Climate change, workplace heat exposure, and occupational health and productivity in Central America

Climate change is increasing heat exposure in places such as Central America, a tropical region with generally hot/humid conditions. Working people are at particular risk of heat stress because of the intrabody heat production caused by physical labor. This article aims to describe the risks of occupational heat exposure on health and productivity in Central America, and to make tentative estimates of the impact of ongoing climate change on these risks. A review of relevant literature and estimation of the heat exposure variable wet bulb globe temperature (WBGT) in different locations within the region were used to estimate the effects. We found that heat stress at work is a real threat. Literature from Central America and heat exposure estimates show that some workers are already at risk under current conditions. These conditions will likely worsen with climate change, demonstrating the need to create solutions that will protect worker health and productivity.     

Climate Change,Workplace Heat Exposure,and Occupational Health and Productivity in Central America

Abstract

Climate change is increasing heat exposure in places such as Central America, a tropical region with generally hot/humid conditions. Working people are at particular risk of heat stress because of the intrabody heat production caused by physical labor. This article aims to describe the risks of occupational heat exposure on health and productivity in Central America, and to make tentative estimates of the impact of ongoing climate change on these risks. A review of relevant literature and estimation of the heat exposure variable wet bulb globe temperature (WBGT) in different locations within the region were used to estimate the effects. We found that heat stress at work is a real threat. Literature from Central America and heat exposure estimates show that some workers are already at risk under current conditions. These conditions will likely worsen with climate change, demonstrating the need to create solutions that will protect worker health and productivity.     

Serosurvey for "acute hemorrhagic conjunctivitis" virus (Enterovirus 70) antibodies in the Southeastern United States, with review of the literature and some epidemiologic implications.

Acute hemorrhagic conjunctivitis (AHC) has been epidemic throughout much of the Eastern Hemisphere since its emergence in central West Africa in 1969. The disease had a distinctive clinical picture and an unusual geographic epidemiology. Between 1969 and 1975 AHC has occurred almost exclusively in crowded coastal areas of tropical countries during hot, rainy seasons. Only a few documented outbreaks have occurred in inland cities and in subtropical or temperate climate zones. Of 1014 residents of the eastern or southeastern United States who were screende for neutralizing antibodies to three or four strains of AHC virus (enterovirus type 70), three (0.3%) had titers ranging from 1:10 to 1:40. However, no clinical evidence of prior experience with AHC disease could be ascertained for these persons, so that the antigenic specificity of the detected antibodies is unknown. We conclude that populations of coastal tropical areas of northern South America and all of Central America are vulnerable to AHC epidemics.     

The effect of heat exposure on cortisol and catecholamine excretion rates in workers in glass manufacturing unit

The aim of the investigation was to study the effect of long term repeated heat exposure on the excretion rates of stress hormones of workers in glass manufacturing unit. Sixteen operators, exposed to heat, were studied during the hot period and compared to a control group of 16 subjects, working in the same manufacturing unit. Both groups had moderate work load. The microclimate components and the Wet Bulb Globe Temperature were used for defining the heat exposure. The excretion rates of cortisol, adrenaline and noradrenaline were followed during the early morning shifts on three hour intervals using RIA and fluoriphotometric methods. Heart rate was followed, too. The psychosocial factors were measured by the "My job" questionnaire. Highly significantly higher cortisol, noradrenaline and adrenaline values were measured in the heat exposed operators compared to the control group, while significant differences of the psychosocial factors between the two groups lacked. Even if the heart rate was in the safe limits, the found alterations in the stress system are considerable and indicate heat stress. The work in conditions of overheat is associated with considerable heat stress and the possible health implications need to be clarified.     

