Use of wood stoves and risk of cancers of the upper aero-digestive tract: a case-control study.
(1/1149)
BACKGROUND: Incidence rates for cancers of the upper aero-digestive tract in Southern Brazil are among the highest in the world. A case-control study was designed to identify the main risk factors for carcinomas of mouth, pharynx, and larynx in the region. We tested the hypothesis of whether use of wood stoves is associated with these cancers. METHODS: Information on known and potential risk factors was obtained from interviews with 784 cases and 1568 non-cancer controls. We estimated the effect of use of wood stove by conditional logistic regression, with adjustment for smoking, alcohol consumption and for other sociodemographic and dietary variables chosen as empirical confounders based on a change-in-estimate criterion. RESULTS: After extensive adjustment for all the empirical confounders the odds ratio (OR) for all upper aero-digestive tract cancers was 2.68 (95% confidence interval [CI] : 2.2-3.3). Increased risks were also seen in site-specific analyses for mouth (OR = 2.73; 95% CI: 1.8-4.2), pharyngeal (OR = 3.82; 95% CI: 2.0-7.4), and laryngeal carcinomas (OR = 2.34; 95% CI: 1.2-4.7). Significant risk elevations remained for each of the three anatomic sites and for all sites combined even after we purposefully biased the analyses towards the null hypothesis by adjusting the effect of wood stove use only for positive empirical confounders. CONCLUSIONS: The association of use of wood stoves with cancers of the upper aero-digestive tract is genuine and unlikely to result from insufficient control of confounding. Due to its high prevalence, use of wood stoves may be linked to as many as 30% of all cancers occurring in the region. (+info)
Health status of Persian Gulf War veterans: self-reported symptoms, environmental exposures and the effect of stress.
(2/1149)
BACKGROUND: Most US troops returned home from the Persian Gulf War (PGW) by Spring 1991 and many began reporting increased health symptoms and medical problems soon after. This investigation examines the relationships between several Gulf-service environmental exposures and health symptom reporting, and the role of traumatic psychological stress on the exposure-health symptom relationships. METHODS: Stratified, random samples of two cohorts of PGW veterans, from the New England area (n = 220) and from the New Orleans area (n = 71), were selected from larger cohorts being followed longitudinally since arrival home from the Gulf. A group of PGW-era veterans deployed to Germany (n = 50) served as a comparison group. The study protocol included questionnaires, a neuropsychological test battery, an environmental interview, and psychological diagnostic interviews. This report focuses on self-reported health symptoms and exposures of participants who completed a 52-item health symptom checklist and a checklist of environmental exposures. RESULTS: The prevalence of reported symptoms was greater in both Persian Gulf-deployed cohorts compared to the Germany cohort. Analyses of the body-system symptom scores (BSS), weighted to account for sampling design, and adjusted by age, sex, and education, indicated that Persian Gulf-deployed veterans were more likely to report neurological, pulmonary, gastrointestinal, cardiac, dermatological, musculoskeletal, psychological and neuropsychological system symptoms than Germany veterans. Using a priori hypotheses about the toxicant effects of exposure to specific toxicants, the relationships between self-reported exposures and body-system symptom groupings were examined through multiple regression analyses, controlling for war-zone exposure and post-traumatic stress disorder (PTSD). Self-reported exposures to pesticides, debris from Scuds, chemical and biological warfare (CBW) agents, and smoke from tent heaters each were significantly related to increased reporting of specific predicted BSS groupings. CONCLUSIONS: Veterans deployed to the Persian Gulf have higher self-reported prevalence of health symptoms compared to PGW veterans who were deployed only as far as Germany. Several Gulf-service environmental exposures are associated with increased health symptom reporting involving predicted body-systems, after adjusting for war-zone stressor exposures and PTSD. (+info)
Effects and interactions of opioids on plasma exudation induced by cigarette smoke in guinea pig bronchi.
