Nationwide distribution of per- and polyfluoroalkyl substances (PFAS) in road dust from India

In India, information on the occurrence and distribution of legacy and emerging per- and polyfluoroalkyl substances (PFAS) is deficient. In the present study, nationwide 79 road dust samples were collected from 12 states and 1 union territory for the analysis of 34 PFAS. Overall, total concentrations of 21 quantified PFAS (∑21PFAS) ranged 23-861 pg/g (median: 116 pg/g), with perfluorooctane sulfonic acid (PFOS) being predominant (median: 19.9 pg/g). Short to long chain perfluoroalkyl carboxylic acids (PFCAs; C4 - C18) were detected, where the concentrations of PFAS decreased with the increase in PFAS carbon chain length. ∑21PFAS was highest in road dust from urban area (n = 27; median: 230 pg/g), followed by suburban (n = 21; median: 126 pg/g) and rural areas (n = 31; median: 76 pg/g), suggesting environmental impacts of industriallization and urbanization on PFAS distribution. PFAS composition in rural road dust was significantly different from those in suburban and urban samples (p < 0.01). Regarding 4 geographical regions of India, PFAS in road dust showed spatial difference where higher concentrations were found in South India compared to other regions. ∑21PFAS were positively associated with city-wise population of India (rs = 0.40, p < 0.01). Strong to moderate positive correlation was observed between ∑21PFAS, fluorotelomer sulfonic acids, and PFCAs (rs = 0.23, 0.30, and 0.28, respectively; p < 0.05) and the total state-wise vehicles in India, suggesting that vehicles exhaust or non-exhaust (e.g., vehicle tire debris and polishing material) might contribute to the PFAS occurrence in Indian road dust. Toddlers (2-5 years) had the highest estimated daily intake of ∑PFAS via road dust ingestion under average-case and worst-case scenarios (0.55 and 1.16 pg/kg bw/day, respectively). This is the first time to evaluate PFAS in Indian road dust nationwide, aiding to provide first-hand data for human exposure to PFAS in India.

Nationwide distribution and potential risk of bisphenol analogues in Indian waters

Bisphenol A (BPA) has been frequently found in surface waters worldwide, and its estrogenic effects in humans are well documented. Nevertheless, less is known about other bisphenol analogues (BPs), such as bisphenol S (BPS) and bisphenol F (BPF) which are alternative to BPA. There have been few environmental investigations on BPs in developing countries, especially India. In the present study, eight BPs were analyzed, among which BPA, BPS, and BPF were found prevalent in surface water and wastewater from drains collected from 12 states and Delhi-National Capital Territory in India. The detection frequencies of BPA, BPS, and BPF were 67.6%, 41.9%, and 29.7%, respectively in all samples (n = 74). BPA was the predominant species among the three analogues. The highest BPA concentration was observed in the Yamuna River (14,800 ng/L), followed by the Cooum River (1,420 ng/L). The highest concentrations of BPS and BPF were 438 ng/L and 333 ng/L, respectively, both found in wastewater samples. The occurrence of BPS and BPF in nationwide surface water and wastewater samples from India for the first time suggests that new BPs as BPA replacements are being used and released in India. Ecological risk assessment of BPA, BPS and BPF exposure was performed using hazard quotient (HQ) for three aquatic taxonomic groups: algae, crustaceans, and fish, with the last group exhibiting the highest HQs (0.89-148) for BPA exposure. The human exposure risk of BPA through drinking river water was observed negligible in the present study. Our findings indicate the urgent need for, (1) regulations on the use and release of BPs in India, (2) effective processes to remove BPs in wastewater treatment plants, (3) more investigations on the distribution and toxicity of BPs in India, in particular BPA, BPS and BPF, as these analogues were detected at substantial concentration in Indian waters.

Accumulation of perfluoroalkyl substances in lysimeter-grown rice in Japan using tap water and simulated contaminated water

Perfluoroalkyl substances (PFASs) are a group of contaminants of concern in agricultural crops, but little is known of their accumulation or behavior in grains. We grew Japanese rice (Oryza sativa subsp. indica) in lysimeters irrigated with tap water or tap water plus simulated contaminated water for 2 years, then analyzed the roots, straw, unhulled rice, white rice, bran, soil, and water for PFASs residues. Total fluorine was measured by combustion ion chromatography. Estimated per-plant residue levels were 3.0 pg perfluorooctanesulfonic acid (PFOS) (bran: 0.5%, hull: 99.5%), 0.54 pg N-ethylperfluorooctanesulfonamide (N-EtFOSA) (white rice: 67%, hull: 33%), 1.2 pg perfluorobutanoic acid (PFBA) (white rice: 13%, bran: 7%, hull: 79%), 0.68 pg perfluoropentanoic acid (hull: 100%), 0.50 pg perfluorohexanoic acid (PFHxA) (white rice: 65%, bran: 16%, hull: 19%), 0.21 pg perfluoroheptanoic acid (hull: 100%), 0.25 pg perfluorooctanoic acid (PFOA) (hull: 100%), and 0.12 pg perfluorodecanoic acid (PFNA) (white rice: 81%, bran: 19%). Estimated daily PFASs intakes were <1-3 ng perfluorooctanesulfonamide, <1-7 ng N-EtFOSA, 1-2 ng PFBA, <3-4 ng PFHxA, and 1-2 ng PFNA. Estimated PFOS, PFOA, and total PFASs in straw feed were 0.4, 0.1, and 2 kg yr^-1 and 0.7, 0.4, and 8 kg yr^-1 in 2015 and 2016, respectively. Estimated PFOS, PFOA, and total PFASs in straw fertilizer were 4, 1, and 23 kg yr^-1 and 7, 4, and 86 kg yr^-1 in 2015 and 2016, respectively. PFASs accumulation may cause longer residence time in agricultural systems owing to straw being used as animal feed and organic fertilizer.

Assessing exposure to legacy and emerging per- and polyfluoroalkyl substances via hair - The first nationwide survey in India

In recent years, environmental issues emerging from per- and polyfluoroalkyl substances (PFAS) have raised high concern worldwide. Levels of human exposure to PFAS remain unknown in India. Biomonitoring data obtained from hair analysis have been evidenced to provide insight into retrospective human exposure to PFAS. In this study, 25 PFAS, including perfluoroalkyl acids and their precursors, were measured in 39 human hair samples collected from 14 cities in India. The inuflence of gender on the PFAS levels was also examined. To our knowledge, this is the first attempt to provide preliminary indicative data (due to the limited sample size and variability in hair-length sampling) on the levels of PFAS in Indian hair. The concentrations of total PFAS in hair varied from below matrix-specific limit of quantification (<0.02 ng/g) to 3.78 ng/g. Among 9 PFAS quantified, perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), and perfluorooctanoic acid (PFOA) were the predominant compounds. Categorized into 4 regions, PFAS contamination exhibited certain regional difference where South India may show higher levels than the other regions. Highly significant positive correlation was observed between PFHxS and PFOS (p ≪ 0.001; r = 0.644), suggesting similar pathways of exposure to the two compounds. Higher PFAS occurrence was generally observed in the hair of females. Our results highlighted the urgent need to investigate the deposition mechanism of PFAS in hair.