Respiratory health and its determinants among Nunavimmiut: results from the Qanuilirpitaa? 2017 Nunavik Health Survey

OBJECTIVES

Respiratory diseases are the leading cause of hospitalization in Nunavik (northern Québec, Canada) and contribute to disparities in life expectancy with the rest of Canada. As part of Qanuilirpitaa? 2017, a cross-sectional population-based health survey, we sought to describe the prevalence of respiratory health indicators, including the first estimate of airway obstruction based on spirometry in an Inuit population, and explore their associated characteristics.

METHODS

We analyzed data from 1296 participants aged 16 years and older, using multivariate logistic regression to assess characteristics associated with spirometry-determined airway obstruction and self-reported respiratory symptoms, i.e., wheezing in the last year and chronic cough during at least 3 months.

RESULTS

In this relatively young population (83% aged 16 to 54), the prevalences of wheezing, chronic cough, and airway obstruction were, respectively, 27% (95% CI 24-30), 21% (18-23), and 17% (14-20). These estimates are prone to biases due to the relatively low participation rate (about 37%). The most consistent associations were with smoking (≥ 15 pack-years; odds ratio [OR] 3.13, 3.39, and 2.86 for the three indicators, respectively) and food security (OR 0.55 with wheezing and OR 0.26 with chronic cough), as defined in the Household Food Security Survey Module. Wheezing was also associated with allergic sensitization to dogs (2.60) and obesity (2.18). Chronic cough was associated with respiratory infections during childhood (2.12), housing in need of major repairs (1.72), and housing crowding (1.50), and was negatively associated with participation to traditional activities (0.62) and going on the land (0.64). Airway obstruction was associated with being underweight (3.84) and post-secondary education (0.40). Among young adults and women, wheezing was also associated with any inhalation of solvents for recreational purposes during their lifetime (2.62 and 1.56, respectively), while airway obstruction was associated with regular marijuana use (2.22 and 1.84, respectively).

CONCLUSION

Smoking and food insecurity are both highly prevalent and strongly associated with respiratory symptoms in Nunavik. Together with essential smoking prevention and cessation programs, our findings suggest that solving food security and housing crises, improving socioeconomic conditions, and promoting traditional lifestyle may improve respiratory health in Nunavik.

Prevalence and determinants of hypertension in the adult Inuit population of Nunavik (northern Quebec, Canada)

OBJECTIVES

To assess the prevalence of arterial hypertension among Inuit adults living in Nunavik (northern Quebec, Canada) in 2017 and identify its sociodemographic and lifestyle determinants.

METHODS

We used data obtained from 1177 Inuit adults aged ≥ 18 years who participated in the cross-sectional Qanuilirpitaa? Nunavik Inuit Health Survey during late summer-early fall of 2017. Resting blood pressure (BP) and anthropometric characteristics were measured during a clinical session, while sociodemographic characteristics and lifestyle habits were documented using validated questionnaires. Information on current medication was retrieved from medical files. Sex-stratified population-weighted log-binomial regressions were conducted to identify determinants of hypertension, adjusting for potential confounders.

RESULTS

Hypertension (systolic BP ≥ 140 mm Hg or diastolic BP ≥ 90 mmHg or taking antihypertensive medication) was present in 23% of the adult population and was more frequent in men than women (29% vs. 18%). About a third of hypertensive individuals (34%) were taking antihypertensive medication. These estimates are prone to biases due to the relatively low participation rate (37%). As expected, the prevalence of hypertension increased with age, but values were surprisingly elevated in 18 to 29-year-old men and women (18% and 8%, respectively) compared with 20 to 39-year-old adults of the general Canadian population (3% in both sexes, according to data from the Canadian Health Measures Survey, 2012-2015). Hypertension was associated with obesity and alcohol consumption in both men and women, and with higher socioeconomic status among men.

CONCLUSION

This survey revealed a high prevalence of hypertension among young Nunavimmiut adults in 2017 and the need to improve hypertension diagnosis and treatment in the region. Curbing obesity and alcohol consumption, two actionable determinants of hypertension, will require improving food security and addressing the consequences of historical trauma linked to colonization.

Impact of improved indoor air quality in Nunavik homes on children's respiratory health

Between 2007 and 2012, hospitalization rate related to respiratory system diseases in children ≤1-year-old was near 7 times higher in Nunavik compared with the whole province of Quebec. To assess the impact of poor indoor air quality (IAQ) in residential environments on children's respiratory health, the Nunavik's intervention study investigated the impact of the optimization of ventilation systems on the incidence rates of respiratory infections in children in Nunavik. Children under 10 years were recruited and categorized according to the type of ventilation system in their home: energy recovery ventilator (ERV), heat recovery ventilator (HRV), no HRV or ERV, and control groups. Children's' medical records were analyzed over a period of 50 weeks pre- and post-intervention. Clinical diagnoses were classified into 4 categories: upper respiratory infections, lower respiratory infections, otitis media, and asthma. A decrease in respiratory infections episodes was observed in all groups following intervention with the highest impact observed for HRV systems (-53.0%). Decreases in the ERV group were not significant (-21,7%) possibly due to the presence of some volatile organic compound (such as propylene glycol) and inerrant experimental bias. Nevertheless, no significant association was found between health episodes incidence and household's behaviors or IAQ.

Seroprevalence and risk factors of antibodies against Coxiella burnetii among dog owners in southwestern Québec, Canada

Coxiella burnetii is a zoonotic agent responsible for human Q fever, a potentially severe disease that can lead to persistent infection. This cross-sectional study aimed to estimate the seroprevalence to C. burnetii antibodies and its association with potential risk factors in the human population of five regions of Québec, Canada. A serum bank comprising sera from 474 dog owners was screened by an enzyme-linked immunosorbent assay followed by confirmation of positive or equivocal sera by an indirect immunofluorescence assay. Observed seroprevalences of 1.2% (95% confidence interval (CI): 0.0–6.6), 2.6% (95% CI: 0.5–7.4) and 5.9% (95% CI: 3.4–9.6) were estimated in the regions of Montréal, Lanaudière and Montérégie, respectively, which all included at least 83 samples. Having lived or worked on a small ruminant farm (prevalence odds ratio (POR) = 5.4; 95% CI: 1.6–17.7) and being a veterinarian or veterinary student (POR = 6.1; 95% CI: 1.6–24.0) were significantly associated with C. burnetii seropositivity. Antibodies against C. burnetii were detected in the human population of Québec. Although seropositivity to this agent was associated with occupational contact with domestic animals, antibodies were also detected in people with no reported professional exposure. No associations with ruminant farm proximity were identified.

