Mortality and cancer incidence among sawmill workers exposed to chlorophenate wood preservatives

A longitudinal study comparing the effort - reward imbalance and demand - control models using objective measures of physician utilization

Background: The objectives of this study were to compare the predictive validity of the demand - control and effort - reward imbalance models using objective measures of physician utilization. Methods: Self-reports for psychosocial work conditions were obtained in interviews with 1,028 workers using the demand - control and effort - reward imbalance models. Physician utilization outcomes were obtained through linkage to the British Columbia Linked Health Database. Outcomes were any visit to a physician for mental health reasons and 30 or more physician visits for any reason. The predictive validity of both models was compared in a longitudinal study using logistic regression. Results: Neither job strain nor effort - reward imbalance predicted either outcome. However, low esteem reward and low status control increased the risk for 30 or more physician visits by, respectively, approximately 60% and 30%. Conclusions: In a sample of middle-aged blue-collar current and ex-sawmill workers in Western Canada, followed prospectively, after controlling for sociodemographic and workplace confounders, and reducing the potential for adverse health selection into high-stress jobs, low esteem reward and low status control were associated with a significantly greater risk for 30 or more physician visits for any reason.

Characteristics of work-related fatal and hospitalised injuries not captured in workers' compensation data

OBJECTIVES

(1) To identify work-related fatal and non-fatal hospitalised injuries using multiple data sources, (2) to compare case-ascertainment from external data sources with accepted workers' compensation claims and (3) to investigate the characteristics of work-related fatal and hospitalised injuries not captured by workers' compensation.

METHODS

Work-related fatal injuries were ascertained from vital statistics, coroners and hospital discharge databases using payment and diagnosis codes and injury and work descriptions; and work-related (non-fatal) injuries were ascertained from the hospital discharge database using admission, diagnosis and payment codes. Injuries for British Columbia residents aged 15-64 years from 1991 to 2009 ascertained from the above external data sources were compared to accepted workers' compensation claims using per cent captured, validity analyses and logistic regression.

RESULTS

The majority of work-related fatal injuries identified in the coroners data (83%) and the majority of work-related hospitalised injuries (95%) were captured as an accepted workers' compensation claim. A work-related coroner report was a positive predictor (88%), and the responsibility of payment field in the hospital discharge record a sensitive indicator (94%), for a workers' compensation claim. Injuries not captured by workers' compensation were associated with female gender, type of work (natural resources and other unspecified work) and injury diagnosis (eg, airway-related, dislocations and undetermined/unknown injury).

CONCLUSIONS

Some work-related injuries captured by external data sources were not found in workers' compensation data in British Columbia. This may be the result of capturing injuries or workers that are ineligible for workers' compensation, or the result of injuries that go unreported to the compensation system. Hospital discharge records and coroner reports may provide opportunities to identify workers (or family members) with an unreported work-related injury and to provide them with information for submitting a workers' compensation claim.

The mystery of chronic lymphocytic leukemia (CLL): Why is it absent in Asians and what does this tell us about etiology, pathogenesis and biology?

Chronic lymphocytic leukemia/small lymphocytic lymphoma is common in persons of predominately European descent but rare in Asians. Why is unknown but is likely genetically-determined. Environmental factors may also operate but are likely to be less important. When CLL occurs in Asians it has different features than CLL in persons of predominately European descent. The reason(s) for this is also not understood. We reviewed data on CLL in Asians (mostly Han Chinese but also other ethnic groups) and compared these data with those from persons of predominately European descent with CLL. CLL incidence was about 5-10-fold less in Asians. Asians with CLL are younger, have atypical morphologic and immunologic features, an increased proportion of IGHV mutations and rearrangements and briefer freedom-from-progression than persons of predominately European descent with CLL. These observations provide clues to the etiology and biology of CLL. But the mystery continues; more research is needed.

Non-hodgkin's lymphoma and work in agriculture: Results of a two case-control studies in Saskatchewan, Canada

OBJECTIVES

The objective was to examine the association between non-Hodgkin's lymphoma (NHL) and farming-related activities, gender, pesticides exposure, and exposure to chemicals other than pesticides in Saskatchewan.

MATERIALS AND METHODS

Male and female study participants were taken from two separate case-control studies conducted in Saskatchewan province, Canada. A case was defined as any man or woman aged 19 years and older with a first diagnosis of NHL registered by the Saskatchewan Cancer Agency during the study period. Conditional logistic regression was used to fit the statistical models.

RESULTS

Farming exposure and exposure to pesticides-contaminated cloths were related to an increased risk of NHL. Exposure to pesticides was strongly associated with an increased risk of NHL, especially for men.

CONCLUSION

For men, the incidence of NHL was associated with exposure to pesticides after adjusting for other independent predictors.

Occupational exposure to pentachlorophenol causing lymphoma and hematopoietic malignancy for two generations

Objective:

Pentachlorophenol (PCP) is characterized as likely carcinogen of lymphoma and hematopoietic neoplasm. But the carcinogenicity to human was uncertain based on population studies. A systematic review was conducted to explore two kinds of associations, one was between the workers exposed to PCP with lymphoma and hematopoietic neoplasm, the other was between childhood lymphoma and leukemia with their parents exposed to PCP.

Methods:

Systematic search for epidemiologic studies was carried out and the data were collected from MEDLINE database and from the reference lists of relevant studies. Data were extracted from 20 included studies published between 1986 and 2012.

Results:

The meta-analysis suggested a significant association between lymphoma and workers’ occupational exposing to PCP, for the pooled odds ratio = 2.57 (95% confidence interval (CI) = 1.52–4.35). The subgroup analysis indicated significant association for non-Hodgkin’s lymphoma, but not for Hodgkin’s disease. The cohort studies also showed comparatively higher relative risk (RR) and standardized mortality ratio (SMR). Two of the cohort studies found increased RR as the cumulative exposure time added. Another cohort study discovered that the white males had significantly elevated non-Hodgkin’s lymphoma mortality (SMR = 1.98, 95% CI = 1.15–3.17), and males of other races had increased leukemia mortality (SMR = 4.57, 95% CI = 1.25–11.7). For the relationship of childhood leukemia and parental exposure to PCP, three published studies suggested an increased risk of childhood leukemia because of their parental exposure to PCP at the preconception period.