Influenza-related deaths and hospitalizations in Hong Kong: a subtropical area

BACKGROUND: While influenza vaccination has been widely used in developed countries to reduce mortality and morbidity in high-risk populations, the lack of regional data on the health burden of influenza and the uncertainty of the applicability of data from temperate areas have been major impediments to establishing an evidence-based policy on the wider use of influenza vaccine in tropical and subtropical regions of the world. OBJECTIVES: The aim of this study was to estimate the annual excess deaths and hospitalizations related to influenza in the Hong Kong Special Administrative Region (HKSAR) for the years 1999 and 2000. STUDY DESIGN AND METHODS: Correlation and regression models were used to estimate the excess deaths and hospitalizations related to influenza in the general population of HKSAR for the years 1999 and 2000, using routinely collected mortality and hospitalization data, and virological laboratory data collected by the HKSAR Influenza Surveillance System. RESULTS: The annual mean excess numbers of deaths related to influenza in Hong Kong were estimated to be 613 for pneumonia and influenza, and 2302 for respiratory and circulatory diseases. The mean excess numbers of hospitalizations attributable to influenza were 4051 for pneumonia and influenza, and 15,873 for respiratory and circulatory diseases. The crude influenza-related mortality and hospitalization rates in Hong Kong, a subtropical area, exceeded those documented in temperate regions. CONCLUSIONS: The finding of significant mortality and morbidity related to influenza in a subtropical area is in accordance with the results of previous studies in tropical and subtropical regions. This simple methodology can be used for the development of influenza immunization policy in many developing countries in tropical and subtropical regions. The enormous potential of influenza vaccination in saving lives and reducing suffering warrants serious consideration of the expanded use of influenza vaccine in tropical and subtropical regions.     

Enteroviruses in shrimp harvested from contaminated marine waters

Marine shrimp (genus Penaeus) live primarily in tropical and subtropical coastal locations, sometimes contaminated by domestic sewage. However, sanitary quality and importance of shrimp as a potential vehicle for enteric disease transmission have not been reported previously. The shrimp Penaeus schmitti were either collected directly from Lake Maracaibo, in western Venezuela, or obtained from local seafood outlets. Of a total of 33 pooled samples, 16 (49%) yielded virus. Six types of enteroviruses were isolated during this study: polioviruses 1 and 2, and echovirus types 20, 21, 27, and 29. Viruses not typeable with the pools of specific antiserum used during this study were isolated from seven samples. Analysis of the results indicate that enteroviruses may be present in shrimp populations present in sewage—contaminated marine and estuarine waters.     

Evaluation of the health hazards involved in house-spraying with DDT

The dermal and respiratory exposure of workers during house-spraying operations has been measured to find out the main factors affecting the exposure, and to develop effective, acceptable protective measures and clothing. Dermal exposure was found to be much greater than respiratory exposure. The major factors affecting exposure with a single concentration of formulation appeared to be spray-pump pressure, height of area being sprayed, and absorbency of surface. Temperature, type of formulation, and nozzle size had little or no effect on exposure. A plastic cape, a hard hat with a plastic visor, and rubberized gauntlet gloves gave a fully clothed man almost complete protection from dermal and respiratory exposure. A tropical helmet equipped with a plastic-netting veil is proposed for field testing. This equipment gave good protection of the shoulders, back, and chest and excellent protection of the face and neck.     

Chromobacterium violaceum in siblings, Brazil

Chromobacterium violaceum, a saprophyte bacterium found commonly in soil and water in tropical and subtropical climates, is a rare cause of severe, often fatal, human disease. We report 1 confirmed and 2 suspected cases of C. violaceum septicemia, with 2 fatalities, in siblings after recreational exposure in northeastern Brazil.     

Tropical diabetic hand syndrome--Dar es Salaam,Tanzania, 1998-2002

Patients with diabetes mellitus have impaired immunologic responses to combat infections. Infection and ulceration of the hand is a major cause of morbidity and mortality in certain populations in Africa; however, the condition is less well recognized than foot infections and is not classified generally as a specific diabetes complication. Hand ulceration and infection in diabetic patients was first described in the United States in 1977 and in Africa in 1984. Subsequently, the majority of reported cases have been from various parts of the African continent. The term "tropical diabetic hand syndrome" (TDHS) has been used to describe diabetes among patients who have progressive, fulminant hand sepsis. More recently, TDHS has been reported among patients in India. These data suggest that TDHS occurs primarily in diabetic patients who live in tropical or coastal areas and might result in loss of hand function, amputation, or death. This report describes the characteristics of 72 patients with TDHS examined at Muhimbili National Hospital (MNH) in Dar es Salaam, Tanzania. Early recognition by patients, prompt medical attention, and improved glycemic control might reduce the incidence of disability or death.     

Hand arm vibration syndrome among quarry workers in Vietnam

Few studies have focused on the health effects of vibrating tools on workers in the tropical area. Work conditions and health effects related to rock drill operation were studied in 102 quarry workers, including 73 rock drill operators in Vietnam. We aimed to clarify (1) risk of vibration exposure, (2) occurrence of vibration-induced white finger (VWF), and (3) characteristics of hand-arm vibration syndrome (HAVS). Total weighted r.m.s. acceleration of the Chinese -or Russian-made rock drills, was 45-55 m/s(2). According to work observation studies, daily exposure time to vibration was 160-210 min. ISO5349 predicted that this exposure level would be associated with a high risk of HAVS in workers. We found no clear evidence of VWF. There may be several reasons why no worker exhibited VWF: (1) warmer work conditions, (2) younger and less experienced workers, (3) seasonal changes in work operations, and (4) healthy worker effect. On the other hand, 5-10% of rock drill operators might be suffering from moderate HAVS which was sensori-neural type dominant. There may be some characteristic features of HAVS among quarry workers in the tropical area.     

