Chlorpyrifos risk assessment for aquatic biota and exceedence probability in Tres Arroyos-Claromecó (Argentina) basin

ALVAREZ M.; DU MORTIER C; VENTURINO A

Natal

Congreso; 9th Congress of Toxicology in Developing Countries and XIX Congress of Brazilian Society of Toxicology; 2015

Soc. Bras. Toxicol. - IUTOX

Buenos Aires Province (Argentina) has undergone in the last decades agreat increase in agricultural activities based on new technologies, with areduction of cultivar diversity. I.e., in Buenos Aires the area covered withsoybean was 5.9 million Ha during the cycle 2010-2011. Chlorpyrifos (CPF) isone of the insecticides most widely used in these crops and may constitute arisk for human health, birds, and aquatic biota such as macroinvertebrates andfishes.The objective of this study was to assess the risk derived from CPF usein aquatic life establishing P5-P10 percentiles for acute and chronic effects,to compare these endpoints with current aquatic life protection criteria, andto determine probabilities of exceedence of all these values considering CPFconcentrations in water and sediment at TresArroyos-Claromecó basin.CPF contents found in water and sediment samples obtained in 4 campaignsat different seasons in 4 streams of the basin were used to perform exceedence riskassessment. Reference CPF data for 40 (acute toxicity) and 28 (chronic effects)aquatic species were used to perform a Risk Assessment probit analysis andestablish P5 and P10 values (CPF concentrations affecting 5% or 10% of totalspecies respectively). Environmental CPF data at the local basin were alsoordered in a percentile distribution, and a probit model was fitted to data toobtain the probabilities of exceedence respect to risk endpoints(Joint-Probability curves). Aquatic life protection criteria from Canada(long term exposure: 0.002 µg/L; CCME, 2008) and the Water Resources ofArgentina (0.006 µg/L; 2005) were introduced in the analysis.Environmental CPF concentrations in water (N=40) ranged 0.0118-2.857µg/L, mean-SD 0.443±0.705 µg/L, median (25-75% quartiles) 0.171 (0.0761-0.432)µg/L. Sediment contained 2.90-242.5 µg/Kg, and CPF transfer to water wasestimated in 0.0125-0.0197% considering physical-chemical properties of thesamples. Exceedence probability analysis showed that water criteria wereexceeded 75% (Argentina) to 87% (Canada) of cases. Risk assessment P5 endpointswere 0.0141 and 0.00050 µg/L CPF for acute and chronic effects in aquatic liferespectively. These no conservative limits were respectively exceeded by 62%and 96% of cases in Tres Arroyos-Claromecó basin.Despite the relatively low CPF concentrationsfound in the basin, the probabilistic analysis suggests that a significantnumber of aquatic species may be seriously and unacceptably affected. Theprobability of exceeding water quality criteria for CPF concentrations in theregion is also very high. If aquatic life protection criteria are compared withthe probability risk curves, they should be established in 0.0005 µg/Lconsidering P5-CPF chronic effects.