Conclusion:

Our review provided the evidence that occupational exposure of workers to PCP might increase the risk of lymphoma and hematopoietic neoplasm in themselves and in their children.

Research opportunities using administrative databases and existing surveys for new knowledge in occupational health and safety in Canada, Quebec, Ontario and British Columbia

In Canada, many datasets are initially collected for purposes other than occupational health and safety (OHS) research. These include administrative health care billing records, pharmaceutical records, vital statistics, provincial cancer registries and workers' compensation claims data. In addition, many national and provincial health surveys, while not focused specifically on occupational health and safety, collect data on the health status and health determinants of populations, and such data can be used for investigating OHS issues among Canadian workers. This paper provides examples of the use of administrative and survey data for OHS research projects from the provinces of Quebec, Ontario and British Columbia to illustrate the potential of such data. These three provinces have a long history of using administrative and survey data for OHS research and have developed capacity in this regard for improving access to data, for linkage of records across databases and for developing methods to answer OHS questions. As research using these data sources expands, a consistent understanding within the work and health research community must be forged concerning the strengths and limitations of these data resources and their comparability.

Rural-urban migration patterns and mental health diagnoses of adolescents and young adults in British Columbia, Canada: a case-control study

BACKGROUND

The identification of mental health problems early in life can increase the well-being of children and youth. Several studies have reported that youth who experience mental health disorders are also at a greater risk of developing psychopathological conditions later in life, suggesting that the ability of researchers and clinicians to identify mental health problems early in life may help prevent adult psychopathology. Using large-scale administrative data, this study examined whether permanent settlement and within-province migration patterns may be linked to mental health diagnoses among adolescents (15 to 19 years old), young adults (20 to 30 years old), and adults (30 years old and older) who grew up in rural or urban communities or migrated between types of community (N = 8,502).

METHODS

We conducted a nested case-control study of the impact of rural compared to urban residence and rural-urban provincial migration patterns on diagnosis of mental health. Conditional logistic regression models were run with the following International Classification of Diseases, 9th Revision (ICD-9) mental health diagnoses as the outcomes: neurotic disorders, personality disorder, acute reaction to stress, adjustment reaction, depression, alcohol dependence, and nondependent drug abuse. Analyses were conducted controlling for paternal mental health and sociodemographic characteristics.

RESULTS

Mental health diagnoses were selectively associated with stability and migration patterns. Specifically, adolescents and young adults who were born in and grew up in the same rural community were at lower risk of being diagnosed with acute reaction to stress (OR = 0.740) and depression (OR = 0.881) compared to their matched controls who were not born in and did not grow up in the same rural community. Furthermore, adolescents and young adults migrating between rural communities were at lower risk of being diagnosed with adjustment reaction (OR = 0.571) than those not migrating between rural communities. No differences were found for diagnoses of neurotic disorders, personality disorder, alcohol dependence, and nondependent drug abuse.

CONCLUSIONS

This study provides some compelling evidence of the protective role of rural environments in the development of specific mental health conditions (i.e., depression, adjustment reaction, and acute reaction to stress) among the children of sawmill workers in Western Canada.

A case control study of differences in non-work injury and accidents among sawmill workers in rural compared to urban British Columbia, Canada

Background

Using a cohort of British Columbian male sawmill workers, we conducted a nested case-control study of the impact of rural compared to urban residence as well as rural/urban migration patterns in relation to hospitalization for non-work injury. We postulate that for many types of non-work injuries, rates will be higher in rural communities than in urban ones and that rates will also be higher for workers who migrate from urban to rural communities.

Methods

Using conditional logistic regression, univariate models were first run with each of five non-work injury outcomes. These outcomes were hospitalizations due to assault, accidental poisoning, medical mis-adventure, motor vehicle trauma, and other non-work injuries. In multivariate models marital status, ethnicity, duration of employment, and occupation were forced into the model and associations with urban, compared to rural, residence and various urban/migration patterns were tested.

Results

Urban or rural residence and migration status from urban to other communities, and across rural communities, were not associated with hospitalization for medical misadventure, assault, or accidental poisoning. The likelihood of a rural resident being hospitalized for motor vehicle trauma is higher than for an urban resident. The likelihood that a rural resident is hospitalized for "other" non-work injury is higher than for an urban resident.

Conclusion

In a relatively homogenous group of workers, and using a rigorous study design, we have demonstrated that the odds of other non-work injury are much higher for workers resident in and migrating to rural regions of Canada than they are for workers resident in or migrating to urban places.

Determinants of use of hearing protection devices in Canadian lumber mill workers

BACKGROUND

In a cohort study of lumber mill workers' exposure to noise and incidence of heart disease, initial noise estimates were likely overestimated because they did not account for reductions afforded by the use of hearing protection. As such information was seldom available for individual workers, modeling was necessary to predict hearing protection use and derive adjusted noise measures.

OBJECTIVE

To develop a multilevel model of the likelihood of use of hearing protection devices (HPDs) for British Columbia (Canada) lumber mill workers.

METHOD

The study population included 13,147 workers in 14 sawmills for whom we had information on HPD use. Subjects self-reported their use of hearing protectors during routine hearing tests over their work history period. Separate multilevel logistic regression models with increasing complexity were developed for a subcohort of workers with complete information (n = 1493) and for a subcohort comprised subjects with hearing tests coinciding with their jobs (n = 10 203). The models included random intercepts for worker and for sawmill.

RESULTS

HPD use was associated in both subcohorts with factors such as noise exposure and age. We also showed that specific jobs (such as sawfiling) and departments (planer, in particular) were strongly associated with the use of HPDs. The model illustrates the quantitative importance of including a hierarchical structure which allows for explaining potential sources of outcome variability.

CONCLUSIONS

We developed a hierarchical model to predict hearing protection use to enable correction of exposure assessments for use in retrospective epidemiological studies. We showed that this was feasible even in the absence of complete determinant information.

Dioxins and cardiovascular disease mortality

OBJECTIVE

In this systematic review we evaluated the evidence on the association between dioxin exposure and cardiovascular disease (CVD) mortality in humans.

DATA SOURCES AND EXTRACTION

We conducted a PubMed search in December 2007 and considered all English-language epidemiologic studies and their citations regarding dioxin exposure and CVD mortality. To focus on dioxins, we excluded cohorts that were either primarily exposed to polychlorinated biphenyls or from the leather and perfume industries, which include other cardiotoxic coexposures.

