Cancer incidence among workers in six Norwegian aluminum plants

Exposure to benzene and other hydrocarbons and risk of bladder cancer among male offshore petroleum workers

BACKGROUND

Occupational exposures constitute the second leading cause of urinary bladder cancer after tobacco smoking. Increased risks have been found in the petroleum industry, but high-quality exposure data are needed to explain these observations.

METHODS

Using a prospective case-cohort design, we analysed 189 bladder cancer cases (1999-2017) and 2065 randomly drawn non-cases from the Norwegian Offshore Petroleum Workers cohort. Cases were identified in the Cancer Registry of Norway, while work histories (1965-1998) and lifestyle factors were recorded by questionnaire at baseline (1998). Occupational petroleum-related hydrocarbon exposures were assessed by expert-developed job-exposure matrices. Hazard ratios were estimated by weighted Cox-regressions, adjusted for age, tobacco smoking, education, and year of first employment, and with lagged exposures.

RESULTS

Increased risks were found in benzene-exposed workers, either long-term exposure (≥18.8 years, HR = 1.89, 95% CI: 1.14-3.13; p-trend = 0.044) or high-level cumulative benzene exposure (HR = 1.60, 95% CI: 0.97-2.63; p-trend = 0.065), compared with the unexposed. Associations persisted with 20-year exposure lag. No associations were found with skin or inhalation exposure to crude oil, mineral oil (lubrication, hydraulics, turbines, drilling), or diesel exhaust.

CONCLUSIONS

The results suggest that exposures in the benzene fraction of the petroleum stream may be associated with increased bladder cancer risk.

Risk of Lung Cancer and Occupational Exposure to Polycyclic Aromatic Hydrocarbons Among Workers Cohorts - Worldwide, 1969-2022

What is already known about this topic?

Lung cancer has a high mortality, resulting in a severe disease burden. Polycyclic aromatic hydrocarbons (PAHs) are definitive carcinogen to human, and occupational exposure to PAHs is associated with lung cancer.

What is added by this report?

We analyzed the cancer cases from cohort studies on various PAHs exposed workers in China and other countries, calculated the quantitative risk of lung cancer based on meta-analyses, and confirmed the increased risk from lung cancer in selected PAHs exposed occupations.

What are the implications for public health practices?

There is a clear need to prevent lung cancer on a wide range of PAHs-related occupations in China and around the world. It is crucial to establish guidelines for improving the monitoring on exposure and health promotion in related working environments.

Emission characteristics and potential toxicity of polycyclic aromatic hydrocarbons in particulate matter from the prebaked anode industry

The emission factors (EFs) and source profiles of polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM₁₀ and PM_2.5) from the prebaked anode industry were studied to fill the knowledge gap and provide data for emission inventory and source resolution. In 2018, three prebaked anode plants were selected in Central China, each having one calcining chimney as well as one baking chimney, and then 92 samples were collected from the stack gas of the six chimneys. The results of the study are as follows. (1) PM₁₀ and PM_2.5 from the prebaked anode industry contained 37-42% water-soluble ions, 16-20% elements, 11-17% organic carbon, and 9.2-14% elemental carbon. (2) The EFs for PAHs of PM₁₀ and PM_2.5 were 1146.1 ± 899.7 and 866.2 ± 1179.8 mg/(t aluminum produced), respectively. The EF for BaP was seven times lower than that given by the European Environment Agency (EEA), whereas those of BbF, BkF, and IcdP were 2-13 times higher than those given by the EEA. (3) Seven diagnostic ratios for PAHs, including Ant/(Ant+Phe), Flua/(Flua+Pyr), BaA/(BaA + Chr), IcdP/(IcdP+BghiP), Flu/(Flu+Pyr), Phe/Ant and BaA/Chr were discussed. Just by diagnostic ratio, it is hard to precisely distinguish between calcining and baking in prebaked industry. (4) The toxic equivalence of PMs in the baking stack gas in the prebaked anode industry was five times higher than that in the calcining stack gas, and PM_2.5 showed higher potential toxicity risk than PM₁₀.

Construction of a Job Exposure Matrix to Dust, Fluoride, and Polycyclic Aromatic Hydrocarbons in the Norwegian Aluminum Industry using Prediction Models

BACKGROUND

The Norwegian aluminum industry developed and implemented a protocol for prospective monitoring of employees' exposure using personal samplers. We analyzed these data to develop prediction lines to construct a job exposure matrix (JEM) for the period 1986-1995.