(3/1149)
The effects of opioids on cigarette smoke-induced plasma exudation were investigated in vivo in the main bronchi of anesthetized guinea pigs, with Evans blue dye as a plasma marker. Acute inhalation of cigarette smoke increased plasma exudation by 216% above air control values. Morphine, 0.1-10 mg/kg but not 30 mg/kg, inhibited the exudation but had no significant effect on substance P-induced exudation. Both 10 and 30 mg/kg of morphine increased exudation in air control animals, an effect inhibited by antihistamines but not by a tachykinin neurokinin type 1-receptor antagonist. Naloxone inhibited all morphine responses. Cigarette smoke-induced plasma exudation was inhibited by a mu-opioid-receptor agonist (DAMGO) but not by agonists at delta (DPDPE)- or kappa (U-50488H)-receptors. None of these agonists affected exudation in air control animals. DPDPE prevented the inhibition by DAMGO of cigarette smoke-induced plasma exudation, and the combination of DAMGO and DPDPE increased exudation in air control animals. Prevention of inhibition and the combination-induced increase were inhibited by antihistamines or the mast cell-stabilizing drug sodium cromoglycate. U-50488H did not alter the response to either DAMGO or DPDPE. We conclude that, in guinea pig main bronchi in vivo, mu-opioid-receptor agonists inhibit cigarette smoke-induced plasma exudation via a prejunctional mechanism. Plasma exudation induced by mu- and delta-receptor interactions is due to endogenous histamine release from mast cells. (+info)
Air pollution, pollens, and daily admissions for asthma in London 1987-92.
(4/1149)
BACKGROUND: A study was undertaken to investigate the relationship between daily hospital admissions for asthma and air pollution in London in 1987-92 and the possible confounding and modifying effects of airborne pollen. METHODS: For all ages together and the age groups 0-14, 15-64 and 65+ years, Poisson regression was used to estimate the relative risk of daily asthma admissions associated with changes in ozone, sulphur dioxide, nitrogen dioxide and particles (black smoke), controlling for time trends, seasonal factors, calendar effects, influenza epidemics, temperature, humidity, and autocorrelation. Independent effects of individual pollutants and interactions with aeroallergens were explored using two pollutant models and models including pollen counts (grass, oak and birch). RESULTS: In all-year analyses ozone was significantly associated with admissions in the 15-64 age group (10 ppb eight hour ozone, 3.93% increase), nitrogen dioxide in the 0-14 and 65+ age groups (10 ppb 24 hour nitrogen dioxide, 1.25% and 2.96%, respectively), sulphur dioxide in the 0-14 age group (10 micrograms/m3 24 hour sulphur dioxide, 1.64%), and black smoke in the 65% age group (10 micrograms/m3 black smoke, 5.60%). Significant seasonal differences were observed for ozone in the 0-14 and 15-64 age groups, and in the 0-14 age group there were negative associations with ozone in the cool season. In general, cumulative lags of up to three days tended to show stronger and more significant effects than single day lags. In two-pollutant models these associations were most robust for ozone and least for nitrogen dioxide. There was no evidence that the associations with air pollutants were due to confounding by any of the pollens, and little evidence of an interaction between pollens and pollution except for synergism of sulphur dioxide and grass pollen in children (p < 0.01). CONCLUSIONS: Ozone, sulphur dioxide, nitrogen dioxide, and particles were all found to have significant associations with daily hospital admissions for asthma, but there was a lack of consistency across the age groups in the specific pollutant. These associations were not explained by confounding by airborne pollens nor was there convincing evidence that the effects of air pollutants and airborne pollens interact in causing hospital admissions for asthma. (+info)
Toxicity of combustion products from burning polymers: development and evaluation of methods.
(5/1149)
Laboratory and room-scale experiments were conducted with natural and synthetic polymers: cotton, paper, wood, wool, acetate, acrylic, nylon, and urethane. Smoke and off-gases from single materials were generated in a dual-compartment 110-liter exposure chamber. Multicomponent, composite fuel loads were burned within a 100 m(3) facility subdivided into rooms. In chamber experiments, mortality depended on the amount of material burned, i.e., fuel consumption (FC). Conventional dose (FC)/mortality curves were obtained, and the amount of fuel required to produce 50% mortality (FC(50)) was calculated. With simple flame ignition, cotton was the only material that produced smoke concentrations lethal to rats; FC(50) values for cotton ranged from 2 g to 9 g, depending on the configuration of the cotton sample burned. When supplemental conductive heat was added to flame ignition, the following FC(50) values were obtained; nylon, 7 g; acrylic, 8 g; newsprint, 9 g; cotton, 10 g; and wood, 11 g. Mortality resulting from any given material depended upon the specific conditions employed for its thermal decomposition. Toxicity of off-gasses from pyrolysis of phosphorus-containing trimethylol propane-polyurethane foams was markedly decreased by addition of a flame ignition source. Further studies are needed to determine the possible relevance of single-material laboratory scale smoke toxicity experiments. Room-scale burns were conducted to assess the relative contributions of single materials to toxicity of smoke produced by a multicomponent self-perpetuating fire. Preliminary results suggest that this approach permits a realistic evaluation of the contribution of single materials to the toxicity of smoke from residential fires. (+info)
Combined effect of cigarette smoke and mineral fibers on the gene expression of cytokine mRNA.
