Intervention to reduce heat stress and improve efficiency among sugarcane workers in El Salvador: Phase 1.

BACKGROUND: Chronic heat stress and dehydration from strenuous work in hot environments is considered an essential component of the epidemic of chronic kidney disease in Central America. OBJECTIVE: (1) To assess feasibility of providing an intervention modelled on OSHA's Water.Rest.Shade programme (WRS) during sugarcane cutting and (2) to prevent heat stress and dehydration without decreasing productivity. METHODS: Midway through the 6-month harvest, the intervention introduced WRS practices. A 60-person cutting group was provided water supplied in individual backpacks, mobile shaded rest areas and scheduled rest periods. Ergonomically improved machetes and efficiency strategies were also implemented. Health data (anthropometric, blood, urine, questionnaires) were collected preharvest, preintervention, mid-intervention and at the end of harvest. A subsample participated in focus group discussions. Daily wet bulb globe temperatures (WBGT) were recorded. The employer provided individual production records. RESULTS: Over the harvest WBGT was >26°C from 9:00 onwards reaching average maximum of 29.3±1.7°C, around 13:00. Postintervention self-reported water consumption increased 25%. Symptoms associated with heat stress and with dehydration decreased. Individual daily production increased from 5.1 to a high of 7.3 tons/person/day postintervention. This increase was greater than in other cutting groups at the company. Focus groups reported a positive perception of components of the WRS, and the new machete and cutting programmes. CONCLUSIONS: A WRS intervention is feasible in sugarcane fields, and appears to markedly reduce the impact of the heat stress conditions for the workforce. With proper attention to work practices, production can be maintained with less impact on worker health.

Heavy lifting during pregnancy--a hazard to the fetus? A prospective study.

The influence of heavy lifting during pregnancy on gestational age, birthweight and the risk of fetal death (spontaneous abortion or stillbirth) was investigated in a prospective study of 3906 occupationally active women. Information on exposure was collected at the women's first contact with the antenatal care centres in Orebro County from October 1980 to June 1983. Logistic and linear regression were used to analyse the data, allowing for several non-occupational factors in the models. Women who reported heavy lifting did not have in general more unfavourable outcomes than other women, although the risk estimates varied between different occupational categories. Lifting of weights greater than or equal to 12 kg more than 50 times per week increased the risk of pre-term birth (less than 37 weeks of gestation--odds ratio 1.7), but only among women who stopped working before the 32nd week of pregnancy. Unfavourable outcomes were more common among those who reported chemical exposure during pregnancy. The preventive routines and regulations in Sweden may have helped to reduce possible risks from heavy lifting during pregnancy.

Incidence of myocardial infarction and mortality from specific causes among bus drivers in Sweden.

Previous studies have indicated that urban bus drivers have an increased risk of coronary heart disease. In the present investigation two separate studies were carried out. In the first study the mortality from myocardial infarction (MI), as well as from other causes for all male bus drivers in Sweden (9446), was investigated and compared to those of other employed men over a 15-year period. A 50% increase in mortality from MI was observed among drivers in Stockholm and Göteborg and Bohus counties, the two counties where the two largest cities in Sweden are situated. No increased mortality from lung cancer, any cancer (all sites combined), or from all causes combined was observed for these drivers. For bus drivers in the predominantly rural areas no excess mortality from MI, or any other cause, was observed. In the second study the incidence of MI among male bus drivers, as compared with other employed men, was studied in five Swedish counties by case referent methods. An increased incidence of first events of MI, (relative risk = 1.6, 95% confidence interval (CI) 1.1-1.9) was observed for bus drivers in Stockholm county. According to our results, urban bus drivers thus have an increased risk of developing MI. The findings also suggest that factors in the work environment of urban bus drivers may contribute to this increased risk. Factors of possible importance are job strain, irregular working hours, a sedentary job, automobile exhaust fumes, and noise.

Occupation and osteoarthrosis of the hip and knee: a register-based cohort study.

A register-based cohort study was performed to investigate if men and women in certain occupations with high physical workload had increased risks of developing severe symptomatic osteoarthrosis of the hip and knee, resulting in hospital care. The study population consisted of 250,217 people from the 1980 census, in blue-collar occupations, who had reported the same occupation in the 1960 and 1970 censuses. The study population was followed for hospital care for osteoarthrosis of the hip and knee during 1981-1983 by linkage to the Swedish Hospital Discharge Register. Different blue-collar occupations were classified as high or low with regard to exposure to forces acting on the hip and knee and the frequencies of the outcomes were compared. Male farmers, construction workers, firefighters and some food processing workers had an excess risk of hospitalization due to osteoarthrosis of the hip. Male farmers, construction workers and firefighters also had increased risks of osteoarthrosis of the knee. Female mail carriers had an excess risk of osteoarthrosis of the hip, and female cleaners, of osteoarthrosis of the knee. The findings support the hypothesis that heavy physical work load contributes to osteoarthrosis of the hip and knee.

