Brain tumor and exposure to pesticides in humans: a review of the epidemiologic data

Pesticide Residue Intake From Fruit and Vegetable Consumption and Risk of Glioma

We aimed to determine whether intake of pesticide residues from fruits and vegetables was associated with glioma. Within 3 prospective cohorts from 1998-2016-the Nurses' Health Study (NHS), Nurses' Health Study II (NHSII), and Health Professionals Follow-up Study-we computed multivariable-adjusted hazard ratios (MVHRs) and 95% confidence intervals (CI) for glioma by quintiles of intake of low- and high-pesticide-residue fruits and vegetables using Cox proportional hazards regression. Fruits and vegetables were categorized as high or low residue using a validated method based on pesticide surveillance data. We confirmed 275 glioma cases across 2,745,862 person-years. A significant association was observed between intake of high-residue fruits and vegetables and glioma in NHS (MVHR = 2.99, 95% CI: 1.38, 6.44 comparing highest with lowest quintile, P for trend = 0.02). This was not identified in NHSII (MVHR = 0.52, 95% CI: 0.19, 1.45, P for trend = 0.20) or Health Professionals Follow-up Study (MVHR = 1.01, 95% CI: 0.42, 2.45, P for trend = 0.39). No significant associations were observed by intake of low-residue fruits and vegetables; overall intake was not significantly associated with glioma in any cohort. We found no evidence for an inverse relationship of fruit and vegetable intake with glioma. Although limited in power, this study suggests a possible association between fruit-and-vegetable pesticide residue intake and risk of glioma that merits further study.

Risk Factors for Brain Health in Agricultural Work: A Systematic Review

Certain exposures related to agricultural work have been associated with neurological disorders. To date, few studies have included brain health measurements to link specific risk factors with possible neural mechanisms. Moreover, a synthesis of agricultural risk factors associated with poorer brain health outcomes is missing. In this systematic review, we identified 106 articles using keywords related to agriculture, occupational exposure, and the brain. We identified seven major risk factors: non-specific factors that are associated with agricultural work itself, toluene, pesticides, heavy metal or dust exposure, work with farm animals, and nicotine exposure from plants. Of these, pesticides are the most highly studied. The majority of qualifying studies were epidemiological studies. Nigral striatal regions were the most well studied brain area impacted. Of the three human neuroimaging studies we found, two focused on functional networks and the third focused on gray matter. We identified two major directions for future studies that will help inform preventative strategies for brain health in vulnerable agricultural workers: (1) the effects of moderators such as type of work, sex, migrant status, race, and age; and (2) more comprehensive brain imaging studies, both observational and experimental, involving several imaging techniques.

Disability-Adjusted Life Years and Mortality Rate Attributed to Brain and Central Nervous System Cancer in the Middle East and North Africa Countries

BACKGROUND

Primary brain tumors are among the main causes of death. This study aimed to determine the epidemiological features of the brain and central nervous system cancer in the Middle East and North Africa (MENA) region.

METHODS

In this study, data of the Global Burden of Disease (GBD) study were used to estimate the incidence, prevalence, deaths, disability-adjusted life years (DALYs), and mortality in 21 countries in the MENA region from 1990 to 2019 based on age and sex. The percentage of the changes of epidemiologic indicators was calculated between 1990 and 2019.

RESULTS

Palestine and Turkey had the highest rate of brain and central nervous system cancer in 2019. Saudi Arabia, Oman, Iraq, and Lebanon had the highest percentage of incidence rate changes from 1990 to 2019. The prevalence of brain and central nervous system cancer in the MENA region was increased from 7.51 (95% CI: 4.95-11.01) in 1990 to 16.45 (95% CI: 10.83-19.54) in 2019 (percentage of changes = 54.35%). The standardized age mortality rate in the MENA region was increased by 2.7% in 2019 compared to that in 1990. The rate of standardized age of DALY per 100,000 individuals in the MENA region decreased from 135.09 (95% CI: 92.57-199.92) in 1990 to 128.34 (95% CI: 87.81-151.3) in 2019.

