Hip joint arthrosis: an occupational disorder among farmers

Observations among Swedish farmers indicate that coxarthrosis is a common disorder in farming populations. In this case-referent study, we describe relationships between farming and hip joint arthrosis. The case-group consisted of 105 persons who have had surgery because of coxarthrosis and the referents consisted of 222 randomly selected persons. Non-responders totaled 9%. Farming was significantly more common in the case group. The ratio varied between 2.1 and 3.2, varying with the length of time in farming. Longer exposure did not seem to result in greater risk. There was no risk elevation related to forestry or transportation work. Nor was there any over-representation of accidents with injuries to the lower extremities in the case group. Heavy work load did not seem to be related to the genesis of coxarthrosis. Farming is an amalgamation of different types of work. However, we develop the hypothesis from this study that tractor driving may be related to hip arthrosis. Unfavorable angles in the hip joints may occur during tractor driving. Other studies support this hypothesis, as it has been found that unsuitable conditions for the hip joints may be related to arthrosis.     

Magnetic field exposure and neurodegenerative diseases--recent epidemiological studies

Summary. Objectives To analyse the results of recent studies not yet included in a 2003 report of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) on occupational exposure to low-frequency electromagnetic fields as potential risk factor for neurodegenerative diseases. Methods A literature search was conducted in the online databases of PubMed, ISI Web of Knowledge, DIMDI and COCHRANE, as well as in specialised databases and journals. Eight studies published between January 2000 and July 2005 were included in the review. Results The fi ndings of these studies contribute to the evidence of an association between occupational magnetic field exposure and the risk of dementia. Regarding amyotrophic lateral sclerosis, the recent results confirm earlier observations of an association with electric and electronic work and welding. Its relationship with magnetic field exposure remains unsolved. There are only few findings pointing towards an association between magnetic field exposure and Parkinson’s disease. Conclusions The epidemiological evidence for an association between occupational exposure to low-frequency electromagnetic fields and the risk of dementia has increased during the last five years. The impact of potential confounders should be evaluated in further studies. Submitted: 4 August 2005; Accepted: 6 March 2006     

Osteoarthritis of the hand: longitudinal studies

Evaluation of the osteoarthritic grades of the hands of 478 participants of the ongoing Baltimore Longitudinal Study suggests that: 1) Joint degeneration due to osteoarthritis is a relatively slow process. The maximum rate of degeneration is seen in the distal interphalangeal joints where the average increase is about 1 grade per individual in an interval of 12 to 16 years between visits in each age group. The rate of degeneration in the proximal interphalangeal joints is much lower than that of the distal interphalangeal joints. 2) The progress of the degeneration in the distal interphalangeal joints of an individual (longitudinally evaluated) follows closely that which is observed at the population level (cross-sectional joint-digit study). That is, it is directly related to the age and the interval between visits. This is not always seen in the proximal interphalangeal joint data. 3) The rate of change in the osteoarthritic grade of individual hands agrees closely with that of their distal interphalangeal joints. This further supports the conclusions reached in a first report that what has been referred to as osteoarthritic grade of the hand of an individual may actually be the higher grade among the distal interphalangeal joints.     

Prevalence of radiologically defined osteoarthritis in the finger and wrist joints of adult residents of Tecumseh, Michigan, 1962-65

Radiographs of the fingers and wrists of adult participants in the Tecumseh Community Health Study in 1962-65 were examined for signs of osteoarthritis (OA). The severity of OA for each of 32 joints of the fingers and wrists was recorded for each individual. Attention was restricted to the 3035 participants who were 32 years of age or older and for whom a diagnosis of OA was available for each of 32 joints. Joint-specific prevalence rates of OA increased sharply with age for both sexes, and at the older ages, the prevalence rates for most joints were higher for females. Older individuals with OA also had a greater number of affected joints, with females having a greater number of affected joints than males. Of those individuals aged 44 years or younger, only 6.2% had one or more joints affected with OA. The percentages were 21.6 and 42.0% for those aged 45-59 years and 60 or more years, respectively. The distal interphalangeal (DIP) joints were the most frequently affected joints in all age categories for both sexes and OA in the proximal interphalangeal (PIP) joints was positively associated with OA in the DIP joints. However, controlling for the number of affected DIP joints, the PIP joints of older subjects were more likely to exhibit OA than the PIP joints of younger subjects. Though there is an association between OA in the DIP and PIP joints, there was only a small, nonsignificant association (OR = 1.24, 95% CI = 0.83, 1.84) between disease in the DIP and PIP joints of the same finger.     

