Plasma cholinesterase level of Ethiopian farm workers exposed to chemical pesticide

BACKGROUND: Pesticide applications can have unwanted health consequences. AIM: To study cholinesterase levels in farm workers with varying exposure to chemical pesticide. METHODS: Plasma cholinesterase (PChE) was measured in workers at two Ethiopian farms. A standard questionnaire adopted from the British Medical Research Council was used to determine the health status of the subjects. RESULTS: A total of 82 farm workers and 47 controls participated in the study. While the mean values of plasma cholinesterase were generally lower in those exposed, this difference was only significant in the sprayers at Birr farm (P<0.05). In this group, four sprayers had cholinesterase activity lower than 50%. CONCLUSION: The sprayers in both farms were the most affected groups, suggesting that improved controls on workplace exposure to pesticide is required in these groups of workers.     

The problems associated with pesticide use by irrigation workers in Ghana

The use of pesticides in Ghanaian agriculture, though beneficialin reducing crop loss both before and after harvest, has beenassociated with threats to human health often due to the misapplicationof the chemicals. This study was an initial attempt to explorethe knowledge, attitudes and practices of 123 farm workers onthree irrigation project areas in the Accra Plains, Ghana, regardingthe safe handling and use of pesticides, to assess the prevalenceof symptoms associated with organophosphorus pesticides (OPs)and carbamates and to determine the prevalence of pesticide-relatedsymptoms, and blood cholinesterase. The study design was cross-sectionalin type. Methods used were interviews and observation, and biologicalmonitoring. The results revealed moderate levels of knowledgeof the routes of absorption of pesticides and of potential symptomsfollowing exposure. Knowledge of personal protective measureswas poor to moderate. High risk practices included frequenthandling of the chemicals, home storage of pesticides and shortre-entry intervals. Despite knowledge of some health risks associatedwith pesticides, the use of personal protective equipment (PPE)was minimal due primarily to financial constraints. The prevalenceof symptoms was higher and cholinesterase levels lower thanin a control group of teachers. It is suggested that there isa need for more epidemiologic studies to investigate the problemsassociated with pesticide induced ill health as well as researchinto appropriate and affordable PPE. PPE needs to be subsidized.Training of agriculture and health workers in safety precautions,recognition, and management of pesticide-related ill healthis a matter of urgency.     

Musculoskeletal disorders in farmers and farm workers

Farming is a physically arduous occupation and this places farm workers at potential risk of musculoskeletal disorders such as osteoarthritis (OA) of the hip and knee, low back pain (LBP), neck and upper limb complaints, and hand-arm vibration syndrome (HAVS). This review considers the epidemiological evidence concerning such risks. The strongest evidence relates to OA of the hip, for which the public health impact is likely to be considerable. There is also weaker, but suggestive evidence that farmers more often have knee OA and LBP than workers in occupations with fewer physical demands. Tractor drivers, in particular, seem to have more LBP. Relatively little information exists on the risks of soft tissue rheumatism in the limbs and neck. For some outcomes, the link with occupational risk factors (such as heavy loading of joints and whole-body vibration) is sufficient to suggest the course that future prevention should take, but for several outcomes more research is first needed.     

Literature review: dermal monitoring data for pesticide exposure assessment of farm workers

Objective: To conduct a literature review to determine the types of information that existing dermal pesticide monitoring data could provide for future pesticide exposure assessment in occupational epidemiology.

Methods: A systematic literature search was performed on eight online databases. Two screening phases with predetermined criteria identified the qualifying literature. Standard information and dermal pesticide monitoring data were recorded and summarized from each qualifying study to assess its usefulness for future pesticide exposure assessment.

Results: A total of 31 farm studies qualified for review; task information was used to standardize all farm job(s) evaluated into 5 job groups: operators, applicators, mixer-loaders, field workers, and flaggers. When attempting to compare dermal exposure levels between studies, two types of variation were identified: (1) variation in study focus and reporting and 2) variation in exposure levels. The former variation type prevented exposure level comparisons between studies. Within studies, exposure levels were compared across body parts to identify that which had the highest measured exposure and to determine if results were similar in other studies that evaluated the same farm job. Using studies that measured exposure for multiple farm jobs, within study comparisons of total body exposure were performed to evaluate work factors.

Conclusion: Future dermal pesticide exposure monitoring studies should standardize reporting procedures, as suggested in this review, to allow for more extensive dermal data comparisons. Body parts with highest measured levels of dermal exposure were identified by farm job, along with work factors to be further investigated as potential dermal pesticide exposure determinants for farm workers.     

