Occurrence and spatial distribution of organochlorine pesticides in the southwest Buenos Aires using the freshwater snail Chilina parchappii as environmental biomonitor

Organochlorine pesticides are highly toxic compounds for biota and humans that have been used for sanitary and phytosanitary purposes for many years in Argentina and the world due to their low cost and versatility. Despite a worldwide ban in the 1970s and 1980s, Argentina banned their use and production by the 1990s and in particular endosulfan during 2013. In the present research 1300 Chilina parchappii individuals – a wild native snail – were collected from eight freshwater locations in the Buenos Aires Province southwest, Argentina, in a period between April–May 2017, to assess the concentration levels, spatial distribution and putative input sources of 16 selected organochlorine pesticides (OCs) including endosulfan. Average concentration in snails ranged between 2.59 and 6.46 ng.g⁻¹, dry weight (dw) (mean = 4.27 ng.g⁻¹, dw), for ∑OCs, and from lower detection limit (<LD) to 1.21 ng.g⁻¹, dw. (mean = 0.53 ng.g⁻¹, dw), and from 0.39 to 5.25 ng.g⁻¹ (mean = 1.20 ng.g⁻¹, d.w.) for ∑HCHs and ∑DDXs, respectively. ∑Endosulfans ranged from <LD to 4.36 and accounted for 45% of the total OCs burden at the area. The general order of abundance was as follow: β endosulfan> 4,4-DDE> heptachlor exo-epoxide (isomer B)> aldrin>γ HCH>δ HCH> dieldrin>α HCH> 4,4- DDD>α endosulfan> endosulfan sulfate> 4,4-DDT>β HCH> heptachlor> endrin aldehyde> endrin.The principal component analysis allowed the classification of sampling sites according to the main OCs inputs over the area. In comparison to other worldwide freshwater bioindicators, Chilina parchappii DDXs and HCHs levels were in the low range; on the opposite, ∑OCs average was in the medium range.Data indicated that Chilina parchappii is accumulating OCs from the surrounding media (either in use or banned) setting a present alert for the endosulfan environmental burden.