{ "abstract": "Background\n\nBlack and Hispanic women are more likely to present with advanced-stage breast cancer and have lower survival rates compared to white women. Hair products are a source of exposure to environmental chemicals (e.g., formaldehyde, phthalates) that may contribute to these persistent inequities, particularly when used during sensitive exposure windows for breast tissue development (i.e., pregnancy, gestation). In this study, we examined the association between maternal hair product use during pregnancy and breast tissue composition (BTC) later in life among mothers and their adolescent daughters.Methods\n\nWe analyzed data from a prospective cohort of self-identifying non-Hispanic Black and Hispanic mother-daughter pairs in New York City (n = 186 daughters and 180 mothers). Mothers reported on their use of hair relaxers and hair dyes during and prior to pregnancy at a visit occurring in the third trimester. One to two decades later, the BTC of mothers and daughters was measured using optical spectroscopy, which estimates BTC properties that are positively (water, collagen, and optical index [Oindex]) and negatively (lipid) correlated with mammographic breast density, an intermediate marker of breast cancer risk. Adjusted multivariable linear regressions were used to examine the associations between hair product use (categorized as \"never,\" \"before pregnancy only,\" and \"during pregnancy\") and BTC.Results\n\nMaternal hair relaxer use during pregnancy (versus never use) was associated with several BTC measures among daughters and mothers, whereas hair dye use during pregnancy (versus never use) was only associated with Oindex among mothers (Adjusted βmother for Oindex = - 0.38; 95% CI = - 0.70, - 0.05). Consistent associations were reported between hair relaxer use and BTC among daughters and mothers. Specifically, hair relaxer use during pregnancy (versus never use) was associated with lower lipid content (Adjusted βdaughter = - 0.36, 95% confidence interval (CI) = - 0.65, - 0.07; Adjusted βmother = - 0.35, 95% CI = - 0.65, - 0.04), higher collagen content (Adjusted βdaughter = 0.33, 95% CI: 0.01, 0.64; Adjusted βmother = 0.34, 95% CI = 0.04, 0.63), and higher Oindex (Adjusted βdaughter = 0.47, 95% CI: 0.17, 0.77; Adjusted βmother = 0.50, 95% CI = 0.21, 0.79).Conclusions\n\nMaternal hair relaxer use during pregnancy was associated with BTC later in life for both mothers and daughters. The consistency of associations across generations suggest pregnancy and gestation are potentially sensitive periods for this exposure, capturing both maternal and prenatal influences on BTC with potential implications for breast cancer risk.", "abstract_shown": true, "affiliations": [ "Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York City, NY, USA. mc5799@cumc.columbia.edu.", "Department of Epidemiology, Columbia University Mailman School of Public Health, New York City, NY, USA. mc5799@cumc.columbia.edu.", "Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada.", "Laser Research Centre, University of Johannesburg, Johannesburg, South Africa.", "Department of Epidemiology, Columbia University Mailman School of Public Health, New York City, NY, USA.", "Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY, USA.", "Division of Clinical Immunology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York City, NY, USA.", "West Harlem Environmental Action Inc, New York City, NY, USA.", "Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York City, NY, USA.", "Silent Spring Institute, Newton, MA, USA." ], "article_type": "research article", "arxiv": null, "author_total": 12, "authors": [ { "affs": [ 0, 1 ], "name": "Marissa Chan" }, { "affs": [ 2, 3 ], "name": "Lothar Lilge" }, { "affs": [ 2 ], "name": "Jane Walter" }, { "affs": [ 4, 5 ], "name": "Parisa Tehranifar" }, { "affs": [ 6 ], "name": "Rachel L Miller" }, { "affs": [ 7 ], "name": "Anhthu Hoang" }, { "affs": [ 7 ], "name": "Peggy Shephard" }, { "affs": [ 8 ], "name": "Frederica Perera" }, { "affs": [ 8 ], "name": "Julie B Herbstman" }, { "affs": [ 4, 9 ], "name": "Mary Beth Terry" }, { "affs": [ 4, 5 ], "name": "Jasmine A McDonald" }, { "affs": [ 4, 5 ], "name": "Rebecca D Kehm" } ], "bibtex": "https://research.draconitic.com/paper/3n8nhn83km7qv.bib", "cited_by": 0, "doi": "10.1186/s13058-026-02353-1", "fulltext_url": "https://europepmc.org/articles/PMC13700334", "id": "3n8nhn83km7qv", "issns": [ "1465-5411", "1465-542X" ], "landing_url": "https://europepmc.org/article/MED/42928199", "language": "eng", "licence": "CC-BY-NC-ND", "licence_label": "CC BY-NC-ND", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "2307|Effects and risks of endocrine disrupting chemicals" ] ], "openalex": "W7171746049", "pdf_url": "https://europepmc.org/articles/PMC13700334?pdf=render", "pmcid": "PMC13700334", "pmid": "42928199", "published": "2026-07-29", "publisher": null, "ris": "https://research.draconitic.com/paper/3n8nhn83km7qv.ris", "sources": [ { "first_seen": "2026-10-30T12:21:20Z", "native_id": "MED:42928199", "source": "europepmc", "url": "https://europepmc.org/article/MED/42928199" } ], "subjects": [ { "field": "medicine", "origin": "openalex:2307|Effects and risks of endocrine disrupting chemicals", "subfield": "pharmacology-toxicology" } ], "title": "Use of hair relaxers and hair dyes during pregnancy and breast tissue composition in mothers and adolescent daughters.", "title_text": "Use of hair relaxers and hair dyes during pregnancy and breast tissue composition in mothers and adolescent daughters.", "type": "peer-reviewed", "updated_at": "2026-10-30T12:21:20Z", "url": "https://research.draconitic.com/paper/3n8nhn83km7qv", "venue": "Breast cancer research : BCR", "versions": [] }