50 chemical exposures of concern discovered using wearable passive samplers and gas chromatography high-resolution mass spectrometry in South African children

Abstract

BACKGROUND AND AIM: Children and other vulnerable populations in the developing world are increasingly prone to experience adverse health issues from environmental exposures. Comprehensive identification of chemical exposures in children is needed to determine which exposures are of most concern from a public health standpoint. METHODS: We deployed personal exposure monitors in Limpopo South Africa, as part of the Venda Health Examination of Mothers, Babies, and their Environment (VHEMBE) study. These exposure monitors consist of a polydimethylsiloxane (PDMS) as passive samplers, contained in a polytetrafluoroethylene capsule connected to a wristband. Passive samplers were worn by 147 children ages 5-6.5 years for about 2 days. Samplers were then analyzed by direct thermal desorption gas-chromatography high-resolution mass spectrometry. Spectra were screened across nearly 1 million chemicals using compound discover and in-house software, and exposure hazard information was obtained using the US-EPA CompTox Chemicals Dashboard and prototype Hazard Comparison. RESULTS:Personal exposure profiles consisted of 637 exposures with retention index, EI, molecular ion, and exact mass matches. Exposures included biocides, plasticizers, organophosphates, dyes, combustion products, and perfumes. Over 50 of these chemicals had predicted or experimental inhalation toxicity, oral toxicity, dermal toxicity, carcinogenicity, or were on priority lists. Exposure profiles changed across season, with chemicals used for malaria control or mosquito repellant (DDT, propoxur, and DEET) higher in the wet season, and many remaining chemicals reduced in the wet season likely due to heavy rainfalls scrubbing the air of contaminants. CONCLUSIONS:This study shows a diverse array of over 50 chemicals of health concern in South African children and is the first study to characterize exposure profiles of children in rural South Africa. Further work is needed to measure these prioritized chemicals in children’s blood and urine, determine acceptable cutoffs, and design interventions to reduce any chemicals that are shown to have direct health implications. KEYWORDS: Air pollution, external exposome, exposure assessment, omics technologies, mixtures, pesticides