Biomarkers for exposure to ambient air pollution--comparison of carcinogen-DNA adduct levels with other exposure markers and markers for oxidative stress.
Human exposure to genotoxic compounds present in ambient air has been studied using selected biomarkers in nonsmoking Danish bus drivers and postal workers. A large interindividual variation in biomarker levels was observed. Significantly higher levels of bulky carcinogen-DNA adducts (75.42 adducts/10(8) nucleotides) and of 2-amino-apidic semialdehyde (AAS) in plasma proteins (56.7 pmol/mg protein) were observed in bus drivers working in the central part of Copenhagen, Denmark. In contrast, significantly higher levels of AAS in hemoglobin (55.8 pmol/mg protein), malondialdehyde in plasma (0. 96 nmol/ml plasma), and polycyclic aromatic hydrocarbon (PAH)-albumin adduct (3.38 fmol/ microg albumin) were observed in the suburban group. The biomarker levels in postal workers were similar to the levels in suburban bus drivers. In the combined group of bus drivers and postal workers, negative correlations were observed between bulky carcinogen-DNA adduct and PAH-albumin levels (p = 0.005), and between DNA adduct and [gamma]-glutamyl semialdehyde (GGS) in hemoglobin (p = 0.11). Highly significant correlations were found between PAH-albumin adducts and AAS in plasma (p = 0.001) and GGS in hemoglobin (p = 0.001). Significant correlations were also observed between urinary 8-oxo-7, 8-dihydro-2'-deoxyguanosine and AAS in plasma (p = 0.001) and PAH-albumin adducts (p = 0.002). The influence of the glutatione S-transferase (GST) M1 deletion on the correlation between the biomarkers was studied in the combined group. A significant negative correlation was only observed between bulky carcinogen-DNA adducts and PAH-albumin adducts (p = 0.02) and between DNA adduct and urinary mutagenic activity (p = 0.02) in the GSTM1 null group, but not in the workers who were homozygotes or heterozygotes for GSTM1. Our results indicate that some of the selected biomarkers can be used to distinguish between high and low exposure to environmental genotoxins. (+info)
Nitrogen management and the future of food: lessons from the management of energy and carbon.
The food system dominates anthropogenic disruption of the nitrogen cycle by generating excess fixed nitrogen. Excess fixed nitrogen, in various guises, augments the greenhouse effect, diminishes stratospheric ozone, promotes smog, contaminates drinking water, acidifies rain, eutrophies bays and estuaries, and stresses ecosystems. Yet, to date, regulatory efforts to limit these disruptions largely ignore the food system. There are many parallels between food and energy. Food is to nitrogen as energy is to carbon. Nitrogen fertilizer is analogous to fossil fuel. Organic agriculture and agricultural biotechnology play roles analogous to renewable energy and nuclear power in political discourse. Nutrition research resembles energy end-use analysis. Meat is the electricity of food. As the agriculture and food system evolves to contain its impacts on the nitrogen cycle, several lessons can be extracted from energy and carbon: (i) set the goal of ecosystem stabilization; (ii) search the entire production and consumption system (grain, livestock, food distribution, and diet) for opportunities to improve efficiency; (iii) implement cap-and-trade systems for fixed nitrogen; (iv) expand research at the intersection of agriculture and ecology, and (v) focus on the food choices of the prosperous. There are important nitrogen-carbon links. The global increase in fixed nitrogen may be fertilizing the Earth, transferring significant amounts of carbon from the atmosphere to the biosphere, and mitigating global warming. A modern biofuels industry someday may produce biofuels from crop residues or dedicated energy crops, reducing the rate of fossil fuel use, while losses of nitrogen and other nutrients are minimized. (+info)
Domestic biomass fuel combustion and chronic bronchitis in two rural Bolivian villages.