DATA SYNTHESIS

We included results from 12 cohorts in the review. Ten cohorts were occupationally exposed. We divided analyses according to two well-recognized criteria of epidemiologic study quality: the accuracy of the exposure assessment, and whether the exposed population was compared with an internal or an external (e.g., general population) reference group. Analyses using internal comparisons with accurate exposure assessments are the highest quality because they minimize both exposure misclassification and confounding due to workers being healthier than the general population ("healthy worker effect"). The studies in the highest-quality group found consistent and significant dose-related increases in ischemic heart disease (IHD) mortality and more modest associations with all-CVD mortality. Their primary limitation was a lack of adjustment for potential confounding by the major risk factors for CVD.

CONCLUSIONS

The results of this systematic review suggest that dioxin exposure is associated with mortality from both IHD and all CVD, although more strongly with the former. However, it is not possible to determine the potential bias, if any, from confounding by other risk factors for CVD.

Occupational exposures and non-Hodgkin's lymphoma: Canadian case-control study

BACKGROUND

The objective was to study the association between Non-Hodgkin's Lymphoma (NHL) and occupational exposures related to long held occupations among males in six provinces of Canada.

METHODS

A population based case-control study was conducted from 1991 to 1994. Males with newly diagnosed NHL (ICD-10) were stratified by province of residence and age group. A total of 513 incident cases and 1506 population based controls were included in the analysis. Conditional logistic regression was conducted to fit statistical models.

RESULTS

Based on conditional logistic regression modeling, the following factors independently increased the risk of NHL: farmer and machinist as long held occupations; constant exposure to diesel exhaust fumes; constant exposure to ionizing radiation (radium); and personal history of another cancer. Men who had worked for 20 years or more as farmer and machinist were the most likely to develop NHL.

CONCLUSION

An increased risk of developing NHL is associated with the following: long held occupations of faer and machinist; exposure to diesel fumes; and exposure to ionizing radiation (radium). The risk of NHL increased with the duration of employment as a farmer or machinist.

Pentachlorophenol and cancer risk: focusing the lens on specific chlorophenols and contaminants

OBJECTIVE

Pentachlorophenol, a fungicide widely used as a wood preservative, was classified in 1999 by the International Agency for Research on Cancer as a possible human carcinogen. We reviewed currently available data to determine the extent to which recent studies assist in distinguishing the effect of pentachlorophenol from that of its contaminants (e.g., dioxins and other chlorophenols).

DATA SOURCES AND EXTRACTION

We performed a systematic review of published studies pertaining to cancer risk in relation to pentachlorophenol exposure, focusing on results pertaining specifically to all cancer sites and specific hematopoietic cancers, and data pertaining to risks associated with other types of chlorophenols, dioxins, or furans.

SYNTHESIS

The pentachlorophenol studies presented considerable evidence pertaining to hematopoietic cancers, with strong associations seen in multiple studies, in different locations, and using different designs. There is little evidence of an association between these cancers and chlorophenols that contain fewer than four chlorines. The extension of a large cohort study of sawmill workers, with follow-up to 1995, provided information about risks of relatively rare cancers (e.g., non-Hodgkin lymphoma, multiple myeloma), using a validated exposure assessment procedure that distinguishes between exposures to pentachlorophenol and tetrachlorophenol. In contrast with dioxin, pentachlorophenol exposure has not been associated with total cancer incidence or mortality.

CONCLUSIONS

The updated cohort study focusing on pentachlorophenol provides increased statistical power and precision, and demonstrates associations between hematopoietic cancer and pentachlorophenol exposure not observed in earlier evaluations of this cohort. Contaminant confounding is an unlikely explanation for the risks seen with pentachlorophenol exposure.

Paternal psychosocial work conditions and mental health outcomes: a case-control study

BACKGROUND

The role of social and family environments in the development of mental health problems among children and youth has been widely investigated. However, the degree to which parental working conditions may impact on developmental psychopathology has not been thoroughly studied.

METHODS

We conducted a case-control study of several mental health outcomes of 19,833 children of sawmill workers and their association with parental work stress, parental socio-demographic characteristics, and paternal mental health.

RESULTS

Multivariate analysis conducted with four distinct age groups (children, adolescents, young adults, and adults) revealed that anxiety based and depressive disorders were associated with paternal work stress in all age groups and that work stress was more strongly associated with alcohol and drug related disorders in adulthood than it was in adolescence and young adulthood.

CONCLUSION

This study provides support to the tenet that being exposed to paternal work stress during childhood can have long lasting effects on the mental health of individuals.

The impact of psychosocial work conditions on attempted and completed suicide among western Canadian sawmill workers

BACKGROUND

Using a large cohort of western Canadian sawmill workers (n = 28,794), the association between psychosocial work conditions and attempted and completed suicide was investigated.

METHODS

Records of attempted and completed suicide were accessed through a provincial hospital discharge registry to identify cases that were then matched using a nested case control method. Psychosocial work conditions were estimated by expert raters using the demand-control model. Univariate and multivariate conditional logistic regression was used to estimate the association between work conditions and suicide.

RESULTS

In multivariate models, controlling for sociodemographic (marital status, ethnicity) and occupational confounders (job mobility and duration), low psychological demand was associated with increased odds for completed suicide, and low social support was associated with increased odds for attempted suicides.

CONCLUSIONS

This study indicates that workers with poor psychosocial working conditions may be at increased risk of both attempted and completed suicide.

The hospital costs of treating work-related sawmill injuries in British Columbia

OBJECTIVE

This study estimates the hospital costs of treating work-related injury among a cohort of sawmill workers in British Columbia.

METHODS

Hospital discharge records were extracted from 1989 to 1998 for a cohort of 5,876 actively employed sawmill workers. Injury cases were identified as work-related from these records using ICD-9 external cause of injury codes that indicate place of occurrence and the responsibility of payment schedule that identifies workers' compensation as being responsible for payment. The hospitals in British Columbia have a standard ward rate chart prepared annually by the provincial Ministry of Health to bill and collect payment from agency like workers' compensation agency. Costs were calculated from the hospital perspective using this billing chart. All costs were expressed in 1995 Canadian dollars. The workers' compensation claim records for this study population were extracted and matched with the hospitalised work-related injury records. Costs were also calculated for work-related hospitalisations that the hospital did not appear to be reimbursed for by the workers' compensation system.

