OECD Guidelines for the Testing of Chemicals, Section 3

Environmental fate and behaviour

2074-577x (online)
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The OECD Guidelines for the Testing of Chemicals is a collection of about 150 of the most relevant internationally agreed testing methods used by government, industry and independent laboratories to identify and characterise potential hazards of chemicals. They are a set of tools for professionals, used primarily in regulatory safety testing and subsequent chemical and chemical product notification, chemical registration and in chemical evaluation. They can also be used for the selection and ranking of candidate chemicals during the development of new chemicals and products and in toxicology research. This group of tests covers environmental fate and behaviour. In 2017, the section 3 “Degradation and Accumulation” was renamed to “ Environmental fate and behaviour”  to take into account Test Guidelines measuring endpoints such as dispersion, aggregation.

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Test No. 316: Phototransformation of Chemicals in Water – Direct Photolysis

Test No. 316: Phototransformation of Chemicals in Water – Direct Photolysis You or your institution have access to this content

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16 Oct 2008
9789264067585 (PDF)

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This Test guideline describes studies on phototransformation in water to determine the potential effects of solar irradiation on chemicals in surface water, considering direct photolysis only.

It is designed as a tiered approach. The Tier 1 is based on a theoretical screen. The rate of decline of a test chemical in a direct photolysis study is generally assumed to follow pseudo first-order kinetics. If the maximum possible losses is estimated to be superior or equal to 50% of the initial concentration over a 30-day period, an experimental study is proceeded in Tier 2. The direct photolysis rate constants for test chemicals in the laboratory is determined using preferably a filtered xenon arc lamp capable of simulating natural sunlight in the 290 to 800 nm, or sunlight irradiation, and extrapolated to natural water. If estimated losses are superior or equal to 20%, the transformation pathway and the identities, concentrations, and rate of formation and decline of major transformation products are identified. An optional task is the additional determination of the quantum yield for various types of water bodies, seasons, and latitudes of interest.

The test chemical should be directly dissolved in the aqueous media saturated in air at a concentration which should not exceed half its solubility. For linear and non-linear regressions on the test chemical data in definitive or upper tier tests, the minimum number of samples collected should be 5 and 7 respectively. The exact number of samples and the timing of their collection is determined by a preliminary range-finding. Replicates (at least 2) of each experimental determination of kinetic parameters are recommended to determine variability and reduce uncertainty in their determination.

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