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No toxic effects occur at the range of water solubility.


The constituents of the UVCB substance are expected to have a very low water solubility (constituent with highest solubility: Structure A 0.02 mg/L at 20°C). Therefore, bioavailability to aquatic organisms is strongly limited. All available acute tests for the test substance markedly show that toxic effects only occur far beyond the limit of water solubility


Whole substance (192268 -65 -8)


Valid acute data are available for three trophic levels. The test substance is poorly soluble in water and is a mixture of several components, the undiluted filtrate of water accommodated fraction (WAF) of the test substance at a loading rate of 100 mg/l was tested. In the acute tests no effect was observed with the saturated solution (undiluted filtrate up to 100 mg/L nominal test item concentrations) (fish: RCC 1997, Daphnia: Ciba Geigy 1996). Since the test substance is of low water solubility (< 0.1 mg/L) it can be stated that there are no acute toxicity effects in the range of water solubility. A study to determine the toxicity to algae is also available. No effects were observed in a toxicity study with algae conducted according to OECD guideline 201 (RCC, 1997). The ErC50 after 72 hours of exposure was determined as above and the NOEC equal or above the saturation concentration with the undiluted filtrate based on 100mg/L nominal concentration (RCC, 1997).


A chronic toxicity study on daphnids according to OECD guideline 211 under consideration of the OECD no 23 guidance document was performed (BASF, 2015) with uvcb substance showing no effects up to the saturation concentration (undiluted filtrate with a loading rate of 5.5mg/L (WAF)).Based on these data it can be expected that NOEC and EC10 for the major constituents (> 20%) is higher than the saturation concentration using a loading rate of 1mg/L (WAF).


Furthermore, in a BCF study according to (GAKUSHUIN UNIVERSITY 1999) no adverse effects on fish were observed during 56 days of exposure in concentrations within the solubility range. The test concentrations of the main constituents were verified in this test.


Further older chronic studies on fish and Daphnia (Wildlife International, 2003) were re-evaluated for validity considering the latest recommendations of OECD No. 23: Guidance Document on the Aquatic Toxicity Testing of Difficult Substances and Mixtures. It is concluded that both the chronic Daphnia and fish studies suffer from major flaws which are related to improper preparation of the test solutions and therefore, both tests are regarded as invalid.


In a 3-hr acute toxicity study, sewage sludge microorganisms (RCC 1997) were exposed to the test item at nominal concentrations of 1000 mg/L in accordance with OECD 209. The IC50 value based on respiration rate was > 1000 mg/L after a 3 h contact time. The NOEC was 320 mg/L and EC20 403 mg/L.


 


Main component: O,O,O-triphenyl phosphorothioate (CAS 597-82-0; structure A)


No toxic effects occur at the range of water solubility.


The test substance exhibits a very low water solubility (0.020 mg/L at 20°C). Therefore, bioavailability to aquatic organisms is strongly limited.


All available acute tests for the test substance markedly show that toxic effects only occur far above the limit of water solubility.


In a 96-h acute toxicity study of the test item to zebra-fish (Brachydanio rerio) under static conditions the NOEC and LC50 was estimated to be higher than the saturation concentration (undiluted filtrate with a nominal loading rate of 100 mg/L ) (RCC, 2002).


The 48-hr-EC50 of the test item to Daphnia magna under static conditions was determined to be higher than the saturation concentration (undiluted filtrate with a nominal loading rate of 100mg/L), (RCC 2002)


In a 72 hour acute toxicity study of the test item to cultures of Desmodesmus subspicatus the NOErC and ErC50 values based on growth rate were at the saturation concentration and above, respectively (based on undiluted filtrate with a nominal loading rate of 100mg/L) (Noack, 2013).


No long-term toxicity tests to aquatic organisms are available. Based on the Daphnia reproduction study with the whole substance it can be expected that NOEC and EC10 for the major constituent structure A is > 1mg/L.


In a 3-hr acute toxicity study (Ciba-Geigy 1988) sewage sludge micro-organisms were exposed to the test item at nominal concentrations of 100 mg/L in accordance with OECD 209. The IC50 value based on respiration rate was > 100 mg/L after a 3 h contact time. No effects were observed up to the highest test concentration of 100mg/L (nominal).


Based on the available data on aquatic toxicity it can be stated that the substance s not toxic to aquatic organisms up to the limit of solubility in water.