Geographical differences of cancer incidence in Costa Rica in relation to environmental and occupational pesticide exposure.

BACKGROUND: This study describes geographical differences in cancer incidence in Costa Rica, and investigates if some of these differences may be related to pesticides. METHODS: Data were combined from the cancer registry (1981-1993), the 1984 population census, the 1984 agricultural census, and a national pesticide data set. The 81 counties of Costa Rica were the units for the ecological analyses. Adjacent counties were grouped into 14 regions (3 urban and 11 rural) with relatively similar socioeconomic characteristics. County indices for population density and agricultural variables were constructed and categorized. Differences across regions and categories were assessed by comparing observed numbers of incident cases to expected values derived from national rates. Within the tertile of most rural counties, rate ratios between categories of high and low pesticide use were calculated. RESULTS: In urban regions, excesses were observed for lung, colorectal, breast, uterus, ovary, prostate, testis, kidney, and bladder cancers; and in rural regions for gastric, cervical, penile, and skin cancers. Skin cancers (lip, melanoma, non-melanocytic skin and penile cancer) occurred in excess in coffee growing areas with extensive use of paraquat and lead arsenate. In the most rural subset, heavy pesticide use was associated with an increase of cancer incidence overall and at a considerable number of specific sites, including lung cancer (relative risk [RR] 2.0 for men and 2.6 for women) and all female hormone-related cancers (RR between 1.3 and 1.8). CONCLUSIONS: Regions and populations at high risk for specific cancers were identified. Several hypotheses for associations between pesticides and cancer emerged. The findings call for studies at the individual level.

To what extent do current and past physical and psychosocial occupational factors explain care-seeking for low back pain in a working population? Results from the Musculoskeletal Intervention Center-Norrtälje Study.

STUDY DESIGN: A population-based case referent study. OBJECTIVES: To determine whether current and past physical and psychosocial occupational factors are associated with care-seeking for low back pain in working men and women. SUMMARY OF BACKGROUND DATA: The importance of physical and psychosocial workloads as causal factors of low back pain has mostly been investigated in special occupational groups and with a cross-sectional design, which makes generalizability and interpretations more difficult. METHODS: The study comprised 2118 working men and women 20 to 59 years old (695 cases, and 1423 referents). Cases were defined as persons seeking care by any caregiver for low back pain. The exposure assessments were made through questionnaires and interviews about current and past physical and psychosocial loads during work and leisure time. RESULTS: In a logistic regression analysis, physical load from forward bending in men (RR = 1.8) and high physical load, in general, in women (RR = 2.0) showed increased relative risks. Psychosocial factors alone seemed to be of less importance in women, but "poor job satisfaction" and "mostly routine work without possibilities of learning" increased the risk in men. Combined current and past exposures further increased the risks. A combination of high physical and psychosocial loads increased the risk substantially, but few were exposed to such loads. Adjustment for lifestyle and other loads outside work did not change the results. CONCLUSION: Current and past physical and psychosocial occupational factors, both separately and combined, seem to be gender-specific, and to have a moderate impact on care-seeking for low back pain in a general working population.

Sports and osteoarthrosis of the hip. An epidemiologic study.

To investigate if participation in sports increases the risk of developing osteoarthrosis of the hip, we did a case-control study on the sports activities of 233 men (up to age 49) who were recent recipients of a prosthesis because of severe idiopathic osteoarthrosis of the hip and 302 men randomly selected from the general population. Assessments of sports, job history, and health status were made by an interview. Men with high exposure to sports of all kinds combined (in hours) had a relative risk to develop osteoarthrosis of the hip of 4.5 compared to those with low exposure. Track and field sports and racket sports seemed to be the most hazardous to the hip joint. Men who had been exposed to high physical loads both from their occupation and sports had a relative risk of 8.5 to develop osteoarthrosis of the hip compared to those with low physical load in both activities. Potential confounding factors, such as age, body mass index, and smoking, were considered. Long-term exposure to sports among men seems to be a risk factor for developing severe osteoarthrosis of the hip; this is increased when combined with heavy load from occupation.

