Top » What are the problems which are encountered in the GHS aquatic environment hazard classification?

Published by Jeff Burns on 30.09.2009 in and previewed 52 times


The aquatic environment is taken as the aquatic ecosystem in freshwater and marine, and the organisms that live in it. Some of the problems encountered in establishing the adequacy of data, interpreting the data and applying the data to the classification scheme are encountered in the following categories:

1. Poorly soluble substances
2. Unstable Substances
3. Volatile Substances
4. Complex or multi-component substances
5. Polymers
6. Inorganic compounds and metals
7. Ionizable Substances
8. Colored substances
9. Impurities

The basis for the identification of hazard to the aquatic environment for a substance is the aquatic toxicity of that substance. Classification is predicated on having toxicity data for fish, crustacean and algae/aquatic plant available. These factors are generally accepted as representative of aquatic fauna and flora for hazard identification. Data on these particular factors are more likely to be found because of this general acceptance by regulatory authorities and the chemical industry. Other information on the degradation and bioaccumulation behavior is used to better delineate the aquatic hazard.

For classifying substances in the harmonized system, freshwater and marine species toxicity data can be considered as equivalent data. It should be noted that some types of substances, e.g. ionizable organic chemicals or organometallic substances may express different toxicities in freshwater and marine environments. Since the purpose of classification is to characterize hazard in the aquatic environment, the result showing the highest toxicity should be chosen.
While performing testing of substances and mixtures difficulties are encountered. Valid aquatic toxicity tests require the dissolution of the tested substances in the water media under the test condition recommended by the guidelines. In addition, a bioavailability exposure concentration should be maintained for the duration of the test. Common properties of many types of substances which are likely to pose testing difficulties are:

1. Stability
2. Degradation
3. Saturation
4. Perturbation of test media
5. Complex substances

Each of these properties can present a complex interpretational problem, even for experts. While internationally agreed testing guidelines exist and should be used for any and all new data produced. It is clearly the objective of globally harmonized system that, having agreed on a common set of criteria, a common data-set should also be used so that once classified, the classification is globally accepted.

About Author

Jeff Burns is a writer for Nexreg Compliance Inc., a company that offers GHS services, GHS MSDS consulting and MSDS authoring.

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