Assessment of naturally acquired neutralizing antibodies against rabies Lyssavirus in a subset of Nunavik's Inuit population considered most at risk of being exposed to rabid animals

Contact with infected saliva through the bite of a rabid animal is the main route of infection with the rabies Lyssavirus in humans. Although a few individuals have survived the infection, rabies remains the most lethal zoonotic infection worldwide. Over the last century, the dogma that rabies is invariably fatal has been challenged by the survival and recovery of infected animals. In humans, 11 studies have found rabies virus-specific antibodies in unvaccinated individuals exposed to rabies virus reservoir species, suggesting the possibility of asymptomatic rabies virus infection, contact with non-infectious virus or exposure to the virus without viral replication. Two of these studies were conducted in Arctic hunters. Considering the extensive exposure of Nunavik's Inuit to potentially infected animals through hunting, trapping, skinning and the preparation of Arctic carnivores, we analysed archived serum samples from the 2004 Nunavik Inuit Health Survey for the presence of rabies virus-neutralizing antibodies (rVNA) in this sub-population. A total of 196 participants who were considered at highest risk for exposure to rabies virus were targeted. Serum samples were tested for the presence of rVNA using a variation of the fluorescent antibody virus neutralization test, an assay recommended for the quantification of neutralizing antibody titres following vaccination. Our study identified two seropositive individuals among the 196 participants but a review of their medical record and a phone interview revealed previous vaccination. Our results do not provide evidence for naturally acquired rVNA in Nunavik's Inuit population.

Impact of indoor air quality on respiratory health: results of a local survey on housing environment

OBJECTIVES

The 'Mon habitat: plus qu'un simple toit' (MHPQST) survey was designed to identify public health risks and priorities for local decision makers in relation to housing. The aims of the present study were to describe the exposure of households to indoor air contaminants and to verify the relationship between these contaminants and respiratory symptoms/diseases.

STUDY DESIGN

This is a cross-sectional study.

METHODS

MHPQST was conducted in Baie-Saint-Paul, a French Canadian municipality (7000 inhabitants) using a protocol adapted from the 'Large Analysis and Review of European Housing and Health Status' study performed in Europe in 2002-2003. Households were selected from two sectors (less favorable and more favorable). Data collection was achieved using three tools (two questionnaires and one inspection grid). Indoor air variables were analyzed in relation to respiratory symptoms/diseases using logistic regression models adjusted for age, gender, income, smoking status, and proximity.

RESULTS

A total of 161 dwellings (294 inhabitants) participated in the survey. Presence of mold on walls, ceilings, or floors was detected by the investigators in 21% of the dwellings. Nearly half of the households were in contact with a pet at home and 12% with environmental tobacco smoke. Exposure to these three determinants was significantly associated with certain respiratory symptoms/diseases.

CONCLUSION

Molds, pets at home, and environmental tobacco smoke are environmental determinants that were associated with respiratory health in the present survey. These results enabled sensitizing local stakeholders regarding the importance of indoor air quality for the respiratory health of their population.

Dynamic Analysis of a Manipulator in a Fluid Environment

The computation of the generalized forces produced by a fluid acting on the links of manipulators is considered here. The evaluation of these forces is necessary for the controller of an underwater manipulator (partially or totally immersed). This article presents an approximate method for the computation of buoyancy in local coordinates. The drag forces are computed by numerical integration of the local drag force. Numerical integration is necessary here to achieve a good precision. A new local reference frame is also added on each link to allow an easy description of the geometry of the links. When those computations are included in the dynamic model, a compromise must be made between computation time and precision, because this inclusion may result in doubling or tripling the number of operations to be performed in comparison with a standard dynamic algorithm.

Prospective study of acute health effects in relation to exposure to cyanobacteria

We conducted a study to investigate the relationship between exposure to cyanobacteria and microcystins and the incidence of symptoms in humans living in close proximity to lakes affected by cyanobacteria. The design was a prospective study of residents living around three lakes (Canada), one of which has a water treatment plant supplying potable water to local residents. Participants had to keep a daily journal of symptoms and record contact (full or limited) with the water body. Samples were collected to document cyanobacteria and microcystin concentrations. Symptoms potentially associated with cyanobacteria (gastrointestinal: 2 indices (GI1: diarrhea or abdominal pain or nausea or vomiting; GI2: diarrhea or vomiting or [nausea and fever] or [abdominal cramps and fever]); upper and lower respiratory tract; eye; ear; skin; muscle pain; headaches; mouth ulcers) were examined in relation with exposure to cyanobacteria and microcystin by using Poisson regression. Only gastrointestinal symptoms were associated with recreational contact. Globally, there was a significant increase in adjusted relative risk (RR) with higher cyanobacterial cell counts for GI2 (<20,000 cells/mL: RR=1.52, 95% CI=0.65-3.51; 20,000-100,000 cells/mL: RR=2.71, 95% CI=1.02-7.16; >100,000 cells/mL: RR=3.28, 95% CI=1.69-6.37, p-trend=0.001). In participants who received their drinking water supply from a plant whose source was contaminated by cyanobacteria, an increase in muscle pain (RR=5.16; 95% CI=2.93-9.07) and gastrointestinal (GI1: RR=3.87; 95% CI=1.62-9.21; GI2: RR=2.84; 95% CI=0.82-9.79), skin (RR=2.65; 95% CI=1.09-6.44) and ear symptoms (RR=6.10; 95% CI=2.48-15.03) was observed. The population should be made aware of the risks of gastrointestinal symptoms associated with contact (full or limited) with cyanobacteria. A risk management plan is needed for water treatment plants that draw their water from a source contaminated with cyanobacteria.

