Ecotoxicological aspects of chlorinated fatty acids

Abstract

Chlorinated fatty acids have been shown to be the major constituent of compounds contributing to the extractable organically bound chlorine found in fish and other environmental samples. Chlorinated fatty acids may occur naturally, however high concentrations in biota are connected to anthropogenic inputs either directly as in the case of pulp bleaching, or indirectly as they may be formed by metabolism of other chlorinated organic compounds. The ecotoxicological properties of chlorinated fatty acids are different from ‘traditional’ environmental pollutants such as polychlorinated biphenyls and DDT. Normally, three criteria need to be met for a compound to qualify as a persistent organic pollutant: lipophilicity, persistence and toxicity. The chlorinated fatty acids are not persistent in the traditional sense that they resist strong oxidising agents. Still they can be considered ‘biologically stable’ as they may persist within an organism incorporated into depot- and membrane lipids. Chlorinated fatty acids are accumulated by biota with high efficiency from food and they are therefore most probably being transferred in the food web. This transfer from prey to predator may be comprised in the suggested term, biological stability. These compounds have been shown to exhibit adverse effects in several toxicity tests using a variety of species as well as in mammalian cell cultures. For example, sperm motility has been impaired at concentrations as low as 0.057 mg l^-1. Despite their toxicity, chlorinated fatty acids do not induce enzyme systems such as P450 and EROD in fish, nor do they seem to induce other elimination efforts. Thus, they are apparently accumulated and otherwise treated as normal fatty acids. This lack of organism recognition of chlorinated fatty acids as xenobiotic compounds gives a new perspective on the risk assessment of these compounds, concerning both the modelling of their ecosystem fate and the design of test-systems for detection of their ecosystem effects.

Keywords :

• Chloroorganics
• Bioaccumulation
• Food chain transfer
• Biological stability
• Toxicity
• Chlorohydrins