A population-based study on blood lead levels in blood donors.

BACKGROUND: Recent studies suggested that blood transfusion may represent a significant source of lead exposure in premature infants. Objectives of this study were to determine blood lead levels (BLLs) in a representative sample of blood donors and to identify risk factors associated with BLLs of 0.15 µmol/L or more. STUDY DESIGN AND METHODS: A study was conducted in 2006 to 2007 in 49 drive sites in Quebec. Individuals who qualified for blood donation were eligible to participate. Information was harvested from blood donor file and a standardized self-administered questionnaire. Lead analysis was performed by inductively coupled plasma mass spectrometry. Data on Quebec blood donors from 2003 to 2006 (n = 320,543) were used to establish a reference population. Geometric mean (GM) and 95% confidence interval (CI) were used to describe the results. The project was approved by an ethics committee. RESULTS: Of 6715 eligible individuals, 3490 participated (1392 women and 2098 men). Their mean age was 46.5 years. Results were weighted for region, sex, and age. The GM of BLLs was 0.082 µmol/L (95% CI, 0.027-0.247; range, 0.011-2.90 µmol/L). BLLs of more than 0.15 µmol/L were found in 15.5% of participants. In multivariate analysis, BLLs were mainly explained by age and sex of participants (p < 0.001). A significant association was also found between BLLs and the region of residence, education level, dwelling age, occupational and leisure activities at high risk for lead exposure, smoking, and alcohol intake (p < 0.001). CONCLUSION: BLL in blood donors is strongly explained by sex and age, a fact that can be taken into consideration when transfusing neonates.

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.

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.

Escherichia coli O157:H7 outbreak linked to raw milk cheese in Quebec, Canada: use of exact probability calculation and casecase study approaches to foodborne outbreak investigation.

The analytical studies used to investigate foodborne outbreak are mostly case-control or retrospective cohort studies. However, these studies can be complex to perform and susceptible to biases. This article addresses basic principles of epidemiology, probability, and the use of case-case design to identify the source of an Escherichia coli O157:H7 outbreak linked to raw milk cheese consumption in Quebec, Canada; a small number of cases with the same pulsed-field gel electrophoresis (PFGE) profile were involved. Between 4 December 2008 and 15 January 2009, a cumulative total of 16 E. coli O157:H7 cases with the same PFGE profile were reported to Quebec public health authorities. Among the first six cases reported, three had consumed raw milk cheese from the same producer (cheese A). Raw milk cheese is consumed by about 2 % of the Quebec population. By using the exact probability calculation, it was found that a significantly higher proportion of E. coli O157:H7 cases (with the specific PFGE profile) than expected had consumed cheese A (P < 0.001). These computations were updated during the course of the investigation to include subsequent cases and gave the same results. A case-case study corroborated this result. This article considers alternative statistical and epidemiological approaches to investigate a foodborne outbreak-in particular with an exact probability calculation and case-case comparisons. This approach could offer a fast and inexpensive alternative to regular case-control studies to target public health actions, particularly during a foodborne outbreak.

A study of the association between characteristics of CLSCs and the risk of small for gestational age births among term and preterm births in Quebec, Canada.

OBJECTIVES: The objective of this study was to describe whether the social environment of the territory of residence is associated with indicators of foetal growth retardation. METHODS: All newborns (n = 667,254) from 143 Centres locaux de services communautaires (CLSC) territories of Quebec, Canada, 2000-2008 were included in this study. Small for gestational age (SGA), very small for gestational age (VSGA) and SGA-preterm births were identified. Social characteristics and access to medical services of the population in the CLSCs were obtained from the Canadian Community Health Survey. Data on material deprivation, racial diversity and social isolation were obtained from the 2001 and 2006 Canadian censuses. A compromise between two methods, stepwise and best subset, was used to select variables for multivariate logistic modelling. The model was fitted on each studied outcome: SGA, VSGA and SGA among preterm births. RESULTS: When investigating material deprivation, racial diversity, social isolation, proportion of sedentary residents and proportion with fair or poor availability of health care services in the CLSC territories, material deprivation, racial diversity, social isolation and sedentary residents showed increased adjusted risk of SGA. Results of the model fit on VSGA birth and on SGA among preterm births were similar. CONCLUSION: CLSC characteristics of material deprivation, racial diversity, social isolation as well as the contextual variable of sedentary lifestyle were associated with indicators of foetal growth retardation. Further work on features of the CLSCs could help understand how the outcome of SGA is associated with contextual factors and identify groups for intervention.

Maternal exposure to drinking-water chlorination by-products and small-for-gestational-age neonates.

