Aniline

Endpoint summary

Additional information

For aniline a large amount of aquatic ecotoxicity studies is available. However, for risk assessment purposes only the most reliable and sensitive studies were considered. Furthermore, when assessing aquatic toxicity studies for aniline, the rapid phototransformation should be kept in mind. Therfore, tests using flow through or semistatic conditions and with analytical dose verification were preferred within this risk assessment.

The following endpoints were selected for the aquatic risk assessment of Aniline:

a) Acute studies

Oncorhynchus mykiss: LC50 (96h) = 10 .6 mg/l (measured concentration, flow through)

Daphnia magna: EC50 (48h) = 0.16 mg/l (measured concentration, semi-static)

Chlorella pyrenoidosa: ErC₅₀(72h) = 175 mg/L (nominal concentration, growth rate, static)

b) Chronic studies

Pimephales promelas: NOEC (32d) = 0.39 mg/l (measured concentration, flow through)

Daphnia magna: NOEC (21d) = 0.016 mg/l (measured concentration, flow through)

Daphnia magna: NOEC (21d) = 0.004 mg/L (measured concentration, semi-static)

Daphnia magna: NOEC (21d) = 0.024 mg/L (measured concentration, semi-static)

Derivation of PNECaqua

Among the tested species Daphnia was most sensitive in both short-term and long-term tests. Therefore, the results from the Daphnia reproduction tests are used for the derivation of the PNECaqua.

 

Three 21-day NOECs in the narrow range of 4 μg/l to 24 μg/l are available for Daphnia. None of these tests was conducted according to international guidelines but careful examination of the test reports allows the conclusion that they can all be regarded as valid (with restriction) and that it cannot be justified to prefer one of the tests.

 

The three available NOECs are lying close together and thus are supporting each other. As NOECs are dependent on the range and the spacing of the substance concentration used in the tests it is obvious that variation in the test concentrations in different tests is an important and relevant reason for different NOEC values obtained. Therefore, to reduce this uncertainty it seems adequate that the mean value of these three NOECs is calculated and used as basic value for the effects assessment. It could be stated that the NOEC of 4 μg/l should be used for the derivation of the PNEC because it is possible that effects occur at concentrations below 4 μg/l. However, as three Daphnia long-term tests are available that are regarded of equal value, the calculation of the geometric mean seems to be most appropriate.

 

Calculating the arithmetic mean of the three NOECs results in a value of 12 μg/l.

 

For the derivation of the PNECaqua an assessment factor of 10 seems appropriate, as reliable long-term tests are available for daphnids and fish.

 

Therefore: PNECaqua = 12 μg/l / 10 = 1.2 μg/l

Several single species tests and activated sludge tests are available for assessing the toxicity of Aniline to microorganisms. The following studies have been selected as relevant endpoints:

activated sludge: NOEC (2h) = 2mg/l (nitrification inhibition)

Nitrosomonas sp.: EC50 > 1 mg/l (nitrification inhibition)

activated sludge: EC20 = 2800 mg/l (respiration inhibition)

Entosiphon sulcatum: NOEC (72h) = 24 mg/l (growth inhibition)

Derivation of PNECmicroorganism

For the risk assessment of industrial sewage treatment plants the PNECmicroorganism based on the nitrification inhibition test with industrial activated sludge is used as this test is more realistic for this kind of treatment plants than the test with Nitrosomonas spec..

Therefore, the PNECmicroorganism = 2 mg/l .