Chlorination of drinking water in Spain and bladder cancer

Objectives: Drinking water chlorination generates trihalomethanes and other by-products with mutagenic and carcinogenic properties in animal experiments. Epidemiological studies have associated trihalomethanes to an increased risk of bladder cancer. We evaluate trihalomethane levels in four Spanish areas and calculate the bladder cancer risk attributable to this exposure.Methods: Trihalomethanes have been analysed in 111 drinking water samples from four Spanish areas using gas chromatography. Water utilities were contacted and information on drinking water consumption in Spain has been collected. We reviewed the epidemiological studies that assess the association between bladder cancer risk and exposure to chlorination by-products. Attributable risk was calculated on the basis of these levels, mortality data per area and risk estimates obtained from the literature.Results: Mediterranean areas present the highest levels of trihalomethanes with 81, 80, 61 and 52 μg/l in Sabadell, Alicante, Barcelona and Manresa respectively. Lower levels are found in Tenerife and Asturias with 7 and 20 μg/l respectively. The bladder cancer attributable risk in high trihalomethane exposure areas may be, on average, around 20%.Conclusions: The trihalomethane levels found are high compared to those of other European Union countries. In the high exposure areas, drinking water chlorination may generate a considerable number of bladder cancer cases. These estimations have to be carefully interpreted and verified with more extensive studies.     

Within-day drinking water consumption patterns: results from a drinking water consumption survey

Data currently available on drinking water intakes do not support dietary exposure estimates for contaminants that have acute effects lasting less than 24 h. Realistic exposure estimates for these types of contaminants in drinking water require detailed information on amounts and time of consumption for each drinking occasion during a day. A nationwide water consumption survey was conducted to address how often, when, and how much water is consumed at specific times during the day. The survey was conducted in two waves, to represent two seasons, and the survey instrument consisted of 7-day water consumption diaries. Data on total daily amounts consumed, number of drinking occasions per day, amounts consumed per drinking occasion, and intervals between drinking occasions show larger between-subjects variation than within-subject variation. Statistically significant associations were also observed between drinking water consumption patterns and participants' ages and sex and geographical regions in which these participants live. The number of drinking occasions on a given day varied from 0 to 19, with the majority of respondents reporting 6 or less drinking occasions per day. The average interval between drinking occasions varied from 1 to 17 h, with 57% of the person-days reporting average intervals at least 3 h apart. The mean amount consumed per drinking occasion showed little association with the number of drinking occasions and fluctuated between 8 and 10 oz. To our knowledge, this survey is the only source of information on within-day patterns (i.e., when and how much) of drinking water consumption for a nationally representative sample of the US population. The detailed water consumption data from this survey can be used to support less than 24-h dietary exposure estimates for contaminants in drinking water.     

Chlorinated drinking water and bladder cancer: effect of misclassification on risk estimates

Data are presented from the Iowa portion of the National Bladder Cancer Case-Control Study demonstrating the effect of misclassification on depressing odds ratio estimates for years of exposure to chlorinated drinking water and bladder cancer. Four methods (METHODS 1 through 4) of quantifying chlorination exposure with sequentially decreasing degrees of misclassification are presented for the 268 bladder cancer cases and 658 population-based controls fulfilling criteria for inclusion in this study. Twenty-eight other risk factors for bladder cancer were considered along with chlorinated drinking water exposure estimated by METHOD 4. Stepwise regression models included as significant factors cigarette smoking (p less than .001), chlorination exposure (p = .038), and irradiation to the pelvic area (p = .040). Replacement of chlorinated drinking water exposure estimated by METHOD 4 with any of the remaining three methods resulted in models that included cigarette smoking and irradiation to the pelvic area, but not chlorination exposure. Thus, misclassification of chlorination exposure signified the difference between observing and not observing an association with bladder cancer.     

Alcohol drinking and bladder cancer

The relation between alcoholic beverage consumption and bladder cancer risk was investigated using data from a case-control study conducted between 1985 and 1992 in two areas of northern Italy. Cases were 727 patients with incident, histologically confirmed bladder cancer, and controls 1,067 patients admitted to the same network of hospitals for acute, non-neoplastic, nonurologic, or genital tract diseases. Compared to nondrinkers, the odds ratio (OR) was 0.79 (95% confidence interval, CI, 0.58-1.08) for drinkers, and 0.84 (95%CI, 0.58-1.22) for > or =6 drinks/day. The OR was 0.86 (95%CI, 0.60-1.23) for > or =5 wine drinks/day, 0.69 for beer, and 0.85 for spirits. No trend was observed with duration (OR =1.00 for > or =40 years). ORs were consistent across various strata of covariates including age, sex, and smoking habits. Our study, based on a population with high alcohol (mainly wine) intake, found no association between bladder cancer risk and alcohol intake, even at high levels of consumption.     

