High prevalence of chronic kidney disease of unknown etiology among workers in the Mesoamerican Nephropathy Occupational Study.

BACKGROUND: Mortality from chronic kidney disease of unknown etiology (CKDu) is extremely high along the Pacific coast of Central America, particularly among sugarcane workers. The Mesoamerican Nephropathy Occupational Study (MANOS) is a prospective cohort study of CKDu among agricultural and non-agricultural workers in El Salvador and Nicaragua. The objective of this manuscript is to describe the MANOS cohort recruitment, baseline data collection, and CKDu prevalence after two rounds. METHODS: Workers with no known diabetes, hypertension, or CKD were recruited from sugarcane, corn, plantain, brickmaking, and road construction industries (n = 569). Investigators administered questionnaires, collected biological samples, and observed workers for three consecutive workdays at the worksite. Serum specimens were analyzed for kidney function parameters, and used to calculate estimated glomerular filtration rate (eGFR). At six months, serum was collected again prior to the work shift. CKD at baseline is defined as eGFR ≤ 60 ml/min/1.73m2 at both timepoints. Age-standardized prevalence was calculated by industry, country, and demographic measures. Kidney function parameters were compared by CKD status. RESULTS: Prevalence of CKD at baseline was 7.4% (n = 42). Age-standardized prevalence was highest in Salvadoran sugarcane (14.1%), followed by Salvadoran corn (11.6%), and Nicaraguan brickmaking (8.1%). Nicaraguan sugarcane had the lowest prevalence, likely due to kidney function screenings prior to employment. CONCLUSION: Despite efforts to enroll participants without CKD, our identification of prevalent CKD among agricultural and non-agricultural workers in the MANOS cohort indicates notable kidney disease in the region, particularly among sugarcane workers.

Exposure of Nail Salon Workers to Phthalates, Di(2-ethylhexyl) Terephthalate, and Organophosphate Esters: A Pilot Study.

Relatively little is known about the exposure of nail technicians to semivolatile organic compounds (SVOCs) in nail salons. We collected preshift and postshift urine samples and silicone wrist bands (SWBs) worn on lapels and wrists from 10 female nail technicians in the Boston area in 2016-17. We analyzed samples for phthalates, phthalate alternatives, and organophosphate esters (OPEs) or their metabolites. Postshift urine concentrations were generally higher than preshift concentrations for SVOC metabolites; the greatest change was for a metabolite of the phthalate alternative di(2-ethylhexyl) terephthalate (DEHTP): mono(2-ethyl-5-carboxypentyl) terephthalate (MECPTP) more than tripled from 11.7 to 36.6 µg/g creatinine. DEHTP biomarkers were higher in our study participants' postshift urine compared to 2015-2016 National Health and Nutrition Examination Survey females. Urinary MECPTP and another DEHTP metabolite were moderately correlated (r = 0.37-0.60) with DEHTP on the SWBs, suggesting occupation as a source of exposure. Our results suggest that nail technicians are occupationally exposed to certain phthalates, phthalate alternatives, and OPEs, with metabolites of DEHTP showing the largest increase across a work day. The detection of several of these SVOCs on SWBs suggests that they can be used as a tool for examining potential occupational exposures to SVOCs among nail salon workers.

Biological and environmental exposure monitoring of volatile organic compounds among nail technicians in the Greater Boston area.

Nail technicians are exposed to volatile organic compounds (VOCs) from nail products, but no studies have previously measured VOC biomarkers for these workers. This study of 10 nail technicians aimed to identify VOCs in nail salons and explore relationships between air concentrations and biomarkers. Personal and area air samples were collected using thermal desorption tubes during a work shift and analyzed using gas chromatography/mass spectrometry (GC/MS) for 71 VOCs. Whole blood samples were collected pre-shift and post-shift, and analyzed using GC/MS for 43 VOCs. Ventilation rates were determined using continuous CO2 measurements. Predominant air VOC levels were ethyl methacrylate (median 240 µg/m3 ), methyl methacrylate (median 205 µg/m3 ), toluene (median 100 µg/m3 ), and ethyl acetate (median 639 µg/m3 ). Blood levels were significantly higher post-shift than pre-shift for toluene (median pre-shift 0.158 µg/L and post-shift 0.360 µg/L) and ethyl acetate (median pre-shift <0.158 µg/L and post-shift 0.510 µg/L); methacrylates were not measured in blood because of their instability. Based on VOCs measured in these seven nail salons, we estimated that emissions from Greater Boston area nail salons may contribute to ambient VOCs. Ventilation rates did not always meet the ASHRAE guideline for nail salons. There is a need for changes in nail product formulation and better ventilation to reduce VOC occupational exposures.

Heat stress and heat strain among outdoor workers in El Salvador and Nicaragua.