An approach to define potential radon emission level maps using indoor radon concentration measurements and radiogeochemical data positive proportion relationships

The aim of this paper is to present the first step of a new approach to make a map of radonprone areas showing different potential radon emission levels in the Quebec province. This map is a tool intended to assist the Quebec government in identifying populations with a higher risk of indoor radon gas exposure. This map of radon-prone areas used available radiogeochemical information for the province of Quebec: (1) Equivalent uranium (eU) concentration from airborne surface gamma-ray surveys; (2) uranium concentration measurements in sediments; and (3) bedrock and surficial geology. Positive proportion relationships (PPR) between each individual criterion and the 1417 available basement radon concentrations were demonstrated. It was also shown that those criteria were reliable indicators of radon-prone areas. The three criteria were discretized into 3, 2 and 2 statistically significant different classes respectively. For each class, statistical heterogeneity was validated by Kruskal-Wallis one way analyses of variance on ranks. Maps of radon-prone areas were traced down for each criterion. Based on this statistical study and on the maps of radon-prone areas in Quebec, 18% of the dwellings located in areas with an equivalent uranium (eU) concentration from airborne surface gamma-ray surveys under 0.75 ppm showed indoor radon concentrations above 150 Bq/m3. This percentage increases to 33% when eU concentrations are between 0.75 ppm and 1.25 ppm and exceeds 40% when eU concentrations are above 1.25 ppm. A uranium concentration in sediments above 20 ppm showed an indoor radon concentration geometric mean of 215 Bq/m3 with more than 69% of the dwellings exceeding 150 Bq/m3 or more than 50% of dwellings exceeding the Canadian radon guideline of 200 Bq/m3. It is also shown that the radon emission potential is higher where a uranium-rich bedrock unit is not covered by a low permeability (silt/clay) surficial deposit.

Contamination of public whirlpool spas: factors associated with the presence of Legionella spp., Pseudomonas aeruginosa and Escherichia coli

This work explores the factors associated with contamination of public spas by Legionella spp., Pseudomonas aeruginosa and Escherichia coli. Physicochemical and microbiological parameters were measured in water samples from 95 spas inQuébec, Canada. Spa maintenance was documented by a questionnaire. Legionella spp. were detected in 23% of spas, P. aeruginosa in 41% and E. coli in 2%. Bacteria were found in concerning concentrations (Legionella spp. ≥ 500 CFU/l, P. aeruginosa ≥ 51 CFU/100 ml or E. coli ≥ 1 CFU/100 ml) in 26% ofspas. Observed physicochemical parameters frequently differed from recommended guidelines. The following factors decreased the prevalence of concerning microbial contamination: a free chlorine concentration ≥ 2 mg/l or total bromine ≥ 3 mg/l (p = 0.001), an oxidation-reduction potential (ORP) > 650 mV (p = 0.001), emptying and cleaning the spa at least monthly (p = 0.019) and a turbidity ≤ 1 NTU (p = 0.013). Proper regulations and training of spa operators are critical for better maintenance of these increasingly popular facilities.

Microbiological quality of blue mussels (Mytilus edulis) in Nunavik, Quebec: a pilot study

This pilot study was aimed at documenting the presence of fecal indicators and enteric pathogens in blue mussels (Mytilus edulis) from 6 communities in Nunavik, Quebec. One to four 2 kg samples of mussels were collected at low tide in each community. Samples were investigated by enumeration methods for the fecal indicators enterococci, Escherichia coli, F-specific coliphages, Clostridium perfringens, and by molecular identification for the pathogens norovirus, Salmonella spp., Campylobacter jejuni, Campylobacter coli, and Campylobacter lari, verocytotoxin-producing E. coli (particularly serovar O157:H7), Shigella spp., and Yersinia enterocolitica. In 5 communities, the presence of Giardia duodenalis and Cryptosporidium spp. was also tested by microscopy and molecular methods and that of Toxoplasma gondii was tested by molecular methods. Apart from small quantities of Clostridium perfringens in 2 samples, no bacterial or viral pathogens were detected in the mussels. Toxoplasma gondii was also not detected. However, G. duodenalis and Cryptosporidium spp. were present in 18% and 73% of the samples investigated for these pathogens, respectively. When considering the indicators and the viral and bacterial pathogens investigated, the mussels examined were of good microbiological quality, but considering the presence of potentially zoonotic protozoa, it should be recommended that consumers cook the molluscs well before eating them.

Éléments théoriques pour une sociologie de l’entreprise : des classiques aux « néo-classiques »

Dans cet article, les auteurs tentent de caractériser la façon dont les classiques de la sociologie (Durkheim, Weber et Marx) et les auteurs contemporains qui s’en inspirent définissent l’entreprise. Ils montrent ainsi comment chacune de ces traditions sociologiques met l’accent sur l’une ou l’autre des dimensions que sont les rapports sociaux, la dimension institutionnelle, la dimension organisationnelle. Ces dimensions sont cependant présentées par chacune de ces approches comme objets isolés, légitimes certes, mais non articulés. S’inspirant à la fois de l’approche des mouvements sociaux et de l’école de la régulation, les auteurs proposent de transformer ces différentes perspectives en dimensions ou niveaux d’analyse d’une perspective plus large où chacune des dimensions constitue un enjeu propre, ses propres acteurs, sa propre culture. En conclusion, ils expliquent pourquoi, selon les époques, une approche plutôt que l’autre s’est imposée.

Assessment of the effectiveness of radon screening programs in reducing lung cancer mortality

The present study was aimed at assessing the health consequences of the presence of radon in Quebec homes and the possible impact of various screening programs on lung cancer mortality. Lung cancer risk due to this radioactive gas was estimated according to the cancer risk model developed by the Sixth Committee on Biological Effects of Ionizing Radiations. Objective data on residential radon exposure, population mobility, and tobacco use in the study population were integrated into a Monte-Carlo-type model. Participation rates to radon screening programs were estimated from published data. According to the model used, approximately 10% of deaths due to lung cancer are attributable to residential radon exposure on a yearly basis in Quebec. In the long term, the promotion of a universal screening program would prevent less than one death/year on a province-wide scale (0.8 case; IC 99%: -3.6 to 5.2 cases/year), for an overall reduction of 0.19% in radon-related mortality. Reductions in mortality due to radon by (1) the implementation of a targeted screening program in the region with the highest concentrations, (2) the promotion of screening on a local basis with financial support, or (3) the realization of systematic investigations in primary and secondary schools would increase to 1%, 14%, and 16.4%, respectively, in the each of the populations targeted by these scenarios. Other than the battle against tobacco use, radon screening in public buildings thus currently appears as the most promising screening policy for reducing radon-related lung cancer.