RESULTS

There were 173 injuries requiring hospitalisation during the 10-year followup period. The median stay in hospitals was 3 days and the median hospital costs were $847. The most costly cause of injury categories were fire, flame, natural and environmental and struck against with median costs of $10,575 and $1,206, respectively, while the least costly category was cutting and piercing with median costs of $296. The most costly nature of injury categories were burns and fracture of lower limb with median costs of $10,575 and $1,800, respectively, while the least costly category was dislocation, sprains and strains with median costs of $437. The total hospital costs for all the work-related injuries were $434,990. Out of a total hospital cost of $434,990 for the 173 work-related injuries, the provincial compensation agency apparently did not compensate $50,663 (12%).

CONCLUSION

Prevention of work-related injuries can save significant amount of health care resources. Substantial costs remain uncompensated by the provincial compensation agency and are thus transferred to the provincial health care system annually.

Epidemiology of work-related injuries requiring hospitalization among sawmill workers in British Columbia, 1989-1997

This study describes hospitalized injuries among workers in British Columbia lumber industry. Between April 1989 and December 1997, from the hospital records of 5,745 male sawmill workers were analyzed for the present study. Work relatedness was determined using either ICD-9 external cause of injury codes, which have a digit-indicating place of occurrence, or a payment field, which can identify workers compensation agency. Poisson regression models were used to analyze differences in hospitalization rates across race, job category, age group, and calendar year. The crude and adjusted rate ratios were calculated along with the 95% confidence intervals (CIs). During the follow-up period, there were 164 work related hospitalization resulting in a rate for work-related hospitalization of 5.38 per 1,000 person years. The higher rates by nature of injury were for dislocation, sprains & strains, open wounds, and fracture of upper limbs. During the study period, the higher rates of injury by causes were machinery related, falls, and struck against. In the multivariate models, there were no statistically significant relationship of injury risk with age and race. In respect to occupation, compared to foremen/supervisor, other sawmills' workers did not have significantly elevated risk of injury. The trend analyses found a significant negative trend (P = 0.004) of injury risk over the whole study period. Knowing the causes and nature of injury and their related risk factors are helpful to employers, compensation officials, and other stakeholders to target preventive measures.

Cancer and occupational exposure to pentachlorophenol and tetrachlorophenol (Canada)

OBJECTIVE

The objective of this study is to assess the carcinogenicity of pentachlorophenol and tetrachlorophenol using data from the BC sawmill workers cohort study.

METHODS

The cohort consisted of 27,464 men employed by 14 sawmills for 1 year or more between 1950 and 1995. Fatal (1950-1995) and incident (1969-1995) cancers were identified using national registries. Plant records and systematic interviews with senior employees were used to estimate dermal exposure. Comparisons were made with the general BC population and dose-response relationships were assessed using Poisson regression.

RESULTS

There were 1,495 fatal cancer and 2,571 incident cancers. There were no large or statistically significant excesses of any of the specific cancers were observed compared to the general population. Internal analyses showed strong dose-response relationships for non-Hodgkin's lymphoma, multiple myeloma, and kidney cancer. These relationships were strongest when exposure was restricted to pentachlorophenol. The strength of the dose-response increased when exposure was lagged by 20 years.

CONCLUSIONS

Dermal exposure to pentachlorophenol was associated with non-Hodgkin's lymphoma, multiple myeloma, and kidney cancer, but not with other cancers of a priori interest.

Non-Hodgkin lymphoma and pesticide exposure: 25 years of research

Over the past 40 years, a substantial rise in the incidence of non-Hodgkin lymphoma (NHL) has been observed. Epidemiologic studies aimed at understanding this rise have revealed some association with occupational exposure. NHL is common among farmers, where pesticides have been described as the culprit. The association between pesticides and NHL has been demonstrated mainly in case-control studies, while retrospective cohorts have been less convincing. Pesticides including chlorphenol and phenoxyacetic acid herbicides, organochlorines, and organophosphate insecticides, carbamates, and fungicides have been associated with NHL. Although the causality has not been clearly proven, both genotoxic and nongenotoxic mechanisms for lymphomagenesis have been proposed. The leveling-off of NHL incidence in certain countries may be the result of a favorable change in pesticide usage patterns. Future studies, such as the Agricultural Health Study, may clarify the uncertainties regarding this issue.

Costs and compensation of work-related injuries in British Columbia sawmills

OBJECTIVE

To estimate the costs of work-related injury in a cohort of sawmill workers in British Columbia from the perspective of the workers' compensation system.

METHODS

Hospital discharge records were extracted from 1989 to 1998 for a cohort of 5786 actively employed sawmill workers. A total of 173 work-related injury cases were identified from these records using the International classification of diseases-ninth revision (ICD-9) external cause of injury codes and the responsibility of payment schedule. Workers' compensation records were extracted and matched with hospital records by dates and ICD-9 diagnosis codes. All costs were converted into 1995 constant Canadian dollars using the Provincial General Consumer Price Index for the non-healthcare costs and Medical Consumer Price Index for the healthcare costs. A 5% discounting rate was applied to adjust for the time value of money. For the uncompensated cases, costs were imputed from the compensated cases using the median cost for a similar nature of injury.

RESULTS

370 hospitalisation events due to injury were captured, and by either of the two indicators (E Codes or payment schedules), 173 (47%) hospitalisation events due to injury, were identified as work related. The median healthcare cost was 4377 dollars and the median non-healthcare cost was 16,559 dollars for a work-related injury. The median non-healthcare and healthcare costs by injury were falls, 19,978 dollars and 5185 dollars; struck by falling object, 32,398 dollars and 8625 dollars; struck against, 12,667 dollars and 5741 dollars; machinery related, 26,480 dollars and 6643 dollars; caught in or between, 24,130 dollars and 4389 dollars; and overexertion, 7801 dollars and 2710 dollars. The total cost was 10,374,115 dollars for non-healthcare and 1,764,137 dollars for healthcare. The compensation agency did not compensate 874,871 dollars (8.4%) of the non-healthcare costs and 200,588 dollars (11.4%) of the healthcare costs.

