Environmental contamination of chrysotile asbestos and its toxic effects on growth and physiological and biochemical parameters of Lemna gibba.

Abstract

Asbestos was monitored in water, sediment, and aquatic plant samples around an asbestos cement factory. Based on asbestos concentration found in aquatic plants during monitoring, and the propensity of asbestos to cause oxidative stress in animal models, laboratory experiments were conducted to assess toxicity of chrysotile asbestos on an aquatic macrophyte, duckweed (Lemna gibba). L. gibba plants were exposed to two concentrations of chrysotile asbestos (0.5 microg and 5.0 microg chrysotile in 5.0 microl double distilled water) twice per week during a period of 28 days and cultured in medium containing 0.1 g chrysotile/L. Control plants were cultured in medium without chrysotile asbestos. Effect of chrysotile exposure on certain growth and physiological and biochemical parameters was evaluated. An inhibition effect of chrysotile exposure was found on the number of fronds, root length, and biomass. Similar alterations in contents of chlorophyll, carotenoid, total free sugar, starch, and protein were also found. Contrary to effect on these parameters, a dose- and time-dependent increase in efflux of electrolytes, lipid peroxidation, cellular hydrogen peroxide, catalase, and superoxide dismutase activity was found. The results indicate oxidative stress and phytotoxicity of chrysotile asbestos on duckweed.