Cancer incidence among Swedish pulp and paper mill workers: a cohort study of sulphate and sulphite mills

Occupational asbestos exposure and ovarian cancer: updated systematic review

BACKGROUND

The association between asbestos exposure and ovarian cancer has been questioned given the possible misdiagnosis of peritoneal mesothelioma as ovarian cancer.

AIMS

To update a systematic review on ovarian cancer risk in women occupationally exposed to asbestos, exploring the association with the time since first exposure and the duration of exposure.

METHODS

We searched PubMed from 2008 onwards, screened previous systematic reviews, combined standardized mortality ratios (SMR) using random effect models and quantified heterogeneity using the I2 statistic. To assess tumour misclassification, we compared the distribution of observed excess ovarian cancers (OEOC) to that expected (EEOC) from the distribution of peritoneal cancers in strata of latency and exposure duration.

RESULTS

Eighteen publications (20 populations), including a pooled analysis of 21 cohorts, were included. The pooled SMR was 1.79 (95% confidence interval 1.38-2.31), with moderate heterogeneity between studies (I2 = 42%), based on 144 ovarian cancer deaths/cases. The risk was increased for women with indirect indicators of higher exposure, longer duration and latency, and lower for chrysotile than for crocidolite exposure. The effect of duration and latency could not be completely disentangled, since no multivariate analysis was available for time-related variables. The dissimilarity index between OEOC and EEOC for the time since first exposure was small suggesting a similar pattern of risk.

CONCLUSIONS

While some misclassification between ovarian and peritoneal cancers cannot be excluded, the observed excess risk of ovarian cancer should be added to the overall disease burden of asbestos.

Cancer incidence among workers in soft paper mills: A cohort study

OBJECTIVES

To elucidate whether occupational exposure to soft paper dust increases the incidence of cancer.

METHODS

We studied 7988 workers in Swedish soft paper mills from 1960 to 2008, of whom 3233 (2 187 men and 1046 women) had more than 10 years of employment. They were divided into high exposure (>5 mg/m3 for >1 year) or lower exposure to soft paper dust based on a validated job-exposure matrix. They were followed from 1960 to 2019, and person-years at risk were stratified according to gender, age, and calendar-year. The expected numbers of incident tumors were calculated using the Swedish population as the reference, and standardized incidence ratios (SIR) with 95% confidence intervals (95% CI) were assessed.

RESULTS

Among high-exposure workers with more than 10 years of employment, there was an increased incidence of colon cancer (SIR 1.66, 95% CI 1.20-2.31), small intestine cancer (SIR 3.27, 95% CI 1.36-7.86), and thyroid gland cancer (SIR 2.68, 95% CI 1.11-6.43), as well as lung cancer (SIR 1.56, 95% CI 1.12-2.19). Among the lower-exposed workers there was an increased incidence of connective tissue tumors (sarcomas) (SIR 2.26, 95% CI 1.13-4.51) and pleural mesothelioma (SIR 3.29, 95% CI 1.37-7.91).

CONCLUSION

Workers in soft paper mills with high exposure to soft paper dust have an increased incidence of large and small intestine tumors. Whether the increased risk is caused by paper dust exposure or some unknown associated factors is unclear. The increased incidence of pleural mesothelioma is probably linked to asbestos exposure. The reason for increased incidence of sarcomas is unknown.

Occupational asbestos exposure and urinary bladder cancer: a systematic review and meta-analysis

PURPOSE

There is conflicting evidence on the association between asbestos exposure and bladder cancer. We performed a systematic review and meta-analysis to provide evidence on occupational asbestos exposure and the risk of mortality and incidence of bladder cancer.

METHODS

We searched three relevant electronic databases (Pubmed, Scopus, and Embase) from inception to October 2021. The methodological quality of included articles was evaluated using the US National Institutes of Health tool. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) for bladder cancer, as well as respective 95% confidence intervals (CIs), were extracted or calculated for each included cohort. Main and subgroup meta-analyses according to first year of employment, industry, sex, asbestos type, and geographic region were performed.

RESULTS

Fifty-nine publications comprising 60 cohorts were included. Bladder cancer incidence and mortality were not significantly associated with occupational asbestos exposure (pooled SIR: 1.04, 95% CI: 0.95-1.13, P = 0.000; pooled SMR: 1.06, 95% CI: 0.96-1.17, P = 0.031). Bladder cancer incidence was higher among workers employed between 1908 and 1940 (SIR: 1.15, 95% CI: 1.01-1.31). Mortality was elevated in asbestos workers cohorts (SMR: 1.12, 95% CI: 1.06-1.30) and in the subgroup analysis for women (SMR: 1.83, 95% CI: 1.22-2.75). No association was found between asbestos types and bladder cancer incidence or mortality. We observed no difference in the subgroup analysis for countries and no direct publication bias evidence.

