3,4-dichlorophenyl isocyanate

Endpoint summary

Description of key information

Short-term toxicity to fish

For transported isolated intermediates according to REACh, Article 18, >1000 t/a this endpoint is not a data requirement. However, data is available for this endpoint and is thus reported under the guidance of "all available data".

Concerning the acute toxicity for fish (Danio rerio) of 3,4-dichlorohenyl isocyanate a static test was carried out according to a national standard method which is comparable to the OECD Guideline for Testing of Chemicals No. 203 "Fish, Acute Toxicity Test". Based on the geometric mean, a LC50 was found to be 42.1 mg/l after 96 h exposure (Bayer 1988).

In order to investigate the acute toxicity of 3,4-dichlorohenyl isocyanate for fish (Leuciscus idus) a static test was carried out according to DIN 38412, Teil 15. The effect concentration LC50 was found to be 78.3 mg/l after 96 h exposure (Hoechst, 1981).

 

Short-term toxicity to aquatic invertebrates

For 3,4-dichlorophenyl isocyanate no short-term tests on toxicity to invertebrates are available. Therefore, the short-term toxicity test of the main hydrolysis product 3,4-dichloroaniline with the lowest value is used to draw a conclusion on toxicity to invertebrates for the parent compound. 

Weight of evidence approach

The acute toxicity of 3,4-dichloroaniline was assessed following a national standard method for the determination of toxicity to invertebrates. For Daphnia magna, a LC50 of 0.23 mg/l (larvae, 1 mm) after 48 h of exposure was obtained (Adema, 1981). 

The acute toxicity of 3,4-dichloroaniline, the main hydrolysis product of 3,4-dichlorophenyl isocyanate, was assessed (semi-static, freshwater test). For Daphnia magna, a LC50 of 0.12 mg/l after 96 h of exposure was obtained (Van der Meer, 1988).

The acute toxicity of 3,4-dichloroaniline, the main hydrolysis product of 3,4-dichlorophenyl isocyanate, was assessed (static, freshwater test following DIN 38412, Teil 11). For Daphnia magna, an EC50 of 2.8 mg/l after 48 h of exposure was obtained (Kühn, 1989).

The acute toxicity of 3,4-dichloroaniline, the main hydrolysis product of 3,4-dichlorophenyl isocyanate, was assessed (static, freshwater test similar to OECD TG 202). For Daphnia magna, an EC50 of 0.29 mg/l after 48 h of exposure was obtained (Crossland, 1985).

Conclusion

The EC50/LC50 values obtained from these studies are in the same order of magnitude.

48h-EC50/LC50: 0.23 - 2.8 mg/l

96-h LC50: 0.12 mg/l

The most conservative EC50 of 0.23 mg/l (Adema, 1981) obtained for the standard exposure time of 48h as outlined in OECD 202 was chosen as key value for chemical safety assessment.

 

Toxicity to aquatic algae and cyanobacteria

For 3,4-dichlorophenyl isocyanate no short-term tests on toxicity to aquatic plants are available. Therefore, the short-term toxicity test of the main hydrolysis product 3,4-dichloroaniline with the lowest value is used to draw a conclusion on toxicity to aquatic plants for the parent compound.

Weight of evidence approach

Concerning the acute toxicity of 3,4-dichloroaniline to aquatic plants (Scenedesmus pannonicus), a study was performed according to a national standard method (TNO, 1980). After 96 h exposure, an EC50 of 4.8 mg/l and a NOEC of 1.0 mg/l (based on growth rate) was obtained (Adema, 1982). 

Concerning the acute toxicity of 3,4-dichloroaniline to aquatic plants (Desmodesmus subspicatus, previous name: Scenedesmus subspicatus), a study was performed according to DIN 38 412, part 9, 1988 (deviation: shorter exposure time). After 48 h exposure, an EC50 of 27 mg/l (based on growth rate) and 6.8 mg/l (based on biomass) as well as EC10 values of 1.5 mg/l (based on biomass) and 2.4 mg/l (based on growth rate) were obtained (Kuehn, 1990). 

Concerning the acute toxicity of 3,4-dichloroaniline to aquatic plants (Phaeodactylum tricornutum), a study was performed according to ISO 8692. After 72 h exposure, an EC50 of 1.1 mg/l (based on growth rate) was obtained (Kusk, 1992). 

Conclusion

The EC50 values obtained from these studies are in the same order of magnitude, but differ in exposure time and species (1.0-27 mg/L).

As key values for chemical saftey assessment the EC50 of 4.8 mg/l and a NOEC of 1.0 mg/l (based on growth rate) obtained by Adema, 1982 were chosen, as these values were obtained for a test species similar to those recommended by OECD TG 201 and with an appropriate exposure time.

Toxicity to microorganisms

For transported isolated intermediates according to REACh, Article 18, this endpoint is not a data requirement. However, data is available for this endpoint and is thus reported under the guidance of "all available data".

For 3,4-dichlorophenyl isocyanate a test with activated sludge with a duration of 30 minutes was performed using a method comparable to OECD TG 209. An EC50 value of 3213 mg/l (nominal) was observed (Bayer, 1988).

For freshwater effluent bacteria, a toxicity threshhold of approx. 600 mg/L was observed for an exposure period of 24h. The criteria for toxicity are unknown. The conditions of hydrolysis of 3,4-Dichlorophenyl isocyanate towards 1-amino-3,4-dichlorobenzene were described as: 10 g/l, 24 h, pH = 12, 25 °C (Hoechst AG, 1982).