Determination of a guidance value for the communication of individual-level biomonitoring data for urinary arsenic.

BACKGROUND: Available guidance values to interpret individual-level biomonitoring data (ILBD) for the sum of urinary inorganic-related arsenic species (SUIAS) are generally based on population statistical descriptors and not on a predetermined exposure level that should not be exceeded. The objective of this study was thus to propose a range of SUIAS concentrations, reflecting an exposure corresponding to WHO's provisional guideline value (PGV) for arsenic in drinking water (10 µg/L), within which an exposure-based biomonitoring guidance value can be identified. METHOD A comprehensive literature review was carried out in order to identify studies that were relevant to the determination of a guidance value. Drinking water arsenic exposure and urinary biomonitoring concentrations obtained from selected studies were used to conduct a structural equation modeling meta-analysis, from which regression coefficients were obtained to derive an interpretative guidance range. RESULTS Individuals exposed to the arsenic background level comparable to North American and European countries and to a water source contaminated at the WHO's PGV, would have, on average, urinary SUIAS between 9 and 20 µg/L, with the most probable value being 15 µg/L. To address the associated uncertainty, the final guidance value selection within this range may be based on a targeted sensitivity and specificity towards detecting overexposed individuals. Indeed, spans of sensitivity of 60-82%, and of specificity of 58-85%, were estimated for the proposed range based on drinking water exposure raw data from the literature. CONCLUSION The range of guidance values obtained appears suitable for interpreting and communicating ILBD in any population biomonitoring studies in which background exposure is comparable to the North American and European context. Before selecting a single value within the proposed range, it will be important for Public Health officials to assess the possible consequences of this selection on the management and communication of the biomonitoring results.

Spatial Distribution of Parkinson's Disease Prevalence in Québec by Hydrographic Region.

The association between environmental exposures and Parkinson's disease continues to garner interest. In the late 1980s, Barbeau et al. reported in the Canadian Journal of Neurological Sciences a heterogeneous distribution of Parkinson's disease cases across the province of Québec by hydrographic region. Here we report the findings of a validation study based on data obtained from the Québec medication insurance program-information which was unavailable to the previous group. Similar to Barbeau et al., our analysis showed a heterogeneous distribution of cases across the province with higher prevalence in the same region of interest, in addition to other areas.

A Physiologically-Based Pharmacokinetic Modeling Approach Using Biomonitoring Data in Order to Assess the Contribution of Drinking Water for the Achievement of an Optimal Fluoride Dose for Dental Health in Children.

Due to an optimal fluoride concentration in drinking water advised for caries prevention purposes, the population is now exposed to multiple sources of fluoride. The availability of population biomonitoring data currently allow us to evaluate the magnitude of this exposure. The objective of this work was, therefore, to use such data in order to estimate whether community water fluoridation still represents a significant contribution toward achieving a suggested daily optimal fluoride (external) intake of 0.05 mg/kg/day. Therefore, a physiologically-based pharmacokinetic model for fluoride published in the literature was used and adapted in Excel for a typical 4-year-old and 8-year-old child. Biomonitoring data from the Canadian Health Measures Survey among people living in provinces with very different drinking water fluoridation coverage (Quebec, 2.5%; Ontario, 70% of the population) were analyzed using this adapted model. Absorbed doses for the 4-year-old and 8-year-old children were, respectively, 0.03 mg/kg/day and 0.02 mg/kg/day in Quebec and of 0.06 mg/kg/day and 0.05 mg/kg/day in Ontario. These results show that community water fluoridation contributes to increased fluoride intake among children, which leads to reaching, and in some cases even exceeding, the suggested optimal absorbed dose of 0.04 mg/kg/day, which corresponds to the suggested optimal fluoride intake mentioned above. In conclusion, this study constitutes an incentive to further explore the multiple sources of fluoride intake and suggests that a new balance between them including drinking water should be examined in accordance with the age-related physiological differences that influence fluoride metabolism.

Association between consumption of private well water contaminated by low levels of arsenic and dysglycemia in a rural region of Quebec, Canada.