Has the Scandinavian solvent syndrome controversy been solved?

This article discusses the "Scandinavian solvent syndrome" and reviews epidemiologic studies on occupational solvent exposure and two related outcomes. High cumulative exposure to organic solvents in the 1960-1970s was related to early retirement from neuropsychiatric disorders, but solvent exposure alone was an unlikely cause of more severe dementia conditions. Heavy alcohol consumption seemed to modify the effect on solvent-related brain disorders strongly, but no reports exist of alcohol consumption as a confounding factor. Many cross-sectional and experimental studies support functional impairment from high solvent exposure. The mists and myths around the "Scandinavian solvent syndrome" can now be cleared up: it was not a uniform syndrome, it might be reversible in many cases, it is not confined to the Scandinavian countries, the risk of more severe dementia is substantial for combined high solvent exposure and excessive alcohol consumption, and many solvent-exposed workers receive early retirement due to solvent-related neuropsychiatric disorders.

Possible causes of increased lung cancer incidence among butchers and slaughterhouse workers.

An excess of lung cancer among butchers and slaughterhouse workers has been reported in several record-linkage studies. In this case-referent investigation on the possibility of occupational exposures being related to the lung cancer excess, cases and referents were selected from butchers and slaughterhouse workers registered in the Swedish national census of 1960. The case group comprised all men in the study population dying from lung cancer between 1971 and 1982. Two reference groups were formed, ie, all individuals dying from other cancers and a random sample of all dead men in the study population during the same time period. The history of occupations, occupational exposures, and smoking habits was obtained from the next-of-kin by questionnaire. None of the occupational exposures that were studied (work with live animal care, in the bleeding area, on the killing floor, or with meat cutting, processing, curing, smoking, chilling and packaging) were associated with an increased lung cancer rate. Tobacco smoking habits may have contributed to the overall excess of lung cancer found previously for this occupational group.

Mortality and incidence of cancer among Swedish rubber workers, 1952-1981.

The mortality and incidence of cancer was studied among 8,734 workers from two Swedish rubber manufacturing companies. Mortality was investigated from 1952 to 1981 and cancer incidence from 1959 to 1980. The expected numbers of deaths were calculated from national statistics. No significant risk excesses were detected when the cohort was analyzed without consideration of employment time or latency period. However, the mortality from coronary heart disease and the incidence of lung cancer were increased when the study period was limited to greater than or equal 40 years since first employment. The standardized mortality ratio for coronary heart disease correlated positively with employment duration. The mortality from asthma, bronchitis, and emphysema was nonsignificantly increased. The incidence of bladder cancer was increased among individuals with heavy and long-term exposure in the weighing and mixing departments. Twenty-five percent of the individuals in the cohort were not Swedish citizens at the time of employment, and an analysis of the mortality and cancer incidence in this group showed a markedly increased lung cancer incidence for certain immigrant groups, probably mainly due to ethnic factors. The results indicate that ethnic factors must be considered in the analysis of occupational groups when a high proportion of the workers are immigrants.

Parkinson's disease and occupational exposure to organic solvents, agricultural chemicals and mercury--a case-referent study.

Parkinson's disease has been associated with heavy occupational exposure to carbon disulfide, and this solvent, as well as other organic solvents, may cause neurotoxic effects. Therefore, the hypothesis was raised that organic solvents in general may be associated with Parkinson's disease. A case-referent study design was applied, and some other suspected exposures were studied as well. The diagnosis registers of two Swedish hospitals were used as the source of subjects. Male in-patients with Parkinson's disease (the cases) or subarachnoid hemorrhage (referents), with symptom appearance between 35-69 a of age and residence in the vicinity of the hospitals, were included in the study. Occupational exposure to the chemicals under study were determined from questionnaire answers of 91 cases and 75 referents. No differences in exposure frequency to organic solvents in general were observed, but three cases had been exposed to carbon disulfide compared to none of the referents. Six cases, but only two referents, had been exposed to mercury, and further exploration of a possible association between exposure to mercury and Parkinson's disease is recommended. The outcome of the study does not support the hypothesis that occupational exposure to organic solvents in general increases the risk of Parkinson's disease, but the confidence intervals of the odds ratios do not rule out such possibilities.

Primary osteoarthrosis of the knee in men and women as a result of lifelong physical load from work.