CONCLUSION

There is evidence that workers with occupational asbestos exposure have a bladder cancer incidence and mortality similar to the general population.

The association between occupational asbestos exposure with the risk of incidence and mortality from prostate cancer: a systematic review and meta-analysis

BACKGROUND

There is conflicting evidence on the association between asbestos exposure and prostate cancer (PCa). Two recent meta-analyses have claimed that exposure is associated with increased PCa incidence and mortality, but they suffer from some methodological flaws. Given the potential importance of this research question, we aimed to perform a methodologically sound systematic review and meta-analysis to investigate the association between occupational asbestos exposure and the incidence of and mortality from PCa.

METHODS

We followed PRISMA guidelines to systematically search for pertinent articles in three relevant electronic databases: Pubmed, Scopus, and Embase, from their inception to July 2020. The methodological quality of included articles was evaluated using the US National Institutes of Health tool. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) for PCa, as well as respective 95% confidence intervals (CIs), were extracted or calculated for each included cohort. Main and subgroup meta-analyses according to first year of employment, industry, asbestos type, and geographic region were performed.

RESULTS

Sixty-five articles comprising 68 cohorts were included. PCa incidence and mortality were not significantly associated with occupational asbestos exposure (pooled SIR: 1.06, 95% CI: 1.00-1.13, P = 0.062; pooled SMR: 1.03, 95% CI: 0.99-1.06, P = 0.115). PCa incidence was higher among workers employed after 1960 (SIR: 1.10, 95% CI: 1.01-1.20). Pooled SIR was elevated in European (SIR: 1.09, 95% CI: 1.01-1.18) and UK cohorts (SIR: 1.05, 95% CI: 1.02-1.09). Mortality was elevated in North American cohorts (SMR: 1.06, 95% CI: 1.02-1.10). Studies of lower methodological quality appeared to yield elevated SIRs or SMRs.

CONCLUSIONS

This systematic review and meta-analysis provides evidence that men with occupational asbestos exposure have a PCa incidence and mortality similar to that of the general population. Temporal and geographical variables seem to be related to higher SMR or SIR.

Cardiovascular mortality in a Swedish cohort of female industrial workers exposed to noise and shift work

PURPOSE

The aim was to study mortality due to cardiovascular disease as well as total mortality, among female industrial workers, and the association to occupational noise and shift work.

METHODS

Women from cohorts of soft tissue paper mills (N = 3013) and pulp and paper mills (N = 1483) were merged into one cohort. Job exposure matrices were developed and used for classification of shift work and noise exposure. Every year was classified as shift work excluding nights or shift work including nights. Noise was classified into seven 5 dB(A) bins from < 75 to ≥ 100 dB(A). Mortality from cardiovascular diseases and total mortality during 1956-2013 was calculated as a standardized mortality ratio (SMR) with 95% confidence interval (CI) using the female general population as a reference.

RESULTS

Fatal myocardial infarctions (N = 144) were increased in the total cohort, SMR 1.20 (95% CI 1.01-1.41) but not total mortality. The SMR for myocardial infarction for women exposed to noise ≥ 90 dB(A) for > 10 years was 1.41 (95% CI 1.02-1.89) and for those exposed to night shifts > 10 years, 1.33 (95% CI 0.91-1.89). Shift workers without nights ≤ 65 years, with noise exposure ≥ 90 dB(A), had SMR 2.41 (95% CI 1.20-4.31) from myocardial infarction. There was no increased mortality from cerebrovascular disease.

CONCLUSIONS

Female paper mill workers had an increased mortality from acute myocardial infarction, especially before retirement age, when exposed to noise ≥ 90 dB(A) and with long-time employment. Exposure to shift work and noise usually occurred concurrently.

An Occupational Legacy: Malignant Mesothelioma Incidence and Mortality in Wisconsin

OBJECTIVES

The aim of the study was to describe mesothelioma occurrence in Wisconsin from 1997 to 2013 by usual industry and occupation (I&O), including occupations generally considered low risk.

METHODS

Population-based rates and standardized incidence and mortality ratios were calculated. Two case-control analyses were designed to compare mesothelioma incidence and mortality in specific I&O groups with occurrence of (1) brain and central nervous system cancers and (2) other causes of death, using logistic regression.