BACKGROUND: Chronic bronchitis is an important public health problem worldwide. A study was undertaken to examine the association between exposure to air pollution from domestic biomass fuel combustion and chronic bronchitis in two rural Bolivian highland villages: a village in which cooking is done exclusively indoors and a village in which cooking is done primarily outdoors. Apart from this difference, the villages were virtually identical in terms of socioeconomic status, climate, altitude, access to health care, and other potential confounders. METHODS: Pollution exposure was assessed by combining information on concentrations of particulate matter of <10 microm diameter (PM(10)) in 12 randomly selected households in each village in all potential microenvironments of exposure with time allocation information. The prevalence of chronic bronchitis was assessed using the British Medical Research Council's questionnaire on individuals >20 years of age in both villages (n = 241). RESULTS: Daily pollution exposure was significantly higher in the indoor cooking village (range for adults: 9840-15 120 microg-h/m(3)) than in the outdoor cooking village (range for adults: 5520-6240 microg-h/m(3)) for both seasons and for men and women. The overall prevalence of chronic bronchitis was 22% and 13% for the indoor and outdoor cooking villages, respectively. Logistic regression analysis, which excluded the few smokers present in the population, showed a 60% reduced risk of chronic bronchitis in the outdoor cooking village compared with the indoor cooking village (OR 0.4; 95% CI 0.2 to 0.8; p = 0.0102) after adjusting for age and sex. Individuals aged >40 years were 4.3 times more likely to have chronic bronchitis than the younger age group (OR = 4.3; 95% CI 2.0 to 9.3; p = 0.0002). There was no significant difference in the prevalence of chronic bronchitis in men and women. CONCLUSIONS: The results of this study suggest an association between chronic bronchitis and exposure to domestic biomass fuel combustion, but further large scale studies from other areas of the developing world are needed to confirm the association. Results from this and other studies will assist the development of culturally acceptable and feasible alternatives to the high exposure cooking stoves currently being used by most people worldwide. (+info)
Respiratory symptoms in older people and use of domestic gas appliances.
BACKGROUND: Studies in children and young women have indicated an increased risk of respiratory illness in association with the use of domestic gas appliances, possibly caused by oxides of nitrogen generated when gas is burned. It is not known whether risks are similarly increased in older subjects. METHODS: A questionnaire about respiratory symptoms in the past year and potential risk factors for respiratory disease was mailed to 6000 men and women aged 65 years and older who were selected at random from the lists of general practices in North Bristol, UK. Associations between symptoms and the use of gas appliances were examined by logistic regression with adjustment for age, sex, social class, and smoking habits. RESULTS: Questionnaires were completed by 4792 (80%) of those mailed. The most common symptoms were exercise induced breathlessness, wheeze, or chest tightness (51%); wheeze (27%); morning phlegm (20%); and daytime breathlessness at rest (19%). In an analysis that included all subjects only weak associations were found with use of gas appliances, odds ratios all being 1.2 or less. The risks associated with use of a gas hob tended to be higher in women, with odds ratios of 1.36 (95% CI 1.01 to 1.83) for wheeze and 1.33 (95% CI 0.56 to 3.17) for morning chest tightness, but were lower than had been reported previously in younger women. CONCLUSION: The absence of stronger associations cannot readily be explained by bias or confounding. Gas cookers and fires are unlikely to be an important cause of respiratory illness in the elderly. If they do cause such illness, the largest risks are likely to be in women who use gas hobs. (+info)
The effect of gas cooking on bronchial hyperresponsiveness and the role of immunoglobulin E.
Some studies have shown an association between gas cooking and respiratory symptoms. This study investigated whether gas cooking affects bronchial responsiveness and whether particular subjects are more sensitive to this effect. Multiple linear regression analysis was performed with the dose-response slope (Percentage fall in forced expiratory volume in one second (FEV1) divided by total dose of methacholine given) as the dependent variable in 1,921 subjects from a random sample of the Dutch population, aged 20-70 yrs. Whether the association was different according to sex, age, total immunoglobulin (Ig)E, specific IgE to inhalant allergens or smoking habits was tested by including interaction terms into the regression model. Subjects who used gas for cooking had a higher prevalence of bronchial hyperresponsiveness (provocative dose causing a 20% fall in FEV1 (PD20) < or = 2 mg) than those who used electricity (21% versus 14%) and this was dependent on the presence of atopy. Especially subjects with total IgE levels in the highest quartile had a significantly higher dose-response slope when using gas for cooking. This was independent of the presence of specific IgE to inhalant allergens. These results show increased bronchial responsiveness with gas cooking, which was only found in subjects with high total immunoglobulin E levels. This suggests that atopic subjects are sensitive to adverse effects of gas cooking on respiratory health. (+info)
Neonatal tetanus associated with topical umbilical ghee: covert role of cow dung.
