Wet Bulb Globe Temperature and Recorded Occupational Injury Rates among Sugarcane Harvesters in Southwest Guatemala.

As global temperatures continue to rise it is imperative to understand the adverse effects this will pose to workers laboring outdoors. The purpose of this study was to investigate the relationship between increases in wet bulb globe temperature (WBGT) and risk of occupational injury or dehydration among agricultural workers. We used data collected by an agribusiness in Southwest Guatemala over the course of four harvest seasons and Poisson generalized linear modelling for this analysis. Our analyses suggest a 3% increase in recorded injury risk with each degree increase in daily average WBGT above 30 °C (95% CI: -6%, 14%). Additionally, these data suggest that the relationship between WBGT and injury risk is non-linear with an additional 4% acceleration in risk for every degree increase in WBGT above 30 °C (95% CI: 0%, 8%). No relationship was found between daily average WBGT and risk of dehydration. Our results indicate that agricultural workers are at an increased risk of occupational injury in humid and hot environments and that businesses need to plan and adapt to increasing global temperatures by implementing and evaluating effective occupational safety and health programs to protect the health, safety, and well-being of their workers.

Human Heat stress risk prediction in the Brazilian semiarid Region based on the Wet-Bulb Globe Temperature.

OBJECTIVE: the aim of this study is to map thermal stress risks for human health at the São Francisco River Basin (SFRB) in the Semiarid region, for climatic scenarios RCP 4.5 and 8.5. METHODS: The heat stress conditions were defined by the Wet Bulb Globe Temperature (WBGT) indicator and by the average number of annual days in which the WBGT values exceeded the 90th percentile of the reference period. The WBGT was estimated for the climate scenarios RCP 4.5 (intermediate) and 8.5 (pessimistic) for the period 2011-2090 comparing to the period of reference (1961-2005). RESULTS: The projections show that for the pessimistic scenario practically all municipalities of the SFRB region can reach values of WBGT that indicate a high risk for heat stress in the period 2071-2099. For this same scenario and period, the municipalities of the Lower and Under-average regions may present values of WBGT above the 90th percentile of the reference period in more than 90% of the days/year. CONCLUSIONS: These results show that, if the emission of greenhouse gases continues in the present proportions, some municipalities of the SFRB region may present a high risk for heat stress affecting the work capacity and the practice of physical exercises.

Pathophysiologic insight into MesoAmerican nephropathy.

PURPOSE OF REVIEW: Mesoamerican nephropathy (MeN) is an emerging pathophysiological entity of Chronic kidney desease (CKD) not related to traditional risk factors (diabetes and hypertension) that have caused thousands of deaths in Central America, mainly in sugarcane workers. The focus of this review is to discuss the risk factors and probable mechanisms involved in the initiation and progression of this devastating disease. RECENT FINDINGS: Frequent episodes of subclinical Acute kidney injury caused by repetitive heat stress, dehydration, and strenuous work have been regarded as the main risk factors for MeN. The combination of them chronically activates vasopressin, renin angiotensin aldosterone system, and polyol-fructokinase pathway in the kidney. Also, subclinical rhabdomyolysis compound the framework of the disease by exacerbating systemic inflammation and inducing uricosuria. Exposure to nephrotoxins, high fructose intake, and use of NSAIDs could also contribute to further accelerating the progression of the disease. SUMMARY: The evidence supports the notion that recurrent cycles of heat stress, dehydration, and strenuous work may cause CKD. The chronic activation of such mechanisms likely occurs in other conditions of reduced water intake and probably explains why the current management of CKD has not been effective to revert or halt the progression to end-stage CKD.

[Risk of exposure to heatstroke in sugarcane workers in São Paulo State, Brazil]. / Risco de exposição à sobrecarga térmica para trabalhadores da cultura de cana-de-açúcar no Estado de São Paulo, Brasil.

Environmental heat is an aggravating factor for sugarcane workers, and manual cane cutting is one of the heavy work activities that favor the generation of metabolic heat. This can combine with other precarious working conditions to produce heatstroke, potentially leading to serious complications and even death. The study aimed to quantify the risk of overheating in sugarcane cutters in São Paulo, Brazil. Drawing on a specific methodology, the study used four years of data to estimate the Globe Thermometer Wet Bulb Index based on light, moderate, and heavy activities. The results showed that the legal limit was exceeded for continuous activity in periods from 1 to 8 hours, which requires control measures in order to continue working. The principal observation was the risk of heatstroke in the three types of activity: light, moderate, and heavy. The limits were exceeded throughout the work shift on 7% of the days for heavy activity and on 3% of the days for moderate activity. In addition, the areas with the highest risk of heatstroke coincide with predominant cane-growing.

Con: Mesoamerican nephropathy: is the problem dehydration or rehydration?

