Case-control study of intracranial tumors among employees at a petrochemical research facility

Towards Substitution of Hexane as Extraction Solvent of Food Products and Ingredients with No Regrets

Hexane is a solvent used extensively in the food industry for the extraction of various products such as vegetable oils, fats, flavours, fragrances, colour additives or other bioactive ingredients. As it is classified as a "processing aid", it does not have to be declared on the label under current legislation. Therefore, although traces of hexane may be found in final products, especially in processed products, its presence is not known to consumers. However, hexane, and in particular the n-hexane isomer, has been shown to be neurotoxic to humans and has even been listed as a cause of occupational diseases in several European countries since the 1970s. In order to support the European strategy for a toxic-free environment (and toxic-free food), it seemed important to collect scientific information on this substance by reviewing the available literature. This review contains valuable information on the nature and origin of the solvent hexane, its applications in the food industry, its toxicological evaluation and possible alternatives for the extraction of natural products. Numerous publications have investigated the toxicity of hexane, and several studies have demonstrated the presence of its toxic metabolite 2,5-hexanedione (2,5-HD) in the urine of the general, non-occupationally exposed population. Surprisingly, a tolerable daily intake (TDI) has apparently never been established by any food safety authority. Since hexane residues are undoubtedly found in various foods, it seems more than necessary to clearly assess the risks associated with this hidden exposure. A clear indication on food packaging and better information on the toxicity of hexane could encourage the industry to switch towards one of the numerous other alternative extraction methods already developed.

A Case-Control Study on Dietary Acid Load in Relation to Glioma

Limited data are available linking dietary factors to glioma. The current study was conducted to investigate the association between Dietary Acid Load (DAL) and odds of glioma in Iranian adults. This case-control study was done on 128 newly diagnosed patients with glioma and 256 healthy controls in Tehran, Iran. A validated detailed food frequency questionnaire (FFQ) was used to assess dietary intakes of participants. DAL was estimated using the protein to potassium ratio (Pro: K). Glioma was diagnosed based on pathological tests. A detailed questionnaire including several non-dietary confounders was also completed. Participants in the highest tertile of DAL score had a non-significant higher odds of glioma as compared to those in the lowest tertile (OR: 1.50; 95% CI: 0.88-2.57), which remained after controlling for some potential confounders (OR: 1.66; 0.70-3.91). After further adjustment for dietary intakes of meats and processed meats, legumes and nuts, fruits, salt tea, and coffee, those in the top tertile of DAL score were significantly more likely to have glioma than those in the bottom tertile (OR: 3.09; 95% CI: 1.06, 8.99; P = 0.03). This association was also reached following further adjustment for BMI (OR: 3.05; 95% CI: 1.04, 8.91; P = 0.03). We found a significant positive association between dietary acid load, as estimated by Prot:K ratio, and odds of glioma among adults. Further studies, in particular prospective cohorts with long-term follow up, are required to confirm these findings.

Risk Assessment of Workers' Exposure to Volatile Organic Compounds in the Air of a Petrochemical Complex in Iran

Context:

Long-term exposure to volatile organic compounds (VOCs) affects the occupancies health in petrochemical complex.

Objectives:

The aim of this study is to apply the lifetime cancer risk (LCR) and hazard quotient (HQ) in occupational exposure to estimate the risk of VOCs in petrochemical complexes.

Settings and Design:

A cross-sectional study was conducted in the petrochemical complex of Iran for a period of 1 year.

Materials and Methods:

Sorbent tubes were used to obtain air samples from 169 workers at different petrochemical complexes in southern Iran. The compounds analyzed with gas chromatography equipped with a flame ionization detector (FID).

Statistical Analysis Used:

The data were analyzed by SPSS version 16. Comparison between the mean of pollutants concentration in personal samples was performed by one-way analysis of variance (ANOVA) test.

Results:

For all groups of workers, the results showed that exposure to carcinogenic compounds leads to LCR risks higher than 1 × 10^-6. The mean of LCR for benzene is more than 10^-4, and 53.3% of workers' exposed has a definite risk; the mean of LCR for workers exposed to ethyl benzene, epichlorohydrin, styrene, and trichloroethylene was between 10^-4 and 10^-6 and workers' exposure to these compounds was a probability risk for cancer. The mean of HQ was less than 1 for workers exposed to toluene, p-xylene, chlorobenzene, phenol, and methanol.