CONCLUSION

The incidence rate, prevalence, and standardized age mortality (per 100,000) had increased significantly in the MENA region in 2019 compared to those in 1990. Focusing on the diversity of the estimates of such indices in different countries of MENA can lead to the identification of important risk factors for brain cancer in future studies.

The association between incidence and mortality of brain cancer and human development index (HDI): an ecological study

Background

Brain cancer is a rare and deadly malignancy with a low survival rate. The present study aims to evaluate the epidemiology of brain cancer and its relationship with the human development index (HDI) worldwide.

Methods

This is an ecological study. The data on cancer incidence and cancer mortality was extracted from the World Bank for Cancer in 2018 (GLOBOCAN 2018). The incidence, mortality rate, and brain cancer distribution maps were drawn for different countries. We used correlation and regression tests to examine the association of incidence and mortality rates of brain cancer with HDI. The statistical analysis was carried out by Stata-14 and a significance level of 0.05 was considered.

Results

According to the results of Global Cancer Registry in 2018, there were 18,078,957 registered cases of cancer in both sexes, of which 29,681 were related to brain cancer. The highest incidence (102,260 cases, 34.4%) and mortality (77,815 cases, 32.3%) belonged to very high HDI regions. Results showed that incidence (r = 0.690, P < 0.0001) and mortality rates (r = 0.629, P < 0.001) of brain cancer are significantly correlated with HDI. We also observed a positive correlation between brain cancer incidence and Gross National Income (GNI) (r = 0.346, P < 0.001), Mean Years of Schooling (MYS) (r = 0.64, P < 0.001), TABLE (LEB) (r = 0.66, P < 0.001) and Expected Years of Schooling (EYS) (r = 0.667, P < 0.001). Results also revealed that mortality rate was significantly correlated with GNI (r = 0.28, P < 0.01), MYS (r = 0.591, P < 0.01), LEB (r = 0.624, P < 0.01), and EYS (r = 0.605, P < 0.01).

Conclusion

The results of the study showed that the incidence and mortality of brain cancer in countries with higher HDI levels is higher than countries with lower HDI levels, so attention to risk factors and action to reduce it in countries with higher HDI levels in controlling this cancer in this Countries are effective.

A prospective study of cancer risk among Agricultural Health Study farm spouses associated with personal use of organochlorine insecticides

BACKGROUND

Organochlorine insecticides (OCs) have historically been used worldwide to control insects, although most have now been banned in developed countries. Evidence for an association between OC exposures and cancer predominantly comes from occupational and population based-studies among men. We evaluated the association between the use of specific OCs and cancer among the female spouses of pesticide applicators in the Agricultural Health Study.

METHODS

At enrollment (1993-1997), spouses of private applicators in the cohort provided information about their own use of pesticides, including seven OCs (aldrin, chlordane, dieldrin, DDT, heptachlor, lindane, and toxaphene), and information on potential confounders. We used Poisson regression to estimate relative risks (RRs) and 95% confidence intervals (CIs) for cancers (n ≥ 3 exposed cases) reported to state cancer registries from enrollment through 2012 (North Carolina) and 2013 (Iowa), and use of the individual OCs, as well as use of any of the specific OCs.

RESULTS

Among 28,909 female spouses, 2191 (7.58%) reported ever use of at least one OC, of whom 287 were diagnosed with cancer. Most cancers were not associated with OC use. Risk of glioma was increased among users of at least one OC (Nexposed = 11, RR = 3.52, 95% CI 1.72-7.21) and specifically among lindane users (Nexposed = 3, RR = 4.45, 95% CI 1.36-14.55). Multiple myeloma was associated with chlordane (Nexposed = 6, RR = 2.71, 95% CI 1.12-6.55). Based on 3 exposed cases each, there were also positive associations between pancreatic cancer and lindane, and ER-PR- breast cancer and dieldrin. No other associations with breast cancer were found.

