Eau potable et santé publique : défis actuels et futurs

L’eau que nous consommons chaque jour est essentielle à la vie. Sa qualité a toujours été un élément indispensable à un environnement favorable à la santé. Actuellement, loin d’avoir été résolu, le problème de la qualité de l’eau de boisson est toujours une priorité de santé publique, autant dans les pays en voie de développement que dans les pays industrialisés.Ce texte présente six défis pour la santé publique dans le dossier de l’eau potable pour les années futures :Finalement, le problème de la qualité de l’eau potable doit être appréhendé dans une perspective mondiale.Drinking water is essential to human life. Drinking water quality has always been an essential component of a healthy environment. In fact, the risk of waterborne diseases, either from microbiological or chemical contamination of drinking water, is still ubiquitous in both industrialized and non-industrialized countries. Recently, several outbreaks of waterborne enteritis in North America have confirmed the presence of this risk, with some potentially dramatic consequences such as the case that occurred in Walkerton, Ontario. Vulnerable people such as infants, pregnant women, senior citizens and individuals with compromised immune systems are particularly at risk. Other factors such as travel, migration, climate change, and intensive agriculture might increase the risk of emerging diseases. The lack of basic measures of public health such as protection of sources of water, adequate water treatment, or surveillance of drinking water has also been underlined in recent epidemics. Multi-chemical contamination at very low doses by pharmaceuticals or disinfectant by-products is also an issue that public health practitioners must deal with. New technology enables us to detect chemicals that were not detectable a few years ago.With respect to all these potential threats, this paper presents six major challenges in the area of drinking water that are considered by the author as a priority for public health:In conclusion, beyond traditional methods that have to be updated (multi-barriers, quality standards and surveillance of waterborne diseases and investigation of outbreaks), the new components of the public health approach in drinking water are: the quality of the link with the community, the use of transparent and fair criteria for risk management, and a strong research agenda focussing on human health impacts. Finally, the use of a global perspective is paramount. Most drinking water issues are spread worldwide and cooperation between nations and countries is an important component of a healthy world in this twenty-first century

Drinking Water Quality and Human Health

The quality of drinking water is paramount for public health. Despite important improvements in the last decades, access to safe drinking water is not universal. The World Health Organization estimates that almost 10% of the population in the world do not have access to improved drinking water sources. Among other diseases, waterborne infections cause diarrhea, which kills nearly one million people every year, mostly children under 5 years of age. On the other hand, chemical pollution is a concern in high-income countries and an increasing problem in low- and middle-income countries. Exposure to chemicals in drinking water may lead to a range of chronic non-communicable diseases (e.g., cancer, cardiovascular disease), adverse reproductive outcomes, and effects on children’s health (e.g., neurodevelopment), among other health effects. Although drinking water quality is regulated and monitored in many countries, increasing knowledge leads to the need for reviewing standards and guidelines on a nearly permanent basis, both for regulated and newly identified contaminants. Drinking water standards are mostly based on animal toxicity data, and more robust epidemiologic studies with accurate exposure assessment are needed. The current risk assessment paradigm dealing mostly with one-by-one chemicals dismisses the potential synergisms or interactions from exposures to mixtures of contaminants, particularly at the low-exposure range. Thus, evidence is needed on exposure and health effects of mixtures of contaminants in drinking water. Finally, water stress and water quality problems are expected to increase in the coming years due to climate change and increasing water demand by population growth, and new evidence is needed to design appropriate adaptation policies.This Special Issue of International Journal of Environmental Research and Public Health (IJERPH) focuses on the current state of knowledge on the links between drinking water quality and human health

Heterogeneity in the Relationship between Disinfection By-Products in Drinking Water and Cancer: A Systematic Review.

