Abstract
Extensive use of herbicides is common among rural agricultural workers in Sri Lanka. Recent studies have postulated their role in the development of chronic kidney disease of unknown etiology (CKDu). Paraquat and glyphosate are leading herbicides used by sugarcane farmers (SF), hence occupational exposure is inevitable. This study examined the expression of urinary paraquat, glyphosate and biomarkers among residential SF in CKDu emerging regions, Warunagama (WA) and Rahathangama (RH), in the Uva Province with non-endemic Matara (MA) in the Southern Province of Sri Lanka. Urinary glyphosate, Paraquat, kidney injury molecule -1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL) and β2-microglobulin (B2M) were determined using enzyme-linked immunosorbent assays (ELISA). Urinary creatinine, microalbumin, serum creatinine (SCr), serum cystatin C, estimated glomerular filtration rate (eGFR), and albumin creatinine ratio (ACR) were also assessed. Generally, herbicide residues and kidney injury biomarkers were higher in SF compared to the non-endemic MA. Creatinine-adjusted urinary glyphosate and paraquat levels were significantly higher in WA compared to MA. ACR in RH (median 14.9; IQR 5.4–393.1 mg/g) and WA (23.7; 11.5–64.6) was significantly higher than MA (4.3; 2.2–6.7). This study reports 39 individuals with impaired kidney function among SF in Sri Lanka for the first time. Urinary NGAL levels were significantly higher in both WA (median 2.14; IQR 1.28–6.15 ng/mg Cr) and RH (3.09; 1.15–9.09) compared to MA (1.28; 0.56–2.81). However, urinary KIM-1 levels in RH (3.2; 1.29–106.1 ng/g Cr) and WA (3.6; 1.94–115.1) were not significantly higher in MA (1.74; 0.76–116.9). Urinary NGAL (r = 0.493), eGFR (r = −0.147) and ACR (r = 0.171) significantly correlated with urinary glyphosate, but not with urinary paraquat levels. Urinary KIM-1 levels did not correlate with either urinary glyphosate or paraquat, while urinary B2M and serum cystatin C levels showed significant correlation with urinary glyphosate levels. The current study reports higher urinary herbicide levels among sugarcane farmers in WA and RH, and that is potentially linked to the subsequent decline in kidney function, as indicated by ACR, eGFR, and NGAL. We posit that these indicators may serve as markers to detect renal injury among herbicide-exposed SF in Rural Sri Lanka.
Highlights
Herbicide use is increasing in the world in a quest to scale up crop production [1]
Face masks/respirators, protective clothing, gloves, goggles, and boots were identified as the personal protective equipment (PPE) among the farmers
Farmers from all three study locations were found to have glyphosate and paraquat in urine, indicating previous exposure and was supported by the information collected in performed pesticide survey
Summary
In Sri Lanka, rice production is grown by 1.8 million tons, contributing to an annual production of 2.7 million tons. Weed control was mainly done manually, but labor migration and increased labor costs have led to the increased use of herbicides. Sugarcane, and vegetable farmers (90%) use herbicides to control weeds in Sri Lanka [2]. Glyphosate (N-(phosphonomethyl) glycine, C3H8NO5P) is one of the commonly used herbicide in Sri Lanka. Glyphosate exposure may contribute to the development of a wide variety of chronic diseases such as developmental disorders (autism), allergies, gastrointestinal diseases, endocrine dysfunction, cardiovascular diseases, Alzheimer’s disease, Parkinson’s disease, cancer and infertility [5,6,7,8]. Paraquat (1, 1 dimethyl–4, 4 –bipyridium dichloride) is a non-selective contact bipyridilium herbicide in frequent use since the 1980s [9]. Paraquat exerts its effects externally on the skin and eyes
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