Table 3.

Priority questions, current views, and issues for improving risk assessment for MG effects.

Priority question for risk assessment application	Current views	Outstanding issues
Are the rat and mouse adequate models for human MG development?		Current knowledge suggests that the rat and mouse are reasonable surrogates.		Lack of information about human pubertal development; mechanisms may differ among species.
What is the sensitivity of MG developmental effects?		In utero exposure in some studies leads to developmental effects at doses similar to or lower than other developmental and reproductive end points.		Few EDC studies assess both MG development and another sensitive end point of ED; there is a lack of human data to address dose response and a lack of standardized MG development protocol and assessment criteria.
Are MG developmental changes adverse?		These changes in MG are considered adverse because they represent alterations in growth and developmentb and may be a risk factor for lactation and/or cancer outcomes.		Varied definitions of “adversity,” depending on scientific discipline and context.
aBased on the majority viewpoint of the experts at the Mammary Gland Evaluation and Risk Assessment Workshop. bAccording to guidance from the U.S. EPA (1991, 1996).