1,2,3-trichloropropane

Endpoint summary

Additional information

TCP may enter the hydrosphere due to its production, use, and application. However, it can evaporate from the aqueous phase to some extent, thus reducing the exposure concentration for aquatic species. Such loss due to evaporation of TCP from the aqueous phase was demonstrated in a recent study simulating a 48-h daphnid open vessel test (Solvay 2001, Internal Memorandum).

The acute toxicity of TCP was tested using a variety of aquatic species from the relevant trophic levels (producers and primary and secondary consumers) represented by algae, invertebrates and fish. The figures indicate that aquatic invertebrates are most susceptible to TCP toxicity, followed by fish. TCP is not acute toxic to algae until the regulatory cut-off limit of 100 mg/L.

Some of the aquatic toxicity studies are of limited value, because actual concentrations of TCP were not measured and losses of the test item due to volatilization were not taken into account over the tests’ duration (Kielhorn et al 2003). In this dossier such studies are rated „Klimisch 3“ (K3) as they is the following restriction for the interpretation of the study findings. The derived threshold concentrations from these experiments mark the upper exposure level rather than the actual exposure over the test duration. In conclusion the dose descriptors from the K3 studies do on one hand not support to raise the assigned overall effect level for an organism group over a level from a more reliable experiment. On the other hand the results give sufficient evidence to establish the value used for CSA, if they represent the lowest one.

Use of closed test systems to reduce the losses of the test item TCP and to assure exposure has recently been reported for two tests with a microalga (Selenastrum capricornutum, de Groot 2001) and a cladoceran (Daphnia magna, de Groot 2002). Based on measured concentrations the EC₅₀ values for biomass and immobility were 50 and 20 mg/L, respectively.

For invertebrates one acute toxicty GLP and guideline study with analytical measurements is available for Daphnia magna (De Groot 2002). This study reports EC50 of 20 mg/L. Another study with Ceriodaphnia cf. dubia) is referenced by CICAD (Kielhorn 2003), and revealed a noticable lower EC₅₀ value of 4.1 mg/L.

Two studies are available with 21 day exposure. One follows the OECD guideline 211 with Daphnia magna and found an EC10 for growth and reproduction at 6 mg/L (arithmetic mean of measured concentration). The NOEC of this study is 4.5 mgl/L. In another study only survival was reported (EC50=20 mg/L). Given the observed higher sensitivity of Ceriodaphnia cf. dubia as reported by Kielhorn 2003, the additional chronic study for invertebrates is not used in the consideration of the assessment factor.

A flow-through fish test with fathead minnow (Pimephales promelas) revealed a LC₅₀ 96 h value of 66.5 mg/L based on effective (measured) concentrations. For fish, one study was done which included analytical measurements and therefore a robust summary was prepared for this study. However, the study was not done according to GLP and some details of the study were lacking. For this reason two additional robust summaries were prepared for two fish studies that were done in accordance with GLP regulations and a recognized scientific method, although analytical measurements were not conducted. (OECD SIDS 2004)

Aquatic invertebrates are the most sensitive organism group towards 1,2,3 Trichloropropane toxicity.

• Solvay (2001) Internal memorandum: Evaporation of 1,2,3-trichloropropane during a 48-hour acute toxicity test at 20°C. Weesp, Solvay Pharmaceuticals, pp. 1–3 (Reference: AdG/AED/im/01.80, 19 July 2001).