BACKGROUND: There is concern about possible effects of disinfection by-products on reproductive outcomes. The purpose of this study was to evaluate the association between maternal exposure to chlorination by-products and the risk of delivering a small for-gestational-age (SGA) neonate. METHODS: We conducted a population-based case-control study in the Québec City (Canada) area. Term newborn cases with birth weights <10th percentile (n = 571) were compared with 1925 term controls with birth weights ≥10th percentile. Concentrations of trihalomethanes and haloacetic acids in the water-distribution systems of participants were monitored during the study period, and a phone interview on maternal habits was completed within 3 months after childbirth. We estimated chlorination by-products ingestion during the last trimester of pregnancy and trihalomethanes doses resulting from inhalation and dermal exposure. We evaluated associations between chlorination by-products in utero exposure and SGA by means of unconditional logistic regression with control of potential confounders. RESULTS: When total trihalomethanes and the 5 regulated haloacetic acids concentrations were divided into quartiles, no clear dose-response relationship was found with SGA. However, increased risk was observed when haloacetic concentrations were above the fourth quartile and when either trihalomethanes or haloacetic acids concentrations were above current water standards (adjusted OR= 1.5 [95% confidence interval = 1.1-1.9] and 1.4 [1.1-1.9], respectively). Inhalation and dermal absorption of trihalomethanes did not contribute to this risk, but a monotonic dose-response was found with haloacetic acids ingestion. CONCLUSION: Oral exposure to high levels of chlorination by-products in drinking water could be a risk factor for term SGA.

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

BACKGROUND: 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. METHODS: 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 (> or = 90th percentile), moderate (50th to <90th percentile), low (10th to <50th percentile), and very low (<10th percentile) precipitation. RESULTS: 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. CONCLUSIONS: 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.

Plasma omega-3 and psychological distress among Nunavik Inuit (Canada).

Marine omega-3 (n-3) fatty acid eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids have been associated with beneficial effects in mental health. Cultural and social changes have been related to a decline in mental health of the Inuit, but the role of diet has received scant attention. We examined the relationship between psychological distress (PD) and plasma n-3 among 368 Nunavik Inuit aged 18-74 years who took part in a survey in 1992. Participants were categorized as high-level PD if they scored over the 80th percentile of the PD Index Santé-Québec Survey (PDISQS-14), and non-distressed subjects were those who scored less than this cutoff. Compared with the non-distressed group, n-3 concentrations in the PD group were significantly lower in women but not in men. Compared with the lowest tertile of EPA + DHA, the odds ratios for high-level PD among women were 0.32 (95% CI: 0.13-0.82) for the second, and 0.30 (95% CI: 0.10-0.90) for the third tertile, after controlling for confounders. In males, there were no significant associations between EPA+DHA and PDISQS-14 scores. Our findings suggest that marine n-3 may play a role in PD among Inuit women. The gender difference observed in our analysis must be examined more carefully in future studies.

Risk of diarrhea with adult residents of municipalities with significant livestock production activities.

BACKGROUND: The intensification of livestock production has led to situations where the amount of manure that is produced exceeds the amounts needed in some areas. The objective of this study was to evaluate the relationship between the intensity of livestock activities and manure products, particularly in swine farms, and the prevalence of diarrhea in adults. METHODS: A survey was carried out on 8702 adults living in 161 municipalities in Quebec areas with intensive farming activities. Data were collected by a telephonic interview on diarrheal symptoms that occurred during the previous week of the interview, on water consumption and on selected risk factors. Statistical analysis was performed using a 'generalized estimating equations' model. RESULTS: Prevalence of diarrhea was found to be highest in adults aged between 25 and 34 years. No association was found between swine density or liquid manure application and diarrheal prevalence. There was also no association between cattle or total animal density and diarrheal prevalence. In the areas studied, there was no increase in risk associated with the consumption of tap water with suboptimal treatment and susceptible to microbiologic contamination. CONCLUSION: Significant livestock production and excess of manure were not associated with the risk of diarrhea in adults.

Plasma n-3 fatty acids and psychological distress in aboriginal Cree Indians (Canada).