HTLV-1 and tropical spastic paraparesis. 1. Clinical features, pathology and epidemiology

The clinical profile of tropical spastic paraparesis (TSP), described in scattered tropical and subtropical territories over the past 30 years, has been more clearly defined since the discovery of its direct association with human T lymphotropic virus type 1 (HTLV-1). A chronic disease of adults, commoner in women, it usually presents as a progressive spastic paraparesis with sphincter disturbance, sometimes with backache and lower limb sensory disorder. Most cases are chair-bound within 10 years. Histology reveals a chronic lymphocytic meningomyelopathy, predominantly in the spinal cord, together with long tract demyelination and hyalinoid thickening of the media and adventitia of small blood vessels. Geographical areas of high prevalence of TSP are known in the Caribbean, South America, South Africa, southern Japan, the Seychelles and probably in India, and it is sparsely endemic elsewhere. The virus appears to exist within lymphocytes for long periods. Vertical transmission occurs postnatally, and sexual and transfusion infection are also recognized, but much remains to be clarified regarding its pathogenesis and epidemiology.     

Health Impacts of Workplace Heat Exposure: An Epidemiological Review

With predicted increasing frequency and intensity of extremely hot weather due to changing climate, workplace heat exposure is presenting an increasing challenge to occupational health and safety. This article aims to review the characteristics of workplace heat exposure in selected relatively high risk occupations, to summarize findings from published studies, and ultimately to provide suggestions for workplace heat exposure reduction, adaptations, and further research directions. All published epidemiological studies in the field of health impacts of workplace heat exposure for the period of January 1997 to April 2012 were reviewed. Finally, 55 original articles were identified. Manual workers who are exposed to extreme heat or work in hot environments may be at risk of heat stress, especially those in low-middle income countries in tropical regions. At risk workers include farmers, construction workers, fire-fighters, miners, soldiers, and manufacturing workers working around process-generated heat. The potential impacts of workplace heat exposure are to some extent underestimated due to the underreporting of heat illnesses. More studies are needed to quantify the extent to which high-risk manual workers are physiologically and psychologically affected by or behaviourally adapt to workplace heat exposure exacerbated by climate change.     

Observations on the protective effect of BCG vaccination in a South Indian rural population

Doubts have been raised on theoretical grounds concerning the effect of BCG in tropical countries, where in most places a large proportion of the population have a naturally acquired tuberculin allergy of low strength and unknown (but almost certainly non-specific) origin. Furthermore, vaccinations in the tropics may be less efficient if the BCG vaccine used has deteriorated from exposure to heat or light. The BCG trial reported here is relevant to these two problems.     

A study on coastal attrition of Dakshina Kannada district using remote sensing and GIS

Mangalore is one of the important coastal towns in Dakshina Kannada along the west coast of India situated at the mouth of Nethravathi-Gurpur estuary. The remote sensing and GIS (Geographical Information System) is a powerful tool to monitor coastal changes by continuous observation. A study has been carried out on the shoreline changes and coastal processes operating in the Dakshina Kannada coast using remote sensing and GIS technique. Survey of India topographical map of 1967 and IRS 1B, LISS II 1993 imagery (Geocoded) both on the scale of 1:50000 has been analysed to elucidate and quantify erosion and accretion in the study area. Erosion is observed at southern spit (Ullal) upto Talapadi and also northern spit (Bengre) upto New Mangalore Port. Accretion is observed at north of New Mangalore Port. Gradual shifting of the estuarine mouth of Nethravathi-Gurpur to the north is also observed. The changes could be attributed to human interference by way of constructing coastal structures.     

