The ESPINA Study 19th Year Follow-Up: A Longitudinal Investigation of Pesticide Exposures in relation to Fertility and Hormonal Health

Global fertility has declined, with sperm count and quality dropping by 50-60% since the 1970s due to lifestyle, environmental, and metabolic factors. Women face reduced ovarian reserves from delayed maternal age and rising rates of reproductive disorders like polycystic ovarian syndrome and endometriosis. Pesticide exposure is linked to fertility issues in both sexes, with insecticides affecting sperm count, motility, and hormone levels in men, and ovarian reserve and menstrual cycles in women. Most existing studies have been cross-sectional, focused on specialized populations (e.g., fertility patients), had small sample sizes, included participants with limited pesticide exposure potential (urban settings), or lacked biomarker measurements for exposure assessment. Longitudinal population-based studies using biomarkers of exposure are needed. In the Secondary Exposures to Pesticides among Children, Adolescents, and Adults (ESPINA) study, an 18th-year follow-up is proposed for 2026, when participants will be 21-27 years old (N≈500), corresponding to their peak reproductive years. This study, based in Pedro Moncayo County, Ecuador, a region known for one of the largest concentrations of flower crops in the Americas, exporting roses to the USA and globally. Our objective is to assess the long-term impact of pesticide exposure on fertility and endocrine health from early adolescence to young adulthood. We propose to measure reproductive biomarkers in stored biospecimens collected during follow-up years (FUY) 8 (adolescence), 14 (adolescence- young adulthood), and 18 (young-adulthood) and leverage existing insecticide (neonicotinoid, pyrethroid organophosphate) and herbicide (2,4-D, glyphosate) urinary biomarker data at 7 exam periods (FUY 8, 14, 15a, 15b, 16a, 16b and 18 [new]). We propose the following specific aims: Aim 1: Pesticide Exposure and Female Fertility. We hypothesize that insecticide and herbicide biomarkers are associated with: 1a) decreased ovarian reserve. Primary: lower anti-Müllerian hormone concentration (AMH); Secondary: higher early follicular phase follicle-stimulating hormone (FSH) and estrone-3-glucuronide. 1b) endocrine alterations: higher testosterone (T), and thyroid stimulating hormone (TSH); lower free T4 (fT4). 1c) delayed ovulation, confirmed by daily measurements of reproductive hormones during 1 menstrual cycle; secondary: greater oligomenorrhea (cycles>35 days) and dysmenorrhea (pain). Aim 2: Pesticide Exposure and Male Fertility. We hypothesize that these pesticides are associated with: 2a) lower motile sperm concentration and progressive motility; 2b) higher LH, FSH, 17β-estradiol (E2), T and TSH, and lower fT4 assessed in FUY 8, 14, 18; 2c) higher prevalence of erectile dysfunction symptoms. This research builds on long-standing community-engaged efforts in a major agricultural region and is one of the largest studies on pesticide exposure and fertility. The findings will offer critical insights into how chronic pesticide exposure impacts human fertility, with implications for global public health and pesticide regulation.