Assessment of microbiological quality of drinking water from household tanks in Bermuda

Bermuda residents collect rainwater from rooftops to fulfil their freshwater needs. The objective of this study was to assess the microbiological quality of drinking water in household tanks throughout Bermuda. The tanks surveyed were selected randomly from the electoral register. Governmental officers visited the selected household (n = 102) to collect water samples and administer a short questionnaire about the tank characteristics, the residents' habits in terms of water use, and general information on the water collecting system and its maintenance. At the same time, water samples were collected for analysis and total coliforms and Escherichia coli were determined by 2 methods (membrane filtration and culture on chromogenic media, Colilert kit). Results from the 2 methods were highly correlated and showed that approximately 90% of the samples analysed were contaminated with total coliforms in concentrations exceeding 10 CFU/100 mL, and approximately 66% of samples showed contamination with E. coli. Tank cleaning in the year prior to sampling seems to protect against water contamination. If rainwater collection from roofs is the most efficient mean for providing freshwater to Bermudians, it must not be considered a source of high quality drinking water because of the high levels of microbial contamination.

Seroprevalence of zoonoses in a Cree community (Canada)

Cree trappers and hunters are at risk for contracting infectious diseases conveyed by wildlife. We performed a study in a Cree community (Canada) to determine the seroprevalence of 8 zoonotic infections among hunters and trappers for evidence of exposure to Trichinella sp., Toxoplasma gondii, Toxocara canis, Echinococcus granulosus, Leptospira sp., Coxiella burnetii, Francisella tularensis, and Sin Nombre virus. A total of 50 participants (28 women and 22 men) were included in this study. Results indicate no or infrequent exposure to the Sin Nombre virus (0%) and 3 of the 4 parasites investigated (0-4%). Exposure to T. gondii (10%) and some bacteria appeared to be more prevalent (range, 4-18%). Overall, seropositivity was related to fishing, hunting, and trapping activities. Physicians should be aware of these infections in this population, particularly Q fever, tularemia, and leptospirosis.

Étude de la contamination microbienne des myes (Mya arenaria) de la rive nord de l'estuaire maritime du fleuve Saint-Laurent (Québec, Canada)

The aims of the present study were to assess the microbial quality of Mya arenaria clams from the north shore of the St. Lawrence River estuary and to validate various microbial indicator microorganisms of bivalve mollusks contamination. Clams were collected from nine sites, including four harvesting sites closed by virtue of the Canadian Shellfish Sanitation Program (CSSP). Six contamination indicators (fecal coliforms, somatic coliphages, F-specific coliphages, fecal streptococci, Clostridium perfringens, and Escherichia coli) and four pathogens (Campylobacter sp., Cryptosporidium parvum, Giardia sp., and Salmonella sp.) were identified in the clams. Indicators sensibility, specificity and predictive values with respect to the presence of pathogens were calculated. Pathogenic microorganisms detection frequency in clams was important (92%). Globally, pathogens tend to be less frequently detected in opened harvesting sites (p = 0.086). Although the assessed indicators were not perfect, when F-specific coliphages are associated with E. coli or fecal coliforms, a good sensibility (62%–64%) and good positive predictive value (88%) with respect to the investigated pathogens are obtained.Key words: mollusks, coliforms, Giardia, Cryptosporidium, Campylobacter.[Journal translation]

Risk of giardiasis associated with water supply in an endemic context

Consumption of untreated, inadequately treated or simply chlorinated water has been the source of a number of giardiasis epidemics. The aim of this study was to verify if water supply is associated with giardiasis in an endemic context. We conducted a case-control study that included 139 cases and 417 control subjects. To assess risk associated to water consumption, we calculated odds ratios (OR) using "source of water" and "presence and type of filtration" as criteria. A logistic regression model was used to control other risk factors. In children aged 1 - 13, the only significant risk factor was the consumption of at-risk tap water (i.e., filtered or unfiltered surface water or unfiltered shallow well water; OR = 6.13). In people aged 14 - 64, the consumption of this water was not a risk factor for the disease. The divergence in results between age groups could be explained by acquired immunity.

Housing characteristics and indoor concentrations of nitrogen dioxide and formaldehyde in Quebec City, Canada

Concentrations of nitrogen dioxide and formaldehyde were determined in a study of 96 homes in Quebec City, Canada, between January and April 2005. In addition, relative humidity, temperature, and air change rates were measured in homes, and housing characteristics were documented through a questionnaire to occupants. Half of the homes had ventilation rates below 7.5 L/s person. Nitrogen dioxide (NO2) and formaldehyde concentrations ranged from 3.3 to 29.1 microg/m3 (geometric mean 8.3 microg/m3) and from 9.6 to 90.0 microg/m3 (geometric mean of 29.5 microg/m3), respectively. The housing characteristics documented in the study explained approximately half of the variance of NO2 and formaldehyde. NO2 concentrations in homes were positively correlated with air change rates (indicating a significant contribution of outdoor sources to indoor levels) and were significantly elevated in homes equipped with gas stoves and, to a lesser extent, in homes with gas heating systems. Formaldehyde concentrations were negatively correlated with air change rates and were significantly elevated in homes heated by electrical systems, in those with new wooden or melamine furniture purchased in the previous 12 months, and in those where painting or varnishing had been done in the sampled room in the previous 12 months. Results did not indicate any significant contribution of indoor combustion sources, including wood-burning appliances, to indoor levels of formaldehyde. These results suggest that formaldehyde concentrations in Quebec City homes are caused primarily by off-gassing, and that increasing air change rates in homes could reduce exposure to this compound. More generally, our findings confirm the influence of housing characteristics on indoor concentrations of NO2 and formaldehyde.

Housing characteristics and indoor concentrations of nitrogen dioxide and formaldehyde in Quebec City, Canada

Concentrations of nitrogen dioxide and formaldehyde were determined in a study of 96 homes in Quebec City, Canada, between January and April 2005. In addition, relative humidity, temperature, and air change rates were measured in homes, and housing characteristics were documented through a questionnaire to occupants. Half of the homes had ventilation rates below 7.5 L/s person. Nitrogen dioxide (NO2) and formaldehyde concentrations ranged from 3.3 to 29.1 microg/m3 (geometric mean 8.3 microg/m3) and from 9.6 to 90.0 microg/m3 (geometric mean of 29.5 microg/m3), respectively. The housing characteristics documented in the study explained approximately half of the variance of NO2 and formaldehyde. NO2 concentrations in homes were positively correlated with air change rates (indicating a significant contribution of outdoor sources to indoor levels) and were significantly elevated in homes equipped with gas stoves and, to a lesser extent, in homes with gas heating systems. Formaldehyde concentrations were negatively correlated with air change rates and were significantly elevated in homes heated by electrical systems, in those with new wooden or melamine furniture purchased in the previous 12 months, and in those where painting or varnishing had been done in the sampled room in the previous 12 months. Results did not indicate any significant contribution of indoor combustion sources, including wood-burning appliances, to indoor levels of formaldehyde. These results suggest that formaldehyde concentrations in Quebec City homes are caused primarily by off-gassing, and that increasing air change rates in homes could reduce exposure to this compound. More generally, our findings confirm the influence of housing characteristics on indoor concentrations of NO2 and formaldehyde.

