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Ecotoxicological information

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The acute toxicity to fish to 2,2,4-Trimethylpentanediol (TMPD) has been evalauated using a number of species and various concentrations and exposure times. In the key study for fish, bluegill (Lepomis macrochirus) were exposed in a 96 -hour study at concentrations up to 700 mg/L. In that study 50% mortality was not observed (LC50 > 700 mg/L) and a NOEC of 420 mg/L was reported.

In a second study four different fish species were exposed to TMPD for various exposure periods and at concentrations up to 2000 mg/L. Most of the experiments were conducted with short exposure periods of 7 -8 hours, which is insufficient for hazard classification purposes. However, a set of 120 hours exposures at 7.5 and 75 ppm with catfish (Corydoras aeneus) were conducted which resulted in no mortalites being observed at either concentration tested.

The acute toxicity of the test substance to Daphnia magna was determined in two different 48 -hour studies. In the key study a limit test was conducted at a mean measured concentration of 109.1 mg/L. No immobility was observed during this study. In a second study utilizing nominal concentrations ranging from 350 -2000 mg/L, the 48 hour EC0, EC50, and EC100 were determined to be 700, 960 (95% CL= 901 -1080) and 1400 mg/L respectively.

The inhibition of growth of the alga, Selenastrun capricornutum, was evaluated in a 72 -hour limit test following OECD 201. The test was conducted at a mean measured concentration of 110.1 mg/L and inhibition was not observed (NOEC = 110.1 mg/L). A second study evalauated the algistatic concentration of TMPD using the freshwater blue-green alga, Microcystis aeruginosa. While the study did not report NOEC and EC50 values, those endpoints for biomass were empirically derived from the study data. Biomass cell counts were conducted after 72 and 120 hours of exposure and the 72 and 120 hour EC50s for biomass are estimated to be >1000 and >180 mg/L respectively. A 72 hour NOEC for biomass of 100 mg/L can also be emperically estimated from the data.

The toxicity of TMPD to microorganisms has not been evaulated. However, the substance has been shown to be readily biodegradable in two different ready biodegradation studies, and 100% biodegradation was observed in a wastewater simulation study.