Survey of contamination of estrogenic chemicals in Japanese and Korean coastal waters using the wild grey mullet (Mugil cephalus)

We monitored the contamination by environmental estrogens (EEs) of coastal areas in Korea and Japan using the wild grey mullet. The grey mullet were collected from Ansan, Jeju, Yeosu, Tongyeong, and Busan in Korea and Nagasaki, Omuta, and Fukuoka in Japan. Contamination by EEs was determined by measuring vitellogenin (VTG) levels in serum and identifying gonadal abnormalities histologically (i.e., testis-ova). In four sites in Korea (Ansan, Yeosu, Tongyeong, and Busan) and two sites in Japan (Nagasaki and Fukuoka), serum VTG in immature and male grey mullet was detected at levels greater than 1.0 μg/ml, which is considered to be an abnormal level. Although, testis-ova were observed in some individuals collected in Ansan, Tongyeong, and Busan in Korea and Omuta in Japan, there was no correlation between individuals with testis-ova and individuals with abnormal levels of VTG. Furthermore, in Japan, serum VTG levels of fish collected from Nagasaki and Fukuoka were also greater than 1.0 μg/ml. Although individuals with testis-ova were found in Omuta, these fish expressed normal levels of serum VTG. Our results suggest that the grey mullets living in these coastal areas are influenced by EEs in the environment. Furthermore, it appears that the production of VTG and the occurrence of testis-ova are caused by different mechanisms.