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Traditional seed pretreatment methods cause secondary pollution for the application of various chemicals. This study investigated the effect of dielectric barrier discharge (DBD) cold plasma on seedling growth. Effects of plasma-activated tap water (PATW) and plasma-activated seeds (PAS) were compared for germination rates, seedling height, dry weight, and chlorophyll content. Results show that compared with controls these growth parameters were all increased by more than 50%. The yields and contributions of hydrogen peroxide, nitrate, nitrite, and ammonium were quantified. Hydrogen peroxide and nitrate have an important role in seedling growth. By etching, the seed epidermis free radicals can reduce the apparent contact angle and increase the water absorption of the seeds. In addition to the low cost of PATW and PAS compared with commercial fertilizers, DBD does not involve any chemical addition. Thus, both PATW and PAS can be an alternative for improvement of agricultural production.

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The authors report the association between exposure to pulsed electromagnetic fields (PEMFs) and cancer in a nested case-control study of electric utility workers in Quebec, Canada (follow-up, 1970-1988), and France (follow-up, 1978-1989), among whom 2,679 cases of cancer were identified. Exposures were assessed through a job-exposure matrix based on about 1,000 person-weeks of measurements from exposure meters worn by workers. Exposures were considerably higher in Quebec than in France. No association was found between PEMFs and cancers previously suspected of association with magnetic fields (leukemia, other hematopoietic cancers, brain cancer, or melanoma). However, there was a clear association between cumulative exposure to PEMFs and lung cancer, with odds ratios rising to 3.11 (95% confidence interval (CI) 1.60-6.04) in the highest exposure group (84 cases). This association with largely confined to Quebec, where there was a monotonic exposure-response relation with an odds ratio of 6.67 (95% CI 2.68-16.57) in the highest exposure group (32 cases). The association is substantial and was not explained by smoking or other occupational exposures. However, several factors limit the strength of the evidence for a causal relation: lack of precision in what the meters measured; little previous evidence for this association; and no elevated risk for lung cancer in the utility workers overall in comparison with the general population.

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