¹³⁷Cs activity concentration in soil was analyzed yearly for 13 years (2010–2022) in an undisturbed area in Mexico. The temporal variation at 17 sampling points is consistent with the natural radioactive decrease of ¹³⁷Cs, excluding increased activity concentration detected after the Fukushima accident at 4 sampling points. Geospatial analysis was permitted to obtain ¹³⁷Cs activity concentration distributions for each year. The highest ¹³⁷Cs activity concentration was found at higher topography levels and close to intermittent water streams: 87.1 ± 5.5 Bq kg⁻¹ for the year 2011, which increased to 135.5 ± 14.5 Bq kg⁻¹ for the year 2013, and then ¹³⁷Cs decreased down to 46.4 ± 4.0 Bq kg⁻¹ by the year 2022. The lowest ¹³⁷Cs activity concentration was in the range of 0.6 ± 0.1 Bq kg⁻¹ to 13.5 ± 1.0 Bq kg⁻¹ at the points far from the undisturbed area, probably due to anthropogenic activities.

Radiological effects on population and environment due to fracking unconventional hydrocarbons is given in this study. Evaluation on environmental effects concerning extraction process is given. Effects on fauna and humans during fracking process, including on air, water and soil, are mentioned. Unconventional oil and gas extraction generates Natural Occurring Radioactive Materials (NORM); their associations to radiological aspects are comment. Our environmental radiological baseline studies at three prospecting fracking zones in Mexico showed no radiological hazard to population. The natural gamma radioactivity before fracking had a maximum equivalent dose rate of 1.83 mSv a⁻¹, in the low value of the acceptable background interval (1–13) mSv a⁻¹ stated by UNSCEAR. The 226Ra and 228Ra maximum concentration obtained in soil (59.2 ± 3.6 and 38.5 ± 5.0 Bq kg⁻¹, respectively) for this baseline are both in the average global-interval concentration reported by UNSCEAR; gross alpha and gross beta in water were all below the suggested limits by the World Health Organization of 0.5 and 1.0 Bq L⁻¹, respectively, for drinking water. An important conclusion is that water stress is an important issue before considering fracking activities in Mexico.