Response of fouling brown mussel,Perna perna (L.), to chlorine

Perna perna (L.), the edible brown mussel, is very widely distributed in the tropical and subtropical regions and is commonly found in rocky shores. Apart from being a candidate for commercial cultivation, P. perna is also a common pest organism in cooling water systems of coastal power stations. Therefore, a lethal and sublethal response of this mussel to commonly used antifouling biocides is of considerable interest to the industry. Mortality pattern (LT(50) and LT(100)) and physiological activities (oxygen consumption, filtration rate, foot activity index, and byssus thread production) of different size groups (9-34 mm shell lengths) of P. perna were studied in the laboratory under different residual chlorine concentrations (0.25, 0.50, 0.75, and 1.00 mg/L for sublethal responses and 1, 2, 3, and 5 mg/L for mortality). Results showed that exposure time for 100% mortality of mussels significantly decreased with increasing residual chlorine concentration. For example, mussels of 9 mm size group exposed to 1 mg/L chlorine residual took 384 h (16 days) to reach 100% mortality, whereas those exposed to 5 mg/L chlorine took 84 h (4 days). The effect of mussel size on mortality was significant between 1 mg/L and 5 mg/L residual chlorine, with larger mussels showing greater resistance than smaller ones. For example, at 2 mg/L residual chlorine, 9 mm and 34 mm size group mussels took 228 h (10 days) and 304 h (13 days), respectively, to achieve 100% mortality. All size groups of P. perna showed progressive reduction in physiological activities, when chlorine residuals were gradually increased from 0 to 1 mg/L. Reduction in physiological activities was strongly correlated with the residual level. A comparison of present data with data available for other common fouling organisms suggests that P. perna is relatively less tolerant to chlorine than Perna viridis (L.) and Brachidontes striatulus (Hanley), which also cause fouling problems in tropical coastal waters.     

Heat stress standard for hot work environments in Japan

Threshold limit values (TLVs) are intended to protect workers from the severest effects of thermal stress and to establish the exposures to heat in working conditions. Earlier, acute heat strokes often occurred as a result of working in hot environments in Japan. However, acute heat strokes recently sometimes occurred in outdoor work environments such as industrial constructions and agriculture. Seasonal variations in weather are significant and the climatic conditions vary. The criteria are mainly set for working in mines, factories, and so on. WBGT is a useful evaluation index for hot environments; however, it is not commonly used for work practices. WBGT could be calculated and should be commonly used as a standard during summer. Japan mainly has a very hot and humid climate during summer. With regard to the thermal standard for offices, humidity also creates a problem in the indoor thermal conditions. Therefore, it is better to decide the TLVs of the thermal conditions according to seasons and activity levels. Inadequate thermal stress may cause discomfort and adversely affect the performance, safety, and harm to health. Further, thermal factors in the work environment must be measured and evaluated under light workload conditions like desk work for safety and work efficiency.     

Full genome analysis and characterization of influenza C virus identified in Eastern India

In tropical countries of Asia, like India, approximately 0.5 million children of <5 years of age die annually due to acute respiratory illness (ARI). Of common respiratory pathogens, influenza viruses (A & B) are associated with annual worldwide epidemics; while the information on influenza C virus is inadequate. During January 2011 through December 2012, 2737 nasal and/or throat swabs were collected from patients reporting at outpatient department of hospitals in eastern India with ARI. Nucleotide sequencing was carried out using gene specific primers followed by pair-wise sequence alignments, multiple alignments, construction of phylogenetic tree and analysis of deduced amino acid sequences. Study reveals that, out of 2737 samples, 1616 (59.04%) were positive for one or more respiratory viruses; of which 23.72% were positive for influenza A and B viruses. From influenza A & B negative samples, influenza C virus was screened and detected with a frequency of 0.18%. Phylogenetic analysis showed that the HE, matrix, NS, PB1 and PB2 gene of the studied strain (C/Eastern-India/1202/2011) possessed a close relatedness to C/Yamagata/26/81 like strains. The P3 gene shows proximity with C/Mississipi/80 like strains whereas NP gene revealed similarity with C/Miyagi/1/93 like strains. The outcome of the whole genome analysis of the strain C/Eastern-India/1202/2011 provided useful information regarding genetic diversity of influenza C strains in India.     

Economic burden of dengue infections in India

Dengue infections are a significant cause of morbidity and mortality and lead to adverse economic effects in many developing tropical countries. In this study, we estimated the economic burden faced by India during the 2006 dengue epidemic. Costs incurred in managing a cohort of serologically confirmed dengue patients at a tertiary-level private hospital in north India were calculated. The median cost of treatment per hospitalised dengue patient was US$432.2 (95% CI US$343.6-625). A sensitivity analysis was performed to estimate the costs to the health system in India using a regression model. Variables with potentially large variations, including the ratio of unreported to reported cases and of hospitalised to ambulatory cases, the proportion requiring transfusions, loss of economic activities due to loss of workdays and deaths, were used. The average total economic burden was estimated to be US$27.4 million (95% CI US$25.7-29.1 million). Costs in the private heath sector were estimated to be almost four times public sector expenditures. Considerable economic losses (at a macro level) are incurred by developing countries like India during each dengue epidemic. Accurate estimates of the proportions of reported to unreported and of hospitalised to ambulatory dengue cases in India are needed to refine further the estimates of financial burden due to dengue in India.     