METHODS

The protocol for personal monitoring of exposure was implemented in all seven Norwegian aluminum plants in 1986 and continued until 1995. Personal samplers were used to collect total dust, fluorides, and total polycyclic aromatic hydrocarbons (PAH). In addition, exposure could be categorized according to process, i.e. prebake, Søderberg, and 'other'. We constructed four-dimensional JEMs characterized by: Plant, Job descriptor, Process, and Year. Totally 8074, 6734, and 3524 measurements were available for dust, fluorides, and PAH, respectively. The data were analyzed using linear mixed models with two-way interactions. The models were assessed using the Akaike criterion (AIC) and unadjusted R (2). The significance level was set to 10% (two-sided) for retaining variables in the model.

RESULTS

In 1986, the geometric mean (95% confidence interval in parentheses) for total dust, total fluorides, and PAH were 3.18 (0.46-22.2) mg m(-3), 0.58 (0.085-4.00) mg m(-3), and 33.9 (2.3-504) µg m(-3), respectively. During 10 years of follow-up, the exposure to total dust, fluorides, and PAH decreased by 9.2, 11.7, and 14.9% per year, respectively. Each model encompassed from 49 to 72 significant components of the interaction terms. The interaction components were at least as important as the main effects, and 65 to 91% of the significant components of the interaction terms were time-dependent.

CONCLUSION

Our prediction models indicated that exposures were highly time-dependent. We expect that the time-dependent changes in exposure are of major importance for longitudinal studies of health effects in the aluminum industry.

Medical follow-up for workers exposed to bladder carcinogens: the French evidence-based and pragmatic statement

BACKGROUND

The aim of this work was to establish recommendations for the medical follow-up of workers currently or previously exposed to carcinogenic substances for the bladder.

METHODS

A critical synthesis of the literature was conducted. Sectors of activity where workers are or were exposed to carcinogenic substances for the bladder were listed and classified according to the level of bladder cancer risk. Performances of techniques available for the targeted screening of bladder cancer were analysed, including a simulation of results among high-risk populations in France.

RESULTS

The risk level for the professional group and the latency period between the start of exposure and the natural history of the disease were selected to define a targeted screening protocol. The NMP22BC test, exclusive haematuria testing, and combinations of urine cytology with, respectively, the NMP22BC test and haematuria test, generated an extremely high proportion of false positive results.

CONCLUSION

Urine cytology is the test that offers the best specificity. Although poor for all bladder cancer stages and grades combined, its sensitivity is better for high grades, which require early diagnosis since late-stage cancers are of very poor prognosis. These results suggest that urine cytology is currently the only technique suitable for proposal within the context of a first line targeted screening strategy for occupational bladder cancer. An algorithm summarising the recommended medical follow-up for workers currently or previously exposed to carcinogenic substances for the bladder is proposed, based on the level of risk of bladder cancer.

Cancer risks in aluminum reduction plant workers: a review

OBJECTIVE AND METHODS

This review examines epidemiological evidence relating to cancers in the primary aluminum industry where most of what is known relates to Söderberg operations or to mixed Söderberg/prebake operations.

RESULTS AND CONCLUSIONS

Increased lung and bladder cancer risks have been reported in Söderberg workers from several countries, but not in all. After adjustment for smoking, these cancer risks still increase with cumulative exposure to benzo(a)pyrene, used as an index of coal tar pitch volatiles exposure. Limited evidence has been gathered in several cohorts for an increased risk of tumors at other sites, including stomach, pancreas, rectum/rectosigmoid junction, larynx, buccal cavity/pharynx, kidney, brain/nervous system, prostate, and lymphatic/hematopoietic tissues (in particular non-Hodgkin lymphoma, Hodgkin disease, and leukemia). Nevertheless, for most of these tumor sites, the relationship with specific exposures has not been demonstrated clearly and further follow-up of workers is warranted.

Occupational exposure and lung cancer

Lung cancer is the leading cause of cancer death for male and the second most usual cancer for women after breast cancer. Currently there are available several non-specific cytotoxic agents and several targeted agents for lung cancer therapy. However; early stage diagnosis is still unavailable and several efforts are being made towards this direction. Novel biomarkers are being investigated along with new biopsy techniques. The occupational and environmental exposure to carcinogenic agents is an everyday phenomenon. Therefore until efficient early diagnosis is available, avoidance of exposure to carcinogenic agents is necessary. In the current mini-review occupational and environmental carcinogenic agents will be presented.

Occupational risk factors and pancreatic cancer: a review of recent findings

Several occupational exposures have been linked to excess risk of pancreatic cancer; however, most associations are not well established. The objective of this review article is to report on the more recently published studies (1998-2010), and provide a summary of the most consistently reported occupational risk factors for pancreatic cancer, including exposure to chlorinated hydrocarbon compounds, pesticides, polycyclic aromatic hydrocarbons (PAHs), metals, nitrosamines, radiation, various airborne particles, and employment in sedentary occupations. We conclude that the strongest and most consistent findings linking occupational exposures with pancreatic cancer risk to date are for chlorinated hydrocarbons and PAHs.