饮用水氯化消毒副产物与出生缺陷

饮用水氯化消毒处理过程中可形成多种类型的消毒副产物(DBPs)．包括三卤甲烷、卤代乙酸、卤代乙腈、卤代酮及氯代呋喃酮等。一系列研究显示DBPs与神经管缺陷、先天性心脏病、泌尿系统畸形、头面部缺陷等有相关性。但是．以往的一些研究无法正确估计暴露水平及各种DBPs之间或与饮水中其他物质之间的联合作用。因此．有必要通过正确的暴露估计和流行病学研究及合理的毒理学试验．深入探索氯化消毒副产物对出生缺陷的影响。     

Bladder cancer in Massachusetts related to chlorinated and chloraminated drinking water: a case-control study

Consumers of chlorinated drinking water have a small excess of bladder cancer. Risk may have been underestimated because of confounding and misclassification of exposure status. To address these problems, we undertook a case-control study. Detailed residential histories were obtained by telephone interviews with informants of 614 individuals who died of primarily bladder cancer and 1,074 individuals who died of other causes. Their surface water has been disinfected with chlorine or a combination of chlorine and ammonia (cloramine) since 1938. The mortality ratio for bladder cancer among individuals who resided only in communities supplied with drinking water disinfected with chlorine, relative to individuals who resided only in communities supplied with drinking water disinfected with chloramine, was 1.6 (95% confidence interval = 1.2-2.1), using all controls; when the comparison group was restricted to individuals who died of lymphoma, the mortality odds ratio was 2.7 (95% confidence interval = 1.7-4.3).     

Estimation of potential lifetime cancer risks for trihalomethanes from consuming chlorinated drinking water in Taiwan

Data on concentrations of trihalomethanes (THMs) in raw and chlorinated water collected from three water treatment plants in Taiwan and estimates of the lifetime cancer risk for THMs from drinking water, using age-adjusted factors and volatilization terms, are presented. Data on THM levels in drinking water were obtained from the annual reports of the Environmental Protection Administration (EPA) of Taiwan. The methodology for estimation of lifetime cancer risks was taken from the USEPA. Chloroform was the major species of THMs, especially in the water plant of south Taiwan. Chloroform contributed the majority of the lifetime cancer risks (range: 87.5-92.5%) of total risks from the three water supply areas. All lifetime cancer risks for CHCl(3), CHBrCl(2), CHBr2Cl, and CHBr3 from consuming tap water in the three water supply areas were higher than 10(-6). The sum of lifetime cancer risks for CHCl(3), CHBrCl(3), CHBr2Cl, and CHBr3 was highest (total risk for total THMs<1.94x10(-4)) for tap water from south Taiwan.     

Milk consumption and bladder cancer risk: a meta-analysis of published epidemiological studies

Studies investigating the association of milk consumption with bladder cancer risk have reported inconsistent findings. We conducted a meta-analysis of published cohort and case-control studies to pool the risk estimates of the association between milk intake and bladder cancer. We quantified associations with bladder cancer using meta-analysis of odds ratio (OR) associated with the highest vs. the lowest category of milk intake using fixed- or random-effect models depending on the heterogeneity of effects among studies. Nineteen cohort and case-control studies were eligible for inclusion. High milk intake was significantly associated with decreased risk of bladder cancer (OR, 0.84; 95% CI, 0.71-0.97) when comparing the highest with the lowest category of milk intake. The inverse association was stronger in Asia (OR, 0.60; 95% CI, 0.40-0.81) than North America (OR, 0.89; 95% CI, 0.76-1.03), and no association was observed in Europe (OR, 1.05; 95% CI, 0.85-1.26). This relationship also varied significantly by specific dairy products. Our results suggest that milk may be related to the reduction of bladder cancer risk. Further studies need to clarify the biological mechanisms.     

Exposure estimates to disinfection by-products of chlorinated drinking water.

Exposure to disinfection by-products (DBPs) of drinking water is multiroute and occurs in households serviced by municipal water treatment facilities that disinfect the water as a necessary step to halt the spread of waterborne infectious diseases. Biomarkers of the two most abundant groups of DBPs of chlorination, exhaled breath levels of trihalomethanes (THMs) and urinary levels of two haloacetic acids, were compared to exposure estimates calculated from in-home tap water concentrations and responses to a questionnaire related to water usage. Background THM breath concentrations were uniformly low. Strong relationships were identified between the THM breath concentrations collected after a shower and both the THM water concentration and the THM exposure from a shower, after adjusting for the postshower delay time in collecting the breath sample. Urinary haloacetic acid excretion rates were not correlated to water concentrations. Urinary trichloroacetic acid excretion rates were correlated with ingestion exposure, and that correlation was stronger in a subset of individuals who consumed beverages primarily within their home where the concentration measurements were made. No correlation was observed between an average 48-hr exposure estimate and the urinary dichloroacetic acid excretion rate, presumably because of its short biological half-life. Valid biomarkers were identified for DBP exposures, but the time between the exposure and sample collection should be considered to account for different metabolic rates among the DBPs. Further, using water concentration as an exposure estimate can introduce misclassification of exposure for DBPs whose primary route is ingestion due to the great variability in the amount of water ingested across a population.     