Thermal limits of men in moderate to heavy work in tropical farming

The farmers in tropical climate are exposed to high heat during the summer months. The study examined the physiological strains of farmers (N=26) to six combined exposures of work and high heat, with moderate and heavy work (26 to 50%, and 51 to 75% VO(2max)) and three ambient conditions, i.e., 34.4 to 42.2 degrees C WBGT (inside) in an environmental chamber. While the cardio-respiratory responses and Tcr were predominantly influenced by the work severity (p<0.001), the environmental warmth greatly influenced the sweating response (p<0.001). The importance was placed on the segmental Tsk as the first rank indicator of the bodily heat strain. Both the environmental warmth and work severity had independent discernable effects on the dynamic equilibrium of the central and peripheral mechanism to regulate the body temperature. The segmental and compartmental (core, muscle, fat and skin) heat balance analysis indicated the span of convergence of the segmental core and muscle temperatures to the divergence of skin and fat temperatures (CORE-SHELL) as a quantitative estimate of the segmental gradient for heat transfer. The summation of heat exchange across the compartments and segments yielded the transient change in Tcr (0.06 to 0.12 degrees C/min), with significant difference between the moderate and heavy work. The Tcr of 39 degrees C was taken as the limit of tolerance for the farmers, and by defining the criteria limit of Tcr of approximately 2.5 degrees C gradient from the basal Tcr and the rate of change in Tcr, the tolerance times were estimated. Corollary to the development of ISO 7933 standard (PHS index), the predictions of tolerance times from the transient change in Tcr or the exponential relationship with the WBGT (tolerance time, min = 1,841 e (-0.103 WBGT)) were useful to suggest the protective limit for men at work in extremely hot environment. The simplicity of prediction lies in using WBGT as a criterion. The exponential equation estimated the tolerance time of 55 min at 34 degrees C WBGT, and up to 38 degrees C WBGT, the decrease in tolerance time was 4 to 5 min per degree increase in environmental warmth. Beyond 38 degrees C WBGT, the estimated tolerance time decreased by 2 to 3 min per degree increase in WBGT. Further optimization and validation of the knowledge for men and women farmers in different age groups will have application in managing heat illnesses and disorders in tropical farming.     

Evaluation of occupational environment in two textile plants in Northern India with specific reference to noise

Occupational Noise exposure has been linked with a range of negative health effects by various researchers. The resulting injury of occupational hearing loss is also a well recognized and global problem. To protect workers from hearing damage due to noise exposure and other related health effects, a vast store of knowledge has been accumulated till date about its nature, etiology and time course. There is still ignorance, amongst majority of people working in industries in developing and third world countries including India about ill effects of exposure to high values of noise. The study being reported here has been carried out in two textile plants located in Northern Indian state of Punjab. Equivalent sound pressure level L(eq) has been measured in various sections of these plants with the help of a Class-I type digital sound level meter. The noise spectrum has been evaluated with the help of 1/3 octave filter set. A cross sectional study involving 112 workers exposed to different levels of occupational noise has been conducted. The results of the study establish the fact that noise level in certain sections of the plants i.e Loom Shed, Spinning, Ring Frame, TFO Area is more than the acceptable limit of 90 dBA for 8 h exposure stipulated by OSHA. The noise level in other sections like carding, blow room, combing etc., although is less than 90 dB(A), but is quite higher than limits used for assessment of noise for community response. Octave band analysis of the noise shows the presence of high sound level in 4,000 Hz frequency range, which can be a major reason for causing occupational hearing loss. The results of the interview questionnaire which included a number of parameters reveal the following; (i) only 29% workers are aware about the effects of noise on health (ii) 28% workers are using ear protectors (iii) the satisfaction with the working environment is related to noise level, as workers exposed to comparatively less noise level report better satisfaction (iv) 70% of the workers reported that high noise level causes speech interference (v) 42% workers report the noise to be annoying. The study thus demonstrates the presence of gross occupational noise exposure in both the plants and the author believes that occupational noise exposure and the related effects in India is a widespread problem.