Renal cancer risk and occupational exposure to polycyclic aromatic hydrocarbons and plastics

OBJECTIVE

To investigate whether occupational exposure to polycyclic aromatic hydrocarbons and certain plastic monomers increased renal cell carcinoma (RCC) risk.

METHODS

Unconditional logistic regression was used to calculate RCC risk in relation to exposure.

RESULTS

No association between RCC risk and having ever been occupationally exposed to any polycyclic aromatic hydrocarbons or plastics was observed. Duration of exposure and average exposure also showed no association with risk. Suggestive positive associations between RCC risk and cumulative exposure to styrene (P-trend = 0.02) and acrylonitrile (P-trend = 0.06) were found. Cumulative exposure to petroleum/gasoline engine emissions was inversely associated with risk (P-trend = 0.02).

CONCLUSIONS

Results indicate a possible association between occupational styrene and acrylonitrile exposure and RCC risk. Additional studies are needed to replicate findings, as this is the first time these associations have been reported and they may be due to chance.

Relationship between cardiopulmonary mortality and cancer risk and quantitative exposure to polycyclic aromatic hydrocarbons, fluorides, and dust in two prebake aluminum smelters

OBJECTIVES

We examined the risk of mortality and cancer incidence with quantitative exposure to benzene-soluble fraction (BSF), benzo(a)pyrene (BaP), fluoride, and inhalable dust in two Australian prebake smelters.

METHODS

A total of 4,316 male smelter workers were linked to mortality and cancer incidence registries and followed from 1983 through 2002 (mean follow-up: 15.9 years, maximum: 20 years). Internal comparisons using Poisson regression were undertaken based on quantitative exposure levels.

RESULTS

Smoking-adjusted, monotonic relationships were observed between respiratory cancer and cumulative inhalable dust exposure (trend p = 0.1), cumulative fluoride exposure (p = 0.1), and cumulative BaP exposure (p = 0.2). The exposure-response trends were stronger when examined across the exposed categories (BaP p = 0.1; inhalable dust p = 0.04). A monotonic, but not statistically significant trend was observed between cumulative BaP exposure and stomach cancer (n = 14). Bladder cancer was not associated with BaP or BSF exposure. No other cancer and no mortality outcomes were associated with these smelter exposures.

CONCLUSIONS

The carcinogenicity of Söderberg smelter exposures is well established; in these prebake smelters we observed an association between smelter exposures and respiratory cancer, but not bladder cancer. The exploratory finding for stomach cancer needs confirmation. These results are preliminary due to the young cohort and short follow-up time.

Oxidative damage of workers in secondary metal recovery plants affected by smoking status and joining the smelting work

In Taiwan, secondary copper smelters and zinc recovery plants primarily utilize recovering metal from scrap and dross, and handles mostly fly ash and slag with high temperature to produce ZnO from the iron and steel industry. The materials may contain organic impurities, such as plastic and organic chloride chemicals, and amounts of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are produced during the smelting process. Therefore, secondary metal recovery industries are major emission sources of PCDD/Fs, which may have been demonstrated to elicit oxidative stress and to involve the production of plasma malondialdehyde (MDA). Many studies have also indicated that the intake of antioxidants, smoking, age and exposure to environmental pollutants may be implicated to DNA damage or lipid peroxidation. This study therefore aims to elucidate the roles of occupational exposure like joining the smelting work, age, smoking and alcohol status, and antioxidant intake on oxidative damage in secondary metal recovery workers in Taiwan. 73 workers were recruited from 2 secondary metal recovery plants. The analysis of 8-hydroxydeoxyguanosine (8-OH-dG) in urine, DNA strand breakage (comet assay) and lipid peroxidation (MDA) in blood samples were completed for all of the workers. The results showed that the older subjects exhibited significantly lower levels of 8-OH-dG and MDA than younger subjects. Our investigation also showed that working departments were in related to plasma MDA and DNA strand breakage levels of nonsmokers, however, the observation become negligible in smokers. And it is implicated that cigarette type might affect 8-OH-dG levels in secondary metal recovery workers. Since, adding to results above, the MDA level in production workers was significantly higher than those in managerial departments, it is important for the employers to make efforts on improving occupational environments or serving protective equipments to protect workers in secondary metal recovery factories.

Comparison of two indices of exposure to polycyclic aromatic hydrocarbons in a retrospective aluminium smelter cohort

BACKGROUND

The association between coal tar-derived substances, a complex mixture of polycyclic aromatic hydrocarbons, and cancer is well established. However, the specific aetiological agents are unknown.

OBJECTIVE

To compare the dose-response relationships for two common measures of coal tar-derived substances, benzene-soluble material (BSM) and benzo(a)pyrene (BaP), and to evaluate which among these is more strongly related to the health outcomes.