BACKGROUND: Previous studies in Pakistan have shown that ghee (clarified butter) is commonly applied to umbilical wounds of neonates, and have documented that such applications are a risk factor for neonatal tetanus (NNT). In-use contamination of ghee with Clostridium tetani has been demonstrated, but mechanisms underlying the risk of ghee have been incompletely evaluated epidemiologically. METHODS: Detailed information on ghee usage, including fuels used to heat it, was obtained from cases of NNT (n = 229) and their matched controls (n = 687) from a population-based study of NNT in Punjab Province, Pakistan. Design variables were created to evaluate the impact of different fuel sources on risk of ghee applications. RESULTS: Nearly one-third of all infants had ghee applied, and it was nearly always heated before application to umbilical wounds of newborns. After controlling for all factors found to be significantly associated with NNT in conditional logistic regression, only ghee that had always been heated with dried cow dung fuel was significantly associated with NNT. Topical antimicrobials and ghee were never applied together. CONCLUSIONS: Ghee applications to umbilical wounds, when heated with 'clean' fuels, appear to pose no increased risk of NNT, although handling practices undoubtedly result in hazardous microbial contamination. In contrast, ghee heated with dung fuel was significantly associated with NNT. The effective promotion of topical antimicrobials might help reduce ghee use, since the intended purpose of each is to enhance healing. (+info)
Occupational risk factors for lung cancer in the French electricity and gas industry: a case-control survey nested in a cohort of active employees.
The main aim of this study was the analysis of occupational lung cancer risk factors in the French national electricity and gas company (Electricite de France-Gaz de France (EDF-GDF)). A case-control survey nested in a cohort of male employees was undertaken. The study population consisted of all male staff who were active at EDF-GDF between January 1, 1978, and December 31, 1989. During this period, 310 cases of lung cancer were identified in the cancer register set up by the medical department of the company. For each case, four age-matched controls who were free of cancer at the time of occurrence of the case's lung cancer were randomly selected. Occupational exposures to 21 chemical agents were assessed for each subject using a job exposure matrix. The associations between lung cancer and the different agents were estimated using conditional logistic regression analysis. After adjustment for various occupational confounding factors, the analysis showed increased lung cancer risks linked to exposure to crystalline silica (highest exposure class: odds ratio = 2.27; 95% confidence interval: 1.10, 4.68) and creosotes (highest exposure level: odds ratio = 2.14; 95% confidence interval: 1.06, 4.31), with significant dose-response relationships for both exposures. (+info)
Global warming in the twenty-first century: an alternative scenario.
A common view is that the current global warming rate will continue or accelerate. But we argue that rapid warming in recent decades has been driven mainly by non-CO(2) greenhouse gases (GHGs), such as chlorofluorocarbons, CH(4), and N(2)O, not by the products of fossil fuel burning, CO(2) and aerosols, the positive and negative climate forcings of which are partially offsetting. The growth rate of non-CO(2) GHGs has declined in the past decade. If sources of CH(4) and O(3) precursors were reduced in the future, the change in climate forcing by non-CO(2) GHGs in the next 50 years could be near zero. Combined with a reduction of black carbon emissions and plausible success in slowing CO(2) emissions, this reduction of non-CO(2) GHGs could lead to a decline in the rate of global warming, reducing the danger of dramatic climate change. Such a focus on air pollution has practical benefits that unite the interests of developed and developing countries. However, assessment of ongoing and future climate change requires composition-specific long-term global monitoring of aerosol properties. (+info)