Case-control study of bladder cancer and chlorination by-products in treated water (Ontario, Canada)

Chlorine is by far the most commonly used chemical for the disinfection of water supplies in North America. However, chlorine reacts with organic material in the raw water producing a number of halogenated hydrocarbon by-products. This population-based case-control study in Ontario, Canada examined the relationship between bladder cancer and exposure to chlorination by-products in public water supplies. Residence and water source histories and data from municipal water supplies were used to estimate individual exposure according to water source, chlorination status, and by-product levels (represented by trihalomethane [THM] concentration). Exposures were estimated for the 40-year period prior to the interview, using 696 cases diagnosed with bladder cancer between 1 September 1992 and 1 May 1994 and 1,545 controls with at least 30 years of exposure information. Odds ratios (OR) adjusted for potential confounders were used to estimate relative risk. Those exposed to chlorinated surface water for 35 or more years had an increased risk of bladder cancer compared with those exposed for less than 10 years (OR=1.41, 95 percent confidence interval [CI]=1.10–1.81). Those exposed to an estimated THM level50 g/liter for 35 or more years had 1.63 times the risk of those exposed for less than 10 years (CI=1.08–2.46). These results indicate that the risk of bladder cancer increases with both duration and concentration of exposure to chlorination by-products, with population attributable risks of about 14 to 16 percent. Chlorination by-products represent a potentially important risk factor for bladder cancer.Dr King is with the Department of Community Health and Epidemiology, Queen's University, Kingston, Ontario, Canada. Dr Marrett is with the Ontario Cancer Treatment and Research Foundation and the Department of Preventive Medicine and Biostatistics, University of Toronto Canada. Address correspondence to Dr King, Department of Community Health and Epidemiology, Queen's University, Kingston, Ont., Canada, K7L 3N6. This research was funded by Health Canada and also was supported by the National Health Research and Development Program through a fellowship to W.D.K.     

First-aid reports of acute chlorine gassing among pulpmill workers as predictors of lung health consequences

Workers in pulpmills can be exposed to a multitude of gases hazardous to respiratory function, the most common of which is chlorine gas. First-aid reports of acute gas overexposure incidents ("gassings") over an 8 year period were used to generate exposure data on a group of pulpmill workers whose respiratory function had been studied cross-sectionally in 1981 and 1988. Three hundred forty-eight incidents representing 174 workers were identified, 78% of these being treated solely by the first-aid attendant with the administration of O2 and cough suppression medication. Among 316 workers tested during a 1988 respiratory health survey, 78 had at least one chlorine or chlorine dioxide "gassing" incident. There was a significant decrease in the FEV1/FVC ratio (p less than .05) as well as increased risk for workplace associated chest symptoms in this group with at least one "gassing" incident. In an age- and smoking-matched analysis, among workers tested both in 1981 and 1988, there was a greater decline in FEV2/FVC ratio and MMF (p less than .05) in the "gassed" group than in the nonexposed group over the 7 year period of observation. These results emphasize the need for worker protection against accidental chlorine gas exposures.     

In situ demonstration of T cell subsets in atrophic parapsoriasis

It has been demonstrated recently in mycosis fungoides and lichen planus that T lymphocyte subsets may be identified in cutaneous lymphocytic infiltrates using the immunoperoxidase technic in conjunction with monoclonal antibodies produced by the technic of Kohler and Milstein. This communication describes the application of this technic to cutaneous lymphoid infiltrates of parapsoriasis in which T cell predominance has been demonstrated previously. The lymphoid infiltrates of six patients with atrophic parapsoriasis were examined by the indirect immunoperoxidase technic using monoclonal antibodies (from two commercial sources) directed against "helper" and "suppressor" T cell subsets. Both "helper" and "suppressor" cells (as defined by a positive reaction with monoclonal antibodies) could be identified in cutaneous infiltrates. "Helper" cells predominated, but in varying degrees among patients. The relevance of these findings in relation to the possible development of clinical mycosis fungoides from atrophic parapsoriasis is discussed. In addition, factors causing difficulty in the consistent identification of cell subtypes are discussed. These factors suggest that in the present state of imperfection, difficulty will be experienced in using this technic for the accurate quantification of percentages of lymphocyte subsets in tissue sections.U     

万福金安消毒剂对医院器械的消毒效果

目的观察万福金安消毒剂对医院不同科室器械的消毒效果。方法采用定量和定性杀菌试验方法。结果1500mg/L、2000mg/L有效氯溶液浸泡器械连续使用至第10天,对器械头上的枯草杆菌黑色变种芽胞杀灭率达到100%所作用的时间分别为40min和30min。口腔科、外科换药室、手术室连续使用含有效氯1500mg/L、2000mg/L的溶液浸泡器械,经定性培养有菌生长的时间分别是第6、8、10天和第10、10、14天。结论应用有效氯1500～2000mg/L万福金安溶液浸泡器械消毒时,对Ⅱ、Ⅲ类环境类别的科室使用时限分别为8～12d和4～8d。     