Acute respiratory symptoms among sisal workers in Tanzania

Background Few studies have focused on respiratory health effectsamong sisal workers. Aim To report on the prevalence of acute respiratory symptomsamong sisal processors. Methods We interviewed 163 dust-exposed brushing and decorticationworkers and 31 low-exposed security workers from six sisal estatesin Tanzania using a modified symptom score questionnaire todetermine the prevalence of acute respiratory symptoms duringwork. Groups were compared using chi-square tests, Fisher'sexact tests, t-tests and logistic regression, adjusting forconfounding factors. Results After the first working day of the week, 73% of thebrushing workers reported dry cough, 66% sneezing, 65% productivecough, 63% running nose and 34% stuffy nose. Brushing workershad a significantly higher prevalence of these symptoms thandecortication workers. Brushing and decortication workers hadsignificantly more dry cough and sneezing than the control groupof security workers, when adjusting for age, smoking, past respiratorydiseases and residence. Conclusion Processors of sisal fibre have a high prevalenceof acute respiratory symptoms. More detailed studies on workand health in sisal estates are needed, including exposure studies.     

The recovery of plasma cholinesterase and erythrocyte acetylcholinesterase activity in workers after over-exposure to dichlorvos

Plasma cholinesterase and erythrocyte acetylcholinesterase activities have a long history of use in monitoring both workers at risk of organophosphorus pesticide (OP) exposure and in investigating accidental exposures to OPs. On account of wide inter-individual variation, the establishment of unexposed, baseline enzyme activities is necessary for accurate interpretation. This paper describes the rate of recovery of the two enzymes' activity after substantial over-exposure of eight subjects to the OP dichlorvos. Plasma cholinesterase activity, immediately after exposure, was substantially more inhibited than erythrocyte acetylcholinesterase activity. The plasma enzyme activity showed an exponential pattern of recovery with a half-life of around 12 days, so recovery was essentially complete after about 50 days. This reported half-life of recovery is consistent with the reported de novo synthesis rate of plasma cholinesterase. The mean recovery of erythrocyte acetylcholinesterase activity appeared linear over time, attaining unexposed activity after about 82 days, which is somewhat shorter than the life-span of erythrocytes. These indicate the sort of time period, after an OP incident, before a valid unexposed level can be established in an individual; and substantiate the guidance given in the Health & Safety Executive's document MS17 on a minimum period of 60 days without exposure in order to establish pre-exposure baseline levels.     

Indicators of cardiovascular risk among workers exposed to high intermittent levels of carbon disulphide

The effects of exposure to carbon disulphide have been studied mostly among workers in the viscous rayon industry, where the usual exposure profile has been relatively steady exposure over work shifts. We investigated 13 workers in a small chemical company who were exposed to low levels, peaking intermittently to relatively high levels in the range of 100-200 ppm at the end of the work shift, a pattern that may change the risk profile. Our investigation was part of a compliance order that was fought by the company and our access and follow-up was limited. Two workers had burns on their bodies associated with exposure to caustic. Four had elevations in total serum cholesterol, one had elevated serum triglycerides and three had elevations in fasting blood glucose--two of them were known to be diabetics before employment and one had a history of unexplained peripheral neuropathy. No consistent pattern suggestive of a defined lipoprotein abnormality was obvious but several atherogenic profiles were observed. Five had abnormalities on electrocardiogram, four of whom appeared to be among the most heavily exposed. The presence of these changes taken together in this context may suggest accelerated atherosclerotic changes. Tests of liver and kidney function were within the normal range for all workers, as was a complete blood count. Four of the workers had evidence of a bilateral reduction in hearing threshold at 4,000 Hz. A complete set of recommendations was forwarded to the employer, emphasizing further control of exposure to carbon disulphide, personal protection requirements and a cardiovascular risk reduction programme. Conditions improved in the plant following modifications introduced in response to a stop work order from the provincial government's occupational health and safety agency. However, a fire in 1998 put the company out of business and ended further follow-up or interventions. We conclude that these findings, while difficult to interpret because of the circumstances of the investigation, are compatible with an atherogenic effect of exposure to peaking levels of carbon disulphide. The observation should be tested in a larger population with fewer confounding factors and greater control over the investigation.     