The epidemiological evidence demonstrating the effect of disinfection by-products (DBPs) from drinking water on colon and rectal cancers is well documented. However, no systematic assessment has been conducted to assess the potential effect measure modification (EMM) in the relationship between DBPs and cancer. The objective of this paper is to conduct a systematic literature review to determine the extent to which EMM has been assessed in the relationship between DBPs in drinking water in past epidemiological studies. Selected articles (n = 19) were reviewed, and effect estimates and covariates that could have been used in an EMM assessment were gathered. Approximately half of the studies assess EMM (n = 10), but the majority of studies only estimate it relative to sex subgroups (n = 6 for bladder cancer and n = 2 both for rectal and colon cancers). Although EMM is rarely assessed, several variables that could have a potential modification effect are routinely collected in these studies, such as socioeconomic status or age. The role of environmental exposures through drinking water can play an important role and contribute to cancer disparities. We encourage a systematic use of subgroup analysis to understand which populations or territories are more vulnerable to the health impacts of DBPs

Multilevel analysis of childhood nonviral gastroenteritis associated with environmental risk factors in Quebec, 1999–2006

Childhood nonviral gastroenteritis is a priority for various public health authorities. Given that waterborne transmission is sometimes incriminated during investigation of gastroenteritis outbreaks, the authors hypothesized that watershed characteristics may influence the occurrence of this disease and could contribute additional insights for better prevention and control. The study described here aimed to investigate watershed characteristics in relation to nonviral gastroenteritis and specifically three bacterial and parasitic forms of childhood gastroenteritis to assess their relative importance in the province of Quebec, Canada. Information on children aged 0–4 years with bacterial or parasitic enteric infections reported through ongoing surveillance between 1999 and 2006 in the province of Quebec was collected. Factors measured at the municipal and watershed levels were analyzed using multilevel models with a Poisson distribution and log link function. Childhood nonviral gastroenteritis, giardiasis, and campylobacteriosis were positively associated with small ruminants and cattle density. Childhood salmonellosis was positively associated with cattle density. Also, childhood campylobacteriosis incidence was positively associated with larger watershed agricultural surface. In addition to local agroenvironmental factors, this analysis revealed an important watershed effect

The impact of drinking water, indoor dust and paint on blood lead levels of children aged 1-5 years in Montreal (Quebec, Canada)

Lead is neurotoxic at very low dose and there is a need to better characterize the impact of domestic sources of lead on the biological exposure of young children. A cross-sectional survey evaluated the contribution of drinking water, house dust and paint to blood lead levels (BLLs) of young children living in old boroughs of Montreal (Canada). Three hundred and six children aged 1 to 5 years and currently drinking tap water participated in the study. For each participant, residential lead was measured in kitchen tap water, floor dust, windowsill dust and house paint and a venous blood sample was analyzed. Multivariate logistic regression was used to evaluate the association between elevated BLL in the children (>/= 75th percentile) and indoor lead contamination by means of odds ratios (OR) using 95% confidence intervals (CI). There was an association between BLL >/=75th percentile (1.78 mug/dL) and water lead when the mean water concentration was >3.3 mug/L: adjusted OR=4.7 (95% CI: 2.1-10.2). Windowsill dust loading >14.1 mug/ft(2) was also associated with BLL >/=1.78 mug/dL: adjusted OR=3.2 (95% CI: 1.3-7.8). Despite relatively low BLLs, tap water and house dust lead contribute to an increase of BLLs in exposed young children

Workgroup Report: Drinking-Water Nitrate and Health—Recent Findings and Research Needs

Human alteration of the nitrogen cycle has resulted in steadily accumulating nitrate in our water resources. The U.S. maximum contaminant level and World Health Organization guidelines for nitrate in drinking water were promulgated to protect infants from developing methemoglobinemia, an acute condition. Some scientists have recently suggested that the regulatory limit for nitrate is overly conservative; however, they have not thoroughly considered chronic health outcomes. In August 2004, a symposium on drinking-water nitrate and health was held at the International Society for Environmental Epidemiology meeting to evaluate nitrate exposures and associated health effects in relation to the current regulatory limit. The contribution of drinking-water nitrate toward endogenous formation of N-nitroso compounds was evaluated with a focus toward identifying subpopulations with increased rates of nitrosation. Adverse health effects may be the result of a complex interaction of the amount of nitrate ingested, the concomitant ingestion of nitrosation cofactors and precursors, and specific medical conditions that increase nitrosation. Workshop participants concluded that more experimental studies are needed and that a particularly fruitful approach may be to conduct epidemiologic studies among susceptible subgroups with increased endogenous nitrosation. The few epidemiologic studies that have evaluated intake of nitrosation precursors and/or nitrosation inhibitors have observed elevated risks for colon cancer and neural tube defects associated with drinking-water nitrate concentrations below the regulatory limit. The role of drinking-water nitrate exposure as a risk factor for specific cancers, reproductive outcomes, and other chronic health effects must be studied more thoroughly before changes to the regulatory level for nitrate in drinking water can be considered