Case-control study of bladder cancer and drinking water arsenic in the western United States

Numerous epidemiologic investigations have identified links between high concentrations of arsenic in drinking water and cancer, although the risks at lower exposures are largely unknown. This paper presents the results of a case-control study of arsenic ingestion and bladder cancer in seven counties in the western United States. These counties contain the largest populations historically exposed to drinking water arsenic at concentrations near 100 microg/liter. All incident cases diagnosed from 1994 to 2000 were recruited. Individual data on water sources, water consumption patterns, smoking, and other factors were collected for 181 cases and 328 controls. Overall, no increased risks were identified for arsenic intakes greater than 80 microg/day (odds ratio=0.94, 95% confidence interval: 0.56, 1.57; linear trend, p=0.48). These risks are below predictions based on high dose studies from Taiwan. When the analysis was focused on exposures 40 or more years ago, an odds ratio of 3.67 (95% confidence interval: 1.43, 9.42; linear trend, p<0.01) was identified for intakes greater than 80 microg/day (median intake, 177 microg/day) in smokers. These data provide some evidence that smokers who ingest arsenic at concentrations near 200 microg/day may be at increased risk of bladder cancer.     

Different frames,different fears: communicating about chlorinated drinking water and cancer in the Canadian media

Risk issues become complicated when scientific evidence concerning a potential environmental exposure is equivocal; particularly when many argue that the public health benefits of a policy action outweigh any potential negative health effects. Chlorinated drinking water, and chlorinated disinfection byproducts (CDBPs) that are formed during the disinfection process, represent a useful case-study for examining these complications. We conduct a media analysis of chlorinated drinking water stories in the Canadian print media from 1977 to 2000. We examine media presentations of science compared to framings by scientists, regulators, the chlorine industry, water utility representatives, and non-governmental organizations of the CDBP issue based on key informant interviews. We argue that there are two main framings of the debate, each of which are powerful in constructing risk perceptions. On the one hand, many frame the debate as a 'voluntary' risk: we choose chlorine disinfection to protect against microbial risks with a possible adverse consequence of that protection. On the other hand, others frame the issue as an 'involuntary' risk: chlorine disinfection was a 'choice' imposed by public health and water utility officials; a choice that carries a potential cancer risk, and alternative disinfection technologies are advocated. We demonstrate these different frames by examining metaphorical constructs of water, chlorine and cancer contained within them.     

饮酒与肺癌发病关联的Meta分析

目的探讨饮酒与肺癌的关系。方法全面检索相关文献,应用Meta分析方法对各研究进行数据合并与分析。结果纳入合并分析的文章共21篇,其中队列研究6篇,随访人数累计122288例,病例3053例;病例对照研究15篇,累计病例8838例,对照21591例。Meta分析饮酒与肺癌合并OR值为1.17(95%CI:0.96～1.42);男、女饮酒合并OR值分别为1.67(95%CI:0.61～4.59)和0.93(95%CI:0.51～1.68);男性饮啤酒合并OR值为1.46(95%CI:1.28～1.67);饮烈酒合并OR值为1.34(95%CI:1.02～1.74);饮酒≥7次/周与肺癌呈正相关(P<0.05)。结论饮用啤酒、烈酒和经常饮酒与肺癌有统计学关联。     

合肥市水源与饮用水中挥发性卤代烃健康风险评价

目的调查合肥市水源与饮用水中挥发性卤代烃污染水平,评估对人体潜在健康风险。方法顶空气相色谱法测定合肥市A、B两水厂水源水、出厂水及管网末梢水中7种卤代烃;采用美国环保暑(USEPA)水环境健康风险评价模型,从摄入、皮肤接触和吸入3种途径进行定量评估。结果水源水检出CHCl3、CCl4和C2Cl43种卤代烃,出厂水和管网末梢水除CHBr3,其余6种均有检出,平均浓度范围分别为0.17～3.64μg/L、0.11～37.05μg/L和0.03～52.25μg/L,均未超过国家标准。致癌风险主要来自CHCl3、C2HCl3和CHBrCl2,风险值男性6.61E-07～8.21E-05,女性6.70E-10～7.69E-05。不同暴露途径致癌风险,经口摄入>吸入>皮肤接触。引起非致癌风险的化合物主要为CHCl3和C2HCl3,风险指数男性5.05E-02～7.83E-01,女性5.11E-02～7.94E-01。A、B两水厂所检挥发性卤代烃种类和浓度不同,致癌风险和非致癌风险有所差异。结论目前合肥市水源及饮用水中挥发性卤代烃致癌风险和非致癌风险均在可接受水平,不会对成人产生明显的健康危害。