CONCLUSION

Eliminating avoidable work-related injury events can save valuable resources.

Data quality in an information-rich environment: Canada as an example

This review evaluates the quality of available administrative data in the Canadian provinces, emphasizing the information needed to create integrated systems. We explicitly compare approaches to quality measurement, indicating where record linkage can and cannot substitute for more expensive record re-abstraction. Forty-nine original studies evaluating Canadian administrative data (registries, hospital abstracts, physician claims, and prescription drugs) are summarized in a structured manner. Registries, hospital abstracts, and physician files appear to be generally of satisfactory quality, though much work remains to be done. Data quality did not vary systematically among provinces. Primary data collection to check place of residence and longitudinal follow-up in provincial registries is needed. Promising initial checks of pharmaceutical data should be expanded. Because record linkage studies were ''conservative'' in reporting reliability, the reduction of time-consuming record re-abstraction appears feasible in many cases. Finally, expanding the scope of administrative data to study health, as well as health care, seems possible for some chronic conditions. The research potential of the information-rich environments being created highlights the importance of data quality.

How many work-related injuries requiring hospitalization in British Columbia are claimed for workers' compensation?

BACKGROUND

Workplace compensation claims datasets represent an important source of information on work-related injuries. This study investigated the concordance between hospital discharge records and workers' compensation records for work-related serious injuries among a cohort of sawmill workers in British Columbia (BC), Canada. It also examined the extent to which workers' compensation capturing patterns varied by cause, severity of injuries, and demographic characteristics of workers.

METHODS

Work-related injuries were identified in hospitalization records between April 1989 and December 1998, and were matched by dates and description of injury to compensation records.

RESULTS

The agreement between the hospital records and compensation records was good (kappa = 0.84, P < 0.01). A lower claim reporting rate for work-related hospitalization was observed for older and non-white workers. More serious injuries defined by longer length of stay and emergency admissions were more likely to be reported. Falls, struck against, and overexertion injuries had lower reporting rates; whereas, machinery-related, cutting/piercing, and caught in/between injuries had higher reporting rates.

CONCLUSIONS

When compared with hospital discharge records, the compensation agency underreported incidents of serious work-related injuries by 10-15% among the sawmill workers.

An evaluation of hospital discharge records as a tool for serious work related injury surveillance

OBJECTIVES

To identify and describe work related serious injuries among sawmill workers in British Columbia, Canada using hospital discharge records, and compare the agreement and capturing patterns of the work related indicators available in the hospital discharge records.

METHODS

Hospital discharge records were extracted from 1989 to 1998 for a cohort of sawmill workers. Work related injuries were identified from these records using International Classification of Disease (ICD-9) external cause of injury codes, which have a fifth digit, and sometimes a fourth digit, indicating place of occurrence, and the responsibility of payment schedule, which identifies workers' compensation as being responsible for payment.

RESULTS

The most frequent causes of work related hospitalisations were falls, machinery related, overexertion, struck against, cutting or piercing, and struck by falling objects. Almost all cases of machinery related, struck by falling object, and caught in or between injuries were found to be work related. Overall, there was good agreement between the two indicators (ICD-9 code and payment schedule) for identifying work relatedness of injury hospitalisations (kappa = 0.75, p < 0.01). There was better concordance between them for injuries, such as struck against, drowning/suffocation/foreign body, fire/flame/natural/environmental, and explosions/firearms/hot substance/electric current/radiation, and poor concordance for injuries, such as machinery related, struck by falling object, overexertion, cutting or piercing, and caught in or between.

CONCLUSIONS

Hospital discharge records are collected for administrative reasons, and thus are readily available. Depending on the coding reliability and validity, hospital discharge records represent an alternative and independent source of information for serious work related injuries. The study findings support the use of hospital discharge records as a potential surveillance system for such injuries.

The impact of fathers' physical and psychosocial work conditions on attempted and completed suicide among their children

BACKGROUND

Adverse employment experiences, particularly exposure to unemployment and the threat of unemployment, have been strongly associated with several adverse mental and physical health outcomes including suicide. However, virtually no research has been conducted on the trans-generational impact of parental working conditions on attempted or completed suicide among their children.

METHODS

We conducted a nested case control study based on a cohort, gathered in the western Canadian province of British Columbia, of male sawmill workers and a second cohort of their children. Physical and psychosocial work conditions to which fathers were exposed during the first 16 years of their children's lives, measured using the demand/control model, were linked to hospital suicide records (attempted and completed) among their children.

RESULTS

Two hundred and fifty children in the cohort attempted or committed suicide between 1985 and 2001. Multivariate models, with partial control for father's mental health outcomes prior to their child's suicide demonstrate, 1) a strong association between low duration of father's employment at a study sawmill and attempted suicide for their male children, 2) elevated odds for attempted suicide among female children of fathers' employed in a sawmill job with low control and, 3) a strong association between fathers in jobs with low psychological demand and completed suicides among male children.

CONCLUSION

Exposure of fathers to adverse psychosocial work conditions during the first 16 years of their children's life was associated with greater odds for attempted and completed suicide among their children.

Cancer and wood-related occupational exposure in the Amazon region of Brazil

The occurrence of neoplasms, particularly nasal cavities and paranasal sinus tumors, has been associated with exposure to wood dust. The wood industry occupies an important place in the State of Pará, Brazil, where are located 90% of all the wood-related companies in the Brazilian Amazon market as a whole. The aim of this study was an exploratory analysis of cancer occurrence in woodworkers in the State of Pará. The proportional cancer incidence ratio (PCIR) was calculated for a group of 138 male woodworkers 20 years or older with a histological diagnosis of neoplasm treated at the Ofir Loyola Cancer Hospital in the state capital of Belém from 1991 to 1999. The cancer mortality odds ratio (CMOR) was also calculated in order to compare the cancer mortality among men 20 years or older residing in the State of Pará whose occupations involved wood exposure with that of men of the same age and place of residence but with different occupations. High and statistically significant PCIRs were observed for tumors of the oral cavity/pharynx, 2.44 (1.44--3.85), and stomach, 3.57 (2.41--5.10), in comparison to the population of Goiânia as well as in comparison to the population of Porto Alegre (oral cavity/pharynx, 1.97 (1.17--3.12), stomach, 3.12 (2.11--4.47)). We also observed a high and statistically significant PCIR for Hodgkin's disease, 5.30 (1.09--15.47), in comparison to the population of Goiânia. A CMOR of 8.86 (5.26--14.83) was observed for liver cancer. CMORs greater than 1 but not statistically significant were observed for neoplasms of the larynx. In agreement with the literature, woodworkers in Pará presented a high cancer incidence in specific anatomical sites. The results highlight the need for further epidemiological investigation to better evaluate this occupational exposure in the Amazon region.

