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Toxicity to aquatic algae and cyanobacteria

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Description of key information

Based on read across some components of alkenes C11-14 are acutely toxic to algae at concentrations below their limit of solubility.

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Additional information

Data were read across from dodec-1 -ene. The toxicity of dodec-1 -ene to Pseudokirchneriella subcapitata was investigated in an OECD 201 test (Brixham Environmental Laboratories, 2010). Due to the low solubility of the test substance the study used a solvent carrier. The test substance was mixed with the solvent before being added to the dilution water. It was then stirred for 48 hours under sealed conditions to maximise the exposure concentrations. The test was carried out in sealed test vessels to minimise the loss of the test substance.

At the lower loading rates (0.032 -0.25mg/l) the measured concentrations were below the limit of detection (0.01mg/l) throughout the test. No effects were seen at these loading rates. A 96% effect was observed at 0.5mg/l, the next highest loading rate and a similar level of effect was also observed at the 1 and 2mg/l loading rates. Exposure concentrations at the 0.5mg/l loading rate were at the limit of detection at the start of the exposure and had dropped below the limit of detection after 72 hours. An EC50 has therefore not been calculated. Instead the results based on loading rate are a 72 EC50 of 0.25 -0.5mg/l and are interpreted as indicating effects below the limit of solubility.

Data are also read across from tetradecene. Hudson (1999) tested the toxicity of tetradecene to Skeletonema costatum in an ISO 10253 test. Due to the low solubility of the test substance test organisms were exposed to water accommodated fractions (WAF) and exposure concentrations expressed as a loading rate. The test was conducted with four exposure concentrations up to a maximum loading rate of 1000mg/l WAF. The 48 hour EL50 was >1000mg/l WAF, a NOELR was not reported.

These data indicate that the lower carbon number components of alkenes C11 -14 are more acutely toxic to algae than the higher carbon number components, as expected.