Conclusions:

The risk assessment with LCR showed that carcinogenic compounds are the main threat to workers' health and precautions should be taken to control workers' risk.

Red and processed meat consumption and risk of glioma in adults: A systematic review and meta-analysis of observational studies

BACKGROUND

These findings from several observational studies, investigated the association between red meat consumption and gliomas, were inconsistent. We conducted a systematic review and meta-analysis of observational studies to summarize available date on the relation between meat intake and risk of glioma.

MATERIALS AND METHODS

A systematic literature search of relevant reports published until May 2014 of the PubMed/Medline, ISI Web of Knowledge, Excerpta Medica database, Ovid database, Google Scholar, and Scopus databases was conducted. From 723 articles yielded in the preliminary literature search, data from eighteen publications (14 case-control, three cohort, and one nested case-control study) on unprocessed red meat, processed meat, and/or total red meat consumption in relation to glioma in adults were included in the analysis. Quality assessment of studies was performed. Random effects model was used to conduct the meta-analysis.

RESULTS

We found a positive significant association between unprocessed red meat intake and risk of glioma (relative risk [RR] = 1.30; 95% confidence interval [CI]: 1.08-1.58) after excluding three studies with uncertain type of brain cancer. This analysis included only one cohort study which revealed no relation between unprocessed red meat intake and glioma (RR = 1.75; 95% CI: 0.35-8.77). Consumption of processed meats was not related to increased risk of glioma in population-based case-control studies (RR = 1.26; 95% CI: 1.05-1.51) and reduced risk in hospital-based case-controls (RR = 0.79; 95% CI: 0.65-0.97). No significant association was seen between processed red meat intake and risk of glioma in cohort studies (RR: 1.08; 95% CI: 0.84-1.37). Total red meat consumption was not associated with risk of adult glioma in case-control or cohort studies.

CONCLUSION

In this meta-analysis of 18 observational studies, we found a modest positive association between unprocessed red meat intake and risk of gliomas based almost entirely on case-control studies. Processed red meat was overall not associated with risk of gliomas in case-control or cohort studies.

Brain cancer in workers employed at a specialty chemical research facility

ABSTRACT This study evaluated unique exposures and their relationship to brain cancer mortality in employees of a specialty chemical research facility. Following an exposure assessment that concerned compounds distinct to this facility, the authors conducted a cohort mortality study of 5,284 workers to assess mortality in reference to the general population and a nested case-control study to evaluate brain cancer risk associated with specific jobs and unique chemical exposures. Four hundred eighty-six deaths, including 14 brain cancer deaths, were identified. Overall mortality was lower than expected. Brain cancer mortality was elevated (standardized mortality ratio [SMR] = 2.02, 95% confidence interval [CI] = 1.11-3.40). Exposures to 5 specific chemical categories were assessed. Exploration of work history and the specific chemical exposures did not explain the brain cancer cases. No clear occupational etiology was identified.

Retrospective exposure assessment in a chemical research and development facility

The objective of this exposure assessment was to reconstruct cumulative historical exposures for workers who have been exposed to multiple chemicals and chemical groups to better understand a cluster of brain cancers within a research and development lab. Chemicals of interest, including acrylates, bis-chloromethyl ether (BCME), chloromethyl methyl ether (CMME), isothiazolones and nitrosoamines, were selected on the basis of the plausibility of penetrating the blood-brain barrier and the uniqueness of the chemical's biological activity. In a complicated exposure setting such as a chemical R&D facility, multiple exposure estimation methods were needed. First, similarly exposure groups (SEGs) were created for these materials based on department group, time period of the department's existence and function associated with job titles. A probabilistic framework for assessing exposures was developed using Bayesian analysis of historical monitoring data, mathematical exposure modeling and professional judgments of current and former industrial hygienists at the facility were used to reconstruct the exposure history for acrylates, BCME and CMME for each SEG over the time period of interest. Since sufficient measurement data for isothiazolones and nitrosoamines were not available, the exposure histories for each SEG for these chemicals were estimated. This was done using objective formaldehyde levels and subjective employee interviews. The interviews assessed workplace determinants of exposure as distinct surrogates for estimating inhalation and dermal exposures. The exposure assessments by these methods were compared against each other to estimate the potential for exposure misclassification. A job exposure matrix (JEM) was constructed that contained the exposures obtained from above multiple approaches for each of these chemical groups for each SEG for each year of interest. The combination of methods used in this work is a unique and potentially helpful framework that can be used in analogous workplace settings involving multiple exposures with incomplete objective measurement information.