In recent years, an increasing number of inhabitants of Central America have developed a form of chronic kidney disease, now named Mesoamerican nephropathy. This disease is characterized by minimal proteinuria, hyperuricemia, hypokalemia and reduced glomerular filtration rate. Histologically the kidneys manifest tubulointerstitial nephritis. The cause(s) of this disease remain unknown. Some have proposed that dehydration, in combination with hyperuricemia, may be primarily responsible for Mesoamerican nephropathy. In this article, I propose the hypothesis that the disease may be largely due to rehydration with large amounts of contaminated water, whereas dehydration would play only a contributing role.

Pro: Heat stress as a potential etiology of Mesoamerican and Sri Lankan nephropathy: a late night consult with Sherlock Holmes.

Epidemics of chronic kidney disease are now recognized in Central America, Mexico, India and Sri Lanka, and there is also some evidence that similar epidemics may be occurring in the USA, Thailand and elsewhere. A common denominator for each location is manually working outside in extremely hot environments. Here we review the evidence that the primary etiology may be heat stress related to repeated subclinical or clinical acute kidney injury that eventually manifests as chronic kidney disease. In some aspects, the disease may manifest as subclinical heat stroke, subclinical rhabdomyolysis or a subclinical tumor lysis syndrome. While toxins could be involved, it would be difficult to attribute this as a main mechanism, given the wide range of occupations and geographic regions manifesting this disease. While some of the epidemics may be due to better reporting, we believe the most important reasons are increasing heat extremes (heat waves) coupled with hydration with sugary or, less commonly, alcoholic beverages.

Risco de exposição à sobrecarga térmica para trabalhadores da cultura de cana-de-açúcar no Estado de São Paulo, Brasil / Risk of exposure to heatstroke in sugarcane workers in São Paulo State, Brazil / Riesgo de exposición a la sobrecarga térmica para trabajadores de plantaciones de caña de azúcar en el estado de São Paulo, Brasil

Resumo: O calor ambiental é um agravante às atividades dos trabalhadores da cultura de cana-de-açúcar, sendo o corte manual uma das atividades pesadas que favorece a elevada geração de calor metabólico. Isso associado com outras condições precárias de trabalho favorece o estresse térmico, podendo provocar graves doenças ou até levar à morte. O objetivo deste estudo é quantificar o risco de sobrecarga térmica que os cortadores de cana-de-açúcar de São Paulo, Brasil, são expostos. Por meio de metodologia específica, foram utilizados quatro anos de dados para estimar o Índice de Bulbo Úmido - Termômetro de Globo sob a consideração das atividades leve, moderada e pesada. Os resultados mostram extrapolação do limite legal de exposição para atividade contínua em períodos de 1 a 8 horas, o que requer medidas de controle para continuidade do trabalho. A principal constatação é a observância do risco de sobrecarga térmica para os três tipos de atividade: leve, moderada e pesada. Os limites de tolerância são ultrapassados durante todo o turno de trabalho em cerca de 7% dos dias, para atividade pesada, e em cerca de 3%, para atividade moderada. Além disso, percebeu-se que as áreas com maior risco de sobrecarga térmica são as mesmas onde há predominância da cultura de cana-de-açúcar.

Abstract: Environmental heat is an aggravating factor for sugarcane workers, and manual cane cutting is one of the heavy work activities that favor the generation of metabolic heat. This can combine with other precarious working conditions to produce heatstroke, potentially leading to serious complications and even death. The study aimed to quantify the risk of overheating in sugarcane cutters in São Paulo, Brazil. Drawing on a specific methodology, the study used four years of data to estimate the Globe Thermometer Wet Bulb Index based on light, moderate, and heavy activities. The results showed that the legal limit was exceeded for continuous activity in periods from 1 to 8 hours, which requires control measures in order to continue working. The principal observation was the risk of heatstroke in the three types of activity: light, moderate, and heavy. The limits were exceeded throughout the work shift on 7% of the days for heavy activity and on 3% of the days for moderate activity. In addition, the areas with the highest risk of heatstroke coincide with predominant cane-growing.