The association between arsenic (As) exposure and diabetes is not clearly defined for populations exposed to low or moderate levels of inorganic As (iAs) in drinking water (< 150µg/L). In the present study, the relationship between iAs concentration in drinking water (contaminated at a median level of 10.5µg/L) or As biomarkers (ie, urine and nails) and diabetes or prediabetes (defined as level of glycosylated hemoglobin - HbA1c - higher than 6%, self-reported diagnosis of diabetes by a physician, or the use of insulin or oral hypoglycemic drugs) was evaluated in 257 adults from Canada. For that we used logistic regression models and reported the odds ratio (OR) comparing participants in the 80th vs 20th percentile of iAs exposure indicators. The association between iAs exposure indicators and HbA1c was also explored for 234 adults and 35 children not taking insulin or oral hypoglycemic drugs using a linear regression analysis. All models were controlled for confounding variables (age, gender, first-degree family history of diabetes, obesity or overweight in adults' model). We attempted to exclude adults with organic arsenic of marine origin in their urine by removing participants with detectable arsenobetaine or arsenocholine in urinary models. iAs biomarkers (toenail and urine) were not associated with diabetes or prediabetes in adults. iAs in well water was associated with a borderline significantly increased odds of diabetes or prediabetes (OR = 2.39; 95% CI: 0.99-5.72). Higher well water iAs concentrations were significantly associated with increased HbA1c in both adults and children (ß: 0.002; p = 0.041 and ß: 0.003; p < 0.0001 respectively). In children, HbA1c was also associated with toenail As concentration (ß: 0.18; p = 0.016). These results suggest low-level iAs exposure is associated with a continuum of dysglycemia.

Implementation of a radon measurement protocol and its communication plan by child care centre managers in Québec.

OBJECTIVES: To invite and support managers of child care centres to measure radon concentrations in their buildings. Their ability to carry out a measurement protocol and communication plan was also evaluated as well as the intention of parents and educators to test for radon at home. PARTICIPANTS: Managers, parents and educators of child care centres. SETTING: 36 child care centres located in two priority investigation areas in Québec. INTERVENTION: A kit containing radon detectors with installation and recovery instructions was shipped by mail in addition to factsheets intended for parents and educators. Site visits and phone calls were also conducted with a sample of child care centres and participants. OUTCOMES: The instructions related to detector installation were generally well respected. Afterward, more than half (18) of the 34 parents and educators interviewed said that they had been directly informed of this radon testing by managers or other educators, and not by the factsheet provided. This radon measurement intervention was considered very relevant by 91% of them and a quarter (26%) expressed their intention to test for radon at home, while 6% had already done so. Two child care centres (5.5%) had at least one measurement above the Canadian guideline level of 200 Bq/m3. CONCLUSION: This intervention has demonstrated the ability of child care centre managers to carry out this type of autonomous procedure, which can be centralized to minimize costs. This type of intervention may influence parents to become more familiar with this contaminant and measure their family's exposure at home.

Measurements of Arsenic in the Urine and Nails of Individuals Exposed to Low Concentrations of Arsenic in Drinking Water From Private Wells in a Rural Region of Québec, Canada.

Chronic exposure to inorganic arsenic leads to an increased risk of cancer. A biological measurement was conducted in 153 private well owners and their families consuming water contaminated by inorganic arsenic at concentrations that straddle 10 µg/L. The relationship between the external dose indicators (concentration of inorganic arsenic in wells and daily well water inorganic arsenic intake) and the internal doses (urinary arsenic--sum of As(III), DMA, and MMA, adjusted for creatinine--and total arsenic in toenails) was evaluated using multiple linear regressions, controlling for age, gender, dietary sources of arsenic, and number of cigarettes smoked. It showed that urinary arsenic was associated with concentration of inorganic arsenic in wells (p < .001) and daily well water inorganic arsenic intake (p < .001) in adults, and with daily well water inorganic arsenic intake (p = .017) and rice consumption (p = .022) in children (n = 43). The authors' study reinforces the drinking-water quality guidelines for inorganic arsenic.

Radon measurement in schools located in three priority investigation areas in the province of Quebec, Canada.

The purpose of this study was to measure radon concentration in public primary schools located in priority investigation areas, with the aim of decreasing occupants' exposure to radon in public buildings where concentrations exceed the Canadian Federal guidelines (i.e. 200 Bq m(-3)). In addition, the association between radon levels, substratum geological characteristics and schools' structural characteristics were investigated. The results showed that radon concentrations measured in the 65 investigated schools are generally below the Federal guideline levels. Eleven schools (17 %) had at least one measurement above the Federal guideline, while one had a level above 600 Bq m(-3). On average, targeted schools' occupants are exposed to radon concentrations of 56 Bq m(-3). Although statistical analysis, which was limited by the sample size, did not show any link between aggregated radon measurements and geochemical or radiological signatures of investigated sites, the geological evidence that led to the choice of the studied regions remains relevant.

