Reproductive effects and bioconcentration of 4-nonylphenol in medaka fish (Oryzias latipes)

The objective of this study was to investigate the reproductive success (fertility and fecundity) of medaka (Oryzias latipes) exposed to 4-nonylphenol (4-NP) in water and the viability of their F1 offspring. In addition, we measured the bioconcentration of 4-NP in eggs. After a 21-d exposure to 100 μg/l 4-NP, medaka showed reduced egg production and fertility. Hepatic vitellogenin levels were increased significantly in males treated with 10, 50 and 100 μg/l of 4-NP. In the F1 generations, the hatchability and time to hatching of embryos in the 100 μg/l treatment group were adversely affected, and 2–7 μg 4-NP/g egg was found in spawned eggs (the bioconcentration factor: 30–100). These results indicate that (1) 4-NP adversely affected the reproduction (fecundity and fertility) of adult medaka, (2) 4-NP accumulated in eggs through maternal transfer and (3) these levels of 4-NP were associated with adverse effects in the F1 offspring.