Tetanus in a central Italian region: scope for more effective prevention among unvaccinated agricultural workers

In 1997, Italy had the highest number of tetanus cases in the European Union; cases in the Marches region were more numerous than in France or Germany. In a retrospective study of the patients infected in Marches in 1996-1999, subjects or relatives were interviewed to ascertain disease severity, infection mode, occupation and immunization state at the time of infection. There were 32 cases, 29 (90.6%) females and three (9.4%) males, mean age 74.65 years (SD 9.06). The raw annual incidence was 5.6 per million and raw annual mortality 0.5 (n = 3). Twenty-seven patients (84.4%) were agricultural workers and five (15.6%) housewives; 25 (78.2%) had never been vaccinated, two (6.2%) had been immunized several years earlier and five (15.6%) had received only the first dose of vaccine at least 15 years earlier. In Italy, tetanus vaccination is compulsory for agricultural workers. Occupational health physicians should monitor workers' tetanus immunization state during their periodic surveillance visits.     

Agricultural injury in California migrant Hispanic farm workers

BACKGROUND: Agriculture is among the most hazardous industries in the United States. METHODS: A longitudinal study of injury among migrant Hispanic farm workers residing in six Northern California Migrant Family Housing Centers (MHCs) during the 1997 harvest season was conducted. Participants completed an initial interviewer-administered work-and-health questionnaire at the beginning of the harvest season addressing the preceding year; there were three periodic follow-up surveys. RESULTS: There were 1,201 adult farm workers (participation 85.2%) who completed the initial questionnaire. Of these, 837 (69.7%) completed the final follow-up survey. There were 86 agricultural injuries (incidence 9.3/100 full-time equivalent employees (FTEs), 95% CI 7.5-11.5/100 FTE). Increased risk for agricultural injury occurred among women paid piece-rate (RR 4.9, 95% CI 1.8-12.8). Sprains and strains were most common (31%), followed by lacerations (12%). CONCLUSIONS: Agricultural injury experience in this cohort is comparable to that of agricultural workers in other U.S. settings. Increased risk among women paid piece-rate suggests further study and potential policy changes regarding payment regimens. Heterogeneity of injury in this population presents a major prevention challenge. In view of high frequency of strain and sprain injuries, ergonomic interventions deserve further study.     

The decay of blood lead levels in workers suspended under the control of lead at work regulations

AIMS: To study the rate of decline in blood lead levels post-suspension under Control of Lead at Work Regulations (CLAW) and thereby suggest sampling frequencies for follow-up blood lead measurements. METHODS: A retrospective cohort of lead workers with blood lead levels over the current suspension level were identified from blood lead records. Data on their suspension and follow-up blood lead measurements were obtained. RESULTS: Sixteen per cent of the identified cohort did not appear to return to lead work under CLAW. Twenty-seven suspension cases with an initial mean blood lead of 79 microg/dl (3.82 micromol/l) formed the dataset for analysis of decline in blood lead levels. The mean length of time between the blood sample indicating suspension and the first follow-up blood sample was 32 days. The mean length of suspension under CLAW was 61 days. The mean initial rate of blood lead decay was 0.659 microg/dl per day (0.032 micromol/l per day), although with a wide range. The rate of decline in blood lead after suspension was increased by the blood lead level at suspension, but was decreased by increasing past cumulative exposure. CONCLUSIONS: A follow-up blood lead sample 1 month after suspension should show a mean decrease between 13 and 26 microg/dl (0.63-1.25 micromol/l), which is substantially greater than that due to analytical 'noise' associated with two sequential measurements (approximately 5 microg/dl). Therefore, a follow-up blood sample taken around 3-4 weeks after suspension would seem practical. A decrease in blood lead of 7-8 mug/dl (0.36 micromol/l) or less in the month after suspension may suggest continuing lead exposure.     

Is working in greenhouses healthy? Evidence concerning the toxic risks that might affect greenhouse workers

Greenhouses are essentially microcosms aimed at providing physicalenvironments suitable for the survival and growth of plants.Crops grown intensively in greenhouses in Great Britain includecut flowers, pot plants and edible crops such as tomato, lettuce,cucumber and celery. The enclosed conditions mean that greenhouseworkers are more likely to be exposed to higher levels of plantmaterial, plant pests and plant protection products than generalhorticulture workers. The potential for ill-health in greenhouseworkers is examined with particular reference to Great Britain.The principal potential effects expected include irritancy,asthma, allergic aleveolitis and dermatitis. Although biologicalcontrol agents are widely used, there were no reports of theirhaving caused ill-health in greenhouse workers. About two peopleper year are found to have suffered ill-health as a consequenceof greenhouse exposure to chemical pesticides in reported pesticidesincidents in Great Britain.     