Cancer incidence in a petrochemical industry area in Sweden

Emissions from petrochemical industries may contain suspected or established carcinogens. As increased incidence of cancer in residential areas close to petrochemical industries has been reported in the literature, we conducted a study of cancer incidence in Stenungsund, Sweden, where petrochemical industries were established in the mid 1960s. A number of cancer cases in the central parts of Stenungsund were collected from the regional cancer registry for each year between 1974 and 2005. In addition to the total number of cases, the numbers of leukemia, lymphoma, liver cancer, lung cancer, and brain cancer were also collected. Expected numbers for each year were calculated based on age- and sex-specific incidence rates in reference areas. Levels of carcinogenic volatile hydrocarbons (VOC) were estimated from measurements and emission data. A dispersion model was used to classify Stenungsund into a "low" and "high" ethylene level area. Standardized Incidence Ratio (SIR) for all cancer for the entire period was 1.02 (95% CI 0.97-1.08). The occurrence of leukemia, lymphoma, and cancer in the central nervous system was slightly lower than expected for the entire period. SIR for lung cancer was 1.37 (95% CI 1.10-1.69), and SIR for liver cancer was 1.50 (0.82-2.53). VOC levels were low. Taking estimated exposure and demographic factors into account, our assessment is that occurrence of cancer was not affected by industrial emissions in any of the studied sites.

Cancer incidence among male Massachusetts firefighters, 1987-2003

BACKGROUND

Firefighters are known to be exposed to recognized or probable carcinogens. Previous studies have found elevated risks of several types of cancers in firefighters.

METHODS

Standardized morbidity odds ratio (SMORs) were used to evaluate the cancer risk in white, male firefighters compared to police and all other occupations in the Massachusetts Cancer Registry from 1986 to 2003. Firefighters and police were identified by text search of the usual occupation field. All other occupations included cases with identifiable usual occupations not police or firefighter. Control cancers were those not associated with firefighters in previous studies.

RESULTS

Risks were moderately elevated among firefighters for colon cancer (SMOR = 1.36, 95% CI: 1.04-1.79), and brain cancer (SMOR = 1.90, 95% CI: 1.10-3.26). Weaker evidence of increased risk was observed for bladder cancer (SMOR = 1.22, 95% CI: 0.89-1.69), kidney cancer (SMOR = 1.34, 95% CI: 0.90-2.01), and Hodgkin's lymphoma (SMOR = 1.81, 95% CI: 0.72-4.53).

CONCLUSIONS

These findings are compatible with previous reports, adding to the evidence that firefighters are at increased risk of a number of types of cancer.

Chemical exposures in research laboratories in a university

Research laboratories in a university were investigated for air-borne levels of legally designated organic solvents and specified chemical substances. Repeated surveys in 2004-5 (four times in the two years) of about 720 laboratories (thus 2,874 laboratories in total) revealed that the solvent concentrations were in excess of the Administrative Control Levels only in a few laboratories (the conditions improved shortly after the identification) and none with regard to specified chemicals. Thus, working environments were in Control Class 1 in almost all (99.5%) laboratories examined. Such conditions were achieved primarily by extensive installation and use of local exhaust systems. The survey further revealed that types of chemicals used in research laboratories were extremely various (only poorly covered by the regulation) whereas the amounts of each chemical to be consumed were quite limited. For protection of health of researchers (including post- and under-graduate students) in laboratories, therefore, it appeared more appropriate to make personal exposure assessment rather than evaluation of levels of chemicals in air of research laboratories. Considering unique characteristics of research activity, it is important to educate each researcher to make his/her own efforts to protect his/her health, through supply of knowledge on toxicity of chemicals as well as that on proper use of protective equipments including exhaust chambers.