(6/1149)
To investigate which parameters are stimulated by mineral fibers and whether cigarette smoke enhanced a fiber-induced response, we examined the level of cytokine mRNA from alveolar macrophages (AMs) and lungs of rats exposed to mineral fibers and cigarette smoke in vivo. Male Wistar rats were given a single intratracheal instillation of 2 mg of Union Internationale Contre le Cancer chrysotile or refractory ceramic fiber (RF1). The animals then inhaled a side stream of smoke 5 days per week for 4 weeks. The expression of manganese superoxide dismutase, inducible nitric oxide synthase (iNOS), basic fibroblast growth factor (bFGF), interleukin-1[alpha] (IL-1[alpha]), interleukin-6 (IL-6), and tumor necrosis factor-[alpha] (TNF[alpha]) mRNA from lipopolysaccharide-stimulated AMs and lungs of rats exposed to mineral fibers and/or cigarette smoke were assessed using semiquantitative reverse-transcriptase polymerase chain reaction. Exposure only to cigarette smoke increased in IL-1[alpha] mRNA levels in AMs. Chrysotile stimulated the expression of IL-1[alpha], TNF[alpha], and IL-6 in AMs, and the expression of bFGF in lungs. RF1 resulted in increased expression of IL-1[alpha] and TNF[alpha] in AMs. Cigarette smoke stimulated the gene expression of iNOS in AMs and IL-6 and bFGF in lungs treated with chrysotile; IL-1[alpha] in AMs and bFGF in lungs did the same in lungs with RF1. Among these cytokines, message levels of IL-1[alpha], iNOS, and bFGF were increased in rats stimulated with mineral fibers, and the stimulating effects of mineral fibers were enhanced by cigarette smoke. Therefore, IL-1[alpha], iNOS, and bFGF would be the possible parameters of the lung remodeling induced by mineral fibers. (+info)
Early alterations of lung injury following acute smoke exposure and 21-aminosteroid treatment.
(7/1149)
In a simulated fire-related smoke exposure protocol, New Zealand white rabbits were utilized to investigate the potential effects of the 21-aminosteroid (lazaroid) analog U75412E on the early events of acute lung injury. Inhalation of a total of 1.6 mg/kg U75412E aerosolized at a rate of 1.53 mg/min at 0.5 hr after smoke exposure significantly attenuated the extent of lung injury at 1 hr, as evidenced by decreased bronchoalveolar lavage (BAL) concentration of total protein, 6-keto-prostaglandin F1-alpha, and blood gas defect. Histopathologic examination demonstrated that the lazaroid significantly attenuated smoke-induced lung injury as evidenced by a decrease in wet lung/body weight ratio, necrosis, and sloughing of airway epithelial cells. Electron microscopy showed that the lazaroid decreased smoke-induced interstitial edema and the vacuolization of alveolar type II epithelium (21.6 +/- 9.7 vs 8.5 +/- 3.6 vacuoled blebs/cell, smoke only vs smoke + lazaroid). However, U75412E did not attenuate smoke-induced changes in BAL concentration of tumor necrosis factor-alpha, total cell count, and granulocyte percentage. These observations suggest that U75412E may exert its action through cooperative mechanisms, such as the modulation of arachidonic acid metabolism, in addition to its characterized antioxidative effects. (+info)
Chemoprevention of tobacco smoke-induced lung tumors in A/J strain mice with dietary myo-inositol and dexamethasone.
(8/1149)
Male A/J strain mice were fed AIN-76A diet supplemented with myo-inositol/dexamethasone (10 g and 0.5 mg/kg diet) or acetylsalicylic acid (300 mg/kg) and exposed for 5 months to a mixture of sidestream and mainstream cigarette smoke at a concentration of 132 mg total suspended particulates/m3. After tobacco smoke exposure, they were allowed to recover for another 4 months in filtered air. In the animals fed AIN-75A diet alone or acetylsalicylic acid, the average number of tumors/lung was 2.1, whereas in the animals given the myo-inositol/dexamethasone diet, the average lung tumor multiplicity was 1.0 (P < 0.05). In animals exposed to filtered air, lung tumor multiplicities were 0.6 for animals fed AIN-76A or myo-inositol/dexamethasone and 1.2 for animals fed acetylsalicylic acid. It was concluded that the combination of myo-inositol and dexamethasone constitutes an effective chemopreventive regimen against tobacco smoke-induced lung tumorigenesis. (+info)