Objectives There is an epidemic of Mesoamerican nephropathy (MeN) in Central America, where sugarcane production is prominent. Numerous causes are proposed, but to date limited evidence supports any one hypothesis. A nested case–control study using biosamples from a rural, community-based follow-up study of 350 young adults from Northwest Nicaragua at risk of MeN was conducted with the aim of characterising the associations between urinary concentrations of metals, pesticides and mycotoxins from samples collected in the first 6 months and decline in kidney function over 2 years.
Methods Urine samples collected at baseline (pre-sugarcane harvest) and the first 6 month follow-up (post-sugarcane harvest) visit were tested. Twelve metals and metalloids (aluminium, total arsenic, cadmium, chromium, cobalt, copper, lead, manganese, mercury, selenium, silicon and strontium) were analysed by inductively coupled plasma-mass spectrometry. Twelve pesticides or their metabolites (2,4-dichlorophenoxyacetic acid, 3-phenoxybenzoic acid, 4-fluoro-3-phenoxybenzoic acid, chloro-3,3,3-trifluoro-1-propen-1-yl-2,2-dimethylcyclopropanecarboxylic acid, cis/trans 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid, ethylenethiourea, glyphosate, 4-chloro-2-methylphenoxy acetic acid, 3-hydroxy-pyrimetanil, 5-hydroxytiabendazole, hydroxy-tebuconazole and 3,5,6-trichloro-2-pyridinol) and two mycotoxins (ochratoxin A (OTA) and citrinin (CIT)) were analysed by liquid chromatography coupled-mass spectrometry. Differences in the creatinine-corrected urinary concentrations of the measured exposures between outcome groups (participants with stable vs declining kidney function) were examined.
Results Elevated levels of aluminium and total arsenic as well as metabolites of several pesticides were detected across the population. No differences were identified between the declining and stable groups in the levels of metals or pesticides tested. OTA and CIT were below the limit of detection.
Conclusions The tested metals, metalloids, pesticides and mycotoxins were not associated with loss of kidney function in participants at-risk of MeN.
- chronic kidney disease of unknown origin (CKDu)
- mesoamerican nephropathy (MeN)
- environmental toxins
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Contributors ETS, BC, MGQ, JN, JM, DN and NP conceived and designed the studies. ETS analysed the data. ETS, MGQ, BC, JM, CM, CHL and PA contributed to data collection. All authors were involved in writing the paper and approved the submitted version.
Funding This study was supported by the Colt Foundation (Grant number CF/03/14 and through a PhD fellowship awarded to ETS). Additional support was received from the Dutch National Postcode Lottery providing additional funding through Solidaridad. Thanks are due for the financial support to CESAM (UID/AMB/50017/2019), to FCT/MEC through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval All participants provided written informed consent. The study was approved by the bioethical review board at the Medical Faculty of UNAN-León (Ref: FWA00004523/IRB00003342), and the research ethics committee of the London School of Hygiene and Tropical Medicine (Ref: 8643) in 2014.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.