Total and specific immunoglobulin E and their relationship to respiratory symptoms in Quebéc children and adolescents

BACKGROUND

Respiratory disease is a major cause of morbidity in young people. It is now recognized that atopy plays an important role in the development of chronic respiratory symptoms in children.

OBJECTIVE

To examine the determinants and consequences of serum total and specific immunoglobulin E (IgE) in a general population sample of Québec children and adolescents.

METHODS

In 1999, 2349 children and adolescents (nine, 13 or 16 years of age) who had participated in a respiratory symptom and disease questionnaire had their total IgE measured. Of these participants, a subsample of 451 children and adolescents was analyzed to detect antibodies to eight specific allergens (ie, allergens of dust mites [Dermatophagoides farinae and Dermatophagoides pteronyssinus], cat, dog, ragweed, Timothy grass, mould [alternaria] and cockroach).

RESULTS

The geometric mean of the total IgE was 44.4 U/mL among all participants. Concentrations were higher in boys and increased with age. More than 41% of the participants were sensitized to at least one specific allergen. Such sensitization was strongly associated with the occurrence of respiratory conditions and symptoms, namely asthma, wheezing and rhinitis. Family history, school location and ethnic origin had an impact on the prevalence of atopy and total IgE levels.

CONCLUSIONS

Allergic sensitization is a major determinant in the development of asthma, wheezing and rhinitis in children and adolescents in the province of Québec.

Spatio-temporal distribution of hypothyroidism in Quebec

This study estimates the incidence and prevalence of hypothyroidism in Quebec, based on a data bank produced by the Régie de l'assurance maladie du Québec (RAMQ) on the use of thyroid hormones by persons insured under RAMQ's public drug insurance plan between 1992 and 2001. In 2001, the prevalence of thyroid hormone use in women and men respectively was 10.8 and 2.9 percent. Prevalence increases with age, reaching, among those aged 65 and over, 21.9 percent in women and 8.0 percent in men in 2001. Incidence is highest in women between the ages of 45 and 64 and in men aged 65 and over. Age-related incidence is relatively stable in women but tends to increase in men. On a regional and local basis (by Centre local de services communautaires [CLSC]), incidence rates up to 2.4 times higher than anticipated on the basis of provincial incidence rates were observed.

Asthma and allergic rhinitis in Quebec children

BACKGROUND

The Health and Social Survey of Quebec Children and Youth, conducted on representative samples of children nine, 13 and 16 years of age, provided data on the prevalence and determinants of asthma and allergic rhinitis in Quebec.

OBJECTIVES

To determine the prevalence of asthma and allergic rhinitis among children in the province of Quebec and to identify the determinants of these pathologies.

METHODS

Three groups of more than 1100 children aged nine, 13 and 16 years were recruited. Respiratory symptoms were documented using the International Study of Asthma and Allergies in Childhood questionnaire. Questions enquiring about family income, smoking, degree of urbanization of the child's school's location and various variables related to indoor air were also included. The comparisons of proportions were done using the chi2 test.

RESULTS

The prevalence rates for reported history of asthma varied from 14% to 15% depending on the age group. The prevalence of wheezing in the past year was 7% to 8%. Asthma was the primary cause of the limitation of activities due to a health problem in nine- and 13-year-old Quebecers, and the second most common cause in 16-year-old Quebecers. The prevalence of rhinitis, rhinoconjunctivitis and reported history of hay fever increased with age, reaching 28.0%, 15.9% and 21.1%, respectively, in the 16-year-old group. The prevalence of asthma and wheezing was associated with family history and allergies, and inversely related to family income.

CONCLUSIONS

The prevalence of childhood asthma is high in the province of Quebec. It is a major cause of the limitation of activities due to a health problem for young Quebecers. A family history of asthma and an atopic predisposition are important determinants in the development of asthma in Quebec.

[Environmental hazards for falls in elders in low income housing]

BACKGROUND

About 35% of elders living at home fall each year. The objectives of this study were to evaluate the environmental hazards associated with falls in 58 low income housings for elders and to determine the contribution of environmental factors to these falls.

METHODS

Participants were interviewed to document their health problems, their knowledge concerning the Issue of falls, and their history of falls during the last year. Environmental hazards were identified and evaluated with a standardised checklist. The levels of hazards (percentage of factors identified which represent a hazard) were measured for the different sectors and for the entire dwelling and communal spaces. The hazards were also evaluated according to four main variables (structure of the building, characteristics of the floor surface, environmental obstacles, risk-taking behaviour).

RESULTS

A total of 172 participants were recruited for the study. For dwellings and communal spaces, the hazards were respectively higher in bathrooms (mean=27.0%; p<0.05) and interior stairs (mean=22.5%; p<0.05). For the communal spaces of buildings of less than 20 Years, the global hazard was higher in the smaller buildings (<or=three stories, mean=14.2%;>three stories, mean=12.6%; p<0.001). For dwellings of the larger buildings, the global hazard was higher for younger buildings (<20 years, mean=16.6%; >or=20 years, mean=13.5%; p<0.001). Among the variables documented, risk-taking behaviour was the more frequent factor for the dwellings (mean=32.0%; p<0.05) as for the communal spaces (mean=42.5%; p<0.05). Finally, only 34% of the participants mentioned receiving information concerning the falls among elders. Among the 27 falls documented, an environmental factor was identified in 55% of the cases.

CONCLUSION

The study helped to document the presence of environmental factors which could be a hazard for falls in elders' housing and to suggest preventive and remedial actions.