OBJECTIVE: To examine the relationship between psychological distress (PD) and plasma n-3 long-chain (LC) PUFA, i.e. EPA, docosapentaenoic acid (DPAn-3) and DHA. DESIGN: Population-based, cross-sectional Santé-Québec Health Survey (1991). Participants were categorized as high-level PD if they scored over the 80th percentile of the PD Index in the Santé-Québec Survey; non-distressed subjects were those who scored less than this cut-off. Associations between tertiles of n-3 fatty acids (FA) and the risk of high-level PD were expressed as odds ratios, with the lowest tertile as the reference group. SETTING: Québec, Canada. SUBJECTS: Data were analysed from a representative sample of 852 James Bay Cree Indian adults aged 18 years and over. RESULTS: Proportions of n-3 FA were statistically significantly lower in the PD than in the non-distressed group. After adjustment for confounders, EPA was the only individual n-3 FA significantly associated with the risk of high-level PD. Combinations of EPA + DHA or EPA + DPAn-3 + DHA or the sum of n-3 were also associated with the risk of high-level PD. Compared with the lowest tertile of EPA + DHA, the OR for high-level PD was 0.89 (95 % CI 0.59, 1.36) for the second and 0.56 (95 % CI 0.32, 0.98) for the third tertile, after controlling for confounders. CONCLUSIONS: In the present retrospective, cross-sectional study, we found that proportions of n-3 LC PUFA in plasma phospholipids, markers of n-3 LC PUFA consumption from fish, were inversely associated with PD.

[Evaluation of the efficacy of the Toxoplasma gondii screening program among pregnant women in Nunavik, 1994-2003]. / Evaluation du Programme de dépistage de la toxoplasmose chez les femmes enceintes du Nunavik, 1994-2003.

OBJECTIVES: (1) To evaluate the efficacy of the Toxoplasma gondii screening program among Nunavik pregnant women in identifying seroconversions during pregnancy and performing an appropriate follow-up of the seroconverted women and their child; and (2) to evaluate the consequences of congenital Toxoplasma gondii infection. PARTICIPANTS: Women of child-bearing age and their children born between January 1994 and September 2003. SETTING: Nunavik. INTERVENTION: Potential cases of infection during pregnancy and of congenital toxoplasmosis were identified on the basis of serologic and hospitalization data. A medical chart revision was then performed. Descriptive statistics regarding the medical follow-up and treatment of suspected cases were compiled. OUTCOMES: 31 women who gave birth to 32 children were identified as potential cases. According to the medical charts, 19 women had a potential infection during pregnancy, the others were deemed to have been infected before conception. One woman had a definite infection. This woman and most of the 18 other potentially infected women and their children were treated appropriately. Because of missing data, it was impossible to determine with certainty the final status of two children. A diagnosis of congenital infection was rejected among the other children. CONCLUSION: Women with suspected infection and their children were generally well managed by the health care system. No clinical effect of congenital toxoplasmosis was noted during the studied period.

Comparison of diagnostic criteria of the metabolic syndrome in 3 ethnic groups of Canada.

The metabolic syndrome (MetS) is a cluster of metabolic abnormalities in which visceral obesity is a prominent feature. Although a matter of debate, the MetS essentially represents "at risk obesity." The purpose of this study was to compare the various definitions of MetS, with a special focus on abdominal obesity, and to explore sex and ethnic differences in the prevalence and nature of this syndrome in 3 ethnic groups residing in the Canadian province of Québec. The study population included adult participants of 3 cross-sectional health surveys conducted in southern Québec, James Bay, and Nunavik between 1990 and 1992. A total of 2613 adults (18-74 years old) were included: 1417 Quebecers, 817 Indian Crees, and 379 Inuit. The prevalence of MetS varied by definitions, and the highest agreement was observed between the National Cholesterol Education Program-Adult Treatment Panel III and the International Diabetes Federation (79%). Most women (25%), regardless of ethnic origin, presented with a "triad" profile characterized by high waist circumference, elevated triglycerides, and low high-density lipoprotein, whereas 20% of men had the "deadly quartet" of high blood pressure with the triad mentioned above. Furthermore, our results highlight an obvious difference in the impact of the increased abdominal obesity on metabolic parameters such as insulin resistance measured by the homeostasis model assessment according to ethnic origin (P < .001). These 3 unique population-based samples suggest that abdominal obesity does not have a similar deleterious impact according to ethnicity, suggesting the need for an ethnic-based MetS definition.

Drinking water intake by infants living in rural Quebec (Canada).

Drinking water is a potential source of toxic contaminant and it is well known that water intake on a body weight basis decreases rapidly with increasing age. Nevertheless, few studies have been conducted on water intake of very young infants who might be particularly sensitive to some toxic chemicals. The objective of this study was to describe the mean and distribution of total water intake of 2-month old infants living in agricultural areas. Mothers (n=642) of 8 to 9 week old infants were interviewed by phone to evaluate their feeding practice, including juice and cereal intake. There were 393 infants (61%) who drank some quantity of water and 278 (43%) consumed formula reconstituted with water. For formula-fed infants, the 10, 50 and 90th percentiles of daily water intake were 79, 112, and 179 ml/kg respectively. These values are much higher than the intake recommended by US EPA for infants under one year (US EPA, 1997). This study demonstrates the importance of considering water distribution intake in very young infants who may be particularly susceptible to water contaminants.