The association between farming activities, precipitation, and the risk of acute gastrointestinal illness in rural municipalities of Quebec, Canada: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Increasing livestock density and animal manure spreading, along with climate factors such as heavy rainfall, may increase the risk of acute gastrointestinal illness (AGI). In this study we evaluated the association between farming activities, precipitation and AGI.</p> <p>Methods</p> <p>A cross-sectional telephone survey of randomly selected residents (n = 7006) of 54 rural municipalities in Quebec, Canada, was conducted between April 2007 and April 2008. AGI symptoms and several risk factors were investigated using a phone questionnaire. We calculated the monthly prevalence of AGI, and used multivariate logistic regression, adjusting for several demographic and risk factors, to evaluate the associations between AGI and both intensive farming activities and cumulative weekly precipitation. Cumulative precipitation over each week, from the first to sixth week prior to the onset of AGI, was analyzed to account for both the delayed effect of precipitation on AGI, and the incubation period of causal pathogens. Cumulative precipitation was treated as a four-category variable: high (≥90^thpercentile), moderate (50^thto <90^thpercentile), low (10^thto <50^thpercentile), and very low (<10^thpercentile) precipitation.</p> <p>Results</p> <p>The overall monthly prevalence of AGI was 5.6% (95% CI 5.0%-6.1%), peaking in winter and spring, and in children 0-4 years old. Living in a territory with intensive farming was negatively associated with AGI: adjusted odds ratio (OR) = 0.70 (95% CI 0.51-0.96). Compared to low precipitation periods, high precipitation periods in the fall (September, October, November) increased the risk of AGI three weeks later (OR = 2.20; 95% CI 1.09-4.44) while very low precipitation periods in the summer (June, July, August) increased the risk of AGI four weeks later (OR = 2.19; 95% CI 1.02-4.71). Further analysis supports the role of water source on the risk of AGI.</p> <p>Conclusions</p> <p>AGI poses a significant burden in Quebec rural municipalities with a peak in winter. Intensive farming activities were found to be negatively associated with AGI. However, high and very low precipitation levels were positively associated with the occurrence of AGI, especially during summer and fall. Thus, preventive public health actions during such climate events may be warranted.</p

The assessment of population exposure to chlorination by-products: a study on the influence of the water distribution system

<p>Abstract</p> <p>Background</p> <p>The relationship between chlorination by-products (CBPs) in drinking water and human health outcomes has been investigated in many epidemiological studies. In these studies, population exposure assessment to CBPs in drinking water is generally based on available CBP data (e.g., from regulatory monitoring, sampling campaigns specific to study area). Since trihalomethanes (THMs) and haloacetic acids (HAAs) are the most documented CBP classes in drinking water, they are generally used as indicators of CBP exposure.</p> <p>Methods</p> <p>In this paper, different approaches to spatially assign available THM and HAA concentrations in drinking water for population exposure assessment purposes are investigated. Six approaches integrating different considerations for spatial variability of CBP occurrence within different distribution systems are compared. For this purpose, a robust CBP database (i.e., high number of sampling locations selected according to system characteristics) corresponding to nine distribution systems was generated.</p> <p>Results and conclusion</p> <p>The results demonstrate the high impact of the structure of the distribution system (e.g., presence of intermediary water infrastructures such as re-chlorination stations or reservoirs) and the spatial variability of CBPs in the assigned levels for exposure assessment. Recommendations for improving the exposure assessment to CBPs in epidemiological studies using available CBP data from water utilities are also presented.</p