Monitoring of umbilical cord blood lead levels and sources assessment among the Inuit

Analyses completed on samples collected between 1993 and 1996 showed that about 7% of 475 Inuit newborns from northern Quebec (Canada) had a cord blood lead concentration equal to or greater than 0.48 micromol/l, an intervention level adopted by many governmental agencies. A comparison between the cord blood lead isotope ratios of Inuit and southern Quebec newborns showed that lead sources for these populations were different. Our investigation suggests that lead shots used for game hunting were an important source of lead exposure in the Inuit population. A cohort study conducted in three Inuit communities shows a significant decrease of cord blood lead concentrations after a public health intervention to reduce the use of lead shot. Lead shot ammunition can be a major and preventable source of human exposure to lead.

Investigation of an outbreak of cercarial dermatitis

We present the investigation of an outbreak of cercarial dermatitis that occurred in a recreational-tourist lake in the Quebec City region (Canada) in the summer of 1999. A case-reporting form was sent to 450 families likely to have activities that would bring them in contact with the lake's water. The snails were characterized and the prevalence of their infestation by schistosomes was investigated. In total, 63 episodes consistent with cercarial dermatitis were reported. Sixty-nine percent of the cases occurred from swimming at the same beach. This location was the one where the only population of snails in the lake was identified. Shoreline residents were informed that they should not feed waterfowl, and a clean-up of the snail population was done at the start of the following summer. There were no cases of cercarial dermatitis at this site the following summer.

Cancer risk associated with household exposure to chloroform

Chloroform (CHCl3) the trihalomethane most prevalent in drinking water, is a proven animal carcinogen and a suspected human carcinogen. Consequently, standards have been issued by health authorities to limit its concentration in drinking water. These limits are based solely on ingestion, without taking into account inhalation and skin contact. Exposure to CHCl3 was assessed for 18 men (age: mean 38 years; range 23-51) following a 10-min shower in their respective residences located in the Quebec City region (Canada). CHCl3 concentration was measured in alveolar air samples collected before, immediately after, and 15 min and 30 min following the shower. Indoor air and water concentrations were determined concomitantly. Mean CHCl3 concentrations in the air of the shower stall and in water were respectively 147 microg/m3 (SD = 56.2 microg/m3) and 20.1 microg/L (SD = 9.0 microg/L). Water concentrations were comparable to those documented in a large proportion of distribution networks in Canada. The mean increase in alveolar air CHCl3 concentration (deltaCHCIALV) at the end of the shower was 33 microg/m3 (SD = 14.7 microg/m3). A multiple-regression analysis revealed that deltaCHCl3ALV values were only associated with chloroform concentration in air of the shower stall. DeltaCHCl3ALV were described using a physiologically based pharmacokinetic (PBPK) model. This model was then used to estimate concentrations of CHCl3 metabolites bound to liver and kidney macromolecules following a shower, and also according to exposure scenarios that integrate drinking-water ingestion and air inhalation. The concentration predicted in the liver following a worst-case exposure scenario was 0.41 microg CHCl3 equivalents/kg of tissue, some 6,000 times lower than the lowest concentration that did not increase the incidence of hepatic tumors in laboratory animals. Data indicate that for this range of exposure the safety margin appears therefore considerable with respect to the potential carcinogenic effect of household exposure to CHCl3.

[1998 Quebec Social and Health Survey: determinants of chronic respiratory diseases]

In the course of the "1998 Health and Social Survey", questions were included to verify the prevalence of chronic respiratory diseases and also of wheezing. The objectives of this study were 1) to verify the prevalence of wheezing and its validity as an indicator of chronic respiratory diseases in Québec; and 2) to examine the relationship between chronic respiratory diseases and some of their potential determinants. A total of 30,386 individuals participated in the study. For all ages, the prevalence of wheezing was 5.4%. It was associated with asthma, allergies, chronic bronchitis and emphysema. A low familial income and tobacco smoking were associated with wheezing, asthma, chronic bronchitis and emphysema. Passive smoking was associated with wheezing whereas the presence of carpets was associated with wheezing and asthma. Between 32 and 48% of families with an asthmatic or an allergic member modified their dwelling to alleviate respiratory problems. The prevalence of wheezing documented here was lower than in anglosaxon countries. This result could be explained by a cultural factor (the French translation or the perception of wheezing). This study emphasizes the role of reducing tobacco smoking in the prevention of chronic respiratory diseases.

Evaluation of the health risk associated with exposure to chloroform in indoor swimming pools

The exposure of swimmers to chloroform (CHCl3) was investigated in indoor swimming pools of the Quebec City region along with the associated carcinogenic risk. Six training sessions involving 52 competition swimmers (11 to 20 yr old) were conducted in 3 different pools, while 12 adult leisure swimmers attended 5 sessions, each held in a different pool. For each session, water and ambient air CHCl3 concentrations were measured and CHCl3 levels in alveolar air samples (CHCl3 ALV) collected from swimmers prior to entering the swimming pool premises and after 15, 35, and 60 min of swimming. Mean water concentrations varied from 18 microg/L to 80 microg/L, while those in air ranged from 78 microg/m3 to 329 microg/m3. Multiple linear regression analyses revealed that CHCl3 ALV values in competition swimmers were strongly correlated to ambient air and water levels, and to a lesser degree to the intensity of training. Only ambient air concentration was positively correlated to CHCl3 ALV in the leisure group. Concentrations of CHCl3 metabolites bound to hepatic and renal macromolecules, estimated using a physiologically based pharmacokinetic (PBPK) model, were 1.6 and 1.9 times higher for the competition swimmers than for the leisure swimmers, respectively. The highest hepatic concentration predicted in competition swimmers, 0.22 microg CHCl3 equivalents/kg of tissue, was at least 10,000 times lower than the smallest no observed effect level for liver tumors in animals. Data indicate that the safety margin is therefore very large, for competitive swimmers as well as for leisure swimmers.

Air quality monitoring during indoor Monster Truck and car demolition shows

This article describes the results of air quality monitoring in an indoor ice skating rink during three Monster Truck and car demolition exhibitions, and the public health study that was carried out. The exposure of the people present to carbon monoxide and nitrogen dioxide was continuously monitored in order to determine the time-weighted average concentrations and the maximum peaks. Nitrogen dioxide concentrations were generally under the limit of detection of the device (0.5 ppm). However, carbon monoxide levels exceeded standards for workers. Maximum time-weighted average concentrations during the exhibitions were 100 parts per million with several peaks exceeding 200 parts per million (maximum value: 1600 parts per million). Recommendations were made and during a subsequent event, the carbon monoxide concentrations were reduced to protect health. Indoor exhibitions of motorized vehicles generate significant amounts of combustion gases, which can be a health hazard. There must be sufficient ventilation and the carbon monoxide and nitrogen dioxide concentrations must be monitored. In addition, the motors of the most polluting vehicles should be adjusted before the events in order to limit the emission of combustion products. If these steps are not met, the events should be held outdoors.