A Nested Case-Control Study of Brain Tumors Among Employees at a Petroleum Exploration and Extraction Research Facility

Work-related exposures potentially associated with a cluster of brain tumors at a petroleum exploration and extraction research facility were evaluated in a nested case-control study. Fifteen cases were identified in the original cohort and 150 matched controls were selected. Odds ratios (ORs) for occupational exposure to petroleum, radiation, solvents, magnetic fields, and work activities were near or below 1.0. ORs near 1.5 were observed for: working with computers (OR = 1.47; 95% confidence interval [CI] = 0.30-9.35); work-related travel (OR = 1.48; 95% CI = 0.25-5.95), and travel immunizations (OR = 1.62; 95% CI = 0.23-9.45). Higher ORs were observed for work in administrative and marketing buildings and for achieving a master's or higher degree (OR = 2.0, 95% CI = 0.4-10.7). While some ORs above 1.5 were noted, no work-related chemical and physical exposures were significantly associated with the occurrence of brain tumors among employees at this facility.

Are gliomas preventable?

Gliomas are a family of primary central nervous system tumors of variable malignancy that are derived from supporting glia (astrocytes, oligodendrocytes, ependymal cells) or their progenitors/stem cells. There are two potential strategies to prevention: preventing gliomas from forming and preventing lower-grade gliomas from developing into higher-grade gliomas. Each would lower time-dependent mortality. Each also depends on an understanding of what causes gliomas so that these factors can be modulated. In this presentation, I will discuss primary prevention, chemoprevention, and screening. I will first focus on the known chromosomal, genetic, and protein changes associated with the different histologic varieties of glioma and the environmental, hereditary, and infectious/viral factors that may promote glioma development and malignant progression. I will discuss a number of clinical scenarios that eventuate from the known genetic patterns of these tumors and the changes in genetic patterns that reflect malignant progression. The basic thinking is that if one could prevent specific gene mutations and/or deletions or gains of specific chromosomes that lead to the development of low-grade (WHO 2) gliomas, then theoretically this would reduce the occurrence of high-grade (WHO 3 and 4) gliomas and hence the almost certain death that now is the fate of most patients with these tumors. In the case of de novo WHO 3 and 4 tumors, being able to prevent or counter specific gene mutations and/or the deletion of specific chromosomes would in itself reduce the occurrence of these gliomas and increase survival. Alternatively, a curative treatment for low-grade glioma that prevents these chromosomal/gene changes would prevent some glioblastomas (WHO 4) from forming and would have the same desired effect on survival. Obviously, for the latter to be achieved, we must also be able to diagnose and treat low-grade gliomas earlier.

Occupation and risk of meningioma and acoustic neuroma in the United States

BACKGROUND

Workplace exposures may be related to the development of brain tumors. In this case-control study, we examine occupation as a risk factor for meningioma and acoustic neuroma.

METHODS

A lifetime work history was obtained for 197 incident cases of meningioma, 96 cases of acoustic neuroma and 799 controls with non-malignant diseases enrolled from three hospitals in the United States between 1994 and 1998. Jobs considered to have similar tasks and chemical exposures were assigned to an occupational group. Logistic regression was used to estimate odds ratios (OR) adjusted for study matching factors (hospital, age, sex, race/ethnicity, and proximity of residence to the hospital) and education.

RESULTS

Elevated risk of meningioma was observed for individuals who had ever worked in the following occupational groups: auto body painters, designers and decorators, military occupations, industrial production supervisors, teachers, and managers. For acoustic neuroma, increased risk was noted for having worked as an athlete, gas station attendant, purchasing agent, sales representative, or teacher.

CONCLUSIONS

Although limited by multiple comparisons and the relatively small number of cases and controls in many occupational groups, these results nevertheless provide clues that deserve additional study in future epidemiologic studies.

Primary Brain Tumor Mortality at a Petroleum Exploration and Extraction Research Facility

A cohort mortality study was conducted among 3,779 employees at a petroleum exploration and extraction research facility to evaluate workplace exposures and brain tumor risk. Deaths were identified by searches against the National Death Index, Social Security Administration, and California state mortality files. Work histories were classified by job titles, laboratory activity, and company division. Eleven brain tumor deaths were observed among the cohort (standardized mortality ratio [SMR] 1.8; 95% confidence interval = 0.9-3.2). SMR analyses for scientists, employment in laboratory work, and in the research division were not associated with an increased brain tumor SMR, whereas an increased SMR was observed for administrative and nonresearch employees. Although conclusions are limited by the small study population and lack of specific exposure data, these findings were not consistent with an occupational explanation for the observed brain tumor cluster.