DIN 38412 L33 (1991 a, b)

Deviations:

yes

Remarks:

NaHCO3 concentration in the test solution was 300 mg/L.

GLP compliance:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Formaldehyde
- Composition of test material, percentage of components: No data
- Lot/batch No.: Merck KGaA, Darmstadt, Cat. No. 104025

Analytical monitoring:

no

Details on sampling:

not applicable

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: No data, however formaldehyde is not volatile from aqueous solution at the concentration range tested.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Scenedesmus subspicatus CHODAT
- Strain: SAG 86.81
- Source (laboratory, culture collection): Collection of algal cultures (SAG), Institute of Plant Physiology, University of Goettingen, Germany
- Method of cultivation: ISO 8692 (1989)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

None

Hardness:

No data

Test temperature:

23°C ± 2°C

pH:

No data

Dissolved oxygen:

Not applicable

Salinity:

Not applicable

Nominal and measured concentrations:

No data. Actual concentrations of the test substance are not required in OECD 201 (1984).
5 different concentrations were tested but details were not reported.

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type open / closed: No data. The test substance is not volatile from aqueous solutions at the concentration range tested
- Material, size, headspace, fill volume: 100 mL Erlenmeyer flasks
- Initial cells density: 10Exp4 algae/mL
- Control end cells density: 10Exp6 cells/mL (mean of six replicates)
- No. of vessels per concentration (replicates): No data, however, according to guideline(s) 3 replicates per concentration are required
- No. of vessels per control (replicates): No data, however, according to guideline(s) 6 replicates for controls are required
- Culturing apparatus: Infors MULTITRON Incubator-Shaker
- Procedure for suspending algae: Shaking: rotational speed: 130 min-1 for 10 min and 100 min-1for 50 min in intervals to avoid adhesion of algae at the flasks, throw: 25 mm

GROWTH MEDIUM
- Standard medium used: According to DIN 38412 L33 and ISO 8692. NaHCO3 concentration in the test solution was 300 mg/L.

OTHER TEST CONDITIONS
- Photoperiod: No data
- Light intensity and quality: No data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Cell multiplication inhibition (chlorophyll fluorescence measurement, excitation wavelength: 450 nm, emission wavelength: 685 nm). Sampling after 0 h, 24 h, 48 h and 72 h. Calculation of biomass production and growth rate.

TEST CONCENTRATIONS
- Test concentrations: Single test concentrations are not reported

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.48 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Remarks on result:

other: 95% C.l.: 3.45 - 3.52 mg/L

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.89 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: 95% C.l.: 2.74 - 8.69 mg/L

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.44 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Remarks on result:

other: 95% C.I.: 4.42 - 4.46 mg/L

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

6.61 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: 95% C.I.: 4.56 - 9.57 mg/L

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Inhibition values were calculated from three parallels according to ISO 8692 (1989).
EC values were calculated from sigmoidal concentration-inhibition curves by probit analysis.
Confidence limits were derived by the equation of Fieller.

Validity criteria fulfilled:

not specified

Conclusions:

The test results indicate that the test item is acutely toxic towards Desmodesmus subspicatus.

Executive summary:

The toxicity of the test item to aquatic algae was assessed in two independent tests according to OECD guideline 201. Although no detailed test parameters (e.g., detailed test concentrations, temperature measurements, light intensity, irridation time, etc.) are presented, the tests were performed thoroughly according to guidelines and national/international standards. Therefore, the limited reporting of study details appears negligible and there are no indications that would challenge the study results.  The test species Desmodesmus suspicatus was exposed to five different test concentrations of the test item for 72 h.  The cell multiplication inhibition (chlorophyll fluorescence measurement, excitation wavelength: 450 nm, emission wavelength: 685 nm) was measured after 0 h, 24 h, 48 h and 72 h. Based on this the biomass production and growth rate were calculated. After 72 h an EC50 of 4.89 mg/L and 6.61 mg/L (two tests) were measured based on the growth rate. The EC50 based on the biomass were also calculated with lower results. But ECx values based

upon average specific growth rate (ErCx) will generally be higher than results based upon yield (EyCx) according to the test design of the OECD 201 Guideline. The guideline acknowledges this difference and recommends that it should not be interpreted as a difference in sensitivity between the two response variables, simply that the values are different due to mathematical bias. Furthermore, the guideline states that the use of average specific growth rate forestimating toxicity is scientifically preferred. Hence, the most sensitive effect value based on the growth rate was used for further assessment (EC50(72) = 4.89 mg/L).