Resumen: El calor ambiental es un agravante para las actividades de los trabajadores de plantaciones de caña de azúcar, siendo el corte manual una de las actividades pesadas que favorece la elevada generación de calor metabólico. Esto, asociado con otras condiciones precarias de trabajo, favorece el estrés térmico, pudiendo provocar graves enfermedades o incluso llevar a la muerte. El objetivo de este estudio es cuantificar el riesgo de sobrecarga térmica a la que los cortadores de caña de azúcar de São Paulo, Brasil, están expuestos. Mediante una metodología específica, se utilizaron cuatro años de datos para estimar el Índice de Bulbo Húmedo-Termómetro de Globo, considerando a las actividades como: leves, moderadas y pesadas. Los resultados muestran la extrapolación del límite legal de exposición para la actividad continua en períodos de 1 a 8 horas, lo que requiere medidas de control para la continuidad del trabajo. La principal constatación es la observancia del riesgo de sobrecarga térmica para los tres tipos de actividad: leve, moderada y pesada. Los límites de tolerancia se sobrepasan durante todo el turno de trabajo en cerca de un 7% dos días, en el caso de la actividad pesada, y en cerca de un 3% en la actividad moderada. Además, se percibió que las áreas con mayor riesgo de sobrecarga térmica son las mismas donde hay predominancia de plantaciones de caña de azúcar.

Heat stress, hydration and uric acid: a cross-sectional study in workers of three occupations in a hotspot of Mesoamerican nephropathy in Nicaragua.

OBJECTIVES: To study Mesoamerican nephropathy (MeN) and its risk factors in three hot occupations. DESIGN: Cross-sectional. SETTING: Chinandega and León municipalities, a MeN hotspot on the Nicaraguan Pacific coast, January-February 2013. PARTICIPANTS: 194 male workers aged 17-39 years: 86 sugarcane cutters, 56 construction workers, 52 small-scale farmers. OUTCOME MEASURES: (1) Differences between the three occupational groups in prevalences/levels of socioeconomic, occupational, lifestyle and health risk factors for chronic kidney disease (CKD) and in biomarkers of kidney function and hydration; (2) differences in prevalences/levels of CKD risk factors between workers with reduced estimated glomerular filtration rate (eGFRCKD-EPI <80 mL/min/1.73 m2) and workers with normal kidney function (eGFRCKD-EPI ≥80 mL/min/1.73 m2). RESULTS: Sugarcane cutters were more exposed to heat and consumed more fluid on workdays and had less obesity, lower blood sugar, lower blood pressure and a better lipid profile. Reduced eGFR occurred in 16%, 9% and 2% of sugarcane cutters, construction workers and farmers, respectively (trend cane > construction > farming, p=0.003). Significant trends (cane > construction > farming) were also observed for high serum urea nitrogen (blood urea nitrogen (BUN) >20 mg/dL), high serum creatinine (SCr >1.2 mg/dL), low urinary pH (≤5.5) and high BUN/SCr ratio (>20) but not for high urinary specific gravity (≥1.030). Sugarcane cutters also more often had proteinuria and blood and leucocytes in the urine. Workers with eGFR <80 mL/min/1.73 m2 reported a higher intake of water and lower intake of sugary beverages. Serum uric acid levels related strongly and inversely to eGFR levels (adj ß -10.4 mL/min/1.73 m2, 95% CI -12.2 to -8.5, p<0.001). No associations were observed for other metabolic risk factors, pesticides, non-steroidal anti-inflammatory drugs or alcohol. Among cane cutters, consumption of electrolyte hydration solution appeared preventive (adj ß 8.1 mL/min/1.73 m2, p=0.09). CONCLUSIONS: Heat stress, dehydration and kidney dysfunction were most common among sugarcane cutters. Kidney dysfunction also occurred to a lesser extent among construction workers, but hardly at all among small-scale farmers. High serum uric acid was associated with reduced kidney function.

Climate Change and the Emergent Epidemic of CKD from Heat Stress in Rural Communities: The Case for Heat Stress Nephropathy.

Climate change has led to significant rise of 0.8°C-0.9°C in global mean temperature over the last century and has been linked with significant increases in the frequency and severity of heat waves (extreme heat events). Climate change has also been increasingly connected to detrimental human health. One of the consequences of climate-related extreme heat exposure is dehydration and volume loss, leading to acute mortality from exacerbations of pre-existing chronic disease, as well as from outright heat exhaustion and heat stroke. Recent studies have also shown that recurrent heat exposure with physical exertion and inadequate hydration can lead to CKD that is distinct from that caused by diabetes, hypertension, or GN. Epidemics of CKD consistent with heat stress nephropathy are now occurring across the world. Here, we describe this disease, discuss the locations where it appears to be manifesting, link it with increasing temperatures, and discuss ongoing attempts to prevent the disease. Heat stress nephropathy may represent one of the first epidemics due to global warming. Government, industry, and health policy makers in the impacted regions should place greater emphasis on occupational and community interventions.

Heat Stress Nephropathy From Exercise-Induced Uric Acid Crystalluria: A Perspective on Mesoamerican Nephropathy.

