LAUSR

In recent decades, changes in human behavior and new technologies have introduced thousands of new compounds into the environment called "contaminants of emerging concern" (CEC). These compounds have been detected in different environmental compartments such as soil, surface water, air, and groundwater. The presence of these contaminants in groundwater may pose risks to human health when used as potable water. In some urban areas in Brazil, groundwater is normally consumed without previous treatment. This study aimed to use statistical analysis by self-organizing maps (SOM) to evaluate the trends of CEC in urban groundwater systems. A total of 23 CEC compounds including pesticides, pharmaceuticals, and hormones were determined in groundwater samples using solid phase extraction and liquid chromatography-mass spectrometry. The CEC most frequently detected were atrazine and degradation products, fipronil, simazine, tebuconazole, hexazinone, and caffeine in concentrations up to 300 ng L-1. All studied compounds were detected in groundwater at least in one sample. Patterns in the data through SOM have shown a strong positive correlation between atrazine, hexazinone, simazine, tebuthiuron, 2-hydroxyatrazine, and 17β-estradiol. The hormones estrone and testosterone also show a positive correlation due to their similar chemical properties. On the other hand, caffeine was detected in 90% of the samples, likely due to a population habit of taking daily a hot drink made of yerba mate associated with low rates of treated domestic sewage in the study area.