Purpose <p>This study tested the impact of a breast cancer screening decision aid (DA) that was adapted to include environmental risk information.</p> Methods <p>This was a pre-post study in communities with known per- and poly-fluoroalkyl substances (PFAS) contamination. Participants were 100 women ages 39–49, with no history of breast cancer and no mammogram in the past year. Participants completed a baseline survey, used the DA, then completed a final survey. Baseline surveys measured demographics, PFAS exposure, and PFAS-related risk perceptions. Paired pre-post survey measures included breast cancer risk perceptions, screening knowledge, decisional conflict, and screening intentions.</p> Results <p>Mean age of participants was 43&#xa0;years; most non-Hispanic white (97%); 43% resided in micropolitan, small town, or rural areas. Potential PFAS exposure included private well use for 35%; 19% had tested their water for PFAS contamination; 54% used a home water filter. While most (62%) did not experience PFAS-related stress, 27% felt stress about family well-being, and 25% often/constantly worried about the health effects of PFAS in the prior month. Pre-DA, 29% felt likely that they would develop breast cancer in the next 10&#xa0;years, versus 19% post-DA. Median knowledge scores increased from 8 to 10 out of 10 before and after DA use. Intentions to get a mammogram in the next year slightly decreased from 85 to 78%.</p> Conclusion <p>Use of a DA incorporating information about environmental risk information reduced perceptions of breast cancer risk and improved knowledge and decisional conflict about breast cancer screening among women living in PFAS-contaminated communities.</p> Clinical Trial Registration <p>NCT06098118.</p>