METHODS

The study population consisted of 6423 men with > or =3 years of work experience at an aluminium smelter (1954-97). Three health outcomes identified from national mortality and cancer databases were evaluated: incidence of bladder cancer (n = 90), incidence of lung cancer (n = 147) and mortality due to acute myocardial infarction (AMI, n = 184). The shape, magnitude and precision of the dose-response relationships and cumulative exposure levels for BSM and BaP were evaluated. Two model structures were assessed, where 1n(relative risk) increased with cumulative exposure (log-linear model) or with log-transformed cumulative exposure (log-log model).

RESULTS

The BaP and BSM cumulative exposure metrics were highly correlated (r = 0.94). The increase in model precision using BaP over BSM was 14% for bladder cancer and 5% for lung cancer; no difference was observed for AMI. The log-linear BaP model provided the best fit for bladder cancer. The log-log dose-response models, where risk of disease plateaus at high exposure levels, were the best-fitting models for lung cancer and AMI.

CONCLUSION

BaP and BSM were both strongly associated with bladder and lung cancer and modestly associated with AMI. Similar conclusions regarding the associations could be made regardless of the exposure metric.

Occupational exposures to polycyclic aromatic hydrocarbons, and respiratory and urinary tract cancers: a quantitative review to 2005

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been reported in several industries, including those of the aluminum production, coal gasification, coke production, iron and steel foundries, coal tar and related products, carbon black and carbon electrodes production.

PATIENTS AND METHODS

This paper reviews the results from cohort studies conducted on workers exposed to PAHs in these industries, with a focus on cancers of the respiratory and urinary tract.

RESULTS

An excess risk from lung/respiratory cancers was found in most industries, the pooled relative risk (RR) being 2.58 (95% CI 2.28-2.92) for coal gasification, 1.58 (95% CI 1.47-1.69) for coke production, 1.40 (95% CI 1.31-1.49) for iron and steel foundries, 1.51 (95% CI 1.28-1.78) for roofers and 1.30 (95% CI 1.06-1.59) for carbon black production. The evidence for cancers of the bladder and of the urinary system is less consistent, with a significant increased risk only for workers in aluminum production (pooled RR = 1.29, 95% CI 1.12-1.49), coal gasification (pooled RR = 2.39, 95% CI 1.36-4.21), and iron and steel foundries (pooled RR = 1.29, 95% CI 1.06-1.57).

CONCLUSIONS

Increased risks from lung and bladder cancers were found in PAH-related occupations. These were modest in most industries, apart from those for coal gasification, and whether they are due at least partially to some bias or confounding remains open to discussion.

Lung cancer risk after exposure to polycyclic aromatic hydrocarbons: a review and meta-analysis

Typical polycyclic aromatic hydrocarbon mixtures are established lung carcinogens, but the quantitative exposure-response relationship is less clear. To clarify this relationship we conducted a review and meta-analysis of published reports of occupational epidemiologic studies. Thirty-nine cohorts were included. The average estimated unit relative risk (URR) at 100 Mu g/m (superscript)3(/superscript) years benzo[a]pyrene was 1.20 [95% confidence interval (CI), 1.11-1.29] and was not sensitive to particular studies or analytic methods. However, the URR varied by industry. The estimated means in coke ovens, gasworks, and aluminum production works were similar (1.15-1.17). Average URRs in other industries were higher but imprecisely estimated, with those for asphalt (17.5; CI, 4.21-72.78) and chimney sweeps (16.2; CI, 1.64-160.7) significantly higher than the three above. There was no statistically significant variation of URRs within industry or in relation to study design (including whether adjusted for smoking), or source of exposure information. Limited information on total dust exposure did not suggest that dust exposure was an important confounder or modified the effect. These results provide a more secure basis for risk assessment than was previously available.

Occupational exposure and urological cancer

Occupational exposure is definitely a major cause of cancer. In the field of urology, the urinary bladder is the most important target. A classical cause of bladder cancer is exposure to carcinogenic aromatic amines, especially benzidine and beta-naphthylamine. Such exposures were related to work places in the chemical industry, implying production and processing of classical aromatic amines, and in the rubber industry. Occupational bladder cancer has also been observed in dyers, painters and hairdressers. Even some occupations with much lower exposures to carcinogenic aromatic amines, like coke oven workers or workers in the rubber industry after the ban on beta-naphthylamine, are at risk. In these occupations, exposure to complex mixtures of substances containing combustion products (e.g. polycyclic aromatic hydrocarbons) or nitrosamines is common. Renal cell cancer has been observed as an occupational disease in cases of very high exposure to trichloroethylene having led to narcotic or prenarcotic symptoms. Occupationally related cancers of the prostate or the testes appear currently not relevant.