Potential developmental toxicities of three different cigarette butt leachates were evaluated using the frog embryo teratogenesis assay-Xenopus (FETAX). Xenopus laevis embryos were exposed to regular cigarette butt (RCB), menthol (MCB) and electronic (ECB) in concentrations ranging from 0 to 4 butts/l for RCB and MCB and 0-10 butts/l for ECB. The embryos were from stage 8 to 11 and were exposed for a 96-h period in static renewal test conditions. Median lethal concentration (LC50), malformation (EC50), non-observed adverse effect concentration (NOAEC), and lowest observed adverse effect concentration (LOAEC) were calculated. Results from these studies suggest that each tested leachate is teratogenic for X. laevis embryos. The lowest LC50 was determined for ECB exposure at 17.9 cigarette butts/L. The LC50 value was the highest with RCB and MCB having LC50 s of approximately 1 cigarette butt/L. There were notable EC50 differences with RCB having the highest and ECB the lowest. The NOAEC and LOAEC levels for RCB and MCB were below 1 cigarette butt/L for both mortality and malformations; over 8 butts/L for ECB mortality and over 4 butts/L for malformations. From these results, we conclude that RCB leachate is the most toxic compound, while MCB leachate has the higher teratogenicity. ECB leachate has the lowest toxic and teratogenic effects on embryos but there were still noticeable effects. The results confirmed that the FETAX assay can be useful in an integrated biological hazard assessment for the preliminary screening for ecological risks of cigarette butts, and electronic cigarettes, in aquatic environment.
Keywords: Cigarette butt leachate; Development; Xenopus laevis.