A Physiologically Based Approach To the Study of Bisphenol a and Other Estrogenic Chemicals On the Size of Reproductive Organs, Daily Sperm Production, and Behavior

TLDR

Bisphenol A and octylphenol, used in plastics and detected in food and water, are present at environmentally relevant levels, with a 2 ppb dose lower than the amount ingested after a plastic dental sealant. The study aimed to assess how gestational exposure to bisphenol A and octylphenol affects male offspring reproductive organ size and daily sperm production, and to introduce a physiologically relevant dosing framework for endocrine disruptors. Female mice were dosed from gestation day 11–17 with bisphenol A or octylphenol at 2 ng g⁻¹ (2 ppb) and 20 ng g⁻¹ (20 ppb) dissolved in oil. A 2 ppb bisphenol A dose permanently enlarged preputial glands while shrinking epididymides, a 20 ppb dose reduced sperm production efficiency by 20 %, and octylphenol only lowered daily sperm production and efficiency at 2 ppb.

Abstract

Two chemicals previously shown to have estrogenic activity, bisphenol A and octylphenol, were examined for their effects on accessory reproductive organs and daily sperm production in male offspring of mice fed these chemicals during pregnancy. These chemicals are used in the manufacture of plastics and other products, and have been detected in food and water consumed by animals and people. From gestation day 11-17 female mice were fed an average concentration (dissolved in oil) of bisphenol A or octylphenol of 2 ng/g body weight (2 ppb) and 20 ng/g (20 ppb). The 2 ppb dose of bisphenol A is lower than the amount reported to be swallowed during the first hour after application of a plastic dental sealant (up to 931 μg; 13.3 ppb in a 70 kg adult). We found that the 2 ng/g dose of bisphenol A permanently increased the size of the preputial glands, but reduced the size of the epididymides; these organs develop from different embryonic tissues. At 20 ng/g, bisphenol A significantly decreased efficiency of sperm production (daily sperm production per g testis) by 20% relative to control males. The only significant effect of octylphenol was a reduction in daily sperm production and efficiency of sperm production at the 2 ng/g dose. A new approach to studying physiologically relevant doses of environmental endocrine disruptors is discussed, particularly with regard to the development of the reproductive organs, the brain, and behavior.