Groundwater is considered the primary source of agricultural irrigation and drinking water in many regions of the world. La Comarca Lagunera in Mexico is one of the most important metallurgical centers and farming regions. The extensive and intensive agricultural activity in the area has led to a significant increase in pesticide use, resulting in the presence of organochlorine and organophosphorus pesticides in environmental and biological matrices. This research aims to evaluate the presence of organochlorine and organophosphorus pesticides in La Comarca Lagunera groundwater and their relationship with spatial factors and the physicochemical characteristics of the water. Thirty-eight wells (supply and irrigation) in eight localities were monitored in the study area. Sampling was performed following NOM-AA-104-(Jaramillo, et al., 1988) regulation, and extraction was done using solid-phase extraction. For glyphosate and AMPA, samples were processed using high-performance liquid chromatography (HPLC) coupled with a fluorescence detector (FLD). The other compounds were analyzed by gas chromatography coupled with tandem mass spectrometry (GC-MS) using an electron capture detector (ECD) and a nitrogen–phosphorus detector (NPD). Sixteen pesticides and byproducts were detected. DDT, DDE, ethyl parathion, and methyl parathion in 25 wells and α-BHC in 28 wells were the most detected compounds. γ-BHC (9 wells) and ethyl parathion were the organochlorine and organophosphorus compounds with the highest concentration, 331.853 ng L −1 and 5.432 ng L −1 , respectively. Malathion, ethyl, and methyl parathion were widely detected. However, these compounds are not regulated in water for use and consumption despite their possible environmental and human health risks. Sampling depth, crop type, and water use play an important role in pesticide distribution in the area; additionally, dissolved oxygen, pH, and temperature were water factors affecting the pesticide concentration in wells. The presence of numerous pesticides in water intended for human consumption is a serious concern in La Comarca Lagunera.
Góngora-Echeverría et al. (Fri,) studied this question.