Residential proximity to industrial pollution and mammographic density

Abstract

[EN] Background: Mammographic density (MD), expressed as percentage of fibroglandular breast tissue, is an important risk factor for breast cancer. Our objective is to investigate the relationship between MD and residential proximity to pol-lutant industries in premenopausal Spanish women. MeOds: A cross-sectional study was carried out in a sample of 1225 women extracted from the DDM-Madrid study. Multiple linear regression models were used to assess the association of MD percentage (and their 95% confidence in-tervals (95%CIs)) and proximity (between 1 km and 3 km) to industries included in the European Pollutant Release and Transfer Register. Results: Although no association was found between MD and distance to all industries as a whole, several industrial sectors showed significant association for some distances: "surface treatment of metals and plastic" (j3 = 4.98, 95%CI = (0.85; 9.12) at <_1.5 km, and j3 = 3.00, 95%CI = (0.26; 5.73) at <_2.5 km), "organic chemical industry" (j3 = 6.73, 95%CI = (0.50; 12.97) at <_1.5 km), "pharmaceutical products" (j3 = 4.14, 95%CI = (0.58; 7.70) at <_2 km; j3 = 3.55, 95%CI = (0.49; 6.60) at <_2.5 km; and j3 = 3.11, 95%CI = (0.20; 6.01) at <_3 km), and "urban waste-water treatment plants" (j3 = 8.06, 95%CI = (0.82; 15.30) at <_1 km; j3 = 5.28; 95%CI = (0.49; 10.06) at <_1.5 km; j3 = 4.30, 95%CI = (0.03; 8.57) at <_2 km; j3 = 5.26, 95%CI = (1.83; 8.68) at <_2.5 km; and j3 = 3.19, 95%CI = (0.46; 5.92) at <_3 km). Moreover, significant increased MD was observed in women close to industries releasing specific pollutants: ammonia (j3 = 4.55, 95%CI = (0.26; 8.83) at <_1.5 km; and j3 = 3.81, 95%CI = (0.49; 7.14) at <_2 km), dichloromethane (j3 = 3.86, 95%CI = (0.00; 7.71) at <_2 km), ethylbenzene (j3 = 8.96, 95%CI = (0.57; 17.35) at <_3 km), and phenols (j3 = 2.60, 95%CI = (0.21; 5.00) at <_2.5 km). Conclusions: Our results suggest no statistically significant relationship between MD and proximity to industries as a whole, although we detected associations with various industrial sectors and some specific pollutants, which suggests that MD could have a mediating role in breast carcinogenesis.