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.

Plasma organochlorine concentrations and bone ultrasound measurements: a cross-sectional study in peri-and postmenopausal Inuit women from Greenland.

BACKGROUND: Inuit women are highly exposed through their traditional seafood based diet to organochlorine compounds, some of them displaying endocrine disrupting properties. We hypothesized that this exposure might be related to bone characteristics that are altered in osteoporosis, because hormone deficiency is a known risk factor for the disease. METHODS: We measured quantitative ultrasound parameters (QUS) at the right calcaneum of 153 peri- and postmenopausal Inuit women (49-64 year old) from Nuuk, Greenland, and investigated the relation between these parameters and plasma organochlorine concentrations. We used high-resolution gas chromatography with electron capture detection to analyze plasma samples for 14 polychlorinated biphenyls (PCB) congeners and 11 chlorinated pesticides and metabolites. We analysed morning urine samples for cadmium, a potential confounder, by atomic absorption spectrometry. We used a validated questionnaire to document dietary and lifestyle habits as well as reproductive and medical histories. RESULTS: Concentrations of PCB 153, a surrogate of exposure to most organochlorines present in plasma samples, were inversely correlated to QUS parameters in univariate analyses (p < 0.001). However, PCB 153 concentrations were not associated with QUS values in multivariate analyses that comprised potential confounding factors such as age, body weight, former oral contraceptive use and current hormone replacement therapy (HRT) use, which were all significant predictors of bone stiffness (total R2 = 0.39; p < 0.001). CONCLUSION: Overall we found little evidence that organochlorines exposure is related to osteoporosis in Greenlandic Inuit women, but the hypothesis that exposure to dioxin-like compounds might be linked to decreased bone quality and osteoporosis deserves further attention.

[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.

Alterations of visual evoked potentials in preschool Inuit children exposed to methylmercury and polychlorinated biphenyls from a marine diet.

The aim of the present study was to assess the impact of chronic exposure to polychlorinated biphenyls (PCBs) and methylmercury on visual brain processing in Inuit children from Nunavik (Northern Québec, Canada). Concentrations of total mercury in blood and PCB 153 in plasma had been measured at birth and they were again measured at the time of testing in 102 preschool aged children. Relationships between contaminants and pattern-reversal visual evoked potentials (VEPs) were assessed by multivariate regression analyses, taking into account several potential confounding variables. The possible protective effects of selenium and omega-3 polyunsaturated fatty acids against methylmercury and PCB toxicity were also investigated. Results indicate that exposure to methylmercury and PCBs resulting from fish and sea mammal consumption were associated with alterations of VEP responses, especially for the latency of the N75 and of the P100 components. In contrast, the concomitant intake of omega-3 polyunsaturated fatty acids was associated with a shorter latency of the P100. However, no significant interactions between nutrients and contaminants were found, contradicting the notion that these nutrients could afford protection against environmental neurotoxicants. Interestingly, significant associations were found with concentrations of neurotoxicants in blood samples collected at the time of testing, i.e. at the preschool age. Our findings suggest that VEP can be used as a valuable tool to assess the developmental neurotoxicity of environmental contaminants in fish-eating populations.

The determinants of prevalence of health complaints among young competitive swimmers.

OBJECTIVES: Chloramines, which are produced by the reaction of chlorine with the organic matter present in indoor pools, are potential airway irritants in swimmers. The objective of this study was to compare the prevalence of health complaints of young swimmers and young indoor soccer players and to evaluate the relationship between chloramine concentrations and the athletes' health complaints. METHODS: Health complaints were first (Part 1) documented by questionnaire in 305 competitive swimmers and 499 indoor soccer players of the Québec City region (Canada). Then, (Part 2) health complaints were documented during five training sessions in 72 competitive swimmers in comparison to 73 soccer players. The chloramines in the swimming pool air and water were measured as well as the peak expiratory flow (PEF) before and after the training session. RESULTS: In Part 1, the swimmers reported more lower (adjusted OR: 1.5; IC95%= 1.0-2.2) and upper respiratory symptoms (adjusted OR: 3.7; IC95%= 2.4-5.8). In Part 2, the swimmers experienced more frequent lower (adjusted OR: 3.5; IC95%= 2.0-6.0) and upper respiratory symptoms (adjusted OR: 3.1; IC95%= 1.8-5.4). Overall, swimmers exposed to the highest levels of chloramines in the air and water had more respiratory complaints. CONCLUSIONS: Swimmers exposed to chlorination by-products in both the water and air of indoor swimming pools experience frequent respiratory symptoms that could potentially be reduced by limiting exposure to these products.