Exposure of Chironomus riparius larvae to 17alpha-ethynylestradiol: effects on survival and mouthpart deformities.

Evidence from field studies shows that mouthpart deformities in chironomid larvae are a sublethal response to pollution. Interest has been shown to use this end-point in programs for monitoring sediment quality. During laboratory studies, however, deformities were induced in only a few single pollutant exposures. These deformities develop at the endocrine regulated molting stage and disruption of this complex process is likely at the base of their ontogeny. Aiming to clarify the processes involved in the rise of such deformities, we tested the effects of ethynylestradiol (EE2) in an in vivo lab study. Chironomus riparius larvae were exposed to 1, 10 and 100 microg l(-1) EE2 (nominal concentrations). No adverse effects on the larvae, for the investigated end-points (survival and deformity induction), were found.