Case-control assessment of the association between non-Hodgkin's lymphoma and occupational radiation with doses assessed using a job exposure matrix

BACKGROUND: Epidemiologic data for an association between radiation exposure and non-Hodgkin's lymphoma (NHL) have been inconclusive though the strongest evidence has been provided by studies of patients treated with radiotherapy. METHODS: We evaluated the association between occupational radiation exposure and non-Hodgkin's lymphoma in men using a population-based case-control study with 1,056 case and 1,860 control subjects sampled from eight geographic areas in the United States. Because dosimetry data were not available, doses were estimated for individuals who reported occupational radiation exposure using a radiation job exposure matrix developed for this purpose. Conditional logistic regression was used to model the association between reported occupational radiation exposure and NHL incidence. RESULTS: We found that most men (> 90%) did not report exposure to occupational sources of radiation. Among those who reported exposure, estimated cumulative doses were low, with an estimated mean of less than 0.02 Gray and a maximum of 0.12 Gray. The risk for NHL was not associated with ever having reported an occupational radiation exposure (OR = 0.90, 95% CI = 0.74-1.10) nor was there evidence of a dose-response relationship between risk and either the estimated cumulative doses or duration of exposure. CONCLUSIONS: The findings in this study are consistent with results from most current research on occupational radiation and NHL risk that have found no increased risk of NHL at low levels of occupational radiation exposure. While it should be noted that exposure misclassification likely biased our results toward the null, this large population-based case-control study adds to existing evidence which suggests that there is little to no increased risk for NHL associated with exposure to low levels of radiation such as that commonly found in many occupational settings. Copyright Published 2000 Wiley-Liss, Inc.     

Chronic exposure to organophosphate (OP) pesticides and neuropsychological functioning in farm workers: a review

Background: Previous studies have demonstrated that acute poisoning from exposure to organophosphate (OP) pesticides in agricultural workers causes adverse health effects. However, neuropsychological and cognitive effects of chronic occupational exposure to OP pesticides remain controversial.

Objective: To identify, evaluate, and systematize existing evidence regarding chronic exposure to OP pesticides and neuropsychological effects in farmworkers.

Methods: Using the PubMed search engine, a systematic review process was implemented and replicated according to the PRISMA statement. Eligibility criteria included workers over 18 years of age exposed to OP pesticides as well as assessment of neuropsychological and cognitive functioning. Search terms were in English and Spanish languages and included organophosphate and workers.

Results: Of the search results, 33 of 1,256 articles meet eligibility criteria. Twenty-four studies found an association between chronic occupational exposure to OP pesticides and low neuropsychological performance in workers. We classified nine of the studies to have study design limitations. Studies indicated occupational exposure to OP pesticides is linked to difficulties in executive functions, psychomotor speed, verbal, memory, attention, processing speed, visual–spatial functioning, and coordination. Nine studies find no relationship between OP pesticides exposure and neuropsychological performance.

Conclusions: Overall, evidence suggests an association between chronic occupational exposure to OP pesticides and neuropsychological effects. However, there is no consensus about the specific cognitive skills affected.     

Exposure to electromagnetic fields and the risk of leukemia

Evidence from animal experiments and human studies suggests that electromagnetic fields may be human leukemogens. Epidemiological studies of leukemia in occupational groups and in the general populations are reviewed. The results are inconsistent. In the few studies showing an association between exposure to electromagnetic fields and the risk of leukemia, the temporal relationship between exposure and effect was not established, the observed associations were weak, the dose-response relationships were based on qualitative levels of exposure without regard to the duration of exposure or secondary sources of exposure, and the risk ratios were probably biased due to the population selection procedures used and misclassification of exposure. The proportionate mortality or cancer incidence ratios are unreliable estimates of relative risk. Further epidemiological research is needed to establish an association between exposure to electromagnetic fields and the risk of leukemia.     

Osteoarthritis of the Hands in the Rural Population: A Follow-Up Study

The aim of this study was to analyze the progression of hand osteoarthritis in rural population and to determine the factors which could influence that progression. Participants of both sexes were 54-56 years of age at the first visit. Radiographs of both hands, anthropometry and blood pressure measurement were performed at baseline and than repeated 10 years later. Total number of 286 participants completed the study. Radiographs were red according to Kellgren-Lawrence criteria. Distal interphalangeal (DIP) joints were most frequently affected with osteoarthritis at the baseline and after 10 years. The worst deterioration (three grades) was found in DIP joints in women and in proximal interphalangeal joints in men. Grip strength in men was significantly related with progression of the disease, which allow us to conclude that in our population sample mechanical factors, probably occupational workload, are associated with the more rapid progression of the disease.     

