New Research Highlights Pesticide Link to Early Menarche
Recent research from Spain indicates a potential link between certain agricultural chemicals and earlier onset of menstruation in girls. The study, featured in Environmental Research, tracked 506 female participants from the Spanish INMA (Environment and Childhood) project. It identified a correlation between increased levels of ethylene thiourea (ETU), a pesticide-related chemical, and a higher likelihood of earlier menarche.
Researchers analyzed urine samples of the children, collected when they were between 7 and 10 years old, and monitored them into adolescence. They investigated exposure markers to various modern pesticides, noting that some act as endocrine-disrupting chemicals that interfere with hormonal systems.
Public Health Concern Over Early Puberty
The study noted that earlier puberty is a rising public health concern. In many countries, the typical age for menarche now falls between 12 and 13, and there is evidence this age has decreased significantly over the past century. Early puberty has been associated with increased risks of metabolic, cardiovascular, and mental health issues, alongside certain hormone-related cancers.
Findings and Implications
The most significant finding involved ETU, a byproduct of ethylene-bis-dithiocarbamate fungicides like mancozeb. Girls with elevated ETU levels had a 32 to 39 percent higher chance of experiencing menarche during the study. The primary source of exposure for the general population is diet, especially from eating conventionally grown fruits and vegetables. Although pesticides also appear in some non-agricultural contexts, food remains the leading exposure route.
The average age at menarche among girls in the study was a little over 12, ranging from 9 to 15. Contrastingly, another finding linked detectable levels of TCPy, a metabolite of the insecticide chlorpyrifos, to later menarche.
Limitations and Future Research
Researchers emphasized that the study does not definitively prove that pesticides cause earlier puberty. While there are potential biological mechanisms, such as thyroid hormone effects, it was an observational study that cannot confirm causation. Primary limitations include estimating pesticide exposure from a single urine sample in childhood. This might not accurately represent long-term exposure, as these chemicals leave the body relatively quickly.
The study offers some of the initial prospective evidence connecting non-persistent pesticide exposure to the timing of puberty in girls. The authors urge further, larger-scale studies to validate these findings and understand how exposure to pesticide mixtures affects child development.
Reference: Freire, C., Olivas-Martinez, A., Castiello, F., Jimeno-Romero, A., Lopez de Calle, S., Suárez, B., Tardón, A., Rodriguez-Suarez, M.M., Guxens, M., Vrijheid, M., Beneito, A., Lopez-Espinosa, M.-J. (2026). Age at menarche and exposure to non-persistent pesticides in Spanish girls from the INMA (environment and childhood) project. Environmental Research, 300, p.124450. doi:10.1016/j.envres.2026.124450.
For additional details on this study, contact Newsweek editors Kara Dolman and Emma Lee-Sang.
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