急性有机磷农药中毒时血清胆碱酯酶活性动态监测的临床意义

目的：探讨急性有机磷农药中毒（AOPP）患者血清胆碱酯酶（ChE）变化特点及其临床意义。方法：将88例AOPP患者根据中毒的程度分为轻度中毒、中度中毒和重度中毒组,采用硫代丁酰胆碱法检测患者血清ChE活性的动态变化,并结合患者临床症状改变进行分析和比较。实验中以31例健康体检者作为正常对照。结果：与正常对照组比较,AOPP患者血清ChE活性均明显降低（P〈0.01）,其下降幅度与临床中毒程度呈平行关系。结论：检测AOPP患者血清ChE活性对明确诊断、判断中毒程度及用药剂量等均有重要参考价值。     

Mortality among workers in an Italian cigarette factory

A cohort study was conducted to evaluate the mortality pattern among female and male workers in a cigarette factory. The study followed 972 female workers and 761 male workers with at least 6 months of cumulative employment from 1 January 1962 through 1 July 1996. Among women, mortality from all causes of death [standardized mortality ratio (SMR) = 0.9; 95% confidence interval (CI) = 0.8-1.1] and mortality from all malignant neoplasms (SMR = 1.1; CI = 0.9-1.3) were consistent with reference rates. Male workers had a significantly reduced overall mortality (SMR = 0.8; CI = 0.7-0.9), while mortality from all malignant neoplasms was as expected (SMR = 0.9; CI = 0.7-1.0). Among female workers the frequencies of deaths from diseases of nervous system (SMR = 2.0; CI = 1.1-3.4) and from non-Hodgkin's lymphoma (NHL) (SMR = 2.7; CI = 1.0-5.6) were elevated at a statistically significant level. No association between duration of employment and diseases of nervous system was observed. A higher risk for NHL, based on three deaths, was reported among female workers with 15 or more years of employment (SMR = 8.1; CI = 2.2-21.0). Although based on small numbers, the excess of NHL here reported suggests that potential exposure to foliar residues of pesticides should be thoroughly considered in tobacco manufacturing.     

Visual evoked potentials in rubber factory workers

Pattern reversal visual evoked potentials (pVEP) were studiedin 39 male rubber factory workers in the age range of 18–55years and 20 control subjects (aged 18–46 years) not exposedto the rubber factory environment. Results revealed that 20(51%) rubber factory workers had abnormal latencies of waveP₁ (dominant component of pVEP) as per accepted criteria of99% tolerance limit set for the control group (i.e. any valueabove mean + 3 SD of control was considered abnormal). The section-wiseper cent distribution of abnormalities was vulcanization (83%),tubing (75%), calendering (60%), loading (38%) and mixing (14%).This study provides electrophysiological evidence that rubberfactory environments affect the conduction processes in opticalpathways from their origin in the retina to striate cortex.However, this study has its limitations in not identifying thespecific chemical(s) causing these changes in VEP.     

The use of personal protective equipment in pregnant greenhouse workers

AIM: To determine the use of personal protective equipment (PPE) among pregnant greenhouse workers in Italy and to identify risk factors related to the non-use of appropriate preventive measures. METHODS: A structured questionnaire was administered by trained interviewers, to Italian female greenhouse workers regarding their use of PPE and the occurrence of adverse pregnancy outcomes in their first pregnancy. RESULTS: Two hundred and thirty-two workers participated. Although most pregnant women used at least one form of PPE while working, there were differences in PPE use in different social groups. Overall, the protection was inadequate in the south of Italy and among the less educated. Pregnant women performing the most dangerous jobs often did so without using PPE. Even the use of gloves was absent in 50% of pregnant women who during their pregnancy prepared and mixed pesticides, and among 38% of those who applied pesticides directly. CONCLUSIONS: The use of protective measures was inadequate in the south of Italy and among less educated women. The study indicates the need for urgent interventions aimed at improving PPE use during pregnancy.     

