Urinary Concentrations of Neonicotinoid Insecticides and Tubular Biomarkers, and Clinical Symptoms in Chronic Kidney Disease Patients, Their Family Members and Others in Dry-zone of Sri Lanka: a Small Scale Field-based Case-Control Study

Abstract

Background: The growing worldwide prevalence of chronic kidney disease of unknown etiology (CKDu) has been reported since the 1990’s. Neonicotinoids are systemic insecticides started to use in 1990’s with nicotinic acetylcholine receptor competitive modulator action, which may cause renal dysfunction as well as neurological symptoms.Methods: We conducted a field-based case-control study in the North Central Dry-zone of Sri Lanka where CKDu was prevailing. We collected spot urine samples of 92 residents, including 15 CKD patients, 15 CKD family members, and 62 neighbors in May or in December 2015, and analyzed seven neonicotinoids and a metabolite by LC-ESI/MS/MS, in addition to two biomarkers of renal tubule activity, Cystatin-C and L-FABP. The symptoms they complained of were also investigated by interview.Results: Urine was almost acidic and significant correlation was found in urinary concentration of Cystatin-C and L-FABP (r=0.71, p<0.001). In CKD patients in compare to non-CKD participants, urine Cystatin-C and L-FABP were significantly higher (p=0.0013, p<0.001, respectively) and more symptoms complained, e.g. finger tremor, fever, and abnormal behavior, as well as high urine volume, appetite loss, and reduced body weight. The detection rates of neonicotinoids were highest in N-desmethyl-acetamiprid 92.4 %, following dinotefuran 17.4 %, thiamethoxam 17.4 %, clothianidin 9.8%, thiacloprid 3.3%, imidacloprid 2.2%, nitenpyram and acetamiprid 0%. Dinotefuran and thiacloprid had not registered in 2015 in Sri Lanka. Between the concentration of urine Cystatin-C and N-desmethyl-acetamiprid, weak negative correlation was observed (r=-0.19, p=0.077)Conclusions: In CKD patients in the area, high urine Cystatin-C/L-FABP and more neurological symptoms were observed. Neonicotinoids exposure of people living in CKDu-epidemic area in Sri Lanka was common. Further investigation is needed to elucidate that occupational neonicotinoid exposure is one of the causes of CKDu and some neurological symptoms, e.g. appropriate timing of urine sampling.