Ruth Hershler

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

OBJECTIVES This study examined the association between exposure to chlorophenates and the risk of soft tissue sarcoma; non-Hodgkins lymphoma; Hodgkins disease; and cancers of the lung, nose, and nasopharynx. METHODS A retrospective cohort study was conducted of 26487 workers employed for at least 1 year between 1950 and 1985 in 11 chlorophenate-using and 3 non-using sawmills in British Columbia, Canada. Exposures by job were ascertained with interviews of senior employees. RESULTS Probabilistic record linkage to the Canadian Mortality Data Base and the British Columbia Cancer Registry found 4710 deaths between 1950 and 1990, and 1547 incident cases of cancer between 1969 and 1989. None of the cancers of interest had elevated mortality related to chlorophenate exposure. Non-Hodgkins lymphoma incidence (n = 65) increased with increasing chlorophenate exposure hours, yielding the following standardized incidence ratios: less than 120 hours 0.68; 120 to 1999 hours, 0.59; 2000 to 3999 hours, 1.04; 4000 to 9999 hours, 1.02; and 10000 or more hours, 1.30. CONCLUSIONS These results are consistent with the borderline positive associations seen in other recently reported studies of chlorophenate-exposed workforces.

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.

Fertility among a cohort of male sawmill workers exposed to chlorophenate fungicides

The purpose of this study was to determine whether exposure to chlorophenate fungicides and their dioxin contaminants is associated with male infertility among sawmill workers. The study was conducted using fertility data compiled from 26,487 sawmill workers in 14 British Columbian sawmills. Our analysis was restricted to workers who had been employed for at least 1 continuous year between 1950 and 1985 and to live-births born at least 1 year after the initiation of employment in the period 1955–1988. We assessed fertility trends by internal comparison using Mantel-Haenszel rate ratios and by calculating standardized fertility ratios using an external and an internal reference population. We identified 19,684 births in the study period. Initially, both external and internal analyses showed that sawmill workers from mills using chlorophenates had lower fertility than workers employed in mills not using chlorophenates. After controlling for time since first hire, however, we found no inverse relation between cumulative exposure to chlorophenate fungicides and fertility. Based on the results of our study, there is little evidence for a reduction in fertility among chlorophenate-exposed sawmill workers in British Columbia. The analyses indicate the importance of time since hire as a potentially strong confounder in this type of investigation.

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.

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.

Reliability of retrospective chlorophenol exposure estimates over five decades

For a cohort study of chlorophenate-exposed sawmill workers, historical exposures from the 1940s to the 1980s were estimated by teams of 9-20 employees (each interviewed individually). The mill histories were divided into eras when jobs and exposures were relatively stable. Raters with at least 5 years of work experience in an era were asked to estimate the frequency and duration of exposure for each job in the mill. Reliability measures for these estimates were calculated for each of the 39 mill and time period combinations, using the individual intraclass correlation coefficient (ICCind) to assess agreement between raters and the group intraclass correlation coefficient (ICCgroup) to assess the stability of the mean estimates of exposure. ICCind were low, with means that increased from 0.24 to 0.35 over the five decades. ICCgroup were considerably higher (means increasing from 0.78 to 0.88 over time), indicating that the number of raters used in this study was sufficient to produce stable average estimates of exposure throughout the study period. These data confirm the intuitive expectation that reliability of exposure estimates decreases when reconstruction of conditions in the distant past is required, and therefore that the random component of exposure misclassification is a greater threat to validity in these earlier time periods.

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

BackgroundThe 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).MethodsWe 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.ResultsMental 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.ConclusionsThis 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.

The use of population‐level data to advance interdisciplinary methodology: a cell‐through‐society sampling framework for child development research

The authors argue that population‐level data should be used to advance interdisciplinary research about community effects on early development. These data permit the identification of neighborhoods in which development patterns deviate from predictions based on local socioeconomic status (SES). So‐called ‘off‐diagonal’ places signal where researchers are likely to discover processes that either deflect the risks of low SES or dampen the salutary impact of favorable SES. Since such neighborhoods will be best understood relative to nearby ‘on‐diagonal’ neighborhoods where macro‐economic and/or public policy factors are constant, the authors present a methodology for illuminating these regional clusters. The method is deployed in British Columbia, Canada, where a team has collected developmental observations from two censuses of kindergarten children (n = 82,632). The article discusses how these clusters can be used to coordinate sampling decisions among academics representing the range of disciplines needed to study child development from cell‐through‐society, as is recommended in the literature.

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

BackgroundThe 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.MethodsWe 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.ResultsMultivariate 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.ConclusionThis 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.

Peak inspiratory pressure requirements in infants born weighing less than 750 g.

The possibility that peak inspiratory pressure requirements or the arterial:alveolar oxygen ratio can predict the clinical outcome in infants weighing less than 750 g at birth was explored in a consecutive series. Nine of 10 infants (90%) with a peak inspiratory pressure requirement of more than 18 cm H2O at 48 hours or more than 16 cm H2O at 72 hours from age subsequently died later of respiratory causes (defined as death after 72 hours of pulmonary interstitial emphysema, bronchopulmonary dysplasia, or cor pulmonale). Twenty of 21 remaining infants (95%) survived until discharge. Using these data a 95th centile for peak inspiratory pressure requirement during the first 72 hours of life was constructed. The potential value of this centile in predicting later death of respiratory causes was examined in a separate series. Twelve of 15 infants (80%) whose peak inspiratory pressure requirements remained below the 95th centile, or were not ventilated (n = 6), survived. In contrast, 11 of 12 (92%) infants whose requirements crossed the 95th centile died later of respiratory causes. The infants who died had more radiological changes and higher mean arterial carbon dioxide pressure than survivors suggesting that the severity of the initial lung disease rather than the way that ventilation was managed determined prognosis. Peak inspiratory pressure requirement was more useful than arterial:alveolar oxygen ratio in clearly distinguishing between survivors and infants who died later of respiratory causes.