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Acute immobilisation in Daphnia has been investigated in a 48 hour test according to OECD test methods and using dissolution/dispersion agents to increase concentration of the substance in the test medium. The EC50 (48h) was determined to be >180 mg/L and the NOEC was 180 mg/L, the highest concentration investigated.


 


Algal growth inhibition has been investigated in a 72 hour test according to OECD test methods and using dissolution/dispersion agents to increase concentration of the substance in the test medium. The EC50 (72h) was determined to be >100 mg/L and the NOEC was 100 mg/L, the highest concentration examined.


 


Acute toxicity to fish has been investigated in a 96 hour test according to OECD test methods and using dissolution/dispersion agents to increase concentration of the substance in the test medium. The LC50 (96h) was determined to be >100 mg/L.


 


Chronic toxicity to Daphnia has been investigated in a 21 -day reproduction test 48 hour test according to OECD test methods and using dissolution/dispersion agents to increase concentration of the substance in the test medium. The NOEC (21 -day, reproduction) was 55.6 mg/L; LOEC (21 -day, reproduction) was >100 mg/L and the EC50 (21 -day, reproduction) was 89.1 mg/L. A second chronic Daphnia study has been conducted according to ASTM/EPA test methods, again using dissolution/dispersion agents to increase concentration of the substance in the test medium. The following values were calculated: NOEC (21 -day, reproduction): 0.082 mg/L; LOEC (21 -day, reproduction): >0.082 mg/L; EC50 (21 -day, reproduction): >0.082 mg/L. These lower values compared with the first study reflect the achieved concentrations of the substance in the test media, this influenced by the agents used to achieve dissolution/dispersion.


 


Toxicity to fish has been investigated in 14 day test according to OECD test methods using dissolution/dispersion agents to increase concentration of the substance in the test medium. The 14 day NOEC was determined to be 75.0 mg/L. It is recognised that the duration of the OECD TG 204 test is shorter than that currently accepted for investigating long-term toxicity in fish.


 


A recent OECD 234 Fish Sexual Development Test has been conducted utilising Danio rerio LWT embryos (<12 hours post fertilisation) exposed mean measured concentrations of 0.35, 0.65, 1.37, 2.98 and 9.38 µg/L. Mean hatch success, time to last hatch, post-hatch survival and cumulative survival (pre- and post-hatch) in the solvent control was 96%, 4.0 days, 91% and 87%, respectively. There was no effect of exposure to TOTM on survival or time to hatch.  Statistical analysis indicated an apparent effect of TOTM (at concentrations of 0.35, 0.65 and 1.37 µg/L) exposure on post-hatch survival (and cumulative survival).  However, a negative trend between concentration and survival was not observed, and survival in the higher concentrations (2.98 and 9.38 µg TOTM/L) was comparable to that observed in the controls indicating that TOTM exposure does not impact fish survival. Mean wet weights and total body lengths, at 60 days post hatch, were 80.3 mg and 17.8 mm, respectively, for the solvent control. Statistical analysis indicated an apparent effect of TOTM on fish body size at 60 days post hatch in the intermediate exposure group (1.37 µg TOTM/L). However, there was no evidence for a relationship between concentration and magnitude of effect and fish body sizes were comparable in the higher concentrations (2.98 and 9.38 µg TOTM/L) and controls, suggesting that TOTM exposure does not impact fish growth. There was no evidence for an effect of exposure to TOTM on the proportion of male, female, undifferentiated or intersex fish (NOEC >9.38 µg/L).  Mean vitellogenin titres (in the head/tail homogenates) were 412 and 185022 ng/mL for the phenotypic male and female fish respectively.  There was no evidence for an effect of exposure to TOTM on male or female vitellogenin concentrations (NOEC >9.38 µg/L). Thus aqueous exposure of early life stages of zebrafish to concentrations up to 9.38 µg/L does not adversely affect health.  There is no evidence for an effect on the endocrine system (as assessed through determinations of phenotypic sex ratio and vitellogenin levels).