Connecting Environmental Exposures to Toxicology: Exposure studies using Silicon Wristbands and Whole Model Organisms

Abstract

Silicone wristbands have emerged as passive sampling tools to monitor environmental contaminant exposures. They work by mimicking the skin, where SVOCs (semi volatile organic compounds) and VOCs (volatile organic compounds) can sorb onto the surface of the wristband and accumulate over time, providing time aggregated measures of chemical burden especially by dermal and inhalation routes of exposure. They are non-invasive compared to traditional techniques used to assess exposure, such as urine and serum collection, and relatively easy to transport and store, allowing for more participation. My research introduces an approach using zebrafish (Danio Rerio) to investigate biological responses to wristband extracts, focusing on neurobehavior as an endpoint. Neurobehavior is evaluated using a light/dark assay, wherein larvae respond to light and dark stimuli and deviation from the expected response to these stimuli is interpreted as indicative of potential developmental issues. After developing a protocol, I applied this methodology to explore the toxicity of chemicals captured on wristbands from a cohort based in a farming community at high risk of exposure to agrochemicals in Sri Lanka. The wristbands were worn for 7 days during a non farming season and captured varying exposures to chemical classes such as PAHs, Phthalates, Flame Retardants and Pesticides. Upon analyzing the total distance zebrafish swam in light and dark conditions, a Dunnet’s post hoc test revealed that zebrafish behavior in 7 out of 10 wristbands in the farmer group and 8 out of 10 wristbands in the non farmer group was statistically significantly different compared to the field blank. Most groups were showing hyperactivity in terms of the total distance traveled compared to the field blank, with one wristband exposure group showing hypoactivity. This was the first study to utilize wristband extracts for exposures in zebrafish, helping bridge the gap between exposure science and mixtures toxicology.