CONCLUSIONS

Overall, there were some associations with OC use and cancer incidence, however we were limited by the small number of exposed cancer cases. Future research should attempt to expand on these findings by assessing environmental sources of OC exposures, to fully evaluate the role of OC exposures on cancer risk in women.

OptiPhy, a technical-economic optimisation model for improving the management of plant protection practices in agriculture: a decision-support tool for controlling the toxicity risks related to pesticides

The health, environmental and socio-economic issues related to the massive use of plant protection products are a concern for all the stakeholders involved in the agricultural sector. These stakeholders, including farmers and territorial actors, have expressed a need for decision-support tools for the management of diffuse pollution related to plant protection practices and their impacts. To meet the needs expressed by the public authorities and the territorial actors for such decision-support tools, we have developed a technical-economic model "OptiPhy" for risk mitigation based on indicators of pesticide toxicity risk to applicator health (IRSA) and to the environment (IRTE), under the constraint of suitable economic outcomes. This technical-economic optimisation model is based on linear programming techniques and offers various scenarios to help the different actors in choosing plant protection products, depending on their different levels of constraints and aspirations. The health and environmental risk indicators can be broken down into sub-indicators so that management can be tailored to the context. This model for technical-economic optimisation and management of plant protection practices can analyse scenarios for the reduction of pesticide-related risks by proposing combinations of substitution PPPs, according to criteria of efficiency, economic performance and vulnerability of the natural environment. The results of the scenarios obtained on real ITKs in different cropping systems show that it is possible to reduce the PPP pressure (TFI) and reduce toxicity risks to applicator health (IRSA) and to the environment (IRTE) by up to approximately 50 %.

Assessing plant protection practices using pressure indicator and toxicity risk indicators: analysis of therelationship between these indicators for improved risk management, application in viticulture

The excessive use of plant protection products (PPPs) has given rise to issues of public and environmental health because of their toxicity. Reducing the use of toxic PPPs and replacing them with products that are less toxic for human health and the environment have become socially, environmentally and economically indispensable. In this article, we assess the plant protection practices of a small group of winegrowers practicing "integrated agriculture" in the south of France, in order to measure the benefit of using toxicity risk indicators as a decision-support tool for different players in land management. An analysis of plant protection practices using indicators of the risk to operator health and the environment (IRSA, IRTE), together with a frequency-of-treatment indicator (TFI), enabled us to (i) show the variability of these indicators depending on the production system and farmers' pesticide use strategies and (ii) calculate correlations between these indicators. This analysis of plant protection practices at different scales (farm, field), carried out in collaboration with the growers, enabled us to perform an initial validation of decision-support tools for determining risk management strategies regarding the use of pesticides.

The Upper Midwest Health Study: a case-control study of pesticide applicators and risk of glioma

BACKGROUND

An excess incidence of brain cancer in farmers has been noted in several studies. The National Institute for Occupational Safety and Health developed the Upper Midwest Health Study (UMHS) as a case-control study of intracranial gliomas and pesticide uses among rural residents. Previous studies of UMHS participants, using "ever-never" exposure to farm pesticides and analyzing men and women separately, found no positive association of farm pesticide exposure and glioma risks. The primary objective was to determine if quantitatively estimated exposure of pesticide applicators was associated with an increased risk of glioma in male and female participants.

METHODS

The study included 798 histologically confirmed primary intracranial glioma cases (45 % with proxy respondents) and 1,175 population-based controls, all adult (age 18-80) non-metropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. The analyses used quantitatively estimated exposure from questionnaire responses evaluated by an experienced industrial hygienist with 25 years of work on farm pesticide analyses. Odds ratios (ORs) and 95 % confidence intervals (CIs) using unconditional logistic regression modeling were calculated adjusting for frequency-matching variables (10-year age group and sex), and for age and education (a surrogate for socioeconomic status). Analyses were separately conducted with or without proxy respondents.

