Human health risk assessments of plastic-related compounds (phenolics, phthalates and PBDEs) in selected stream water and fish consumed in Nigeria

Abstract

In this study, we conducted human health risk assessments of plastic-related chemicals (phenolics, phthalates, and polybrominated diphenyl ethers) associated with drinking water and fish consumption in Nigeria. Water samples were obtained from three typical streams that provide drinking water for some rural populace. Twenty-three species of fish were obtained from sources typical of where members of the public obtain fish for consumption — a major market, artisanal fishery on the Lagos Lagoon, and artisanal fishery on the Osun River. Phenolic, phthalate and PBDE compounds were extracted separately from the water and fish samples, and quantified by gas chromatography–mass spectrometry (GC–MS). Risk assessments were performed using established models provided by the United States Environment Protection Agency (US EPA). Hazard index (HI) for the individual groups — phenolics, phthalates and PBDEs — exceeded the safe threshold of 1.0 in all the stream waters. This implies that the sum of concentration of chemicals of each group is sufficiently high to induce non-carcinogenic effects in exposed humans. The individual chemical (4-NP, BPA, DEHP, DBP, BBP and DnOP) had 100% detection frequency in all the fish samples. Sum of PBDEs (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153 and BDE-154) in fish from the different sources also exceeded the set Environmental Quality Standard (EQS) value of 8.5 × 10⁻⁶ by several orders of magnitude. Target cancer risk (TCR) for DEHP in the stream waters ranged from 0.003 to 0.007, exceeding the cancer risk acceptable threshold of 10⁻⁶ to 10⁻⁴. Similarly, TCR due to DEHP in the fish species from all sources ranged from 2 × 10⁻⁵ to 1.5 × 10⁻³, exceeding the 10⁻⁶ safe threshold. The results indicate that prolonged consumption of DEHP-contaminated fish from these sources poses a significant risk of cancer to exposed persons.