Reproductive Toxicity of 3,4-dichloroaniline (3,4-DCA) on Javanese Medaka (Oryzias javanicus, Bleeker 1854)

SIMPLE SUMMARY: Compound 3,4-dichloroaniline (3,4-DCA) is a degradation product of some herbicide and intermediate industrial chemicals of many products. Unregulated use of 3,4-DCA affects the reproduction of non-target organisms. In this study, the potential reproductive toxicity of 3,4-DCA on Javanese medaka, a native sentinel organism distributed around aquatic ecosystems of Southern Asia, was evaluated. Low fecundity was observed in female exposed fish to 250 µg/L of 3,4-DCA. Gonad tissue alternation and interference of gametes development were observed both in male and female exposed fish. The response pattern indicated that a low concentration of 3,4-DCA exerted endocrine disruption in Javanese medaka. This finding would provide additional data on the toxicity effect of 3,4-DCA, and it will strengthen the potential of native species in monitoring local and regional aquatic environments. ABSTRACT: Compound 3,4-dichloroaniline (3,4-DCA) is a metabolite of several urea herbicides and intermediate chemical of several industrial products. Moreover, 3,4-DCA has been frequently detected in aquatic ecosystems around the world. This aniline is more toxic than the parent chemicals, and it affects non-target organisms. This study evaluated a 21-day reproductive response of an emerging aquatic vertebrate model, Javanese medaka (Oryzias javanicus), exposed to 3,4-DCA. Fecundity and gonads histopathology were observed. The spawning rate and fertilisation reduced significantly in the highest exposed-group (250 µg/L). Gonadosomatic index (GSI) was significantly low in females exposed to 250 µg/L. No substantial structural alteration of male gonads. However, oocyte development and ovarian cell structure were disrupted in 250 µg/L exposed females. The gonadal developmental was not affected in the males; however, a significant reduction in the developmental of female gonads was observed at 250 µg/L. These results show that 3,4-DCA interfere with the reproduction of Javanese medaka through fecundity and alteration of gonadal tissues.