RESULTS

No significant positive associations with glioma were observed with cumulative years or estimated lifetime cumulative exposure of farm pesticide use. There was, a significant inverse association for phenoxy pesticide used on the farm (OR 0.96 per 10 g-years of cumulative exposure, CI 0.93-0.99). No significant findings were observed when proxy respondents were excluded. Non-farm occupational applicators of any pesticide had decreased glioma risk: OR 0.72, CI 0.52-0.99. Similarly, house and garden pesticide applicators had a decreased risk of glioma: OR 0.79, CI 0.66-0.93, with statistically significant inverse associations for use of 2,4-D, arsenates, organophosphates, and phenoxys.

CONCLUSIONS

These results are consistent with our previous findings for UMHS of reported farm pesticide exposure and support a lack of positive association between pesticides and glioma.

Occupational pesticide exposures and cancer risk: a review

A review of the epidemiological literature linking pesticides to cancers in occupational studies worldwide was conducted, with particular focus on those articles published after the release of IARC Monograph 53 (1991): Occupational Exposures in Insecticide Applications and Some Pesticides. Important new data are now available. Chemicals in every major functional class of pesticides including insecticides, herbicide, fungicides, and fumigants have been observed to have significant associations with an array of cancer sites. Moreover, associations were observed with specific chemicals in many chemical classes of pesticides such as chlorinated, organophosphate, and carbamate insecticides and phenoxy acid and triazine herbicides. However, not every chemical in these classes was found to be carcinogenic in humans. Twenty-one pesticides identified subsequent to the last IARC review showed significant exposure-response associations in studies of specific cancers while controlling for major potential confounders. This list is not an exhaustive review and many of these observations need to be evaluated in other epidemiological studies and in conjunction with data from toxicology and cancer biology. Nonetheless, it is reasonable and timely for the scientific community to provide a multidisciplinary expert review and evaluation of these pesticides and their potential to produce cancer in occupational settings.

Pesticides and brain cancer linked in orchard farmers of Kashmir

Background:

The atmosphere of valley of Kashmir is ideal for fresh and dry fruit production. Millions of tons of pesticides, insecticides and fungicides (chemicals like chlorpyriphos, mancozeb, captan, dimethoate, phosalone, etc.) are being used by the orchard farmers to spray the plants, fruits and the leaves every year. The increasing trend in the incidence of primary malignant brain tumors in orchard farmers of Kashmir is alarming.

Aim:

To determine the relationship between the patients of primary malignant brain tumors and their occupation.

Materials and Methods:

Retrospectively case files along with death certificates of 432 patients of primary malignant brain tumors and 457 controls (non-tumor neurologic diseases), admitted for treatment simultaneously over a period of 4 years from January 2005 to December 2008, to the Department of Neurosurgery, Sher-I-Kashmir Institute of Medical Sciences (SKIMS), Kashmir, were studied. Follow-up and family contact was established. The serum cholinesterase activity was measured by kinetic/DGKC calorimetric method and ethylenediaminetetraacetic acid (EDTA) samples were sent to the laboratory. The results are expressed in U/l which is U/l×1000. The laboratory at SKIMS, Srinagar, and Dr Lal PathLabs at New Delhi used a reference range for serum cholinesterase as 3167–6333 U/l.

Results:

Analysis revealed that 90.04% (389 out of 432) patients were orchard-farm workers, orchard residents and orchard playing children exposed to the high levels of multiple types of neurotoxic and carcinogenic (chlorpyriphos, dimethoate, mancozeb and captan) chemicals for more than 10–20 years. About 31.9% (124 out of 389) of these from both sexes were younger than 40 years beginning exposure at an early age and had higher (<6334 U/l) serum cholinesterase (SCE) levels. The 9.96% (43 out of 432) patients were not exposed to pesticides. On the other hand, only 119 patients out of 457 controls had recorded history of pesticide exposure and 338 were unrelated to pesticides. Out of 389 patients, 71.7% (279 out of 389) were males and 28.3% (110 out of 389) including 7 members of three families, 6 were females and 1 male.