Activity, functional capacity and well-being in ageing Finnish workers

BACKGROUND: The ageing of the labour force and falling employment rates have forced policy makers in industrialized countries to find means of increasing the well-being of older workers and of lengthening their work careers. AIMS: To longitudinally study the relationship between activity and functional capacity and the well-being of ageing workers. METHODS: Follow-up study to that carried out by the Finnish Institute of Occupational Health in 1981-97 (n = 3817). Activity level was measured using various free-time activities, and functional capacity was measured through daily-life activities. The measure of well-being included items with both positive and negative affects. The associations between activity, functional capacity and well-being were analysed by general linear models with repeated measures. RESULTS: Activity level and functional capacity had a strong positive effect (the effects of one unit increase were 0.32 and 0.30, respectively) on well-being. They were also interdependent. The impact of activity level in maintaining well-being became 31% greater during the follow-up, whereas the effect of functional capacity diminished by 17%. CONCLUSION: The results of the study indicate that both involvement in activities and functional capacity have an important, partly compensatory role in maintaining the well-being of ageing workers.     

Ventilatory function in brass workers of Gadaladeniya, Sri Lanka

A cross sectional study was conducted to determine the respiratoryhazards of brass workers. The study group was selected randomly.The control group was selected from the general population matchedfor age by cluster sampling. There was a total of 154 pairsfor the final analysis. A questionnaire was administered todetermine the prevalence of respiratory symptoms. Forced vitalcapacity (FVC), forced expiratory volume in the first second(FEV_1.0), forced expiratory flow rate in the mid 50% of theFVC(FEF_25%–75%) and peak expiratory flow rate(PEFR) weremeasured. Chest radiography was performed on those with 5 ormore years of service. Cough, phlegm, chronic bronchitis anddyspnoea were significantly higher among brass workers. Theventilatory capacity was significantly lower in all the indicatorsexcept FVC. Smoking had no significant effect and a dose responserelationship could not be demonstrated after inclusion of agein the regression model. Five point five per cent had evidenceof septal lines while 6.4% had emphysema.     

A 24 year cohort study of mortality in slate workers in North Wales

AIM: To study mortality in slate workers in North Wales. METHODS: A cohort study, with a contemporaneous control group (quasi-experimental study) with follow-up from 1975 to 1998. The date and cause of death in those who had died were identified from the Office of National Statistics. RESULTS: Seven hundred twenty six slate workers and 529 age matched controls took part in the survey. We found a clear excess of death rate among slate workers compared with controls, having adjusted for age and smoking habit. This was largely restricted to those ages less than 75. Hazard ratio for all deaths was 1.24 [95% Confidence Interval (CI)=1.04-1.47, P=0.015]. The excess was mainly due to respiratory disease and pneumoconiosis. The hazard ratio for respiratory deaths was 1.85 (95% CI=1.21-2.82). CONCLUSION: It is likely that the excess deaths in the exposed group was due to exposure to slate dust. The accuracy of pneumoconiosis as a cause of death is questionable, but we lack radiographs close to death to confirm it.     

Respiratory abnormalities among male foundry workers in central Taiwan

The objectives of this study were to determine the relationship between exposure levels and respiratory abnormalities, to measure FVC and FEV1(1) changes per year based on work duties and to investigate the prevalence of and factors related to pneumoconiosis. A total of 583 male workers from 50 iron foundries in central Taiwan were investigated. First, workers' respiratory symptoms were categorized using a modified American Thoracic Society (ATS) questionnaire and then were verified by physician's examination. Next, pulmonary function tests were performed including: forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and forced expiratory flow rate. A chest radiograph was used to diagnose pneumoconiosis according to ILO criteria. Furnace workers were found to have the highest prevalence of chronic phlegm, thoracic disorders and chronic bronchitis. In general, smokers had a higher prevalence of respiratory symptoms as compared with non-smokers. Pulmonary function abnormalities and pneumoconiosis were closely linked to smoking and work duration. After adjusting for age, height and smoking there was a significant decrease based on work duration in FVC and FEV1 for furnace and moulding workers compared with after-processing and administrative workers. The overall prevalence of pneumoconiosis was 8.8%, highest among furnace (16.3%) and after-processing workers (11.4%) and lowest among administrative workers (2.5%). Using multiple logistic regression, the risk of developing pneumoconiosis (as compared with the administrative workers) for furnace workers was highest (8.98 times greater risk), followed by after-processing workers (6.77 times greater risk) and moulding workers (5.41 times greater risk). Prolonged exposure to free silica, and smoking habits, can result in respiratory abnormalities among foundry workers.