Diesel exhaust exposure and lung cancer: a case--control study

The presence of polyaromatic hydrocarbons in the particulate phase of diesel engine exhaust has raised questions concerning potential carcinogenicity of diesel exhaust exposure. A case-control study was conducted of 502 male lung cancer cases and 502 controls without tobacco-related diseases to investigate the association of occupational diesel exhaust exposure and lung cancer. Diesel exhaust exposure was appraised by job title. The results show no association between diesel exhaust exposure and risk of lung cancer. They do, however, show the strong association between smoking and lung cancer and as such highlight the importance of smoking information in studies of occupational effect on lung cancer risk.     

B cell neoplasms and occupational asbestos exposure

To evaluate the etiologic role of asbestos exposure in B cell neoplasms, we compared the estimated level of occupational exposure to asbestos of cases with chronic lymphocytic leukemia (CLL; N = 429) and multiple myeloma (MM; N = 698) with that of controls (N = 1,683). Cases were identified through four population-based cancer registries in the U.S. and controls were randomly selected from the same geographic areas. Exposure to asbestos was assessed by classifying each job held by a subject into one of four categories, based on the estimated intensity of exposure to asbestos. Evidence was found for a modest increasing risk of CLL with increasing asbestos exposure. Relative to persons with no known occupational exposure to asbestos, the risk for CLL was 1.1 (95% confidence interval (CI) = 0.8-1.6) for low, 1.2 (CI = 0.8-1.8) for medium, and 1.4 (CI = 0.8-2.3) for high peak asbestos exposure (p value for trend = 0.13). The association was strongest in white study subjects and in those individuals exposed 10 to 19 years prior to the interview. No association was observed between MM and occupational exposure to asbestos in the entire study population or within specific subgroups. Given the pattern of immunologic abnormalities that occur with increased frequency in asbestos-exposed persons, our observation of an association between occupational asbestos exposure and CLL deserves attention in subsequent studies.     

Occupational benzene exposure and the risk of lymphoma subtypes: a meta-analysis of cohort studies incorporating three study quality dimensions

Background

The use of occupational cohort studies to assess the association of benzene and lymphoma is complicated by problems with exposure misclassification, outcome classification, and low statistical power.

Objective

We performed meta-analyses of occupational cohort studies for five different lymphoma categories: Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), multiple myeloma (MM), acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL).

Data extraction

We assessed three study quality dimensions to evaluate the impact of study quality variations on meta-relative risks (mRRs): stratification by the year of start of follow-up, stratification by the strength of the reported acute myelogenous leukemia association, and stratification by the quality of benzene exposure assessment.

Data synthesis

mRRs for MM, ALL, and CLL increased with increasing study quality, regardless of the study quality dimension. mRRs for NHL also increased with increasing study quality, although this effect was less pronounced. We observed no association between occupational benzene exposure and HL.

Conclusions

Our meta-analysis provides support for an association between occupational benzene exposure and risk of MM, ALL, and CLL. The evidence for an association with NHL is less clear, but this is likely complicated by the etiologic heterogeneity of this group of diseases. Further consideration of the association between benzene and NHL will require delineation of risks by NHL subtype.     

Occupational noise exposure and risk of acoustic neuroma

A small number of prior epidemiologic studies of occupational noise exposure based on self-report have suggested an association with acoustic neuroma. The goal of the present study was to further examine the association between noise exposure and acoustic neuroma by using an objective measure of exposure in the form of a job exposure matrix. A total of 793 acoustic neuroma cases aged 21-84 years were identified between 1987 and 1999 from the Swedish Cancer Registry. The 101,756 controls randomly selected from the study base were frequency matched to cases on age, sex, and calendar year of diagnosis. Occupational information, available for 599 of the cases and 73,432 of the controls, was obtained from censuses and was linked to a job exposure matrix based on actual noise measurements. All risk estimates were close to unity, regardless of noise exposure level or parameter. The overall odds ratio for exposure to > or = 85 dB of noise was 0.89 (95% confidence interval: 0.64, 1.23). Contrary to previous study results, the present findings did not demonstrate an increased acoustic neuroma risk related to occupational noise exposure even after allowing for a long latency period. The effect of nondifferential misclassification of exposure must be considered a potential cause of the negative findings.     

Invited commentary: electromagnetic fields and cancer in railway workers

The ideal study of occupational exposure to electromagnetic fields and cancer risk would have a clear exposure source, historically stable exposures, and comparable groups of exposed and unexposed workers. Cohorts of railway workers have marked exposure contrasts and limited job changes and provide marginally adequate study sizes, but there have been important changes in their exposures over time, and the field frequency involved is unusual. The results of Minder and Pfluger's study (Am J Epidemiol 2001;153:825--35) add modest support for an association between electromagnetic field exposure and leukemia. However, given the large size and high quality of a number of previous studies of occupational electromagnetic field exposure and cancer, additional studies similar to past ones are unlikely to yield important new insights.     

