Background:Previous pooled analyses have reported an association between magnetic fields and childhood leukaemia. We present a pooled analysis based on primary data from studies on residential magnetic fields and childhood leukaemia published after 2000.Methods:Seven studies with a total of 10 865 cases and 12 853 controls were included. The main analysis focused on 24-h magnetic field measurements or calculated fields in residences.Results:In the combined results, risk increased with increase in exposure, but the estimates were imprecise. The odds ratios for exposure categories of 0.1–0.2 μT, 0.2–0.3 μT and ⩾0.3 μT, compared with <0.1 μT, were 1.07 (95% CI 0.81–1.41), 1.16 (0.69–1.93) and 1.44 (0.88–2.36), respectively. Without the most influential study from Brazil, the odds ratios increased somewhat. An increasing trend was also suggested by a nonparametric analysis conducted using a generalised additive model.Conclusions:Our results are in line with previous pooled analyses showing an association between magnetic fields and childhood leukaemia. Overall, the association is weaker in the most recently conducted studies, but these studies are small and lack methodological improvements needed to resolve the apparent association. We conclude that recent studies on magnetic fields and childhood leukaemia do not alter the previous assessment that magnetic fields are possibly carcinogenic.

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To assess the effect of road traffic exhaust on the risk of childhood leukemia, we carried out a population-based casecontrol study in the Province of Varese, northern Italy, covered by a population-based cancer registry. All 120 incident cases from 1978 -97 were included in the study. Four controls per case, matched by age and gender, were sampled from population files. As index of exposure to traffic exhaust we estimated the annual mean concentration of benzene outside the home using a Gaussian diffusion model. This model uses traffic density (vehicles/day) on nearby main roads, distance between roads and residence, and information on vehicle emissions and weather conditions to estimate benzene concentration. Compared to children whose homes was not exposed to road traffic emissions (<0.1 g/m 3 of benzene as estimated by the model), the risk of childhood leukemia was significantly higher (relative risk [RR] ‫؍‬ 3.91; 95% confidence interval [CI] ‫؍‬ 1.36 -11.27) for heavily exposed children (over 10 g/m 3 estimated annual average). For the intermediate exposure group (0.1-10 g/m 3 ) the relative risk was 1.51 (95% CI ‫؍‬ 0.91-2.51). These data, considered with other available evidence, suggest that motor traffic emissions can be involved in the etiology of childhood leukemia.

Air pollution is emerging as a risk factor for human health like cancer and other health outcomes in developing countries, especially Iran where air pollutant concentrations are elevated. Additionally, some of the crucial environmental problems are caused by air pollution. Nevertheless, the data on health effects of air pollution are limited. The main objective of this study was to assess the health impacts attributed to particulate matter less than 10 μg/m (PM), nitrogen dioxide (NO), and ozone (O) in Kermanshah City (Iran). The diurnal averages of PM and NO levels and 1-h averages of O concentrations were applied to assess the cardiovascular mortality due to exposure to these pollutants during the years 2014 and 2015. The excess number of cardiovascular mortality was estimated by relative risk (RR) and baseline incidence (BI) defined by the World Health Organization (WHO). The excess in mortality risk for cardiovascular diseases is of 188 premature deaths related to PM, 33 related to NO, and 83 related to O, respectively. The results indicate that a 10-μg/m change in PM, NO, and O generates a relative risk of 1.066, 1.012, and 1.020, respectively. The excess of relative risk is of 6.6, 1.2, and 2.0%, respectively. Immediate policies and actions are needed to reduce the various sources of these pollutants from transport and energy manufacture facilities in Kermanshah.

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