BACKGROUND: There is growing attention on occupational heat stress in Central America, as workers in this region are affected by a unique form of chronic kidney disease. Previous studies have examined wet bulb globe temperatures and estimated metabolic rates to assess heat stress, but there are limited data characterizing heat strain among these workers. OBJECTIVE: The aims were to characterize heat stress and heat strain and examine whether job task, break duration, hydration practices, and kidney function were associated with heat strain. METHODS: We used data from the MesoAmerican Nephropathy Occupational Study, a cohort of 569 outdoor workers in El Salvador and Nicaragua who underwent workplace exposure monitoring, including continuous measurement of core body temperature (Tc), heart rate (HR), physical activity, and wet bulb globe temperature (WBGT), over the course of three days in January 2018 - May 2018. Participants represented five industries: sugarcane, corn, plantain, brickmaking, and construction. RESULTS: Median WBGTs were relatively high (>27 °C) at most sites, particularly when work shifts spanned the afternoon hours (e.g., 29.2 °C among plantain workers). Sugarcane workers, especially cane cutters in both countries and Nicaraguan agrichemical applicators, had the highest estimated metabolic rates (medians: 299-318 kcal/hr). Most workers spent little time on break (<10% of the shift), as determined by physical activity data. Overall, sugarcane workers-particularly those in Nicaragua-experienced the highest Tc and HR values. However, a few workers in other industries reached high Tc (>39 °C) as well. Impaired kidney function (estimated glomerular filtration rate <90 mL/min/1.73 m2) was associated with higher Tc and HR values, even after adjustment. SIGNIFICANCE: This is the largest study to-date examining heat stress and strain among outdoor workers in Central America. Workers at sugar companies regularly experienced Tc > 38°C (76.9% of monitored person-days at Nicaraguan companies; 46.5% at Salvadoran companies). Workers with impaired kidney function had higher measures of Tc and HR. IMPACT STATEMENT: This study examined levels of occupational heat stress and heat strain experienced among outdoor workers in five industries in El Salvador and Nicaragua. We characterized heat stress using wet bulb globe temperatures and estimated metabolic rate and heat strain using core body temperature and heart rate. Sugarcane workers, particularly cane cutters and Nicaraguan agrichemical applicators, performed more strenuous work and experienced greater levels of heat strain. Impaired kidney function was associated with higher heart rates and core body temperatures.

COVID-19 and CKD: Employment, Food Security and Healthcare in El Salvador.

Background: In Central America, the COVID-19 pandemic coexists with a devastating epidemic of chronic kidney disease of unknown origin. The consequences of these overlapping health crises remain largely unknown. Methods: We assessed vulnerability to and impact of the first wave of COVID-19 on participants in a cohort study of chronic kidney disease (CKD) in El Salvador (n = 229). Participants were contacted by phone during August and September 2020. We queried changes to employment, healthcare access, household income and food security due to the pandemic (from March 2020 until the time of the interview) and COVID-19-associated symptoms during that time. Findings: We reached 94% of the cohort (n = 215). Nearly 40% of participants reported an unexpected change in employment or work activities and 8.8% reported new unemployment due to the pandemic. Participants with CKD (n = 27) had higher odds of reporting new income insecurity, food insecurity, and reductions in medical care access due to the pandemic. COVID-19-associated symptoms (an approximation of disease) were reported in 7.0% (n = 15). Participants with CKD were more likely to report COVID-19-associated symptoms compared to those without CKD, although these differences were not statistically significant. Conclusions: Overall, participants with CKD suffered greater economic consequences as a result of the pandemic and may have experienced higher incidence of COVID-19 disease, although laboratory diagnostics would be required to draw this conclusion. Longitudinal analyses are required to comprehensively evaluate the implications of the pandemic for individuals with CKD in Central America.

Climate Trends at a Hotspot of Chronic Kidney Disease of Unknown Causes in Nicaragua, 1973-2014.

An ongoing epidemic of chronic kidney disease of uncertain etiology (CKDu) afflicts large parts of Central America and is hypothesized to be linked to heat stress at work. Mortality rates from CKDu appear to have increased dramatically since the 1970s. To explore this relationship, we assessed trends in maximum and minimum temperatures during harvest months between 1973 and 2014 as well as in the number of days during the harvest season for which the maximum temperature surpassed 35 °C. Data were collected at a weather station at a Nicaraguan sugar company where large numbers of workers have been affected by CKDu. Monthly averages of the daily maximum temperatures between 1996 and 2014 were also compared to concurrent weather data from eight Automated Surface Observing System Network weather stations across Nicaragua. Our objectives were to assess changes in temperature across harvest seasons, estimate the number of days that workers were at risk of heat-related illness and compare daily maximum temperatures across various sites in Nicaragua. The monthly average daily maximum temperature during the harvest season increased by 0.7 °C per decade between 1973 and 1990. The number of days per harvest season with a maximum temperature over 35 °C increased by approximately five days per year between 1974 and 1990, from 32 days to 114 days. Between 1991 and 2013, the number of harvest days with a maximum temperature over 35 °C decreased by two days per year, and the monthly average daily maximum temperature decreased by 0.3 °C per decade. Comparisons with weather stations across Nicaragua demonstrate that this company is located in one of the consistently hottest regions of the country.

Characterizing community-wide housing attributes using georeferenced street-level photography.