Variation spatiotemporelle de la cryptorchidie et de l'hypospadias au Québec : Une étude exploratoire.

RéSUMé: OBJECTIFS: : La majorité des études effectuées au cours des dernières décennies ont mis en évidence une augmentation du nombre de cas de cryptorchidie et d'hypospadias entre 1970 et 1990. De plus, l'importante variabilité géographique de ces anomalies est bien décrite. Cette étude vise à mesurer la prévalence à la naissance de la cryptorchidie et de l'hypospadias au Québec, à vérifier si ces anomalies sont en augmentation et à en évaluer la répartition interrégionale. MéTHODE :: Une étude épidémiologique descriptive a été réalisée à partir du nombre de garçons de cinq ans et moins hospitalisés pour une cryptorchidie ou un hypospadias au Québec de 1989 à 2004 selon les données du fichier administratif d'hospitalisation MED-ÉCHO. Les données sur les naissances provenaient de l'Institut de la statistique du Québec. RéSULTATS :: La prévalence annuelle moyenne pour 1000 naissances vivantes de sexe masculin est de 19,1 (IC à 95 % : 18,8-19,4) pour la cryptorchidie et 11,4 (IC à 95 % 11,1-11,6) pour l'hypospadias au Québec. Au cours de la période étudiée, la prévalence de cryptorchidie a légèrement diminué, alors que celle de l'hypospadias est demeurée stable. Comparativement à la province du Québec, des régions présentent une prévalence significativement différente de cryptorchidie et/ou d'hypospadias. . CONCLUSION: : Au Québec, la prévalence de cryptorchidie est en légère diminution alors que celle de l'hypospadias est stable. Des variations régionales significatives sont observables. D'autres études sont nécessaires afin d'évaluer l'hypothèse d'un lien avec les contaminants environnementaux en émergence. L'implantation d'un système de surveillance des anomalies congénitales permettrait une représentation plus valide de la situation.

Evaluation of the effectiveness of arsenic screening promotion in private wells: a quasi-experimental study.

The Eastern Townships (ETR) is a region in Québec (Canada) where the soil is naturally rich in arsenic (As). About a third of the people in the ETR obtain their water from a private well. A quasi-experimental design was used to compare two campaigns designed to promote As screening in well water: a mass-media campaign (MMC) followed or not by a community-based intervention (CBI). The MMC is based on a press release issued for the ETR, along with a leaflet on As made available on the Internet, and in strategic places. The CBI, formulated according to the factors of the Precede-Proceed model, was aimed at mobilizing local authorities and small media. It targets only one municipality; the intervention community (IC). Using a separate pre-post samples design, two population-based cross-sectional (pre-CBI and post-CBI) surveys were conducted by phone at 6-month intervals, by means of random samples. The samples counted, for the IC and the ETR, respectively, 87 and 156 well owners in pre-CBI, and 106 and 190 in post-CBI. The results in post-CBI showed that the proportion of well owners who had their water test increased by four times in the IC after (16% p = 0.004). When adjusting for age and gender among all the post-CBI respondents, As screening is related with intervention status (exposed to MMC and CBI; p ≤ 0.001) and on previous microbiological water analysis behavior (p ≤ 0.05), but is not related to knowledge. This study demonstrates the superiority of a community-based campaign over a MMC when environmental health is concerned.

Repeated measures of validated and novel biomarkers of exposure to polycyclic aromatic hydrocarbons in individuals living near an aluminum plant in Quebec, Canada.

