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Leukemia incidence in children has increased worldwide in recent decades, particularly due to the rise in acute lymphoblastic leukemia. Studies have associated exposure to non-ionizing radiation generated by low frequency magnetic fields with childhood leukemia. The current article reviews the case-control studies published on this subject. Of 152 articles tracked in different databases, ten studies from North America, Asia, and Europe met the defined selection criteria, with patients diagnosed from 1960 to 2004. Methodological limitations were observed in these articles, including difficulties with the procedures for assessing exposure. An association may exist between exposure to low frequency magnetic fields and acute lymphoblastic leukemia in children, but this association is weak, preventing the observation of consistency in the findings. Future studies from a wider range of geographic regions should focus on the analysis of acute lymphoblastic leukemia, which is the subtype with the greatest impact on the increasing overall incidence of childhood leukemia.

The most solidly established risk factors for laryngeal cancer are tobacco and alcohol. As for occupational factors, the only established carcinogen is exposure to strong inorganic acid mists. However, asbestos, pesticides, paints, gasoline, diesel engine emissions, dusts, and other factors have been reported in the literature as occupational agents that increase the risk of laryngeal cancer. A hospital-based case-control study was conducted to investigate occupational risk factors for laryngeal cancer. Detailed data on smoking, alcohol consumption, and occupational history were collected for 122 laryngeal cancers and 187 controls matched by frequency (according to sex and age). Laryngeal cancer was associated with exposure to respirable free crystalline silica (OR = 1.83; 95%CI: 1.00-3.36), soot (from coal, coke, fuel oil, or wood) (odds ratio - OR = 1.78; 95% confidence interval - 95%CI: 1.03-3.03), fumes (OR = 2.55; 95%CI: 1.14-5.67), and live animals (OR = 1.80; 95%CI: 1.02-3.19).

Dietary factors associated with oral cancer were investigated in a case-control hospital-based study in the city of São Paulo, Brazil, from 1998 to 2002. A total of 835 subjects, 366 with histologically confirmed incident cases of oral-cavity or pharyngeal cancer and 469 controls participated in the study. Dietary data were collected with a food frequency questionnaire (FFQ). Odds ratios (OR) and 95% confidence intervals (95%CI) were obtained from unconditional logistic regression, adjusted for potential confounders. Inverse associations with risk of oral cancer were found for the highest intake of beans, OR = 0.37 (95%CI: 0.22-0.64), raw vegetables, OR = 0.51 (95%CI: 0.29-0.93) and the intermediate tertile of rice and pasta intake, OR = 0.56 (95%CI: 0.38-0.83). Positive associations were observed for the highest intake of eggs, OR = 1.84 (95%CI: 1.23-2.75), potatoes, OR = 2.22 (95%CI: 1.53-3.25), and milk, OR= 1.80 (95%CI: 1.09-2.98). Some traditional Brazilian foods like rice and beans emerged as protective factors against oral cancer, independently of other risk factors.

To estimate the risk of occupation in oral and oropharyngeal cancer, a hospital-based case-control study was conducted in Greater Metropolitan São Paulo, Brazil. The study included 325 cases and 468 controls, frequency-matched with cases by sex and age, and interviewed from January 1999 to March 2002. Occupational risks were examined by industry and job titles and restricted to males (266 cases, 362 controls). Odds ratios (OR) were calculated by unconditional logistic regression, controlling for age, smoking, and alcohol. Males working in vehicle maintenance shops (26 cases, 12 controls) showed adjusted OR = 2.45 (95%CI: 1.14-5.27), increasing among those employed 10 or more years (OR = 7.90; 95%CI: 2.03-30.72). Occupation as vehicle repair worker (14 cases, 7 controls) showed OR = 2.10 (95%CI: 0.78-5.68), increasing among workers exposed 10 or more years (OR = 26.21; 95%CI: 2.34-294.06). Other industries and occupations revealed OR higher than 1.5, but not statistically significant. In conclusion, employment in vehicle maintenance shops and occupation as vehicle repair worker showed risk for oral cancer, independently of smoking and alcohol. More prolonged exposure increased the risk.

The proportion of cancer attributed to occupation varies, and estimates are partially dependent on the characteristics of exposed populations, type of tumor, and methodology. The main difficulty for estimating these proportions is the reconstruction of past individual occupational exposure. Appropriate methods for retrospective occupational exposure assessment are essential in epidemiological studies in order to avoid misclassification. In this review, qualitative and quantitative methods are discussed, considering that such evaluations require progressive approaches without a previously established hierarchy. Methods to evaluate exposure through environmental and biological measurements, questionnaires, interviews, expert panels, and job-exposure matrices are compared as to their advantages, limitations, accuracy, and validity. In health surveillance, all the above-mentioned methods can be applied, but the use of job-exposure matrices is emphasized, especially using secondary databases.

Identification of molecular biomarkers is a common result of current cancer epidemiological research. Both genetic and molecular epidemiology have enjoyed impressive developments in recent decades, with important repercussions on traditional epidemiological approaches. In this paper we evaluate the new frontiers of cancer epidemiology, incorporating both genetic and molecular biology approaches. We examine the current knowledge of molecular biomarkers for exposure and susceptibility to cancer, the role of gene mutations in carcinogenesis, and their application to epidemiological studies. By exploring the status of relevant biomarkers, these approaches become effective in evaluating exposure and susceptibility and show enormous potential for elucidating mechanisms of carcinogenesis and the effect of risk factors in cancer. However, these approaches are necessarily more invasive and raise several ethical issues for consideration by both researchers in public health and society as a whole.

During the last two decades, incidence rates of occupational accidents have been decreasing in Brazil. Mortality has also decreased, but not as sharply as incidence. Changes in reporting of occupational accidents have been the main argument used to explain such trends. This time-series study covering occupational accidents from 1970 to 1995 clearly shows the link between occupational accidents and social and economical determinants. Comparing 14 Brazilian States, a positive linear regression (r=0.80) was detected between proportion of workers in industrial production and accidents. In the 1980s, Brazil's economic recession led to an increase in unemployment. The decline in industrial jobs - those with a higher risk of accidents ( was accented by the restructuring of production and increased use of computer and robotics technologies in various manufacturing sectors. The result was a heavy shift of the work force from industry to commerce and services - jobs entailing lower risk of accidents. These factors influenced trends in occupational accidents in Brazil during this 25-year period.

Over the course of recent decades, Brazil has become an industrialized society. From an epidemiological perspective and considering changes that have been occurring in the Brazilian population, particularly concerning demographic and epidemiological transitions, this paper discusses the need to adapt the epidemiological surveillance system in order to incorporate the surveillance of non-transmissible diseases. The authors analyze the information system for work-related accidents in the Workers' Health Program, under SUDS (the Unified Decentralized Health System) for the Mandaqui Region (in the Northern part of the city of São Paulo), based on data from a local metalworking industry identified by the information system as a high-risk site for work-related accidents. The article also focuses on the importance of organized workers participating in actions to control work-related accidents. Although such participation is not always possible, the health sector must incorporate the workers' own concrete experience in order to develop more effective actions to prevent accidents at the workplace.