Mining leachate contamination and subfecundity among women living near the USA–Mexico border
The contamination of the Sonora River with 40,000 m3 of toxic leachate released from a copper mine on August 6, 2014, was considered the worst environmental disaster of the mining industry in Mexico, exceeding safety levels in the concentrations of heavy metals and arsenic. To explore the potential association of the toxic release with subfecundity, by comparing time to pregnancy (TTP) of women with different levels of exposure at municipalities located along the Sonora River watershed, just 35 km south of the Arizona–Mexico border. Data from 235 pregnancies were included in a retrospective cohort study. Exposure was measured whether pregnancy occurred before or after the disaster and included a non-exposed community outside the watershed. Pregnancies were also compared between communities according to the concentration-level gradient of water pollutants found in the river. Fecundability odds ratios (fORs) were calculated using discrete time analogue of Cox’s proportional hazard models. Multiple analysis included all pregnancies with TTP of no more than 12 months, only first-time pregnancy, or excluding women with TTP = 1. The probability for pregnancy decreased after the disaster (fOR 0.55, 95% CI 0.31, 0.97), when the residency was located mid-or-downstream the watershed (fOR 0.37, 95% CI 0.15, 0.91), when reported chicken consumption, when mining was the father’s occupation, and when surface water was reported to be used for crop irrigation and for animal consumption. There was a decrease in fecundity on women exposed to the contaminated river. There is a need for more studies to prove these findings and to broaden the knowledge of other possible adverse health effects associated with this environmental disaster.
KeywordsWater pollution Time to pregnancy Environmental disaster of the mining industry
We give special thanks to participants of the study, to Derheyz Ochoa for the collaboration during the pilot study, to the research team of the Universidad de Sonora (senior medical students 2017) and from the Universidad Industrial de Santander.
Compliance with ethical standards
Conflict of interests
The authors declare they have no actual or potential competing financial interests.
The study was evaluated as low-risk study by the ethical committee of the Universidad de Sonora, Mexico, and the scientific research ethics committee of the Universidad Industrial de Santander, Colombia.
- Baird, D., Wilcox, A., & Weinberg, C. (1986). Use of time to pregnancy to study enviromental exposures. American Journal of Epidemiology, 124(3), 470–480. https://doi.org/10.1093/oxfordjournals.aje.a114417.CrossRefGoogle Scholar
- Dinno, A. (2011). Discrete time survival analysis. Stata library. https://alexisdinno.com/stata/dthaz.html. Accessed January 23, 2016.
- Fernandez, V. (2016). Massive spill highlights outdated water quality standards, government oversight in Mexico, Arizona. https://azcir.org/outdated-water-standards-poor-government-oversight-sonora-river-mexico/. Accessed November 20, 2016.
- Gomez, A., Valenzuela, J., Meza, D., De la O-Villanueva, M., Ramirez, J., Almendariz, J., et al. (2011). Impact of mining activities on sediments in a semi-arid environment: San Pedro River, Sonora, Mexico. Applied Geochemistry, 26(12), 2101–2112. https://doi.org/10.1016/j.apgeochem.2011.07.008.CrossRefGoogle Scholar
- Ibarra, M., & Moreno, J. (2017). La justicia ambiental en el Río Sonora. RevIISE - Revista de Ciencias Sociales y Humanas, 10, 135–155.Google Scholar
- International Agency for Research on Cancer. Working Group. (1980). Evaluation of the carcinogenic risk of chemicals to humans—some metals and metallic compounds. PhD Proposal, 23, 1–432.Google Scholar
- Jaimes, D. C., Rodríguez, L. A., & Sánchez, L. H. (2015). Tiempo para quedar en embarazo: Evaluación de su reproducibilidad en una cohorte retrospectiva. Revista de la Universidad Industrial de Santander. Salud, 46(1), 41–45.Google Scholar
- Kar, I., Mukhopadhayay, S. K., Patra, A. K., & Pradhan, S. (2017). Bioaccumulation of selected heavy metals and histopathological and hematobiochemical alterations in backyard chickens reared in an industrial area, India. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-017-0799-z.Google Scholar
- Lammers, G. (2014). Río Sonora. La historia detras del derrame. Poder, 5, 22–30.Google Scholar
- Marchenko Y, (StataCorp). (2007). Power analysis and sample-size determination in survival models with the new stpower command. http://www.stata.com/meeting/6nasug/marchenko_boston07.pdf. Accessed January 2, 2016.
- Valdéz, J., Reyes, A., Navarrete, E., & Canún, S. (2017). Bajo peso al nacer y defectos congénitos en relación con sitios mineros y campos agrícolas en Sonora, México. Prevalencia 2008–2012. Región y Sociedad, 5, 9–36.Google Scholar