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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Guideline study with acceptable restrictions Isocyanates are known to rapidly hydrolyse under the formation of the corresponding amine as well as solid polyurea compounds *. However, the insoluble inert polyurea is not assumed to cause environmental hazards due to the reduced uptake of high molecular mass compounds, whereas the amine is assumed to be the ecotoxicological relevant species. Concluding, tests performed using the corresponding amine can equally be used to assess the ecotoxicological hazards of isocyanates assuming the complete transfer of the isocyanate into the corresponding amine while neglecting the formation of a certain fraction ecotoxicological not active polyurea compounds. An underestimation of environmental hazards is thus avoided supporting a conservative and thus protective hazard assessment. * Bayer Industry Services (2004). 4-chlorophenyl-isocyanate: Investigation on Stability in Aqueous Test Solutions. Project No: 200300181. Leverkusen, Germany. Bayer Industry Services (2003). Isopropylisocyante: Investigation on Stability in Aqueous Test Solutions. Project No: 200300095. Leverkusen, Germany.
Justification for type of information:
Guideline study with acceptable restrictions Isocyanates are known to rapidly hydrolyse under the formation of the corresponding amine as well as solid polyurea compounds *. However, the insoluble inert polyurea is not assumed to cause environmental hazards due to the reduced uptake of high molecular mass compounds, whereas the amine is assumed to be the ecotoxicological relevant species. Concluding, tests performed using the corresponding amine can equally be used to assess the ecotoxicological hazards of isocyanates assuming the complete transfer of the isocyanate into the corresponding amine while neglecting the formation of a certain fraction ecotoxicological not active polyurea compounds. An underestimation of environmental hazards is thus avoided supporting a conservative and thus protective hazard assessment. * Bayer Industry Services (2004). 4-chlorophenyl-isocyanate: Investigation on Stability in Aqueous Test Solutions. Project No: 200300181. Leverkusen, Germany. Bayer Industry Services (2003). Isopropylisocyante: Investigation on Stability in Aqueous Test Solutions. Project No: 200300095. Leverkusen, Germany.
Reason / purpose:
read-across: supporting information
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
21 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 19-23
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
12.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
6.7 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 5.9-7.7
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
3.2 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
8.4 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
Isocyanates are known to rapidly hydrolyse under the formation of the corresponding amine as well as solid polyurea compounds *. However, the insoluble inert polyurea is not assumed to cause environmental hazards due to the reduced uptake of high molecular mass compounds, whereas the amine is assumed to be the ecotoxicological relevant species. Concluding, tests performed using the corresponding amine can equally be used to assess the ecotoxicological hazards of isocyanates assuming the complete transfer of the isocyanate into the corresponding amine while neglecting the formation of a certain fraction ecotoxicological not active polyurea compounds. An underestimation of environmental hazards is thus avoided supporting a conservative and thus protective hazard assessment.
* Bayer Industry Services (2004). 4-chlorophenyl-isocyanate: Investigation on Stability in Aqueous Test Solutions. Project No: 200300181. Leverkusen, Germany.
Bayer Industry Services (2003). Isopropylisocyante: Investigation on Stability in Aqueous Test Solutions. Project No: 200300095. Leverkusen, Germany.
Results with reference substance (positive control):
The results with potassium dichromate were within the normal ranges for this reference item (EC50 0.74mg/L, NOEC 0.25 mg/L, growth rate).
Reported statistics and error estimates:
One way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf 1981) and Dunnett's multiple comparison procedure for comparing several treatments with a control (Dunnett 1955) was carried out on the growth rate and yield data after 72 hours to identify any statistically significant differences (alpha = 0.05) between the test and control groups. All statistical analyses were performed using the SAS computer software package (SAS 1999 - 2001).
Validity criteria fulfilled:
yes
Remarks:
(The factor of biomass parameter 116 > 16; -The mean of the replicate coefficients of variation in the section-by-section growth 11.7 % < 35%; - The coefficient of variation of the mean specific growth rate replicates in the control 0.9 % < 7%.)
Conclusions:
The effect of the test item on the growth of Desmodesmus subspicatus gave the following results: ECr50 = 21 mg/L (Nominal), ECr50 = 6.7 mg/L (geom.mean measured).
Executive summary:

The effect of the test item on the growth of Desmodesmus subspicatus gave the following results: ECr50 = 6.7 mg/L (geom.mean measured).

Description of key information

The effect of the test item on the growth of Desmodesmus subspicatus determined the following results: ECr50 = 6.7 mg/L (geom.mean measured).

Key value for chemical safety assessment

EC50 for freshwater algae:
6.7 mg/L
EC10 or NOEC for freshwater algae:
3.2 mg/L

Additional information

Isocyanates are known to rapidly hydrolyse under the formation of the corresponding amine as well as solid polyurea compounds *. However, the insoluble inert polyurea is not assumed to cause environmental hazards due to the reduced uptake of high molecular mass compounds, whereas the amine is assumed to be the ecotoxicological relevant species. Concluding, tests performed using the corresponding amine can equally be used to assess the ecotoxicological hazards of isocyanates assuming the complete transfer of the isocyanate into the corresponding amine while neglecting the formation of a certain fraction ecotoxicological not active polyurea compounds. An underestimation of environmental hazards is thus avoided supporting a conservative and thus protective hazard assessment.

* Bayer Industry Services (2004). 4-chlorophenyl-isocyanate: Investigation on Stability in Aqueous Test Solutions. Project No: 200300181. Leverkusen, Germany.

Bayer Industry Services (2003). Isopropylisocyante: Investigation on Stability in Aqueous Test Solutions. Project No: 200300095. Leverkusen, Germany.