[Study of the incidence of giardiasis in Quebec (Canada) and association with drinking water source and quality]

BACKGROUND

We analyzed data from the notifiable diseases data base in Québec to document the incidence of giardiasis. The objectives were to perform a descriptive analysis of the cases of giardiasis and to verify the relation between their incidence and the quality of drinking water.

METHODS

The Québec notifiable diseases data-base contained 4273 cases of giardiasis declared between January 1st, 1990 and December 31st, 1995. Incidence rates were adjusted for age and calculated monthly. The sources and kinds of treatment of drinking water permitted to elaborate a vulnerability scale for classifying contamination by Giardia sp. into four categories. Incidence of giardiasis was examined in relation with this vulnerability scale. Other socioeconomic indicators possibly associated with the incidence of giardiasis were also analyzed.

RESULTS

Analysis showed that there were few annual variations in the incidence of giardiasis and that there were no epidemic peaks during the study period. According to age, the incidence follows a bimodal pattern with a peak for young children and young adults. The incidence rates showed an increase of the cases at the end of summer and at the beginning of fall, with a higher relative risk for males. Even if no relation was found between the incidence of giardiasis and the vulnerability of the drinking water source, incidence rates were lower for people living in communities that use the St. Lawrence River as a drinking water source than for those using other sources of surface water.

CONCLUSION

This study allowed us to obtain a good description of the cases of giardiasis declared in Québec and to formulate hypothesis about their causes. The lower incidence of giardiasis in communities that use the St. Lawrence river as their drinking water source is possibly related to a lower contamination of this source. However, considering the limits of this work, case-control studies should be considered to understand variables, which influence the incidence of giardiasis in Québec.

Indoor exposure to 222Rn: a public health perspective

The objective of this study was to assess the lung cancer risk resulting from indoor radon exposure in the province of Quebec, Canada, and to evaluate the efficacy of mitigation measures to reduce this exposure. Concentrations of radon were determined in a representative sample of houses, and the corresponding lung cancer risk estimates were generated using the BEIR IV model, taking into account smoking, residential mobility, and regional variations in radon concentrations. Mean (geometric) radon concentrations in basements (n = 418) and on first floors (n = 319) were, respectively, 34.4 (95% CI-30.6 to 38.8) and 16.5 Bq m(-3) (14.2 to 19.3). A total of 109 deaths from lung cancer are predicted to occur as a result of this exposure in a cohort of 60,000 people. Detecting all residences with high radon concentrations (equal to or above 200 Bq m(-3)) and implementing mitigation measures in each of them would reduce by 4 the number of lung cancer deaths attributable to indoor radon exposure. A reduction of 0.05% in the prevalence of smoking would prevent as many deaths from lung cancer as would radon mitigation. From a public health perspective, in order to reduce mortality from lung cancer, most efforts should be focused on smoking, not on the relatively minor and hardly preventable population risk arising from household radon exposure.

New patterns of drinking-water consumption: results of a pilot study

A pilot study on water consumption was carried out in the Québec City region in April and May 1996 with 125 people using a 24-h recall plus a 2-day diary. Consumption of drinking water via liquid and food was assessed as well as the type of water consumed (tap, bottle or filtered water) and place of consumption (home or away from home). Most of the people (56%) were drinking some bottled water or filtered tap water and 25% of water intake was away from home. Food consumption was found to be a non-significant source of drinking-water intake. The average water consumption was nearly similar in exclusively tap-water consumers and bottled- or filtered-water consumers (1.5 vs. 1.7 l/day, P = 0.29) but two-thirds of the consumption in this last group is natural water, while it is mixed water in the bottled/filtered-water group. No significant difference in amounts consumed were found according to age, but older people drank hot beverages and soup more often. The present pilot-study was weakened by a low participation rate (14%). Incentive might be necessary to improve participation rate and data collection methods must also be simplified. A 24-h recall plus a 1-day diary seem sufficient and data on consumption could be limited to liquids, soups and cereals.

[Mortality attributable to tobacco smoking in Quebec]

In industrialized countries, tobacco smoking is the main cause of preventable morbidity and premature deaths. Although mortality attributable to smoking has already been estimated for the population of the province of Québec, it has never been studied on a regional basis. We calculated the mortality attributable to smoking by socio-sanitary regions of the province of Québec for 10 fatal diseases positively associated with smoking. The calculations were made for the years 1984 through 1993 taking into account Canadian Census data (demographic variables), the Santé-Québec survey (prevalence of smoking), the death registry of the "Bureau de la statistique du Québec" (mortalitry data), and the American cohort of the "Cancer Prevention Study II" (relative risks). For the diseases investigated, 24,637 and 62,711 deaths were attributable to smoking for women and men respectively during the period studied, thus representing 29.4% and 51.2% of attributable percentages. There is no statistical difference between the regions, which indicates a general problem for all the province. These data again confirm the incredible impact of smoking on public health. The struggle against smoking should be a primary area for action for the benefit of all Quebecers.

Radon in residences: influences of geological and housing characteristics

222Rn is a radioactive gas emitted during the decay of 238U. 222Rn is a recognized lung carcinogen in humans and a common indoor air contaminant. This paper describes the results of research undertaken in 894 residences of the Province of Quebec (Canada), in which one of the objectives was to evaluate the influence of geological and housing characteristics on 222Rn levels. After a random selection of homes, 222Rn concentrations were measured with alpha track detectors in the basement and the main bedroom during two consecutive 6-mo periods. Geological subsoil characteristics were determined from various sources (e.g., geological maps, databanks on uranium sampling in lake and stream sediments), and housing characteristics were documented with a questionnaire. Statistical variance analysis of data indicates that geological factors only explain 5% and 4.5% of the variations in 222Rn concentrations, respectively, in the basement and on the first floor. When variables relative to housing characteristics are added, the analysis explains only 18% and 15% of the variations in 222Rn concentrations in the basement and on the first floor. These results illustrate the difficulties in predicting 222Rn concentrations in homes.

