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PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

4-Cyclohexan-1-ol, dodecyl, branched was tested for ready biodegradation according to OECD 301B (July 1992). A suspension of the test tem in a mineral medium, corresponding to 20 mg/l TOC was inoculated with activated sludge (30 mg d.s./l) of a predominently domestic wastewater treatment plant. The test vessels were aerated by the passage of carbon dioxide-free air and were incubated under aerobic conditions in diffuse light for 28 days. Degradation was followed by determining the carbon dioxide produced and absorbed to sodium hydroxide via IC-measurement. A reference control (sodium benzoate, 20 mg DOC/l) and a toxicity control (test item and sodium benzoate in an amount of 40 mg organic carbon/l) were tested in parallel. The mean degradation extent of the test item was -7% within 28 days after acidification (mean value of three test vessels). The reference compound sodium benzoate reached the pass levels for ready biodegradability within 4 days. The degradation in the toxicity control reached 40.6% with 11 days, showing that the test item had no toxic effect to the activated sludge.

Therefore the test item 4 -Cyclohexan-1-ol, dodecyl, branched was judged to be not biodegradable according to OECD 301B. Thus the substance may be persistent in the environment.

The log Kow (Pow) for Cyclohexanol, 4-C11-12-alkyl, branched measured according to OECD guideline 117 was 7.1 at approx. 22° C and a pH of 6-7.

Three different structures of possible components of the Cyclohexanol, 4-C11-12-alkyl, branched were used for the calculation of the BCF. There were used C11 and C12-alkyl structures with different branching. The BCFBAF version 3.01 programme of the EPI Suite software (EPIWEB 4.1) was used to predict the BCF of the structures using the smiles codes. Based on a Arnot-Gobas method upper trophic the BCF were between 561.5 and 798.5. Based on the regression-based method the BCF were between 2186 and 11890 L/kg wet-weight. Because the Arnot-Gobas upper trophic model takes also into account the biotransformation rate constant of the substance by the organism it is lower but also much more realistic. Therefore it is concluded that the substance Cyclohexanol, 4-C11-12-alkyl, branched is not bioaccumulative (B) or (vB) because the BCF is below 2000.

Reliable (Klimisch 1) short-term toxicity studies for fish, algae and daphnia are available for Cyclohexanol, 4-C11-12-alkyl, branched and show that the substance is not toxic (T) for aquatic species (acute LL50 and EL50 values for daphnids, fish and algae are all > 100 mg/L).

The short-term toxicity of Cyclohexanol, 4-C11-12-alkyl, branched to fathead minnows (Pimephales promelas) was reported by Brougher et al., (2012) in an OECD 203 guideline and GLP compliant study. Fathead minnows were exposed to the test substance in nominal concentrations based on WAF loading rates for 96 hours, resulting in a 96 -hr LL50 of >100 mg/L. Brougher et al., (2012) reported an OECD 202 guideline and GLP compliant study. Daphnia were exposed to the test substance in nominal concentrations based on WAF loading rates for 48 hours, resulting in a 48-hr EL50 of >100 mg/L. The toxicity of Cyclohexanol, 4-C11-12-alkyl, branched to freshwater green alga Pseudokirchneriella subcapitata was reported by Arnie et al., (2012) in a GLP compiant OECD 201 guideline and EPA OCSPP 850.4500 study. Algae were exposed to the test substance in nominal concentrations based on WAF loading rates for 96 hours, resulting in a 72-hr ErL50 of >100 mg/L.

The median lethal dose of Cyclohexanol, 4-C11-12-alkyl, branched after a single oral administration to female rats, observed over a perid of 14 days is LD50 > 2000 mg/kg. At a dose of 300 mg/kg bw/d after 2 h 3 animals showed slight piloerection. At 2000 mg/kg bw/d after 30 minutes there were no signs of toxicity, after 2 and 3 h slight piloerection was seen in all six animals, 3 animals showed slightly reduced spontaneous activity and bradykinesia after 4 h, after 5 hours the 3 animals showed moderately reduced spontaneous activity and moderate piloerection and d 2 until the end of the observation period no signs of toxicity were seen in all animals. None of the animals showed weight loss during the observation period.

Thus the (T) criterion is not fulfilled.