Conclusion:

All orchard-related 389 patients had high grade tumors as compared to the non-pesticide tumors. Mortality in pesticide exposed tumors was 12%. Higher levels of SCE were found in 31.9% (124 out of 389) patients and decreased levels in only 45.3% (176 out of 389) orchard-related patients. The significantcase/control odds ratio (OR) of 0.28, hospital control SCE OR of 1.1 and family control SCE OR of 1.5, points the finger of suspicion toward the link between pesticides and brain cancer.

Brain cancer and pesticide relationship in orchard farmers of Kashmir

Background:

The increasing trend in the incidence of primary malignant brain tumors in orchard farmers and their families in Kashmir.

Aim:

To determine the relationship between the patients of primary malignant brain tumors and their occupation.

Materials and Methods:

Retrospectively, case files along with death certificates of 432 patients of primary malignant brain tumors and 457 controls (non-tumor neurologic diseases), admitted for treatment simultaneously over a period of 4 years from January 2005 to December 2008, to the Neurosurgery, Sher-i-Kashmir Institute of Medical Sciences (SKIMS), Kashmir, were studied. Follow-up and family interaction was established.

Results:

Analysis revealed that 90.04% (389 out of 432) patients were orchard farm workers, orchard residents and orchard playing children exposed to the high levels of multiple types of neurotoxic and carcinogenic (chlorpyriphos, dimethoate, mancozeb and captan) chemicals for more than 10 years [relative risk (RR) = 10.6; odds ratio (OR) = >10; 95% confidence interval (CI) = >25-40]. The 9.96% (43 out of 432) patients were not exposed to pesticides. On the other hand, only 19 patients out of 457 controls had recorded history of pesticide exposure and 438 were unrelated to pesticides. Out of 389 patients, 71.7% (279 out of 389) were males and 28.3% (110 out of 389), including six members of three families, were females (one male child).

Conclusion:

All orchard-related 389 patients had high-grade tumors as compared to the non-pesticide tumors. Mortality in pesticide-exposed tumors was 12%. The higher or upper-normal levels of serum cholinesterase (AChE) were observed in 54.7% (213 out of 389) patients and decreased levels were found in only 45.3% (176 out of 389) orchard-related patients (RR = 19.4; OR = >5; 95% CI = >1-10). Although serum AChE levels were a routine investigation in malignant brain tumors, this was not a routine in other neurological conditions (hospitalized controls). The familial gliomas have shown an emerging trend in the orchard residents of valley of Kashmir.

Occupational and environmental risk factors for brain cancer: a pilot case-control study in France

INTRODUCTION

The increased incidence of malignant primary brain tumors (MPBT) reported in several studies could be due to environmental factors. To estimate the chemical and physical risk factors of these tumors in southeastern France, a pilot case-control study that included all new MPBT cases diagnosed in 2005 in the main brain cancer treatment centers in the western section of the Provence-Alpes-Côte d'Azur (PACA) region.

MATERIAL AND METHODS

Age-, sex-, and hospital-matched controls were selected from the neurosurgery department of the same hospital. An occupational physician, using a standardized questionnaire, collected information on suspected risk factors of MPBT in a face-to-face interview at the hospital of all case and control subjects. Data collected included jobs held, various exposures throughout working life, and leisure time activities.

RESULTS

The study included 122 cases and 122 controls. No particular job was identified as a major risk factor for brain cancer. Risk was significantly higher among those who used glue (OR=17.58, 95% CI 1.75 - 176.62) during leisure activities and significantly lower among those residing near cellular telephone towers (OR=0.49, 95% CI 0.26 - 0.92).

DISCUSSION

Several new hypotheses about the effects of cellular telephone towers and chemical exposure merit further analytic studies.

Carcinogenicity of agricultural pesticides in adults and children

The role of specific agricultural pesticides in relation to adult and childhood cancers has not been firmly established due to the lack of precise exposure data in previous studies. Improvements in exposure assessment, disease classification, and application of molecular techniques in recent epidemiological evaluations is rapidly improving our ability to evaluate the human carcinogenicity of agricultural pesticides. The role of pesticide exposures in the etiology of human cancer is outlined by anatomical site and recent development in exposure assessment and molecular epidemiology are summarized and evaluated.