Meta-analysis of multiple myeloma and benzene exposure.

Epidemiologic studies have suggested that benzene exposure may be a risk factor of multiple myeloma (MM). We performed meta-analyses of case-control studies to assess the association between occupational exposure to benzene and the risk of MM. We divided the occupational sources of benzene exposure into 4 categories, benzene and/or organic solvents, petroleum, petroleum products, and engine exhaust, for conducting the meta-analysis. As a result, a significant positive association was indicated between exposure to engine exhaust and MM (summary odds ratio or summary OR=1.34, 95% confidence interval or 95%CI=1.14-1.57). However, no significant associations were obtained for benzene and/or organic solvents (summary OR=0.74, 95%CI=0.60-0.90), petroleum (summary OR=1.11, 95%CI=0.96-1.28) and petroleum products (summary OR=1.08, 95%CI=0.89-1.33) with risk of MM. These results suggested that benzene exposure itself was not likely to be a risk factor of MM. It is thought that several harmful chemical agents in engine exhaust, other than benzene, could be etiologically related to the risk of MM. Further case-control studies on MM are needed to obtain more information about detailed occupational exposure to toxic substances.     

Whole-body lifetime occupational lead exposure and risk of Parkinson's disease

BACKGROUND: Several epidemiologic studies have suggested an association between Parkinson's disease (PD) and exposure to heavy metals using subjective exposure measurements. OBJECTIVES: We investigated the association between objective chronic occupational lead exposure and the risk of PD. METHODS: We enrolled 121 PD patients and 414 age, sex, and race, frequency-matched controls in a case-control study. As an indicator of chronic Pb exposure, we measured concentrations of tibial and calcaneal bone Pb stores using 109Cadmium excited K-series X-ray fluorescence. As an indicator of recent exposure, we measured blood Pb concentration. We collected occupational data on participants from 18 years of age until the age at enrollment, and an industrial hygienist determined the duration and intensity of environmental Pb exposure. We employed physiologically based pharmacokinetic modeling to combine these data, and we estimated wholebody lifetime Pb exposures for each individual. Logistic regression analysis produced estimates of PD risk by quartile of lifetime Pb exposure. RESULTS: Risk of PD was elevated by > 2-fold [odds ratio = 2.27 (95% confidence interval, 1.13-4.55); p = 0.021] for individuals in the highest quartile for lifetime lead exposure relative to the lowest quartile, adjusting for age, sex, race, smoking history, and coffee and alcohol consumption. The associated risk of PD for the second and third quartiles were elevated but not statistically significant at the alpha = 0.05 level. CONCLUSIONS: These results provide an objective measure of chronic Pb exposure and confirm our earlier findings that occupational exposure to Pb is a risk factor for PD.     

Breast cancer and electromagnetic fields--a review

PURPOSE: Several statements have been issued to the effect that no consistent, significant link has been demonstrated between cancer and electromagnetic fields (EMF). However, there continues to be much interest in a possible association with breast cancer, in part because breast cancer risk is substantially higher in industrialized countries than in other areas, and electric power generation and consumption is one of the hallmarks of industrialized societies. In 1987, Stevens proposed a biological mechanism whereby two products of electric power generation, EMF and light at night, might contribute to mammary carcinogenesis through inhibition of melatonin. METHODS: We conducted a comprehensive review of the epidemiologic literature and hypothesized mechanisms pertaining to EMF exposure and the risk of breast cancer, in order to assess whether or not there was evidence to suggest a link between EMF and breast cancer. RESULTS: Some occupational epidemiological studies have demonstrated an increased incidence of breast cancer among mainly male electrical workers. It has been difficult to study women, as few are employed in these types of occupations. In all, there have been eleven occupational studies related to breast cancer in women, and statistically significant risk ratios have been observed: 1.98 for pre-menopausal women in occupations with high EMF exposure in one study, 2.17 in all women who worked as telephone installers, repairers, and line workers in another study, and 1.65 for system analysts/ programmers, 1.40 for telegraph and radio operators, and 1.27 for telephone operators in a third study. However, six of the studies did not find any significant effects and two found effects only in subgroups. The results of the eight studies of residential exposure and four electric blanket studies have been inconsistent, with most not demonstrating any significant association. However, this might be attributed, at least to some extent, to difficulties in assessing residential exposure in these studies, as well as other methodological considerations. CONCLUSIONS: The biologic plausibility of an association between EMF and breast cancer, coupled with suggestive data from occupational studies and unexplained high incidence rates of breast cancer, suggests that further investigation of this possible association is warranted.     