含氯复方消毒剂杀灭微生物效果的试验观察

目的:了解含氯复方消毒剂杀菌效果、稳定性及腐蚀性。方法:应用载体定量杀菌试验与金属腐蚀性试验。结果:以含有效氯2000mg/L的该消毒剂对布片上枯草杆菌黑色变种芽孢作用20min,含有效30mg/L的该溶液对布片上金黄色葡萄球菌和大肠杆菌作用10min和3min,含有效氯20mg/L的该溶液对白色念珠菌作用10min,杀灭率均为100%。含有效氯1500mg/L的该消毒剂溶液对不锈钢片上乙型肝炎表面抗原作用30min,可将其抗原性破坏。含有效氯2000ml/L的消毒剂溶液对不锈钢无腐蚀,对铝、铜有轻度腐蚀,对碳钢有中度腐蚀。结论:含氯复方消毒剂具有高效杀菌作用,对金属有腐蚀性。     

生命探测仪电池容量检测电路的设计

介绍了基于bq2050电池容量检测电路的设计，实测结果表明此电池容量检测电路设计合理，实用有效，且精度高、体积小、功耗低，适合生命探测仪使用。     

A dynamic system for delivering controlled bromine and chlorine vapor exposures to weanling swine skin

Context: Assessing the hazards of accidental exposure to toxic industrial chemical (TIC) vapors and evaluating therapeutic compounds or treatment regimens require the development of appropriate animal models.

Objective: The objective of this project was to develop an exposure system for delivering controlled vapor concentrations of TICs to the skin of anesthetized weanling pigs. Injury levels targeted for study were superficial dermal (SD) and deep dermal (DD) skin lesions as defined histopathologically.

Materials and methods: The exposure system was capable of simultaneously delivering chlorine or bromine vapor to four, 3-cm diameter exposure cups placed over skin between the axillary and inguinal areas of the ventral abdomen. Vapor concentrations were generated by mixing saturated bromine or chlorine vapor with either dried dilution air or nitrogen.

Results: Bromine exposure concentrations ranged from 6.5?×?10^?4 to 1.03?g/L, and exposure durations ranged from 1 to 45?min. A 7-min skin exposure to bromine vapors at 0.59?g/L was sufficient to produce SD injuries, while a 17-min exposure produced a DD injury. Chlorine exposure concentrations ranged from 1.0 to 2.9?g/L (saturated vapor concentration) for exposures ranging from 3 to 90?min. Saturated chlorine vapor challenges for up to 30?min did not induce significant dermal injuries, whereas saturated chlorine vapor with wetted material on the skin surface for 30–60?min induced SD injuries. DD chlorine injuries could not be induced with this system.

Conclusion: The vapor exposure system described in this study provides a means for safely regulating, quantifying and delivering TIC vapors to the skin of weanling swine as a model to evaluate therapeutic treatments.     

Mutations Linked to Exercise Intolerance

Abstract

Asthma is common in many types of athletes, but its prevalence appears to be particularly high in swimmers. Long-term and acute exposure to swimming pool disinfectants has been shown to increase asthma risk in swimmers through inducing oxidative stress, which results in inflammation of the pulmonary epithelium and subsequent airway remodeling. Individuals with specific genotypes are more likely to develop asthma when exposed to inhaled irritants. Therefore, it is important for physicians to be knowledgeable about the risks associated with asthma in swimmers, as well as the diagnostic techniques and practices to reduce asthma symptoms.     

The impact of antiviral therapy for HCV on kidney disease: a systematic review and meta-analysis

BackgroundControversy persists about the role of hepatitis C as a risk factor for developing kidney disease in the general population. Some authors have evaluated the effect of antiviral therapy for HCV on the risk of kidney disease.Study Aims and DesignA systematic review of the published medical literature was performed to assess whether antiviral therapy for HCV has an independent impact on kidney survival in the adult general population. A random effects model was used to generate an overall estimate of the risk of kidney disease after anti-HCV therapy across the published studies. Meta-regression and stratified analysis were also carried out.ResultsFifteen studies were eligible (n = 356, 285 patients) and separate meta-analyses were conducted according to the outcome. Pooling studies based on viral responses (n = 7; 34,763 individual patients) demonstrated a relationship between sustained viral response and lower frequency of kidney disease; the overall estimate for adjusted risk of kidney disease was 2.50 (95% CI, 1.41; 4.41) (p = 0.0016) and between-study heterogeneity was found (p-value by Q test = 0.004). Aggregation of studies comparing treated vs untreated cohorts (n = 8, n = 333,312 patients) revealed an association between anti-HCV therapy and lower risk of kidney disease. The overall estimate for adjusted risk of kidney disease across the eight studies was 0.39 (95% CI, 0.25; 0.612) (p = 0.0001). Meta-regression showed that the effectiveness of antiviral therapy in reducing the frequency of kidney disease diminishes as cirrhosis (p = 0.02) and HBV infection (p = 0.0001) increase among HCV-infected individuals.ConclusionsAntiviral therapy for HCV lowers the risk of kidney disease among HCV-infected individuals. Studies to understand the mechanisms underlying this association are ongoing.