Combustion of high-calorific industrial waste in conventional brick kilns: An emerging source of PFAS emissions to agricultural soils

Mujtaba Baqar; Rimsha Saleem; Maosen Zhao; Leicheng Zhao; Zhipeng Cheng; Hao Chen; Yiming Yao; Hongwen Sun

doi:10.1016/j.scitotenv.2023.167612

Combustion of high-calorific industrial waste in conventional brick kilns: An emerging source of PFAS emissions to agricultural soils

Sci Total Environ. 2024 Jan 1:906:167612. doi: 10.1016/j.scitotenv.2023.167612. Epub 2023 Oct 5.

Authors

Mujtaba Baqar¹, Rimsha Saleem², Maosen Zhao³, Leicheng Zhao³, Zhipeng Cheng³, Hao Chen³, Yiming Yao⁴, Hongwen Sun³

Affiliations

¹ MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; Sustainable Development Study Centre, Government College University, Lahore 54000, Pakistan.
² Sustainable Development Study Centre, Government College University, Lahore 54000, Pakistan.
³ MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
⁴ MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China. Electronic address: yimingyao@nankai.edu.cn.

PMID: 37804982
DOI: 10.1016/j.scitotenv.2023.167612

Abstract

The brick kilns in the South Asian region are widely documented to partially combust high-calorific waste components of synthetic-industrial origin, which contain hazardous constituents, including per- and polyfluoroalkyl substances (PFAS). Correspondingly, these establishments are necessarily built on agricultural land to easily acquire clay by excavating soil horizons, thus making cultivation soils vulnerable to PFAS contaminations. In this pioneering study, the occurrence, distribution profile, traceability and human health risk exposure to forty-four legacy and novel PFAS homologues, including two ultrashort-chain (C2-C3) PFAS, were investigated in agricultural soils around thirty-two conventional brick kilns across three districts of Pakistan. ⅀₄₄PFAS concentrations ranged from 14.3 to 465 ng/g (median: 28.2 ng/g), which were 2 to 70 folds higher than those in background soils, and slightly higher than those reported in agricultural soils in the global literature. The highest occurrence was observed for PFAS alternatives, i.e., 6:2 fluorotelomer sulfonate (6:2 FTSA) (40 %) and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) (4.5 %). A significant positive correlation (p < 0.01) was observed among the concentrations of short-chain perfluoroalkyl acids (C4-C7) and novel PFOS substitutes, implying their origin from common sources. Furthermore, ultrashort-chain and short-chain perfluorocarboxylic acids (PFCA) (89 %) and perfluorosulfonic acids (PFSA) (63 %) dominated over long-chain's PFCA (11 %) and PFSA (37 %), respectively. The estimated daily intake to children exposed in surrounding inhabited communities, at 95th percentile concentrations was found to be approaching the European tolerable daily intake limit of 0.63 ng/kg bw/day. Therefore, the brick manufacturing industry is identified as a novel source of PFAS in the adjacent environment and for residents. This suggests the need for further investigations to elucidate the origin of emerging contaminants in the waste streams of the region to safeguard ecological integrity.

Keywords: Agricultural soils; Brick kilns; Human exposure; Per- and polyfluoroalkyl substances (PFAS); Waste combustion.

MeSH terms

Alkanesulfonates
Alkanesulfonic Acids*
Child
Fluorocarbons* / analysis
Humans
Industrial Waste
Soil

Substances

fluorotelomer sulfonic acids
Soil
Industrial Waste
Fluorocarbons
Alkanesulfonates
perfluorosulfonic acid
Alkanesulfonic Acids