New methods are needed to efficiently characterize built environment attributes and residential behaviors to improve exposure assessment in epidemiologic research, given limitations of available databases and approaches. Window-opening and presence of air conditioning (AC) units predict indoor air quality and thermal comfort, but data are not widely available. In this study, we tested the utility of a GIS-based tool for rapidly assessing open windows and window/wall AC units in the city of Chelsea, Massachusetts using georeferenced street-level photographs and crowdsourced online surveys. We characterized open windows and window/wall AC units for 969 parcels in the winter and 1213 parcels in the summer, requiring ~40 person hours per season. In the winter, 21% of parcels surveyed had a window or wall AC unit and 19% had an open window. In the summer, 69% had a window or wall AC unit and 53% had an open window. We demonstrated an efficient method for rapidly characterizing open windows and window/wall AC units across an entire city. This tool can help to characterize exposures for epidemiological research, engage community members, and inform local land use planning and decision-making.

Kidney Function, Self-Reported Symptoms, and Urine Findings in Nicaraguan Sugarcane Workers.

Background: An epidemic of CKD in Central America predominantly affects males working in certain industries, including sugarcane. Urinary tract infections are commonly diagnosed among men in Nicaragua, who often receive antibiotics and nonsteroidal anti-inflammatory drugs for urinary symptoms. Methods: We followed 251 male Nicaraguan sugarcane workers in seven job tasks over one harvest and measured urine dipstick parameters, kidney injury biomarkers, and eGFR. We administered a questionnaire about urinary symptoms, health-related behaviors, and medication history. We cultured urine in a subset of workers. Results: The study population was composed of factory workers (23%), cane cutters (20%), irrigators (20%), drivers (16%), agrichemical applicators (12%), seeders/reseeders (6%), and seed cutters (4%). The mean age of participants was 33.9 years, and mean employment duration was 10.1 years. Cane cutters reported higher proportions of urinary-related symptoms compared with agrichemical applicators, irrigators, and seeders/reseeders. Seed cutters were more likely to take antibiotics (22%), whereas drivers and seeders/reseeders were more likely to take pain medications (27% and 27%, respectively). Proteinuria was uncommon, whereas dipstick leukocyte esterase was relatively common, especially among cane cutters, seed cutters, and seeders/reseeders (33%, 22%, and 21% at late harvest, respectively). Dipstick leukocyte esterase at late harvest was associated with a 12.9 ml/min per 1.73 m2 (95% CI, -18.7 to -7.0) lower mean eGFR and 2.8 times (95% CI, 1.8 to 4.3) higher mean neutrophil gelatinase-associated lipocalin. In general, workers who reported urinary-related symptoms had higher mean kidney injury biomarker levels at late harvest. None of the workers had positive urine cultures, including those reporting urinary symptoms and/or with positive leukocyte esterase results. Amoxicillin, ibuprofen, and acetaminophen were the most commonly used medications. Conclusions: Job task is associated with urinary symptoms and dipstick leukocyte esterase. Urinary tract infection is misdiagnosed based on leukocyte esterase, which may be an important predictor of kidney outcomes.

Human health risks due to airborne polychlorinated biphenyls are highest in New Bedford Harbor communities living closest to the harbor.

In response to concerns raised by communities surrounding the New Bedford Harbor Superfund site, we completed a field and modeling study that concluded the harbor is the primary source of polychlorinated biphenyls (PCBs) in air around the harbor. The follow-up question from residents was whether the PCBs measured in air pose a risk to their health. The US Environmental Protection Agency focuses their site-specific, risk-based decisions for site clean-up on cancers. We focused our assessment on the non-cancer effects on the thyroid based on the congener specific patterns and concentrations of PCBs measured in air near and distant to the harbor. Human and animal studies of PCB-induced effects on the thyroid provide evidence to support our analysis. Drawing from the published toxicological data, we used a Margin of Exposure (MOE) approach to derive a human-equivalent concentration in air associated with human health effects on the thyroid. Based on the MOEs calculated herein, evaluation of the MOE indicates that changes in thyroid hormone levels are possible among people living adjacent to the Harbor. Changes in thyroid hormone levels are more likely among people who live near the harbor compared to residents living in areas distant from the harbor. This risk assessment documents potential health risks associated with proximity to a marine Superfund Site using site-specific ambient air PCB congener data.

Environmental and Occupational Exposures in Kidney Disease.

More than 8 million deaths each year are attributed to noncommunicable environmental hazards where people live, work, and play. Physical or chemical hazards may be inhaled, ingested, or absorbed through the skin, affecting all organ systems, including the kidney. Heavy metals, pesticides, and infections are some of the environmental hazards associated with kidney dysfunction and chronic kidney disease. The severity of the effects of these exposures likely is modulated by the timing and duration of exposure, genetic susceptibility, and other conditions, and may lead to the development of acute and/or chronic kidney disease. In this review, we discuss environmental exposures that are associated with kidney dysfunction in animals and human beings, with a focus on those implicated in causing chronic kidney disease.