OBJECTIVES: This study investigated the effect of lifelong physical load from work on the development of knee osteoarthrosis (OA) leading to prosthetic surgery among men and women. METHODS: In a population-based case-referent study, men and women (N=625) who had had prosthetic surgery due to primary tibiofemoral OA were compared with referents (N=548) as to job titles and exposure to physical load in occupational work, housework, and leisure-time activities from 15 to 50 years of age. RESULTS: Male forestry and construction workers, and both male and female farmers ran the highest risk of knee OA. The men had considerably higher exposure to lifting at work, and also to jumps and vibration, than the women. Among the men there was an association between lifting at work [odds ratio (OR) 3.0, 95% confidence interval (95% CI) 1.6-5.5], squatting or knee bending (OR 2.9, 95% CI 1.7-4.9), kneeling (OR 2.1, 95% CI 1.4-3.3), and jumping (OR 2.7, 95% CI 1.7-4.1) with knee OA. Exposure to physically demanding tasks at home, such as taking care of an elderly or handicapped person, was associated with knee OA among the women (OR 2.2, 95% CI 1.3-3.6). CONCLUSIONS: Working as a farmer or as a construction worker could be associated with the development of knee OA and lead to prosthetic surgery. Men and women differ in the quality and quantity of reported physical load and also in the strength of the risk estimates. A reduction of high physical load at work and at home could probably lower the risk of knee OA later in life.

A case-referent study on neuropsychiatric disorders among workers exposed to solvents.

Published reports give justification for the belief that long-term exposure to solvents might induce chronic but nonspecific neuropsychiatric conditions. This case-referent study of data from a regional Swedish pension fund register indicated a risk ration of 1.8 in regard to nonspecific neuropsychiatric disorders among workers such as painters, varnishers and carpetlayers who are exposed to solvents as compared to workers not so exposed. Moreover a dose-response relationship seems to exist between exposure in terms of occupational years and neuropsychiatric conditions, the result being that persons affected are considered eligible for disability pensions.

A cohort study on mortality among long-time employed Swedish chimney sweeps.

A cohort study on mortality among all members of the Swedish Chimney Sweeps Union who were active in 1950 or later and have been members for at least 10 a has been performed; 2,071 chimney sweeps fulfilled the criteria and the loss in the follow-up was less than 1 %. The observed numbers of death before the age of 80 were compared with sex-, calendar year-, and age class specific expectancy values from the national statistics of 1951-1979. Two hundred and thirty deaths were observed versus 197.6 expected. This result was due to a significant excess of deaths from tumors, particularly lung and esophageal cancer, and from nonmalignant chronic respiratory diseases. The multifold increased risk from these diseases could hardly be explained by extreme smoking or alcohol habits but rather by exposure to polycyclic aromatic hydrocarbons, nitrogen compounds, arsenic, and asbestos in combination with exposure to sulfur dioxide. The excess mortality had occurred in spite of favorable selection factors as demonstrated in different subcohorts. Preventive actions to diminish inhalation of soot and combustion gases should be taken.

Mortality among asbestos-exposed workers in a railroad workshop.

The mortality experience of a cohort of 3 297 railroad maintenance shopworkers exposed to asbestos was investigated. The study period was 1951-1980, and the vital status was assessed for 99.6% of the men. Individual estimates of cumulative asbestos exposure were based on detailed records on work tasks and divisions. Dust measurements were scanty in earlier decades, and estimates of average fiber levels were therefore based on information on the amount and kind of asbestos used, job descriptions, and interviews with older workers. The overall mortality was lower than expected from the national death rates (standardized mortality ratio = 82). The mortality from lung cancer increased as cumulative exposure increased in consistent dose-response relationships. Employment times of less than 30 years in workplaces with moderate levels of mainly chrysotile asbestos was not associated with any apparent increase in the risk of lung cancer. A subgroup exposed for more than 30 years in workplaces repairing steam engines, where amphiboles were used as well, had a standardized mortality ratio of 192 for lung cancer. This figure may be an underestimation due to healthy worker selection and fewer smokers than normal. The "true" standardized mortality ratio was estimated to be about 300. Five cases of mesothelioma were observed.

Pregnancy outcome among working women.

