Occurrence of legacy organochlorine pesticides in small mammals from two mountainous National Parks in southeastern Brazil

In southeastern Brazil, particular altitudinal grassland ecosystems, known as campos de altitude, occur at mountainous summits that host an outstanding level of biodiversity and endemism. However, despite being environmentally protected areas, several studies have shown their susceptibility to the impacts of climate change and airborne pollution. Previous studies highlighted that organochlorine pesticides (OCPs), present higher atmospheric concentrations along altitudinal gradients and can be locally deposited. On top of that, formerly used OCPs are still detected in the atmosphere on those mountaintops, long after their phase-out. Nevertheless, the potential bioaccumulation of OCPs by endemic species has not yet been assessed. Thus, we aimed to investigate the occurrence of OCPs in terrestrial subalpine wildlife and to establish a baseline for further in-depth studies on OCPs, or similar hazardous chemicals, in these endangered environments. In summary, 28 OCP congeners were investigated in 49 liver samples of ten small mammal species collected in 2013 and in 2016. Chemical analyses were based on gas chromatography coupled with electron capture negative ionization mass spectrometry (GC/ECNI-MS). Additional stable isotope analyses (δ 15 N and δ 13C) were performed to elucidate the role of trophic position on OCP bioaccumulation. Mirex, heptachlor, hexachlorobenzene, chlordane, and hexachlorocyclohexane congeners were the most frequently detected OCPs (59–97% of all samples). Regarding OCP contents in liver tissues, Mirex was also dominant. The atmospheric transport from secondary sources was assumed to be the origin of OCPs in the studied environment and their occurrence and difference between the two sampling sites are in good agreement with previous atmospheric monitoring. Further studies are needed to evaluate the exposure of campos de altitude endemic organisms to other airborne hazardous chemicals and to assess the potential toxicity posed by contaminant mixtures.