Band 30, Heft 2

Introduction: Polychlorinated biphenyls (PCBs) are persistent, lipophilic contaminants that are known to increase risk of a number of human diseases. Although ingestion of animal fats is a major route of exposure, there is increasing evidence that inhalation of vapor-phase PCBs is also important and may be as or even more important than ingestion under some circumstances. Methods: The evidence that inhalation of PCBs may cause cancer, heart disease, hypertension, and diabetes is reviewed and presented in this report. Results: PCBs are known human carcinogens. A husband and wife, occupationally required to ‘smell’ PCB-containing oils, both developed thyroid cancer, malignant melanoma/severely melanocytic dysplastic nevus (a precursor to malignant melanoma) and the husband, a non-smoker, developed and died of lung cancer. The serum of both had highly elevated concentrations of lower chlorinated, volatile PCB congeners. In other studies, residents living near PCB-containing hazardous waste sites, and thus breathing PCB-contaminated air, have elevated rates of hospitalization for cardiovascular disease, hypertension, diabetes and reduced cognitive performance, whereas other studies in defined populations show that there is an elevated risk of all of these diseases in individuals with elevated serum PCBs. Conclusions: These results are consistent with the conclusion that inhaled PCBs can increase risk of cancer, cardiovascular disease, hypertension, diabetes and reduce cognitive function.

Six organochlorine pesticides and pesticide metabolites in human blood were tested to determine their relationships with diabetic nephropathy. The data were derived from the National Health and Nutrition Examination Survey (NHANES) 1999–2004 (unweighted, n=2992, population estimate=133,088,752). The six chemicals were p,p ′-DDT (dichlorodiphenyltrichloroethane), p,p ′-DDE (dichlorodiphenyltrichloroethylene), beta-hexachlorocyclohexane, oxychlordane, trans -nonachlor and heptachlor epoxide. In this research, total diabetes included diagnosed and undiagnosed diabetes (glycohemoglobin, A1c ≥6.5%), and nephropathy was defined as a urinary albumin to creatinine ratio >30 mg/g, representing microalbuminuria and macroalbuminuria. The pesticide p,p ′-DDT and pesticide metabolite heptachlor epoxide were significantly associated with total diabetes with nephropathy, with odds ratios of 2.08 (95% CI 1.06–4.11) and 1.75 (95% CI 1.05–2.93), respectively. Organochlorine pesticides are thought to act through the constitutive androstane receptor/pregnane X receptor disease pathway, but this is not well established. When p,p ′-DDT and heptachlor epoxide were both elevated, the odds ratio for diabetic nephropathy was 2.76 (95% CI 1.31–5.81), and when six of six organochlorine pesticides and pesticide metabolites, were elevated, the odds ratio for diabetic nephropathy was 3.00 (95% CI 1.08–8.36). The differences in the odds ratios for these groups appear to be due to differences in the mean heptachlor epoxide concentration of each category. Organochlorine pesticides and pesticide metabolites are known to have estrogenic, antiestrogenic or antiandrogenic activity. The constitutive androstane receptor/pregnane X receptor pathway is thought to interact with the aryl hydrocarbon receptor pathway, and the associations noted may be due to that interaction.

This review considers a paradigm shift on microwave electromagnetic field (EMF) action from only thermal effects to action via voltage-gated calcium channel (VGCC) activation. Microwave/lower frequency EMFs were shown in two dozen studies to act via VGCC activation because all effects studied were blocked by calcium channel blockers. This mode of action was further supported by hundreds of studies showing microwave changes in calcium fluxes and intracellular calcium [Ca2+]i signaling. The biophysical properties of VGCCs/similar channels make them particularly sensitive to low intensity, non-thermal EMF exposures. Non-thermal studies have shown that in most cases pulsed fields are more active than are non-pulsed fields and that exposures within certain intensity windows have much large biological effects than do either lower or higher intensity exposures; these are both consistent with a VGCC role but inconsistent with only a heating/thermal role. Downstream effects of VGCC activation include calcium signaling, elevated nitric oxide (NO), NO signaling, peroxynitrite, free radical formation, and oxidative stress. Downstream effects explain repeatedly reported biological responses to non-thermal exposures: oxidative stress; single and double strand breaks in cellular DNA; cancer; male and female infertility; lowered melatonin/sleep disruption; cardiac changes including tachycardia, arrhythmia, and sudden cardiac death; diverse neuropsychiatric effects including depression; and therapeutic effects. Non-VGCC non-thermal mechanisms may occur, but none have been shown to have effects in mammals. Biologically relevant safety standards can be developed through studies of cell lines/cell cultures with high levels of different VGCCs, measuring their responses to different EMF exposures. The 2014 Canadian Report by a panel of experts only recognizes thermal effects regarding safety standards for non-ionizing radiation exposures. Its position is therefore contradicted by each of the observations above. The Report is assessed here in several ways including through Karl Popper’s assessment of strength of evidence. Popper argues that the strongest type of evidence is evidence that falsifies a theory; second strongest is a test of “risky prediction”; the weakest confirms a prediction that the theory could be correct but in no way rules out alternative theories. All of the evidence supporting the Report’s conclusion that only thermal effects need be considered are of the weakest type, confirming prediction but not ruling out alternatives. In contrast, there are thousands of studies apparently falsifying their position. The Report argues that there are no biophysically viable mechanisms for non-thermal effects (shown to be false, see above). It claims that there are many “inconsistencies” in the literature causing them to throw out large numbers of studies; however, the one area where it apparently documents this claim, that of genotoxicity, shows no inconsistencies; rather it shows that various cell types, fields and end points produce different responses, as should be expected. The Report claims that cataract formation is produced by thermal effects but ignores studies falsifying this claim and also studies showing [Ca2+]i and VGCC roles. It is time for a paradigm shift away from only thermal effects toward VGCC activation and consequent downstream effects.

This paper reviews and reflects on the cholera outbreak that rocked Harare, Zimbabwe, in 2008/2009. We give special attention to the root causes, impacts and debates made by key stakeholders, indicating the political and geographical responses. Based on a desktop study and documentary review, the paper highlights the inadequacy of safe and clean water in most of the suburbs, the collapse of the waste management, water supply and sanitation systems of the city as the major explanations for the scourge. Despite this, Harare remains troubled with the shortage of purification chemicals, making it quite impossible to supply clean and adequate water. The national economic crisis also had a strong bearing against the performance of the public health sector. The paper concludes that sustainable urban health initiatives involving both central and local government will provide a long-term solution to the problems highlighted.

Banana-based weaning food mixes were developed from the Nendran variety to study the nutritional quality of the mixes and feasibility of marketing on a commercial scale. Chemical composition viz., moisture, acid, pH, reducing and total sugars, protein and β-carotene of the developed banana-based weaning mixes were analysed. The trypsin inhibitor activity reduced during cooking, and the flatus compound could not be measured due to its very meagre gas production. The α-amylase activity and in vitro protein and carbohydrate digestibilities were also analysed. A feeding trial of the developed mixes was conducted in infants as a supplement to study the nutritional quality of the developed banana-based weaning food mixes. Results showed an increase in all the anthropometric measurements during the feeding period, and the developed mixes can be prepared on a commercial scale to prevent malnutrition and undernutrition during the rapid growing period of infants.