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The organochlorine insecticide aldrin is commonly used in intensive agriculture, and demonstrates estrogenic activity. Rotifers such as Brachionus calyciflorus are favored test animals in aquatic toxicology because of their more sensitivity to most toxicants. In the tested concentration range of 0.04-1.28 mg/L, aldrin shortened significantly the durations of embryonic development. Lower concentrations of aldrin had an intriguing effect on the reproduction of the rotifers and are beneficial to their survival. Different endpoints of both development and reproduction had different sensitivity to aldrin. The reproductive endpoint of the rotifers is more sensitive to aldrin than the developmental endpoint.

Phthalate esters (PAEs) are mainly used in the polymer industry as external plasticizers in PVC, and tend to migrate slowly out of the plastic, either into the air by volatilization or into water or other solvents by dissolution. Di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP) and di-2-ethylhexyl phthalate (DEHP) are three members of PAEs, identified as priority controlled hazardous substances by the United States Environmental Protection Agency, and have been shown to have potential for endocrine disrupting effects on vertebrates and humans. The effects of DBP, BBP and DEHP on survival and reproduction of the freshwater rotifer Brachionus calyciflorus were studied using life-table demographic methods. The results showed that all the life-table demographic parameters of B. calyciflorus were markedly affected by DBP and BBP, but not by DEHP. The net reproductive rate representing the output of reproduction was more affected than all the other parameters representing population growth, development or survival of the rotifers. Compared to the solvent control, DBP and BBP, both at 500 lg l -1 , significantly increased the net reproductive rate, and prolonged the generation time and the life expectancy at hatching of the rotifers. DBP at 50 lg l -1 markedly decreased the intrinsic rate of population increase of the rotifers, but the reverse was true for BBP at 50 and 500 lg l -1 . Among all the parameters, the intrinsic rate of population increase was the most sensitive to DBP and BBP. The levels of PAEs in water from all the studied rivers and lakes in the world did not affect the population growth of rotifers.

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