Methylcyclohexane

Toxicity to aquatic algae and cyanobacteria

Description of key information

EC50 (72h) = 0.134 mg/L (P. subcapitata, OECD 201)
NOErC (72h) = 0.0221 mg/L (P. subcapitata, OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:

0.134 mg/L

EC10 or NOEC for freshwater algae:

0.022 mg/L

Additional information

One study investigating the toxicity of Methylcyclohexane to freshwater algae is available. The study was conducted according to a Japanese guideline (Circular on Test Methods of New Chemical Substances (Japan), Alga, growth inhibition test) using Pseudokirchnerella subcapitata as test organism. This static GLP study (MOE, 2008) determined an EC50 (72h) of 0.1339 mg/L and a NOEC (72h) of 0.0221 mg/L on the basis of measured concentrations (geometric mean). The static test design had a large influence on the substance stability during the test. During the testing, 99% of the test substance was declined after 24 hours from all vessels at the same level. This indicates, that triggered by the high volatility of Methylcyclohexane, an accumulation of the test substance in the head space has taken place. Thereafter the dissolved concentrations in all test vessels remained constant till the end of the test. This indicated that the steady-state of the closed system, as well as the maximum partition of the test substance in the aqueous phase, were attainted within 24 hours and were stable thereafter. As the dissolved concentrations of the test substance were well coordinated with the nominal concentrations (R2 = 0.9885) and the test results revealed a significant “concentration-effect relationship, the test results are considered to be reliable and to reflect more closely “real-world conditions” for this highly volatile chemical.