Organochlorines in Carpet Dust and Non-Hodgkin Lymphoma

BACKGROUND

The incidence of non-Hodgkin lymphoma (NHL) has risen over the past several decades. Reasons for this increase are largely unexplained.

METHODS

In this population-based case-control study, we examined NHL risk and exposure to organochlorine compounds using concentrations in carpet dust as an exposure indicator. We identified NHL cases, uninfected with HIV, diagnosed between 1998 and 2000 among women and men ages 20-74 years in Iowa, Los Angeles County, and the Detroit and Seattle metropolitan areas. Controls were selected using random-digit-dialing or Medicare files. Organochlorine concentrations were measured in vacuum bag dust from 603 white cases and 443 white controls who had owned most of their carpets for at least 5 years.

RESULTS

NHL risk was elevated if any of the polychlorinated biphenyl (PCB) congeners (PCBs 105, 138, 153, 170, or 180) was detected (odds ratio = 1.5; 95% confidence interval = 1.2-2.0). Risk was elevated in the top tertile of PCB 180 (1.7; 1.1-2.6) and in the top 2 tertiles of total PCBs (middle tertile, 1.6 [1.1-2.4]; top tertile 1.5 [1.0-2.2]). There was a positive trend in risk with increasing PCB 180 levels (P trend = 0.03). NHL risk was elevated if dichlorodiphenyldichloroethylene (DDE) was detected (1.3; 1.0-1.7), but only among men. A positive, but not monotonic, dose-response relationship was observed for DDE (P trend = 0.02).

CONCLUSIONS

Our findings suggest an increased risk of NHL associated with exposure to PCBs, with evidence of greater effects for PCB 180. There is also some evidence of an association with DDE.

Occupational Exposure to Noise and Mortality From Acute Myocardial Infarction

BACKGROUND

Exposure to noise is highly prevalent in the workplace, and an etiologic association with cardiovascular disease has been hypothesized. Although there is evidence of hypertension among noise-exposed workers, evidence of heart disease has been less conclusive.

METHODS

We identified a cohort of 27,464 blue-collar workers from 14 lumber mills in British Columbia who worked at least 1 year between 1950 and 1995 and who were followed up over the same period. Cumulative noise exposure was quantitatively assessed. Vital status was ascertained from the Canadian Mortality Database. We estimated standardized mortality ratios using the general population as referents, and we estimated relative risks using an internal low-exposure group as controls. To examine acute effects of noise, we assessed relative risks during subjects' working years in lumber mills. Because of the possibility of exposure misclassification as a result of hearing-protector use, we investigated a subgroup that had been employed before widespread use of protectors.

RESULTS

During the follow-up period, 2510 circulatory disease deaths occurred. Relative risks for acute myocardial infarction mortality were elevated in the full cohort, with a stronger association in the subgroup without hearing protection. There was an exposure-response trend, with a relative risk in the highest exposed group of 1.5 (95% confidence interval=1.1-2.2). The highest relative risks (2.0-4.0) were observed during subjects' working years. Smoking did not appear to confound these associations.

CONCLUSIONS

Chronic exposure to noise levels typical of many workplaces was associated with excess risk for acute myocardial infarction death. Given the very high prevalence of excess noise exposure at work, this association deserves further attention.

Identification of Occupational Cancer Risks in British Columbia: A Population-Based Case???Control Study of 769 Cases of Non-Hodgkin??s Lymphoma Analyzed by Histopathology Subtypes

We have, as part of a program aimed at detecting occupational risk factors in British Columbia, collected lifetime occupational histories as well as information on lifetime cigarette smoking and alcohol consumption from 15,643 incident cancer cases, of whom 782 had a diagnosis of non-Hodgkin's lymphoma (NHL). Occupational risks for this cancer site are examined using a matched case-control study design, and the results are presented in this report for all cases and for histopathology subtypes. The results of our study indicate excess NHL risk, particularly for a number of occupations that involve exposures to electromagnetic fields, treated and fresh wood, metals, and solvents.

Dechlorination of chlorinated phenols by zero valent zinc

Reductive dechlorination of chlorophenols (Pentachlorophenol, three tetrachlorophenols (TeCPs), six trichlorophenols (TCPs)) with zero valent zinc was examined through batch experiments. Zinc showed much higher reactivity towards PCP than iron and amended iron indicating that zero valent zinc can be a good candidate for reductive dechlorination of chlorinated phenols. Chlorophenols were sequentially dechlorinated and less chlorinated phenols were identified as reduction products. The mass balance was not complete, indicating that by-products are important and/or that products being measured were lost by unknown pathways. The dechlorination rate of the chlorinated phenols usually followed the order: PCP > TeCPs > TCPs. Among the TeCP and TCP isomers, the reactivity was in the order of 2,3,4,5-TeCP > 2,3,4,6-TeCP > 2,3,5,6-TeCP and 2,3,4-TCP > 2,3,6-TCP > 2,3,5-TCP > 2,4,6-TCP > 2,4,5-TCP > 3,4,5-TCP. The first order reaction rates varied by one order of magnitude or more, depending on the chlorines positions on a phenol ring. A regioselectivity was observed and daughter compound distributions could be rationalized by a mechanism in which radical intermediates were more stabilized by chlorine and hydroxyl groups than by hydrogen; positions alpha to the radical were found to be the most important in stabilization, followed by beta-positions.