Pesticides and human cancers

The potential for human carcinogenicity of almost all pesticides currently on the market has been poorly evaluated and is inadequately understood. Generating mechanistic data in both animal studies and epidemiology will play an increasingly important role in the future. Improved exposure assessment, in large prospective studies that generate reliable exposure-response data that focus on individual pesticide exposures are needed. One of the greatest opportunities to make more rapid progress will be to foster more multi-disciplinary collaborations between toxicologists and epidemiologists. Collaborations on molecular epidemiology investigations offers such opportunities to both toxicologists and epidemiologists that were not possible even a decade ago.

Occupational risk factors for brain cancer in Canada

OBJECTIVE

We sought to examine the impact of occupational exposure on brain cancer risk.

METHODS

Mailed questionnaires were used to collect information on lifetime employment history, occupational exposure to 18 chemicals, and other risk factors for 1009 incident cases of brain cancer and 5039 control subjects in Canada in 1994 to 1997.

RESULTS

People exposed to asphalt and welding had respective odds ratio (and 95% confidence interval) of 1.29 (1.02-1.62) and 1.26 (0.98-1.45). An increased risk of brain cancer might be associated with exposure to asbestos, benzene, mineral or lubricating oil, isopropyl oil, and wood dust and with following occupations: teaching; protective service; metal processing and related jobs, and metal shaping and forming; knitting in textile processing; construction trades; and transport equipment operating.

CONCLUSIONS

Our study suggests a possible role for occupational exposure in the etiology of brain cancer.

Gliomas and farm pesticide exposure in women: the Upper Midwest Health Study

An excess incidence of brain cancer in male farmers has been noted in several studies, but few studies have focused on women. The National Institute for Occupational Safety and Health Upper Midwest Health Study evaluated effects of rural exposures for 341 female glioma cases and 528 controls, all adult (18-80 years of age) nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. On average, controls lived longer on farms than did cases. After adjusting for age, age group, education, and farm residence, no association with glioma was observed for exposure to arsenicals, benzoic acids, carbamates, chloroacetanilides, dinitroanilines, inorganics, organochlorines, organophosphates, phenoxys, triazines, or urea-based or estrogenic pesticides. An increased risk of glioma was observed for carbamate herbicides but was not statistically significant (odds ratio = 3.0; 95% confidence interval, 0.9-9.5). No association was observed between glioma and exposure to 12 widely used specific pesticides, after adjustment for age, age group, education, and any other pesticide exposure. These results were not affected after exclusion of proxy respondents (43% of cases, 2% of controls). Women were less likely than men to have applied pesticides, but more likely to have laundered pesticide-contaminated clothes. Storing pesticides in the house was associated with a statistically non-significant increased risk. Results show that exposure to pesticides was not associated with an increased risk of intracranial gliomas in women. Other farm-related factors could be etiologic factors and will be discussed in future reports.

Gliomas and Farm Pesticide Exposure in Men: The Upper Midwest Health Study

The National Institute for Occupational Safety and Health evaluated farm pesticide exposure and glioma risk in a study that included 457 glioma cases and 648 population-based controls, all adult men (18-80 yr old) and nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. Multiple logistic regressions were used to control for farm residence, age, age group, education, and exposure to other pesticides. No associations were found between glioma and 12 specific pesticides. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) and found reduced glioma risk for insecticides (OR = 0.53, CI = 0.37-0.77), fumigants (OR = 0.57, CI = 0.34-0.95), and organochlorines (OR = 0.66, CI = 0.47-0.94). In analyses excluding proxy respondents (47% of cases) most CIs included 1.0. No positive association of farm pesticide exposure and glioma was found. Other farm exposures may explain the excess brain cancer risk seen in previous studies.

