Academic journal article Environmental Health Perspectives

Organophosphate and Pyrethroid Pesticide Exposures Measured before Conception and Associations with Time to Pregnancy in Chinese Couples Enrolled in the Shanghai Birth Cohort

Academic journal article Environmental Health Perspectives

Organophosphate and Pyrethroid Pesticide Exposures Measured before Conception and Associations with Time to Pregnancy in Chinese Couples Enrolled in the Shanghai Birth Cohort

Article excerpt

Introduction

Growing evidence suggests that human fertility rates are declining in both developed and developing countries (Clementi et al. 2008). This reduced fertility has been assumed to be associated with socioeconomic changes and adverse lifestyle factors (Den Hond et al. 2015; Snijder et al. 2012). However, environmental contaminants such as pesticides have attracted international attention and have recently come to be regarded as possible contributors to reduced human fertility (Mehrpour et al. 2014; Smarr et al. 2016).

China is one of the largest agricultural countries in the world, with >300,000 tons of agricultural pesticides used annually (Shu et al. 2016). Organophosphates (OPs) and pyrethroids (PYRs) are the most widely used groups of pesticides in agricultural and residential areas in China (Tan et al. 2006; Ye et al. 2015), with 70,000 tons of OPs used in the year of 2015 and 4,000 tons of PYRs used in the year of 2013, respectively (Shu et al. 2014, 2016). Environmental exposure to OPs and PYRs is thought to occur primarily via consumption of food contaminated with pesticide residues and via inhalation or ingestion of contaminated household dust after the application of pesticides indoors (Ding et al. 2015; Ji et al. 2011; Wang et al. 2012). Human exposure to OPs and PYRs is now widespread in many countries and has become a global health issue (Babina et al. 2012; CDC 2017; Imai et al. 2014; Martenies and Perry 2013; Mehrpour et al. 2014; Wang et al. 2012). Epidemiological studies conducted in China have demonstrated relatively high levels of exposure to OPs and PYRs in women, raising concerns about chronic exposures and potential effects on reproductive health (Ding et al. 2015; Ji et al. 2011; Liu et al. 2016; Wang et al. 2012; Xia et al. 2008).

Animal studies have found adverse effects of OP and PYR exposures on female reproductive functions, including inhibited steroid hormones, disordered estrous cycles, and restrained follicle cells, which might ultimately lead to decreased fertility (Fei et al. 2010; Geng et al. 2015; Guerra et al. 2011; Li et al. 2013; Okamura et al. 2009; Rao and Kaliwal 2002; Rastogi et al. 2014). Only a few cross-sectional studies have estimated associations between fertility and occupational pesticide exposures in women, and results have been inconsistent (Bretveld et al. 2006; Greenlee et al. 2003; Idrovo et al. 2005; Lauria et al. 2006). In a study of female flower workers in Colombia, self-reported occupational pesticide exposure was associated with a longer time to pregnancy (TTP) (Idrovo et al. 2005), but no significant association was found in a multicenter study in Italy based on a questionnaire survey (Lauria et al. 2006). None of these previous epidemiological studies assessed pesticide exposures by measuring pesticide metabolites in urine, and to our knowledge, no cohort study of pesticide exposures and infertility has yet been conducted. Therefore, we aimed to prospectively evaluate the associations between preconception pesticide exposure and couple fertility in Shanghai, China, where OPs and PYRs are the most widely used pesticides.

Methods

Study Population

To improve birth outcomes for couples who plan to become pregnant, the Chinese government promotes preconception care at designated clinics that provide health education and physical examinations (Zhang et al. 2016; Yang et al. 2015). The Shanghai Birth Cohort recruited women from two preconception care clinics in Shanghai, China. Detailed information on study recruitment has been described previously (Zhou et al. 2017). Briefly, women were eligible if they were registered Shanghai residents who were not planning to move in the next two years, were [greater than or equal to] 20 years of age, had stopped using contraception recently, and planned to conceive without assisted reproductive technology and to give birth in one of the hospitals participating in the Shanghai Birth Cohort. …

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