An analysis of the risk of B-lymphocyte malignancies in industrial cohorts

Among numerous studies of occupational groups with varied chemical exposures (e.g., farmers, petroleum workers, and rubber workers), some have reported excess risk for non-Hodgkin's lymphoma (NHL), multiple myeloma, and other cancers of the B-lymphocyte cell line. While not conclusive, these studies raise questions about the effects of chemical exposures on the lymphocytic versus myeloid cell lines. Almost 70 occupational cohort studies were identified that addressed B-cell cancer risks in 9 major industrial categories, in order to look for common patterns across industries. This effort was substantially limited by the inconsistent nature of lymphohematopoietic (LH) classification schemes across studies and over time, and the relative paucity of B-cell-specific results in studies for any given industry. Taking these limitations into consideration, a descriptive, graphical analysis suggested a pattern of B-cell cancer elevations in the rubber and "general chemical" industries, but no consistent patterns in petroleum production/distribution or petrochemical production. The limited data sources, which lack detail about differences in hazard and exposure for different types of products/chemicals, did not allow a comprehensive look at possible common exposures associated with B-cell cancer elevations across industries. This study suggests that evaluation of possible associations between specific chemical exposures and B-cell malignancies would require additional studies with clear and common definitions of B-cell outcomes. The article concludes by giving an example of a possible common framework for categorizing NHL, the diseases for which most classification issues arise.

A comparison between the effort-reward imbalance and demand control models

BACKGROUND

To compare the predictive validity of the demand/control and reward/imbalance models, alone and in combination with each other, for self-reported health status and the self-reported presence of any chronic disease condition.

METHODS

Self-reports for psychosocial work conditions were obtained in a sample of sawmill workers using the demand/control and effort/reward imbalance models. The relative predictive validity of task-level control was compared with effort/reward imbalance. As well, the predictive validity of a model developed by combining task-level control with effort/reward imbalance was determined. Logistic regression was utilized for all models.

RESULTS

The demand/control and effort/reward imbalance models independently predicted poor self-reported health status. The effort-reward imbalance model predicted the presence of a chronic disease while the demand/control model did not. A model combining effort-reward imbalance and task-level control was a better predictor of self-reported health status and any chronic condition than either model alone. Effort reward imbalance modeled with intrinsic effort had marginally better predictive validity than when modeled with extrinsic effort only.

CONCLUSIONS

Future work should explore the combined effects of these two models of psychosocial stress at work on health more thoroughly.

Pentachlorophenol Poisoning

Despite being banned in many countries and having its use severely restricted in others, pentachlorophenol (PCP) remains an important pesticide from a toxicological perspective. It is a stable and persistent compound. In humans it is readily absorbed by ingestion and inhalation but is less well absorbed dermally. Its distribution is limited, its metabolism extensive and it is eliminated only slowly. Assessment of the toxicity of PCP is confounded by the presence of contaminants known to cause effects identical to those attributed to PCP. However, severe exposure by any route may result in an acute and occasionally fatal illness that bears all the hallmarks of being mediated by uncoupling of oxidative phosphorylation. Tachycardia, tachypnoea, sweating, altered consciousness, hyperthermia, convulsions and early onset of marked rigor (if death occurs) are the most notable features. Pulmonary oedema, intravascular haemolysis, pancreatitis, jaundice and acute renal failure have been reported. There is no antidote and no adequate data to support the use of repeat-dose oral cholestyramine, forced diuresis or urine alkalinisation as effective methods of enhancing PCP elimination in poisoned humans. Supportive care and vigorous management of hyperthermia should produce a satisfactory outcome. Chronic occupational exposure to PCP may produce a syndrome similar to acute systemic poisoning, together with conjunctivitis and irritation of the upper respiratory and oral mucosae. Long-term exposure has also been reported to result in chronic fatigue or neuropsychiatric features in combination with skin infections (including chloracne), chronic respiratory symptoms, neuralgic pains in the legs, and impaired fertility and hypothyroidism secondary to endocrine disruption. PCP is a weak mutagen but the available data for humans are insufficient to classify it more strongly than as a probable carcinogen.

Effects of de-industrialization on unemployment, re-employment, and work conditions in a manufacturing workforce

BACKGROUND

The purpose of this study was to investigate the impact of a 20-year process of de-industrialization in the British Columbia (BC) sawmill industry on labour force trajectories, unemployment history, and physical and psychosocial work conditions as these are important determinants of health in workforces.

METHODS

The study is based on a sample of 1,885 respondents all of whom were sawmill workers in 1979, a year prior to commencement of de-industrialization and who were followed up and interviewed approximately 20 years later.

RESULTS

Forty percent of workers, 64 years and under, were employed outside the sawmill sector at time of interview. Approximately one third of workers, aged 64 and under, experienced 25 months of more of unemployment during the study period. Only, 1.5% of workers were identified as a "hard core" group of long-term unemployed. Workers re-employed outside the sawmill sector experienced improved physical and psychosocial work conditions relative to those employed in sawmills during the study period. This benefit was greatest for workers originally in unskilled and semi-skilled jobs in sawmills.

CONCLUSIONS

This study shows that future health studies should pay particular attention to long-term employees in manufacturing who may have gone through de-industrialization resulting in exposures to a combination of sustained job insecurity, cyclical unemployment, and adverse physical and psychosocial work conditions.

Effect of de-industrialisation on working conditions and self reported health in a sample of manufacturing workers

STUDY OBJECTIVE

To explore the impact of de-industrialisation over a 20 year period on working conditions and health among sawmill workers, in the province of British Columbia (BC), Canada.

DESIGN AND SETTING

This investigation is based on a sample of 3000 sawmill workers employed in 1979 (a year before the beginning de-industrialisation) and interviewed in 1998. The sample was obtained by random selection from an already gathered cohort of approximately 28 000 BC sawmill workers. Change in working conditions from 1979 to 1998 are described. Self reported health status, in 1998, was used as a dependent variable in logistic regression after controlling for confounders.

MAIN RESULTS

Downsizing in BC sawmills eliminated 60% of workers between 1979 and 1998. Working conditions in 1998 were better for those who left the sawmill industry and obtained re-employment elsewhere. Workers who remained employed in restructuring sawmills were approximately 50% more likely to report poor health than those re-employed elsewhere.

CONCLUSIONS

Working conditions and health status were better for workers who, under pressure of de-industrialisation, left the sawmill industry and obtained re-employment outside this sector.