Health Effects of Chronic Pesticide Exposure: Cancer and Neurotoxicity

Pesticides are widely used in agricultural and other settings, resulting in continuing human exposure. Epidemiologic studies indicate that, despite premarket animal testing, current exposures are associated with risks to human health. In this review, we describe the routes of pesticide exposures occurring today, and summarize and evaluate the epidemiologic studies of pesticide-related carcinogenicity and neurotoxicity in adults. Better understanding of the patterns of exposure, the underlying variability within the human population, and the links between the animal toxicology data and human health effects will improve the evaluation of the risks to human health posed by pesticides. Improving epidemiology studies and integrating this information with toxicology data will allow the human health risks of pesticide exposure to be more accurately judged by public health policy makers.

Intracranial Neoplasms

This chapter begins with a discussion of the taxonomy of primary brain tumors, with a focus on gliomas, meningiomas, and grading systems for these tumors. It discusses methodological challenges for studies of brain tumor incidence including variations in diagnostic practices. It summarizes descriptive epidemiology studies of brain tumor incidence and mortality by age, sex, histologic type, and ethnicity. Factors associated with survival are discussed including histologic grade, tumor location, and extent of surgical resection. Much work remains to discover the causes of the majority of human brain tumors, as established risk factors account for only a small proportion of these tumors. The chapter critiques evidence regarding possible risk factors for brain tumors, including genetic predisposition, ionizing radiation, chemical carcinogen exposure, electromagnetic fields, infections, head trauma, smoking, and diet.

[Brain tumors mortality in Brazil, 1980-1998]

Brain tumors are rare, but their incidence and mortality have increased in different countries, including Brazil, especially among the elderly. This paper presents the mortality pattern of brain tumors in Brazil, including distribution of mortality rates by gender, age, topography, and tumor staging, from 1980 to 1998. Age-adjusted (by world population) brain cancer mortality rates increased from 2.24/100,000 to 3.35/100,000 inhabitants among the overall population during this period (an increase of 50%). Observed rates were higher during childhood than adolescence and increased with age, reaching the highest levels among the elderly. Among individuals 70 years of age and older, an average annual increase of 6% was observed in the series. Brain and meningeal tumor rates are presented for the entire country and selected State capitals. Further study is needed to elucidate the role of both new diagnostic technologies and environmental exposures potentially associated with the observed changes in brain cancer mortality rates.

Geographical pattern of brain cancer incidence in the Navarre and Basque Country regions of Spain

BACKGROUND

The study of the distribution of brain cancer mortality in Spain shows a grouping of highest risk provinces corresponding to the autonomous regions of Navarre and the Basque Country.

AIM

To explore the possible existence of geographical patterns in these areas.

METHODS

Municipal maps of brain cancer incidence were drawn up and the influence of land use related variables on the distribution of the disease duly analysed. Autoregressive conditional models were used to plot smoothed municipal maps. The influence of explanatory land use variables, ascertained by remote sensing, was assessed.

RESULTS

The maps revealed that certain towns situated in the "Media" and "Cantábrica-Baja Montaña" districts of Navarre were areas of highest risk. Among the towns in question, those in the "Media" district lie very close to the city of Pamplona. However, the pattern of brain cancer incidence in Navarre and the Basque Country could not be conclusively said to be determined by any specific type of land cover and/or crop.

CONCLUSIONS

Results suggest a possible increase of risk linked to areas devoted to a high percentage of non-irrigated arable land.

Cancer risks in populations living near landfill sites in Great Britain

Previous studies have raised concerns about possible excess risks of bladder, brain and hepatobiliary cancers and leukaemias near landfill sites. Several cancers have been implicated, but no consistent pattern has emerged. We present a large nationwide analysis of selected cancers near landfill sites in Great Britain. The base population comprised people living within 2 km of 9565 (from a total of 19 196) landfill sites that were operational at some time from 1982 to 1997, with populations living more than 2 km from a landfill as reference. Risks of cancers at the above sites were computed with adjustment for age, sex, year of diagnosis, region and deprivation. National post-coded registers provided a total of 341 856 640 person-years for the adult cancer analyses and 113 631 443 person-years for childhood leukaemia. There were 89 786 cases of bladder cancer, 36 802 cases of brain cancer, 21 773 cases of hepatobiliary cancer, 37 812 cases of adult leukaemia and 3973 cases of childhood leukaemia. In spite of the very large scale of this national study, we found no excess risks of cancers of the bladder and brain, hepatobiliary cancer or leukaemia, in populations living within 2 km of landfill sites. The results were similar if the analysis were restricted to landfill sites licensed to carry special (hazardous) waste. Our results do not support suggestions of excess risks of cancer associated with landfill sites reported in other studies.