RESULTS

Mesothelioma incidence and mortality were elevated in Wisconsin (SIRadj = 1.20 [1.13 to 1.28]; SMRadj = 1.30 [1.22 to 1.38]). Certain industry (construction, manufacturing) and occupation (construction and extraction) groups were associated with increased odds of mesothelioma, with some evidence of increased risk among teachers.

CONCLUSIONS

Forty years after the Occupational and Safety Health Act, mesothelioma incidence and mortality remain elevated in Wisconsin, with increased risk continuing for certain I&O groups.

Recent Scientific Evidence Regarding Asbestos Use and Health Consequences of Asbestos Exposure

To justify the continuous use of two million tons of asbestos every year, it has been argued that a safe/controlled use can be achieved. The aim of this review was to identify recent scientific studies that present empirical evidence of: 1) health consequences resulting from past asbestos exposures and 2) current asbestos exposures resulting from asbestos use. Articles with evidence that could support or reject the safe/controlled use argument were also identified. A total of 155 articles were included in the review, and 87 % showed adverse asbestos health consequences or high asbestos exposures. Regarding the safe/controlled use, 44 articles were identified, and 82 % had evidence suggesting that the safe/controlled use is not being achieved. A large percentage of articles with evidence that support the safe/controlled use argument have a conflict of interest declared. Most of the evidence was developed in high-income countries and in countries that have already banned asbestos.

Etiology and early pathogenesis of malignant testicular germ cell tumors: towards possibilities for preinvasive diagnosis

Malignant testicular germ cell tumors (TGCT) are the most frequent cancers in Caucasian males (20-40 years) with an 70% increasing incidence the last 20 years, probably due to combined action of (epi)genetic and (micro)environmental factors. It is expected that TGCT have carcinoma in situ(CIS) as their common precursor, originating from an embryonic germ cell blocked in its maturation process. The overall cure rate of TGCT is more than 90%, however, men surviving TGCT can present long-term side effects of systemic cancer treatment. In contrast, men diagnosed and treated for CIS only continue to live without these long-term side effects. Therefore, early detection of CIS has great health benefits, which will require an informative screening method. This review described the etiology and early pathogenesis of TGCT, as well as the possibilities of early detection and future potential of screening men at risk for TGCT. For screening, a well-defined risk profile based on both genetic and environmental risk factors is needed. Since 2009, several genome wide association studies (GWAS) have been published, reporting on single-nucleotide polymorphisms (SNPs) with significant associations in or near the genes KITLG, SPRY4, BAK1, DMRT1, TERT, ATF7IP, HPGDS, MAD1L1, RFWD3, TEX14, and PPM1E, likely to be related to TGCT development. Prenatal, perinatal, and postnatal environmental factors also influence the onset of CIS. A noninvasive early detection method for CIS would be highly beneficial in a clinical setting, for which specific miRNA detection in semen seems to be very promising. Further research is needed to develop a well-defined TGCT risk profile, based on gene-environment interactions, combined with noninvasive detection method for CIS.

Occupational and environmental exposures associated with testicular germ cell tumours: systematic review of prenatal and life-long exposures

Background

Testicular germ cell tumours (TGCT) are the most common cancers in men aged between 15 and 44 years and the incidence has increased steeply over the past 30 years. The rapid increase in the incidence, the spatial variation and the evolution of incidence in migrants suggest that environmental risk factors play a role in TGCT aetiology. The purpose of our review is to summarise the current state of knowledge on occupational and environmental factors thought to be associated with TGCT.

Methods

A systematic literature search of PubMed. All selected articles were quality appraised by two independent researchers using the ‘Newcastle-Ottawa Quality Assessment Scale’.

Results

After exclusion of duplicate reports, 72 relevant articles were selected; 65 assessed exposure in adulthood, 7 assessed parental exposures and 2 assessed both. Associations with occupation was reported for agricultural workers, construction workers, firemen, policemen, military personnel, as well as workers in paper, plastic or metal industries. Electromagnetic fields, PCBs and pesticides were also suggested. However, results were inconsistent and studies showing positive associations tended to had lower quality ranking using the assessment scale (p=0.02).

Discussion

Current evidence does not allow concluding on existence of any clear association between TGCT and adulthood occupational or environmental exposure. The limitations of the studies may partly explain the inconsistencies observed. The lack of association with adulthood exposure is in line with current hypotheses supporting the prenatal origin of TGCT. Future research should focus on prenatal or early life exposure, as well as combined effect of prenatal and later life exposure. National and international collaborative studies should allow for more adequately powered epidemiological studies. More sophisticated methods for assessing exposure as well as evaluating gene–environment interactions will be necessary to establish clear conclusion.