Childhood cancer in the offspring of male sawmill workers occupationally exposed to chlorophenate fungicides

The objective of this study was to determine whether paternal occupational exposure to chlorophenol fungicides and their dioxin contaminants is associated with childhood cancer in the offspring of sawmill workers. We used data from 23,829 British Columbian sawmill workers employed for at least 1 continuous year between 1950 and 1985 in 11 sawmills that used chlorophenates. Probabilistic linkage of the sawmill worker cohort to the provincial marriage and birth files produced an offspring cohort of 19,674 children born at least 1 year after the initiation of employment in the period 1952-1988. We then linked the offspring cohort to the British Columbia Cancer Registry. We included all malignancies in cases younger than 20 years of age that appeared on the cancer registry between 1969 and 1993. We calculated standardized incidence ratios (SIRs) using the British Columbia population as a reference. A nested case-control analysis assessed the effects of paternal cumulative exposure and windows of exposure on the risk of developing cancer in the offspring. We identified 40 cases of cancer during 259,919 person-years of follow-up. The all-cancer SIR was 1.0 [95% confidence interval (CI), 0.7-1.4]; the SIR for leukemia was 1.0 (CI, 0.5-1.8); and the SIR for brain cancer was 1.3 (CI, 0.6-2.5). The nested case-control analysis showed slightly increased risks in the highest categories of chlorophenol exposure, although none was statistically significant. Our analyses provide little evidence to support a relationship between the risk of childhood cancer and paternal occupational exposure to chlorophenate fungicides in British Columbian sawmills.

Identification of occupational cancer risks in British Columbia. Part II: A population-based case-control study of 1516 Prostatic cancer cases

We have, as part of a program aimed at detecting occupational risk factors in British Columbia, collected lifetime occupational histories from 15,643 incident cancer cases, of whom 1519 had a diagnosis of prostate cancer. Occupational risks for this cancer site are examined using this large data set, and the results are presented in this report.

Occupational chlorophenol exposure and non-Hodgkin's lymphoma

Occupational exposure to chlorophenols is suspected to increase non-Hodgkin's lymphoma (NHL) risk. This association was examined using data on 995 NHL cases and 1783 controls from the Selected Cancers Study, a population-based case-control study of men aged 32 to 60 years from eight population-based cancer registries conducted from 1984 to 1988. Potential chlorophenol exposure was characterized by an industrial hygienist using intensity estimates and confidence ratings, based upon review of verbatim job histories. Cases with substantial chlorophenol exposure had a significantly greater number of years of chlorophenol exposure (median years: cases, 4.0; controls, 2.0; P = 0.046); however, in conditional logistic regression models, the odds ratio for more than 8 years of substantial exposure was 1.51 (95% CI, 0.88 to 2.59). Overall, the findings do not provide strong support for an association with NHL risk. Chlorophenol exposure in this study is not based upon measured values and, therefore, may fail to characterize actual chlorophenol exposures accurately. Because of the large presence of machinists in the potentially chlorophenol-exposed group, these results may be underestimated by exposure misclassification if these subjects were not exposed to chlorophenolic biocides. However, these results are consistent with other findings, which suggest that chlorophenol exposure is not likely to be a strong risk factor for NHL.

A case-control study of non-Hodgkin lymphoma and exposure to pesticides

BACKGROUND

The incidence of non-Hodgkin lymphoma (NHL) has increased in most Western countries during the last few decades. Immunodefective conditions are established risk factors. In 1981, the authors reported an increased risk for NHL following exposure to certain pesticides. The current study was designed to further elucidate the importance of phenoxyacetic acids and other pesticides in the etiology of NHL.

METHODS

A population-based case-control study in northern and middle Sweden encompassing 442 cases and twice as many controls was performed. Exposure data were ascertained by comprehensive questionnaires, and the questionnaires were supplemented by telephone interviews. In total, 404 cases and 741 controls answered the questionnaire. Univariate and multivariate analyses were performed with the SAS statistical data program.

RESULTS

Increased risk for NHL was found for subjects exposed to herbicides (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.0-2.5) and fungicides (OR, 3.7; 95% CI, 1.1-13.0). Among herbicides, the phenoxyacetic acids dominated (OR, 1.5; 95% CI, 0.9-2.4); and, when subclassified, one of these, 4-chloro-2-methyl phenoxyacetic acid (MCPA), turned out to be significantly associated with NHL (OR, 2.7; 95% CI, 1.0-6.9). For several categories of herbicides, it was noted that only exposure during the most recent decades before diagnosis of NHL was associated with an increased risk of NHL. Exposure to impregnating agents and insecticides was, at most, only weakly related to NHL.

CONCLUSIONS

Exposure to herbicides in total, including phenoxyacetic acids, during the decades before NHL diagnosis resulted in increased risk for NHL. Thus, the risk following exposure was related to the latency period. Fungicides also increased the risk for NHL when combined, but this group consisted of several different agents, and few subjects were exposed to each type of fungicide.

Opportunities for a broader understanding of work and health: multiple uses of an occupational cohort database

Occupational cohort studies conducted to study cancer incidence and mortality require extensive data gathering about workers' job histories, exposures, and health outcomes. Although this process is expensive, the database created can be looked upon as a resource for broad investigations of the relationship between work and health. This paper presents the example of a retrospective cohort study which began in the traditional way, examining the link between a specific pesticide exposure and mortality and cancer incidence. The cohort register has since been used to investigate whether infertility, adverse reproductive outcomes, and childhood cancers might be associated with this exposure. It is also being used as the basis for studying other sawmill exposures including noise and wood dust as well as socioeconomic factors including job strain, job mobility, unemployment, and retraining. This approach allows both the efficient use of occupational cohorts as well as providing the opportunity for investigators to develop a more comprehensive perspective on the determinants of the health status of workers and their families.

Opportunities for a broader understanding of work and health: multiple uses of an occupational cohort database

Occupational cohort studies conducted to study cancer incidence and mortality require extensive data gathering about workers' job histories, exposures, and health outcomes. Although this process is expensive, the database created can be looked upon as a resource for broad investigations of the relationship between work and health. This paper presents the example of a retrospective cohort study which began in the traditional way, examining the link between a specific pesticide exposure and mortality and cancer incidence. The cohort register has since been used to investigate whether infertility, adverse reproductive outcomes, and childhood cancers might be associated with this exposure. It is also being used as the basis for studying other sawmill exposures including noise and wood dust as well as socioeconomic factors including job strain, job mobility, unemployment, and retraining. This approach allows both the efficient use of occupational cohorts as well as providing the opportunity for investigators to develop a more comprehensive perspective on the determinants of the health status of workers and their families.