Objective To investigate the association of pesticide exposure and reproductive factors with breast diseases such as cysts, hyperplasic nodules, fibroadenomas, intraductal papilloma, and breast cancer in women, and to provide an epidemiological basis for the prevention and treatment of breast diseases.

Methods During the period of October to December in 2020, a breast ultrasound screening was carried out in various urban and rural areas of Liaoning Province, China (Shenyang, Liaoyang, Dandong, and Chaoyang), and 1 432 women were included. A questionnaire was utilized to gather data on their demographic characteristics and reproductive factors. These data were used to investigate the association of pesticide exposure and reproductive factors with breast diseases. We conducted a univariate analysis using the chi-square test as well as a multivariable logistic regression analysis on the indicators with significant differences.

Results The screening results showed that 416 women (29.0% out of total) in the disease group with average age at 46.46±8.57. The other 1 016 women were selected as the control group with an average age of 48.48±10.20. The univariate analysis showed the following significant indicators (P < 0.05): agricultural pesticides, household pesticides, herbicides, fungicides, age of menarche, duration of menstruation, age of amenorrhea, years of menstruation, years after menopause, number of live births, number of abortions, age at first birth, breastfeeding, and interval between menarche and first birth. The multivariate analysis showed that age of menarche < 14 yearsodds ratio (OR)=2.117, P=0.018, duration of menstruation ≥ 7 days (OR=1.717, P=0.049), age of amenorrhea ≥ 50 years (OR=2.375, P=0.007), and exposure to agricultural pesticides (OR=3.549, P=0.022) were risk factors for breast diseases, while breastfeeding (OR=0.437, P=0.014) was a protective factor.

Conclusion In order to reduce the incidence rate of breast diseases, it is necessary to strengthen the education on the knowledge of the use of pesticides and female reproductive physiology, advocate the correct conception of marriage and childbirth, encourage breastfeeding, and reduce pesticide exposure.