Exploratory report phthalic anhydride

Abstract

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This report contains general information on phthalic anhydride concerning the existing standards, emissions, exposure levels and effect levels. Since phthalic anhydride will rapidly hydrolyse to o-phthalic acid in the presence of water, this reaction product is included in the evaluation. In general data on phthalic anhydride are very scarce and incomplete, hampering a sound risk evaluation. In the Netherlands the registered emissions (0.57 tonne per year) are small (0.0005%) compared with the amount of phthalic anhydride produced, imported and applied (approx. 110,000 tonnes per year). For the general population, inhalation is considered the most likely exposure route. In one limited 8-month study with guinea pigs a LO(A)EL of 8,500 mug.m-3 was derived for phthalic anhydride. Based on the registrated emissions the exposure levels will not likely exceed the 1 mug.m-3 level. From this one may conclude that the risk of inhalatory outdoor exposure to phthalic anhydride to the general population seems to be small, if present at all. As to oral exposure, an tentative toxicological limit value of 0.375 mg.kg-1 bw per day NO(A)EL was derived from a two-year carcinogenicity study, applying a large safety factor (1,000). This tentative toxicological limit value is not likely to be exceeded. No data are available on the toxicity of phthalic anhydride and its main conversion product, o-phthalic acid, to aquatic and terrestrial species. Data on the occurrence in the environment in the Netherlands are scanty. Phthalic anhydride has been reported to hydrolyze very rapidly (estimated half-life of approx. 1.5 minutes). Consequently, its product is biodegraded rapidly as well. Taking into account the emission figures the risk for aquatic and terrestrial life is expected to be small. It is concluded that phthalic anhydride does not seem to present a significant risk to humans or ecosystems in the Netherlands. Therefore it is recommended not to stimulate in depth studies on phthalic anhydride but to remove phthalic anhydride from the attention substances list.