Mammary transcriptome of rats treated with low-dose environmental chemicals from birth to adulthood

Exposure to common environmental chemicals, including those found in personal care products has been linked to mammary cancer at high doses in animal models. Their effects at low doses at levels comparable to human exposure remain poorly understood. Using a Sprague-Dawley rat model, we investigated the effects of three prevalently used environmental chemicals – diethyl phthalate (DEP), methyl paraben (MPB), triclosan (TCS) – and their mixture (MIX) on the transcriptome of normal developing mammary at levels mimicking human exposure. Rats were exposed from birth to adulthood in parous and nulliparous settings. We used affymetrix arrays to assess the influence of diethyl phthalate (DEP), methyl paraben (MPB), triclosan (TCS) and their mixture (MIX) on global gene expression profiles in rat mammary tissues, using doses comparable to human exposure. Exposure was from birth to adulthood (postnatal day 1 – 180) in parous and nulliparous rats. Female Sprague-Dawley rats were treated by oral gavage with low doses of diethyl phthalate (DEP), methyl paraben (MPB), triclosan (TCS) or a mixture (MIX) of the three chemicals. These low doses were previously determined to produce urinary biomarker concentrations comparable to those reported for the US population (Teitelbaum SL, 2016). Control animals received the vehicle, olive oil (OIL). Exposure was from birth to adulthood (postnatal day 1 – 180) in parous and nulliparous rats. There were 5 animals in each experimental group.