Volume 27, Issue 1

Radium is a naturally occurring radioactive element in the environment that can exist as several isotopes. Little information is available on the acute (short-term) non-cancer effects in humans. Radium exposure has resulted in acute leukopenia, anemia, necrosis of the jaw, and other effects. Cancer is the major effect of concern. Radium, via oral exposure, is known to cause bone, head, and nasal passage tumors in humans. The US Environmental Protection Agency has not classified radium for carcinogenicity.

The etiology of sporadic amyotrophic lateral sclerosis (ALS), the most common form of this degenerative disease of the motor neurons, is still unknown, despite extensive investigation of several genetic and environmental potential risk factors. We have reviewed laboratory and epidemiological studies assessing the role of exposure to neurotoxic chemicals (metalloid selenium; heavy metals mercury, cadmium, and lead; pesticides) in ALS etiology by summarizing the results of these investigations and examining their strengths and limitations. Despite limitations in the exposure assessment methodologies typically used in human studies, we found suggestive epidemiological evidence and biologic plausibility for an association between ALS and antecedent overexposure to environmental selenium and pesticides. The relation with mercury, cadmium, and lead appears weaker.

Throughout the world, cigarette smoking is a habit that causes serious health, economic, and social problems. Therefore, many countries have taken an active role to control and to ban smoking. The chronic smoking problem in China is particularly acute because China has the largest population of smokers in the world, over 300 million currently. If 30% of these smokers were to die of smoke-related diseases in the next 20 years, the impact from the more than 90 million premature deaths could be damaging to China. In addition, numerous non-smokers also experience health problems from exposure to environmental tobacco smoke. China’s efforts to reduce or to ban smoking in certain public places have not been well-coordinated or enforced compared with those in other countries. Therefore, success has been minimal. Consequently, leaders in China should not be complacent about combating the serious national health problem. A multiprong approach in combination with the MPOWER policy from the World Health Organization that targets different levels of acquisition of the smoking habit must be used. Examples may include the government’s reduced reliance on profits from the sale of cigarettes, the elimination of advertisements that encourage smoking among young individuals, the presentation of more graphic illustration of harmful effects from smoking on every pack of cigarettes, higher taxes/prices on cigarettes, and the implementation of enforceable bans on smoking in public places. As shown in other countries, such coordinated effort can be highly effective in the reduction of smoking and can have healthy consequences.

Background: Since the International Agency for Research on Cancer recently classified radiofrequency electromagnetic fields, such as those emanating from mobile and cordless phones, as possibly carcinogenic to humans (group 2B), two additional reports relevant to the topic have been published. Both articles were new updates of a Danish cohort on mobile phone subscribers and concern the possible association between assumed use of mobile phones and risk of brain tumors. The aim of the present review is to reexamine all four publications on this cohort. Methods: In brief, publications were scrutinized, and in particular, if the authors made explicit claims to have either proved or disproved their hypothesis, such claims were reviewed in light of applied methods and study design, and in principle, the stronger the claims, the more careful our review. Results: The nationwide Danish cohort study on mobile phone subscribers and risk of brain tumors, including at best 420,095 persons (58% of the initial cohort), is the only one of its kind. In comparison with previous investigations, i.e., case-control studies, its strength lies in the possibility to eliminate non-response, selection, and recall bias. Although at least non-response and recall bias can be excluded, the study has serious limitations related to exposure assessment. In fact, these limitations cloud the findings of the four reports to such an extent that render them uninformative at best. At worst, they may be used in a seemingly solid argument against an increased risk – as reassuring results from a large nationwide cohort study, which rules out not only non-response and recall bias but also an increased risk as indicated by tight confidence intervals. Conclusion: Although two of the most comprehensive case-control studies on the matter both have methodological limitations that need to be carefully considered, type I errors are not the only threats to the validity of studies on this topic – the Danish cohort study is a textbook example of that.

Constructed wetlands are among the recently proven efficient technologies for wastewater treatment. Compared with conventional treatment systems, constructed wetlands are low in cost, easily operated and maintained, and have a strong potential for application in developing countries, particularly by small rural communities. Nevertheless, the use of constructed wetlands for the improvement of drinking water quality (such as the purification of river water for drinking purposes) is still uncommon. Treatment technologies that use natural processes and/or passive components continue to be of interest to many segments of society for a wide variety of applications. This article summarizes information on the current methods used for water treatment using constructed wetland systems and presents several case studies.

No abstract available.