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Environ Int. 2019 Sep;130:104897. doi: 10.1016/j.envint.2019.06.007. Epub 2019 Jun 18.

Airborne mammary carcinogens and breast cancer risk in the Sister Study.

Author information

1
Department of Epidemiology, University of North Carolina, 135 Dauer Drive, Chapel Hill, NC 27599, United States of America. Electronic address: nicole.niehoff@nih.gov.
2
Department of Epidemiology, University of North Carolina, 135 Dauer Drive, Chapel Hill, NC 27599, United States of America.
3
Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, United States of America.

Abstract

INTRODUCTION:

Potentially carcinogenic hazardous air pollutants (air toxics) have been inconsistently associated with breast cancer. Whether metabolic factors modify these associations is unknown. We studied 29 non-metallic air toxics classified as mammary gland carcinogens in animal studies in relation to breast cancer risk.

METHODS:

Participants included 49,718 women from the Sister Study. Census tract air toxic concentration estimates from the 2005 National Air Toxics Assessment were linked to enrollment residential addresses. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for individual air toxics were estimated using Cox regression. Body mass index (BMI) was considered a potential modifier. Relevant mixtures were identified using classification trees.

RESULTS:

Over follow-up (average = 8.4 years), 2975 women were newly diagnosed with breast cancer (invasive or ductal carcinoma in situ). Several air toxics, including methylene chloride, polycyclic organic matter, propylene dichloride, and styrene, were associated with increased risk. Of these, methylene chloride was most consistently associated with risk across multiple analyses. It was associated with overall (HRquintile 4vs1 = 1.21 (95%CI = 1.07-1.38)) and estrogen receptor positive (ER+) invasive breast cancer (HRquintile 4vs1 = 1.28 (95%CI = 1.08-1.52)) in individual pollutant models, although no dose-response was observed. Associations were stronger among overweight/obese (vs. non-overweight/obese) women (p < 0.05) for six air toxics. The classification tree identified combinations of age, methylene chloride, BMI, and four other toxics (propylene dichloride, ethylene dibromide, ethylidene dichloride, styrene) related to overall breast cancer.

CONCLUSIONS:

Some non-metallic air toxics, particularly methylene chloride, were associated with the hazard for overall and ER+ breast cancer. Overweight/obese women may be particularly susceptible to air toxics.

KEYWORDS:

Air toxics; Breast cancer; Hazardous air pollutants; Obesity

PMID:
31226564
PMCID:
PMC6679994
[Available on 2020-09-01]
DOI:
10.1016/j.envint.2019.06.007
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