Brain cancer and occupational exposure to magnetic fields among men: results from a Canadian population-based case-control study

BACKGROUND

The relationship between occupational exposure to magnetic fields and brain cancer in men was investigated using population-based case-control data collected in eight Canadian provinces. Emphasis was placed on examining the variations in risk across different histological types.

METHODS

A list of occupations was compiled for 543 cases and 543 controls that were individually matched by age. Occupations were categorized according to their average magnetic field exposure through blinded expert review (<0.3, 0.3-<0.6, and > or = 0.6 microT). In total, 133 cases (14%) and 123 controls (12%) were estimated to have at least one occupation whereby magnetic field exposures exceeded 0.3 microT. Odds ratios (OR) were generated using conditional logistic regression, and were adjusted for suspected occupational risk factors for brain cancer.

RESULTS

A non-significantly increased risk of brain cancer was observed among men who had ever held a job with an average magnetic field exposure >0.6 microT relative to those with exposures <0.3 microT (OR = 1.33, 95% CI : 0.75-2.36). A more pronounced risk was observed among men diagnosed with glioblastoma multiforme (OR = 5.36, 95% CI : 1.16-24.78). Moreover, a cumulative time weighted index score of magnetic field exposure was significantly related to glioblastoma multiforme (P = 0.02). In contrast, magnetic field exposures were not associated with astrocytoma or other brain cancers.

CONCLUSIONS

Our findings support the hypothesis that occupational magnetic field exposure increases the risk of glioblastoma multiforme.

Cancer incidence and risks in selected agricultural settlements in the Negev of Israel

Medical staff of two Negev kibbutzim invited epidemiologists to help them investigate cancer rates among their members. Our objectives were (a) to determine whether the cancer rate in the kibbutzim was elevated or abnormal and (b) to determine the role of agricultural and other relevant exposures if cancer incidence was elevated. We validated cases of cancer by kibbutz records and by surveying other information; we computed expected values on the basis of the age-sex-calendar period and site-specific cancer incidence rates reported by the Israel Cancer Registry for the entire population; and we compared the data for the 2 kibbutzim with data derived for similar age and sex groups in 2 other kibbutzim, which were assumed not to have increased cancer rates. In addition, we planned and conducted a case-referent study, including the design, pretest, and use of questionnaires, including data about lifetime exposures (i.e., type of work and its duration, agricultural and industrial chemicals, smoking and alcohol use, demographic variables, health experiences, and family history). In only one of the kibbutzim, for which high cancer rates were suspected, was there significant excess for all sites in persons who were less than 40 y of age. In one of the "comparison" kibbutzim, we found increased cancer rates overall. Much of the excess in the high cancer kibbutzim was in hematological cancer (i.e., leukemia and lymphoma). Multiple years of work in fields, orchards, and landscape, as well as orchard work that commenced before 1960, were associated with increased risk of cancer (p < .08). We also found an association between cancer rate and numbers of industrial chemicals used (p < .08). Pipe and cigarette smoking were also associated with increased cancer incidence. In the multivariate analysis, the association with calendar year in which orchard work was started and multiple exposures to industrial chemicals was stronger than associations noted in the univariate analyses. Although duration of agricultural work or multiple industrial exposures were clearly associated with increase in cancer risk, we were unable to identify the causal role of specific agent(s). Nonetheless, educational programs for cancer prevention can be based, in part, on the results of such a study.