Utility of a C6-glioma system for exploratory risk assessment of environmentally relevant mixtures of insecticides

ROMERO, D.M; ALAIMO, A; GOROJOD R.M; KOTLER M.L.; WOLANSKY MJ

Baltimore, Maryland,USA

Congreso; SRA 2009 Annual Meeting Risk Analysis: The Evolution of a Science; 2009

Society for Risk Analysis (SRA)

Real environments and food products may carry low levels of multiple hazardous compounds having diverse modes of action. For instance, according to recent single-compound toxicological information from rats and environmental data, organophosphate (OP) and pyrethroid (PYR) insecticide residues pollute indoor and outdoor settings but in levels that imply no health risk for humans. However, there is a data gap on the neurotoxicology of complex insecticide mixtures. Here we present an exploratory, in vitro model, aimed to identify toxicologically relevant combinations of insecticides that require CRA-like research efforts in in vivo models of greater human relevance. We will show time (4-24-48 h)- and dose (0.5-250 uM; DMSO-vehicle control and five insecticide doses)-effect data for two OP and four PYR compounds. We use a C6-glioma culture system and a battery of effect measures to examine the individual and combined action of these insecticides. Moreover, two fetal calf serum (FCS) conditions are assayed (FCS 2-10%). Using 24h-exposed, C6 cultures in D-MEM supplemented with 2% FCS, followed by MTT assays for citotoxicity in 96-well plates, a high correlation between BMD15 estimates for cell viability and rat oral LD50s was apparent for three PYRs (deltamethrin>bifenthrin>tefluthrin). Chlorpyrifos (OP) and alpha-cypermethrin (PYR) did not fit well within this relative potencies trend. Acephate (OP) produced no evident C6-cell viability decrease in any exposure condition. We are presently testing if Hoechst-33258 histological observations and AchE assays in the C6 system may help interpreting above findings. These pilot studies will be used to appropriately design in vivo, environmentally relevant OP-PYR mixture studies aimed to test additivity using a battery of biochemical and neurobehavioral endpoints of neurotoxicity in the rat.