The influence of occupational factors on the outcome of pregnancy was investigated in a prospective study of 3901 women who worked during their pregnancy and received prenatal care in Orebro County from October 1980 to June 1983. Data on occupational factors, social circumstances, and life-style factors were obtained from questionnaires. There were no significant differences in the incidence of adverse pregnancy outcome (spontaneous abortion, perinatal death, birth defects, or low birthweight) between the nine occupational categories used when nonoccupational factors were accounted for. No increased risk was found for exposure to organic solvents, but the adjusted risk ratio of adverse outcome was 1.28 (95% CI 0.91-1.80) for "other chemical exposures." The work conditions in this county have been generally favorable in recent years, and the results therefore cannot be generalized to conditions with higher exposures. Methodological problems such as misclassification of exposure and the possible bias resulting from different rates of legal abortions among occupational groups are discussed.

Shoulder tendinitis and its relation to heavy manual work and exposure to vibration.

Three categories of construction industry workers (54 bricklayers, 55 rockblasters, and 98 foremen) were compared in a cross-sectional study. In a structured interview they reported exposure to loads lifted, vibration, and years of manual work. They were also subjected to a clinical investigation including medical history and a detailed shoulder examination. Among the rockblasters 33% had signs of tendinitis in the left and 40% in the right shoulder. Among the bricklayers and foremen 8-17% had signs of shoulder tendinitis. In a multiple logistic regression being a rockblaster compared with being a foreman showed an odds ratio (OR) of 3.33 for left-sided and 1.71 for right-sided shoulder tendinitis. Vibration exposure yielded an OR of 1.84 and 1.66 for the left and right sides, respectively. Vibration exposure or work as a rockblaster seemed to be risk indicators for tendinitis of the shoulders.

Does long-term concrete work cause silicosis?

The machining of cast concrete often produces heavy exposure to respirable silica dust. Work with concrete in general results in considerably less exposure, however, and only a few cases of silicosis due to work with concrete have been reported. Telephone interviews with detailed questions on occupational history were made with 271 construction workers specializing in concrete work for more than 20 years, and exposure data were evaluated for different work tasks. The mean cumulative exposure of subjects to silica was estimated to be 2.4 mg.years.m-3. Chest radiographs were classified according to the International Labour Office classification. There was no suspicion of silicosis for any of the workers. The risk of contracting silicosis from work with concrete in the Swedish construction industry in recent decades is considered to be slight and does not justify general, periodic chest radiographic screening.

Lung cancer and exposure to diesel exhaust among bus garage workers.

Mortality and cancer incidence was investigated among the 695 bus garage workers employed as mechanics, servicemen, or hostlers for at least six months in five bus garages in Stockholm between 1945 and 1970. The exposure to diesel exhaust and asbestos was estimated by industrial hygienists. A small excess of lung cancer mortality was found in the cohort when occupationally active men in Stockholm were used as the reference group. A case-referent study was performed within the cohort, six referents being selected for each of the 20 lung cancer cases. The lung cancer risk increased with increasing cumulative exposure to diesel exhaust, but not with cumulative asbestos exposure. The relative risk for lung cancer among the highly exposed men was 2.4 (95% CI 1.3-4.5) as compared with those with low exposure. The study indicates that exposure to diesel exhaust increases the risk for lung cancer.

Respiratory symptoms, spirometry and chronic occupational paraquat exposure.

OBJECTIVES: A cross-sectional study was conducted to evaluate the relationship between respiratory health and paraquat exposure. METHODS: The study population was selected from among workers at 15 Nicaraguan banana plantations which relied on paraquat for the control of weeds. All the workers were interviewed after they received their job assignment for the day of the survey, and all who reported never having applied paraquat and all who reported more than 2 years of cumulative exposure as applicators of paraquat with knapsack sprayers were invited for medical evaluation. One hundred and thirty-four exposed workers and 152 unexposed workers were administered a questionnaire interview asking about exposure and respiratory symptoms, and they underwent spirometric testing of forced expiratory volume in 1 s (FEV1.0) and forced vital capacity (FVC). RESULTS: In the exposed group 53% reported having experienced a skin rash or burn resulting from paraquat exposure, 25% reported epistaxis, 58% nail damage, and 42% paraquat splashed in the eyes. There was a consistent dose-response relationship between intensity of exposure (as indicated by a history of skin rash or burn) and the prevalence of dyspnea. This relationship was more marked for more severe dyspnea. There was a 3-fold increase in episodic wheezing accompanied by shortness of breath among the more intensely exposed workers. There was no relationship between exposure and FEV1.0 or FVC. CONCLUSIONS: The high prevalence of respiratory symptoms associated with exposure, in the absence of spirometric abnormalities associated with exposure, could be a result of unmeasured gas exchange abnormalities among workers with long-term exposure to paraquat.