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Short-term toxicity to aquatic invertebrates

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In a GLP study conducted to OECD Guideline 202, exposure of Daphnia magna to Cereclor S52 (a C14-17 chlorinated paraffin; 52% chlorinated) in freshwater (static system) resulted in a 48-h EC50 value of 0.0077 mg/L (nominal) or 0.0059 mg/L (measured concentration), indicating that the test material is very toxic to aquatic invertebrates. Similarly, in another study, the 48-h EC50 in Daphnia of a C14-17 chlorinated paraffin (52% chlorinated) was less than 0.1 mg/L, as immobilisation of all Daphnia was observed at all test substance concentrations. The animals were not fed during either test.
In other OECD guideline studies, Daphnia where exposed to freshwater (static system) containing dilutions of a saturated solution of C14-17 chlorinated paraffins (52% chlorinated), resulting in a measured 48-h EC0 of 140 µg/L and a 48-h EC25 of 339-423 µg/L, and a nominal 48-h NOEC of <0.1 mg/L.
A 96-hr LC50 of >1 mg/L was seen in Gammarus pulex exposed to a C14-17 chlorinated paraffin (52% chlorinated) in freshwater, and 96-hr LC50s of 9 mg/L and >10,000 mg/L have been reported in Nitocra spinipes exposed to a 45 and 52% chlorinated parrafin (C14-17), respectively, in brackish water (probably 7 ‰ salinity).

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In a GLP study conducted according to OECD Guideline 202, exposure of Daphnia magna to Cereclor S52 (C14-17 chlorinated paraffin; 52% chlorinated) for 48 hours in freshwater (static system) results in substantial immobilisation at nominal concentrations of 0.0056 mg/L and above, complete immobilisation at 0.056 mg/L and above, but no immobilisation at 0.0032 mg/L. The 48-h EC50 value of 0.0077 mg/L (nominal) or 0.0059 mg/L (measured concentration) indicates that the test material is very toxic to Daphnia (Thompson et al. 1996). Similarly, in another study, the 48-h EC50 in Daphnia of a C14-17 chlorinated paraffin (52% chlorinated) was less than 0.1 mg/L in freshwater; as immobilisation of all Daphnia was observed at all test substance concentrations (Thompson and Gore, 1999). The lack of feeding in the acute toxicity tests summarised above (possibly resulting in Daphna being more susceptible to the toxic effects of MCCPs), has been put forward as a explanation for the apparent discrepancy between the results of these acute studies and those from the long term toxicity data (where feeding is carried out). As organisms in the environment will be feeding, it is considered most relevant to base the PNEC derivation on a study where feeding occurred. Therefore, the 21-day NOEC of 10 µg/L determined for Daphnia in the Thompson et al. (1997a) study (summarised in IUCLID Chapter 6.1.4) will be used in the PNEC determination.

In other OECD guideline (202) studies, Daphnia were exposed to freshwater (static system) containing dilutions of a saturated solution of MCCPs (52% chlorinated), resulting in a measured 48-h EC0 of 140 µg/L and a 48-h EC25 of 339-423 µg/L (Frank, 1993; Frank and Steinhauser, 1994) and a nominal 48-h NOEC of <0.1 mg/L (Thompson, 2004). These animals were fed during the test.

 

No deaths were seen in Gammarus pulex exposed for 96 h to a C14-17 chlorinated paraffin (52% chlorinated) in freshwater (static system) at up to 1 mg/L. Therefore the 96-h LC50 is greater than 1 mg/L, and MCCPs can be considered as not toxic to this freshwater crustacean at concentrations in excess of the water solubility (Thompson and Gore, 1999). In addition, 96-h LC50s of 9 mg/L and >10,000 mg/L have been reported for a 45 and 52% chlorinated MCCP, respectively, to the brackish water (probably 7‰ salinity) harpacticoid Nitocra spinipes (Tarkpea et al. 1981).

 

 

References (studies for which no ESR has been created; move to reference list in CSR)

Frank U (1993). Ökotoxizität von Chloroparaffinen. Institut für Wasser- Boden und Lufthygiene, 23 November 1993 (cited in EU, 2005).

 

Frank U and Steinhauser FG (1994). Ökotoxizität schwerlöslicher Stoffgemische am Biespiel der Daphnientoxizität von Chlorparaffinen. Vom Wasser 83, 203-211 (cited in EU, 2005).

 

Tarkpea M et al. (1981). Product control studies at the Brackish Water Toxicology Laboratory 1979-1980. Nyköping, Swedish Environmental Protection Agency, NBL Report 1981-03-23 (cited in EU, 2005).

 

Thompson RS (2004). Medium-chain chlorinated paraffin (C14-17, 52% chlorinated): A comparison of acute toxicity to Daphnia magna using two different carrier solvents and water-accommodated fractions. AstraZeneca Confidential Report, BLS3192/B (cited in EU, 2005).