Toxicology of phthalic acid esters in aquatic organisms.

Phthalic acid esters are presently being used in amounts and products that can easily, although inadvertently, contribute to environmental pollution. As plasticizers, phthalic acid esters are added to synthetic plastic resins to impart flexibility to the finished product, improve workability during fabrication, and extend or modify properties not present in the original resins (1). Plastic formulations may contain up to 60% of plasticizers (2). Phthalic acid esters are the most widely used plasticizers, particularly in poly(vinyl chloride) plastics. More than 800 million pounds of these plasticizers were produced in 1969 (1). Di-n-butyl and di-2ethylhexyl phthalates are used as plasticizers and also as an insect repellant and orchard acaricide, respectively (3). Phthalic acid esters have been identified as environmental contaminants because of their discovery in soil (4), a deep sea jellyfish (5), aquatic organisms and water (6), and bovine tissues (7,8). The acute toxicities of various phthalic acid esters have been determined in mammals and birds and the compounds were found to have a very low order of toxicity (3,9-12). Teratogenic effects of phthalic acid esters have been demonstrated in rats (13). Problems of phthalic acid esters leaching from plastics used in human medical practices have also been reported (14-17). The biological significance of phthalic acid ester residues in aquatic organisms is un-