Bis[2-[2-(1-methylethyl)-3-oxazolidinyl]ethyl] hexan-1,2-diylbiscarbamate

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

adult fish: sub(lethal) effects

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

A study does not need to be conducted for the reasons of adaptation rules of column 2, section 9.1 Annex IX as well as section 1 Annex XI (scientifically not necessary).

Column 2, section 9.1., Annex IX states that “Long-term toxicity testing shall be proposed by the registrant if the chemical safety assessment according to Annex I indicates the need to investigate further the effects on aquatic organisms.”

The chemical safety assessment does not indicate the need to further investigate effects on aquatic organisms as outlined in the following. This is also in line with the rule of information requirement adaptation due to no scientific necessity as stated in Annex XI section 1.

The substance was investigated in OECD and GLP compliant studies for its acute toxicity to algae, daphnia, and fish, respectively.

The study assessing the acute toxicity of the test item to fish was conducted with Medaka (Oryzias latipes) according to OECD guideline no. 203. Based on a range-finding test a limit dose of 100 mg/L was chosen for the main test under semi-static conditions. The study is considered valid according to the validity criteria of the guideline. The mean measured concentration (mean of sum of the test substance and the transformation products) of the test group was 101 mg/L. In both the control and the test group, no dead fish and no abnormal symptoms in living fish were observed. Therefore the LC 50 of the test item is >101 mg/L.

The acute immobilisation test with Daphnia magna was conducted in compliance with GLP and OECD 202 with nominal concentrations of 10, 18, 32, 56, 100 mg/L. It is assumed that immobility observed in the definitive test was caused by water-soluble transformation products. The highest concentration with 0% immobility (EC0) was examined to be 15.5 mg/L (mean measured concentration). The lowest concentration with 100 % immobility (EC100) was not observed. Therefore, the Median Effect Concentration (EC50) was estimated to be >87.1 mg/L.

The algae growth inhibition test was conducted according to the OECD guideline no. 201. The ErC50 (0 - 72 h) was determined to be 18.6 mg/L (95% confidence limits: 16.0 – 21.6 mg/L). The no observed effect concentration, NOECr (0 - 72 h) was estimated to be 0.0259 mg/L. The EC10 was calculated to be 0.194 mg/L.

Taken together, the test item did not induce any or only minor effects in fish and daphnia up to the limit dose. Algae were demonstrated to clearly be the most sensitive species when exposed to the test item. This is also assumed for long-term toxicity. NOEC values for a long-term fish test are expected to be well above the NOEC value from the toxicity to algae test. Therefore, long-term toxicity studies in fish are not expected to provide more relevant information in regards to hazard conclusion and would therefore not improve chemical safety assessment.
Furthermore, based on the chemical safety assessment the environmental risk is considered to be adequately controlled. There are no concerns regarding the safe use of the substance. For the aquatic environment RCR values are beyond the threshold of 1, i. e. by a factor of approx. 100 and more.

Another point of consideration is the substance´s behaviour in case of release to the aquatic environment. The substance is not stable in water for a longer period. It is considered to be inherently biodegradable and hydrolyses very rapidly in contact with water. Hydrolysis half- life of the test item was determined to be 2 min at 20 °C. Water solubility of the substance was estimated to be 28.24 mg/L. Due to these properties the substance is expected to be distributed or disintegrated rapidly and therefore well diluted in the compartment water. Thus, aquatic life is not expected to be exposed to higher concentrations of the test item over a longer period. This further supports the point that acute toxicity studies already provide sufficient information for chemical safety assessment.

Isobutyraldehyde (CAS 78-84-2) is expected to be one hydrolysis product of the test item. Its water solubility was determined to be 60 g/L and logPow to be 0.77. Water solubility and logPow values for four other potential hydrolysis products were calculated. For these potentially formed structures water solubility estimations range between approx. 8.4 and 1E+3 g/L. Calculated logPow values range between -2.9 and -1.03, accordingly. As a result water solubility of 8.4 mg/L and a logPow of -1.03 are regarded as worst case assumption for these hydrolysed Incozol 4 structures.
These considerations further support the assumption that also hydrolysis products are very well soluble in water favoring a rapid distribution. Therefore, relevant bioavailability to aquatic organisms is not expected after long-term exposure with potential hydrolysis products of the test item.

Taken together the points outlined above it is concluded that the criteria of Annex IX Section 9.1 column 2 are fulfilled justifying the adaptation of the information requirements, accordingly. Therefore, and considering animal welfare reasons, further studies on long-term toxicity to fish are neither scientifically nor from a regulatory point of view justified.

This is also in line with the rule of information requirement adaptation as stated in Annex XI section 1. Further testing does not appear to be scientifically necessary.

Description of key information

A study does not need to be conducted for the reasons of adaptation rules of column 2, section 9.1 Annex IX as well as section 1 Annex XI (scientifically not necessary). For more detailed information please refer to "Justification for type of information".