Association between parental occupational exposure and childhood malignancy. A review of epidemiological studies

The question whether occupational exposure of parents to chemicals, electromagnetism and radiation causes malignant disease in their offspring has gained much interest. The findings to date, however, have been conflicting perhaps due to differences in the methods employed in these studies. A review was made on 16 case-control epidemiological studies. In 11 studies significant relation was observed between malignant tumor (leukemia, brain tumor and others) and occupational exposure to hydrocarbons, spray paint or other chemicals, ionizing radiation and electromagnetism. Conversely, no association was observed in five studies, in which different populations, different techniques, and different control groups were employed. The purpose of this paper is to examine the role of occupational exposure of the parents to chemicals and other agents in the development of malignant tumors in their offspring in relation to the employed epidemiological methodology.     

A meta-analysis of occupational trichloroethylene exposure and multiple myeloma or leukaemia

BACKGROUND: Trichloroethylene (TCE) has been widely used as an industrial solvent and degreasing agent. AIMS: We conducted a meta-analysis of epidemiologic studies of occupational TCE exposure and multiple myeloma (MM) or leukaemia. METHODS: We identified a total of eight cohort or case-control studies that enumerated a TCE-exposed study population and presented relative risk (RR) estimates for MM (n = 7) and/or leukaemia (n = 7). The individual studies included aerospace or aircraft workers (n = 3 studies), workers from a transformer manufacturing plant (n = 1 study) and workers from numerous occupations who, based on biomonitoring or extensive industrial hygiene exposure measurements, were likely exposed to TCE (n = 4). We used random effects models to calculate summary relative risk estimates (SRRE). In addition, we examined heterogeneity across studies and the relative influence of each individual study on the overall meta-analysis. RESULTS: No association was observed for MM (SRRE = 1.05, 95% CI: 0.80-1.38; P value for heterogeneity = 0.94) or leukaemia (SRRE = 1.11, 95% CI: 0.93-1.32; P value for heterogeneity = 0.50), based on TCE-exposed subgroup meta-analyses. Study-specific RR estimates for MM ranged between 0.57 and 1.62. RRs for leukaemia ranged between 1.05 and 1.15 in five studies, while one study reported a 2-fold increased RR and another study reported an inverse association of 0.60. All confidence intervals (CIs) for study-specific estimates included 1.0. CONCLUSIONS: The results of this meta-analysis do not support an etiologic association between occupational TCE exposure and risk of MM or leukaemia.     

Occupational lead exposure and blood pressure

Recent community studies have suggested that low level lead exposure is significantly associated with blood pressure in the general population. This finding is inconsistent with the results of recent occupational studies of lead exposed workers, although the occupational studies contained serious methodological weaknesses. The present study examined the relation between occupational lead exposure and diastolic and systolic blood pressure in randomly selected samples of 270 exposed and 158 non-exposed workers. Four exposure indicators were examined: employment at a lead battery plant nu a control plant, current blood lead value, current zinc protoporphyrin value, and time weighted average blood lead value. After controlling for other known risk factors such as age, education, income, cigarette usage, alcohol consumption, and exercise, the associations between exposure and blood pressure were small and non-significant. In the absence of a biologically feasible hypothesis regarding the mechanism by which low level lead exposure would influence blood pressure the present findings challenge the validity of the general population association.     

Chlorinated hydrocarbon solvents: Substituting our way toward human carcinogenicity

A discussion of the history of substitutions in industrial solvent use is presented, and animal carcinogenicity studies with certain chlorinated hydrocarbon solvents are reviewed. The present knowledge on the association between occupational exposure to chlorinated hydrocarbon solvents and human carcinogenicity is summarized, including a critical review of 23 studies pertaining to human carcinogenicity. Several deficiencies are identified in these studies that make interpretation of the results uncertain, including poor characterization of exposures in qualitative and quantitative terms, the small numbers of deaths or cases, and short follow-up periods. Despite these weaknesses, we conclude that, when viewed collectively, the evidence strongly suggests that occupational exposures to chlorinated hydrocarbon solvents are associated with an excess human cancer risk. The literature supports an association between occupational exposures to chlorinated hydrocarbons and elevated risks of leukemia, lymphoma, and urinary tract cancer. Parental occupational exposures are consistently associated with an elevated childhood cancer risk in the offspring. © 1993 Wiley-Liss, Inc.