A longitudinal biomonitoring study was conducted to assess exposure to polycyclic aromatic hydrocarbons (PAH) in non-occupationally exposed nonsmoking adults living in the vicinity of an aluminum plant. Metabolites of several PAH (pyrene, naphthalene, chrysene, fluoranthene, benz[a]anthracene) were measured in the urine of the participants, including 1-hydroxypyrene (1-OHP) as a validated biomarker and pyrene diones as novel biomarkers. In total, 73 individuals living about 1 km away from the plant (taken as the exposed group) were compared repeatedly with 71 individuals living at least 11 km from the smelter (used as the control group). Complete first morning voids were collected twice, at a 2-wk interval, in the fall of 2005 and twice weekly for 2 consecutive weeks in the spring of 2006. Urinary biomarker concentrations were then measured by an ultra-performance liquid chromatography (UPLC) method with time-of-flight mass spectrometry detection (MS-TOF) (UPLC-MS-TOF). For most sampling days, individuals living near the plant showed significantly higher excretion values of both 1-OHP and pyrene diones (mean ratio up to 2- and 2.4-fold, respectively) than individuals living further from the plant. In the group living near the plant, geometric mean concentrations of 1-OHP varied from 0.047 to 0.058 micromol/mol creatinine, depending on the sampling day, as compared to 0.025 to 0.04 micromol/mol creatinine in the reference group. Corresponding mean values for pyrene diones were 0.017-0.056 micromol/mol creatinine and 0.014-0.039 micromol/mol creatinine, respectively. Urinary 1- and 2-naphthols were also measured as a reference and showed no significant differences between the two groups for most sampling days; metabolite concentrations of the other monitored PAH (chrysene, fluoranthene, benz[a]anthracene) were mostly below the analytical limit of detection of 0.005 to 0.01 microg/L, depending on the metabolite, with a detection rate varying from 0 to at most 21%. Individuals living near the aluminum plant thus appeared to be repeatedly exposed to higher pyrene levels than the control group, on the basis of both 1-OHP and pyrene dione excretions. However, 1-OHP concentrations observed in this first group were similar to those of other reference populations of nonsmokers studied in the past. Uptake of the other PAH associated with plant emissions was too small to significantly increase the excretion of their metabolites.

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.

Compliance with fluoride supplements provided by a dental hygienist in homes of low-income parents of preschool children in Quebec.

OBJECTIVE: This study aimed to assess the compliance with fluoride supplements provided at home by a dental hygienist to mothers of at-risk preschool children. METHODS: Participants were recruited during pregnancy of low-income women. On the first visit, the mothers of 60 infants aged 6 to 9 months were handed free fluoride supplements. A questionnaire was administered at that time and after 6 and 12 months to assess compliance during the preceding week. RESULTS: At the beginning of the study, none of the mothers reported having given fluoride supplements, in comparison with 73 percent of mothers of 44 infants who received all three visits at the end of follow-up; 48 percent reported fluoride supplement use on a daily basis. CONCLUSIONS: Removal of financial and physical barriers and personal professional involvement are good strategies to achieve compliance with fluoride supplements. Further assessment regarding the possible application of this intervention to other professional or cultural contexts is warranted.

[A study to assess the microbial contamination of Mya arenaria clams from the north shore of the St Lawrence River estuary, (Québec, Canada)]. / Etude 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.

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.

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.

Chemical risks associated with consumption of shellfish harvested on the north shore of the St. Lawrence River's lower estuary.

Shellfish have the capacity to accumulate chemical contaminants found in their biotope and therefore present a potential risk for consumers. This study was conducted to assess the chemical risks associated with consumption of shellfish harvested on the north shore of the St. Lawrence River's lower estuary. A survey was carried out on 162 recreational harvesters, and shellfish were sampled for chemical contaminant analysis. We quantified 10 metals, 22 polycyclic aromatic hydrocarbons (PAHs), 14 polychlorinated biphenyls (PCBs), and 10 chlorinated pesticides. We subsequently evaluated cancer and noncancer risks for four consumption scenarios based on our survey results and published results. Soft-shell clams (Mya arenaria) were by far the most consumed shellfish species. Of the 56 selected contaminants, 36 were detected in the 23 homogenates of soft-shell clam meat. None of the contaminants found in the soft-shell clams were associated with intakes that exceed the main exposure limit recommendations proposed to prevent noncancer effects. However, several limits must be considered before drawing conclusions about the relative safety of shellfish consumption regarding this end point. Furthermore, inorganic arsenic and PCBs were present in sufficient concentrations to lead to cancer risks exceeding the level often considered acceptable for environmental exposure (1 x 10 (-4) to 1 x 10(-6)) in each of the four scenarios, even for the lowest observed scenario of 15 meals of soft-shell clams per year.