Mesoamerican nephropathy (MeN), an epidemic in Central America, is a chronic kidney disease of unknown cause. In this article, we argue that MeN may be a uric acid disorder. Individuals at risk for developing the disease are primarily male workers exposed to heat stress and physical exertion that predisposes to recurrent water and volume depletion, often accompanied by urinary concentration and acidification. Uric acid is generated during heat stress, in part consequent to nucleotide release from muscles. We hypothesize that working in the sugarcane fields may result in cyclic uricosuria in which uric acid concentrations exceed solubility, leading to the formation of dihydrate urate crystals and local injury. Consistent with this hypothesis, we present pilot data documenting the common presence of urate crystals in the urine of sugarcane workers from El Salvador. High end-of-workday urinary uric acid concentrations were common in a pilot study, particularly if urine pH was corrected to 7. Hyperuricemia may induce glomerular hypertension, whereas the increased urinary uric acid may directly injure renal tubules. Thus, MeN may result from exercise and heat stress associated with dehydration-induced hyperuricemia and uricosuria. Increased hydration with water and salt, urinary alkalinization, reduction in sugary beverage intake, and inhibitors of uric acid synthesis should be tested for disease prevention.

Heat-related symptoms in sugarcane harvesters.

BACKGROUND: Exposure to heat stress is a documented risk for Central American sugarcane harvesters. However, little is known about heat-related illness in this population. METHODS: This study examined the frequency of heat-related health effects among harvesters (n = 106) exposed to occupational heat stress compared to non-harvesters (n = 63). Chi-square test and gamma statistic were used to evaluate differences in self-reported symptoms and trends over heat exposure categories. RESULTS: Heat and dehydration symptoms (headache, tachycardia, muscle cramps, fever, nausea, difficulty breathing, dizziness, swelling of hands/feet, and dysuria) were experienced at least once per week significantly more frequently among harvesters. Percentages of workers reporting heat and dehydration symptoms increased in accordance with increasing heat exposure categories. CONCLUSIONS: A large percentage of harvesters are experiencing heat illness throughout the harvest demonstrating an urgent need for improved workplace practices, particularly in light of climate change and the epidemic of chronic kidney disease prevalent in this population.

Heat exposure in sugarcane harvesters in Costa Rica.

BACKGROUND: Occupational heat stress is a major concern in sugarcane production and has been hypothesized as a causal factor of a chronic kidney disease epidemic in Central America. This study described working conditions of sugarcane harvesters in Costa Rica and quantified their exposure to heat. METHODS: Non-participatory observation and Wet Bulb Globe Temperatures (WBGT) according to Spanish NTP (Technical Prevention Notes) guidelines were utilized to quantify the risk of heat stress. OSHA recommendations were used to identify corresponding exposure limit values. RESULTS: Sugarcane harvesters carried out labor-intensive work with a metabolic load of 261 W/m² (6.8 kcal/min), corresponding to a limit value of 26° WBGT which was reached by 7:30 am on most days. After 9:15 am, OSHA recommendations would require that workers only work 25% of each hour to avoid health risks from heat. CONCLUSIONS: Sugarcane harvesters are at risk for heat stress for the majority of the work shift. Immediate action is warranted to reduce such exposures.

The effect of prolonged light intensity exercise in the heat on executive function.

OBJECTIVE: When people are involved in outdoor activities, it is important to be able to assess a situation and make rational decisions. The goal of this study is to determine the effects of 90 minutes of light-intensity exercise in a hot environment on executive functioning capabilities of healthy individuals. METHODS: In this prospective laboratory study, 40 healthy male and female subjects 18 to 45 years of age performed treadmill exercise while wearing athletic clothing and a backpack in either a hot or temperate environment. Vital signs, core and skin temperature, and perceptual measures (thermal sensation, sweating, comfort, and perceived exertion) were measured before, during, and after the treadmill test. Cognitive function was measured before and after the treadmill test using the Wisconsin Card Sorting Test (WCST) and a Psychomotor Vigilance Test (PVT). RESULTS: Subjects in the hot condition reached a similar core temp of 38.2° ± 0.5°C vs 37.7° ± 0.3°C (P = .325) in the temperate group but had a higher heart rate (P < .001) and skin temperature (P < .001). Hot and normal temperature groups did not differ in their PVT performance. There were more correct responses (P < .001), fewer errors (P < .001), and more conceptual responses (P = .001) on the WCST after exertion in both the hot room and normal temperature room conditions. Perseverations and perseverative errors (P = .002) decreased in both groups after exertion. CONCLUSIONS: Conditions of mild heat stress coupled with modest rehydration and short hiking treks do not appear to negatively affect executive function or vigilance.

What is the best clothing to prevent heat and cold stress? Experiences with thermal manikin.

The present study summarizes the current knowledge of the heat and cold stress which might significantly affect military activities and might also occur among travellers who are not well adapted to weather variations during their journey. The selection of the best clothing is a very important factor in preserving thermal comfort. Our experiences with thermal manikin are also represented in this paper.