Although no analytical monitoring of the test substance concentration was performed, the test substance concentration can be assumed to be stable during the exposure period. This is due to the low volatilisation potential from water (cf. 5.4.2) and the low adsorption potential (cf. 5.4.1). Biodegradation of the test substance during the exposure period can not be excluded completely (cf. 5.2). Furthermore, it was demonstrated in the frame of a fish test (Bills 1977) that the effect values did not change when an aged test solution was used indicating that the test substance is stable during the incubation period. Therefore, the effects to fish are not underestimated using the nominal values.

Description of key information

Acute toxic to algae: EC50 (72 h) = 4.89 mg/L based on growth rate

Key value for chemical safety assessment

EC50 for freshwater algae:

4.89 mg/L

Additional information

The toxicity of the test item to aquatic algae was assessed in two independent tests according to OECD guideline 201 (Eisenträger, 2003). Although no detailed test parameters (e.g., detailed test concentrations, temperature measurements, light intensity, irridation time, etc.) are presented, the tests were performed thoroughly according to guidelines and national/international standards. Therefore, the limited reporting of study details appears negligible and there are no indications that would challenge the study results.  The test species Desmodesmus suspicatus was exposed to five different test concentrations of the test item for 72 h.  The cell multiplication inhibition (chlorophyll fluorescence measurement, excitation wavelength: 450 nm, emission wavelength: 685 nm) was measured after 0 h, 24 h, 48 h and 72 h. Based on this the biomass production and growth rate were calculated. After 72 h an EC50 of 4.89 mg/L and 6.61 mg/L (two tests) were measured based on the growth rate. The EC50 based on the biomass were also calculated with lower results. But ECx values based

upon average specific growth rate (ErCx) will generally be higher than results based upon yield (EyCx) according to the test design of the OECD 201 Guideline. The guideline acknowledges this difference and recommends that it should not be interpreted as a difference in sensitivity between the two response variables, simply that the values are different due to mathematical bias. Furthermore, the guideline states that the use of average specific growth rate forestimating toxicity is scientifically preferred. Hence, the most sensitive effect value based on the growth rate was used for further assessment (EC50(72 h) = 4.89 mg/L).

Although no analytical monitoring of the test substance concentration was performed, the test substance concentration can be assumed to be stable during the exposure period. This is due to the low volatilisation potential from water (cf. 5.4.2) and the low adsorption potential (cf. 5.4.1). Biodegradation of the test substance during the exposure period can not be excluded completely (cf. 5.2). Furthermore, it was demonstrated in the frame of a fish test (Bills 1977) that the effect values did not change when an aged test solution was used indicating that the test substance is stable during the incubation period. Therefore, the effects to fish are not underestimated using the nominal values.

In addition, concentration measurements during in experimental study support the assumption of the stability of the test item (Tsai and Chem, 2007).

The results are supported by a publication of Chen et al. from 2005. The green algae P. subcapitata was exposed to the test item in a flow through system for 48 h. The growth rate and dissolved oxygen production was determined.  An EC50 (48 h) of 4.249 mg/L was determined, which is within the same range as the effect value determined in the key study. Since no guideline was followed this study (Chen et al., 2005) was used only to support the findings from Eisentraeger et al..

No adequate chronic values are available for the assessment. Nevertheless, a publication of Chen et al, 2009  estimated chronic values statistically from acute effect values with good correlation. These values can not be used for PNEC derivation but give a hint on the range of possible chronic toxicity. Based on the growth rate a NOEC of 0.801 mg/L was estimated.