[Outbreak of non-bacterial gastroenteritis in a school]

An outbreak of gastroenteritis occurred in a school affecting more than 30% of its 535 students. An epidemiological survey questionnaire was given to all students as well as staff and maintenance personnel. Stool cultures and electronic microscopy were used to detect the presence of a Norwalk-like virus. Several analyses of water samples were also done. This outbreak occurred simultaneously in the two wings of the school (East and South). Those who used the East wing were most affected by the disease (RR = 1.45, CI 95%: 1,14-1,85). There was no indication of food or water supply contamination. A Norwalk-like virus was identified in the stool sample of one child. This along with the clinical characteristics strongly suggested that the pathogen was indeed a Norwalk-like virus. The analysis suggests transmission via contaminated surfaces but also via airborne transport of the infectious agent.

[Outbreak of non-bacterial gastroenteritis in a school]

An outbreak of gastroenteritis occurred in a school affecting more than 30% of its 535 students. An epidemiological survey questionnaire was given to all students as well as staff and maintenance personnel. Stool cultures and electronic microscopy were used to detect the presence of a Norwalk-like virus. Several analyses of water samples were also done. This outbreak occurred simultaneously in the two wings of the school (East and South). Those who used the East wing were most affected by the disease (RR = 1.45, CI 95%: 1,14-1,85). There was no indication of food or water supply contamination. A Norwalk-like virus was identified in the stool sample of one child. This along with the clinical characteristics strongly suggested that the pathogen was indeed a Norwalk-like virus. The analysis suggests transmission via contaminated surfaces but also via airborne transport of the infectious agent.

Seroepidemiologic study of three zoonoses (leptospirosis, Q fever, and tularemia) among trappers in Québec, Canada

This study was undertaken to evaluate the prevalence of antibodies against Francisella tularensis, Coxiella burnetii, and certain serovars of Leptospira interrogans among trappers in Québec, Canada. Muskrat trapping was identified as a risk factor for F. tularensis infection, whereas having a cat at home apparently protected trappers against infection by L. interrogans. High percentages of control sera were positive for antibodies against C. burnetii (15%) and L. interrogans (5%), most frequently serovar bratislava. This is the first report of human infection by serovar bratislava in North America.

Rapid, sensitive, and noninvasive sampling technique for determination of chloroform in alveolar breath

A sampling technique for the determination of chloroform in alveolar breath is presented. Subjects exhale in a homemade device for collection of the alveolar fraction. The collected sample is transferred to a partially evacuated headspace vial and subsequently analyzed by capillary gas chromatography using electron-capture detection. Concentrations greater than 50 micrograms/m3 can readily be detected. Good correlation observed between chloroform levels in alveolar breath and plasma validates the sampling technique.

Evaluation of dermal and respiratory chloroform exposure in humans

Chloroform is a known contaminant of chlorinated drinking water and of swimming pool water disinfected with chlorine or one of its derivatives. Few data exist regarding the importance of dermal and inhalation exposure routes to the chloroform body burden resulting from domestic and recreational use of chlorinated water. In our experimental study involving 11 male swimmers, we quantified the body burden resulting from exposure to various concentrations of chloroform in water and air of an indoor swimming pool, during a daily 55-min exercise period. From the first to the sixth exercise period, CHCl3 mean concentration in water was increased from 159 micrograms/l to 553 micrograms/l. Corresponding mean air CHCl3 level ranged from 597 ppb to 1630 ppb. To dissociate the dermal exposure route from that of inhalation, swimmers used scuba tanks during an additional exercise period. Chloroform concentrations were measured in alveolar air before and after each exercise period, as well as after 35 min of physical activity. Chloroform levels in water and air were measured every 10 min. We examined the relationship between alveolar air concentration (a measure of body burden) at 35 and 55 min and environmental chloroform concentrations by using multiple regression models. The natural logarithm of alveolar air concentration was strongly correlated with aqueous chloroform concentration both at 35 (p2 < 0.001, r2 = 0.75) and 55 min (p < 0.001, r2 = 0.86). The relationship with air concentrations was also statistically significant (35 min: p < 0.001, r2 = 0.58, 55 min: p < 0.001, r2 = 0.63).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of dermal and respiratory chloroform exposure in humans

Chloroform is a known contaminant of chlorinated drinking water and of swimming pool water disinfected with chlorine or one of its derivatives. Few data exist regarding the importance of dermal and inhalation exposure routes to the chloroform body burden resulting from domestic and recreational use of chlorinated water. In our experimental study involving 11 male swimmers, we quantified the body burden resulting from exposure to various concentrations of chloroform in water and air of an indoor swimming pool, during a daily 55-min exercise period. From the first to the sixth exercise period, CHCl3 mean concentration in water was increased from 159 micrograms/l to 553 micrograms/l. Corresponding mean air CHCl3 level ranged from 597 ppb to 1630 ppb. To dissociate the dermal exposure route from that of inhalation, swimmers used scuba tanks during an additional exercise period. Chloroform concentrations were measured in alveolar air before and after each exercise period, as well as after 35 min of physical activity. Chloroform levels in water and air were measured every 10 min. We examined the relationship between alveolar air concentration (a measure of body burden) at 35 and 55 min and environmental chloroform concentrations by using multiple regression models. The natural logarithm of alveolar air concentration was strongly correlated with aqueous chloroform concentration both at 35 (p2 < 0.001, r2 = 0.75) and 55 min (p < 0.001, r2 = 0.86). The relationship with air concentrations was also statistically significant (35 min: p < 0.001, r2 = 0.58, 55 min: p < 0.001, r2 = 0.63).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the microbiological quality of water coolers and that of municipal water systems

The microbiological quality of tap water and that of water from 50 water coolers located in residences and workplaces were comparatively studied. In addition, difference factors that might influence the bacteriological contamination of water dispensers were examined. Aeorbic and facultative anaerobic heterotrophic bacteria, total coliforms, and two indicators for fecal contamination (fecal coliforms and fecal streptococci) as well as three types of pathogenic bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, and Aeromonas spp.) were enumerated. It was found that 36 and 28% of the water dispenser samples from the residences and the workplaces, respectively, were contaminated by a least one coliform or indicator bacterium and/or at least one pathogenic bacterium. The respective proportions of tap water samples contaminated in a similar fashion were 18 and 22%, much less than those observed for water coolers (Chi2(1) = 3.71, P = 0.05). We were unable to discern the dominant factors responsible for the contamination of water coolers, but cleaning the water dispenser every 2 months seemed to limit the extent of contamination.