Evaluation of multigenerational effects of 2-ethylhexyl 4-hydroxybenzoate in Japanese medaka Abstract

The Japanese medaka (Oryzias latipes) extended one-generation reproduction test (MEOGRT) (Test Guideline 890.2200) is a Tier II test within the Endocrine Disruptor Screening Program of the US Environmental Protection Agency (US EPA). A modified MEOGRT was used to evaluate multigenerational effects of 2-ethylhexyl 4-hydroxybenzoate (2-EHHB) under flow-through conditions starting with adults (parent generation, F0) through a 3-week reproductive phase of the second generation (F2). Fish were exposed to one of five 2-EHHB test concentrations or a dechlorinated tap water control. Fecundity was affected at the lowest exposure (5.32 µg/L) and greater sensitivity occurred in the F1 and F2 generations. Percent fertility was also diminished progressing from >101 µg/L in the F0 generation to 101 and 48.8 µg/L in the F1 and F2 generations, respectively. Growth indices were decreased for F0 adult females and F1 subadults and adults at 48.8 µg/L 2-EHHB. Histopathologic examination of gonads, liver, kidney, and thyroid yielded possible delayed reproductive tract development in F1 subadult males, masculinization of the renal phenotype in F1 adult females (renal tubular eosinophilia), and reduced hepatic energy storage (liver glycogen vacuoles) in F1 males at 11.3 µg/L and F1 and F2 generation females at 48.8 µg/L. Endocrine-related findings included a decrease in anal fin papillae in F2 adult males at 101 µg/L. Results of this study demonstrate effects on growth, development, and reproduction that may be mediated by endocrine (weak estrogenic) and non-endocrine mechanisms. Duration of the MEOGRT should not be routinely extended beyond the OCSPP 890 guideline study design. Citation information for this dataset can be found in the EDG's Metadata Reference Information section and Data.gov's References section.