Short communication: Evaluation of a foot dirtiness scoring system for dairy cows.

Lameness in dairy cattle is an important health and welfare concern directly affecting the economic benefits of farmers. Although foot dirtiness is a recognized risk factor for diseases inducing lameness, there is a lack of scoring systems that focus specifically on the foot. Therefore, the aim of this study was to evaluate the reliability of a 3-point dirtiness scoring system recently conceived for the assessment of the dirtiness present at the lower legs and claws of dairy cows. The scores of both the lateral and back views from 4 unfamiliar raters at 4 different times were used to evaluate interrater reliability (3 times) and intrarater scoring consistency (1 time). The findings of this investigation revealed that coefficients for interrater agreement (0.38, 0.62 and 0.63) and rating concordance (0.55, 0.75 and 0.74) of back-view scorings improved over time and were superior or similar to those obtained from lateral-view evaluations (coefficients for interrater agreement = 0.20, 0.35, and 0.69; coefficients for rating concordance = 0.48, 0.59, and 0.78). Additionally, the scoring consistency of the raters using the back-view grid was excellent (Cronbach's α = 0.93). The results suggest that the 3-point back-view dirtiness scoring grid may provide dairy consultants and farmers a reliable and easy tool for assessing cow foot dirtiness.

Association between prenatal care and small for gestational age birth: an ecological study in Quebec, Canada. / Lien entre les soins prénataux et le faible poids pour l'âge gestationnel à la naissance : une étude écologique au Québec (Canada).

BACKGROUND: In Quebec, women living on low income receive a number of additional prenatal care visits, determined by their area of residence, of both multi-component and food supplementation programs. We investigated whether increasing the number of visits reduces the odds of the main outcome of small for gestational age (SGA) birth (weight < 10th percentile on the Canadian scale). METHODS: In this ecological study, births were identified from Quebec's registry of demographic events between 2006 and 2008 (n = 156 404; 134 areas). Individual characteristics were extracted from the registry, and portraits of the general population were deduced from data on multi-component and food supplement interventions, the Canadian census and the Canadian Community Health Survey. Mothers without a high school diploma were eligible for the programs. Multilevel logistic regression models were fitted using generalized estimating equations to account for the correlation between individuals on the same territory. Potential confounders included sedentary behaviour and cigarette smoking. The odds ratios (ORs) were adjusted for mother's age, marital status, parity, program coverage and mean income in the area. RESULTS: Mothers eligible for the programs remain at a higher odds of SGA than non-eligible mothers (OR = 1.40; 95% confidence interval [CI]: 1.30-1.51). Further, areas that provide more visits to eligible mothers (4-6 food supplementation visits) seem more successful at reducing the frequency of SGA birth than those that provide 1-2 or 3 visits (OR = 0.86; 95% CI: 0.75-0.99). CONCLUSION: Further studies that validate whether an increase in the number of prenatal care interventions reduces the odds of SGA birth in different populations and evaluate other potential benefits for the children should be done.

INTRODUCTION: Au Québec, les femmes vivant avec un faible revenu reçoivent un certain nombre de visites de soins prénataux supplémentaires, en fonction de leur lieu de résidence, dans le cadre d'un programme à multiples composantes et d'un programme d'intervention comprenant des suppléments alimentaires. Nous avons examiné si l'augmentation du nombre de visites réduisait le risque de faible poids pour l'âge gestationnel à la naissance (poids inférieur au 10e percentile sur l'échelle canadienne). MÉTHODOLOGIE: Pour cette étude écologique, nous avons sélectionné les naissances dans le registre des événements démographiques du Québec entre 2006 et 2008 (n = 156 404; 134 secteurs). Les caractéristiques individuelles ont été extraites du registre des naissances alors que les portraits de la population générale ont été déduits de données sur l'intervention à multiples composantes et du programme d'intervention comprenant des suppléments alimentaires, ainsi que des recensements canadiens et des Enquêtes sur la santé dans les collectivités canadiennes. Ont été considérées comme admissibles aux programmes les mères sans diplôme d'études secondaires. Les modèles de régression logistique multiniveaux ont été ajustés à l'aide d'équations d'estimation généralisées pour tenir compte de la corrélation entre les individus vivant sur un même territoire. Les principaux facteurs confusionnels potentiels étaient la sédentarité et le tabagisme. Les rapports de cotes (RC) ont été ajustés en fonction de l'âge, de l'état matrimonial et de la parité de la mère ainsi que de la couverture du programme et du revenu moyen dans le secteur. RÉSULTATS: Les mères admissibles aux programmes se sont révélées plus à risque de donner naissance à un bébé de faible poids pour l'âge gestationnel à la naissance que les autres mères (RC = 1,40; intervalle de confiance [IC] à 95 % : 1,30 à 1,51). De plus, les secteurs offrant un plus grand nombre de visites aux mères admissibles (4 à 6 visites dans le cadre du programme d'intervention comprenant des suppléments alimentaires) semblent mieux réussir à réduire la fréquence du faible poids pour l'âge gestationnel à la naissance que ceux offrant soit 1 ou 2 visites, soit 3 visites (RC = 0,86; IC à 95 % : 0,75 à 0,99). CONCLUSION: Il est nécessaire de conduire des études supplémentaires pour valider qu'une augmentation du nombre d'interventions en soins prénataux réduit le risque de faible poids pour l'âge gestationnel à la naissance au sein de différentes populations et pour en évaluer d'autres avantages potentiels pour les enfants.

Arsenic exposure and type 2 diabetes: results from the 2007-2009 Canadian Health Measures Survey.

INTRODUCTION: Inorganic arsenic and its metabolites are considered dangerous to human health. Although several studies have reported associations between low-level arsenic exposure and diabetes mellitus in the United States and Mexico, this association has not been studied in the Canadian population. We evaluated the association between arsenic exposure, as measured by total arsenic concentration in urine, and the prevalence of type 2 diabetes (T2D) in 3151 adult participants in Cycle 1 (2007-2009) of the Canadian Health Measures Survey (CHMS). METHODS: All participants were tested to determine blood glucose and glycated hemoglobin. Urine analysis was also performed to measure total arsenic. In addition, participants answered a detailed questionnaire about their lifestyle and medical history. We assessed the association between urinary arsenic levels and T2D and prediabetes using multivariate logistic regression while adjusting for potential confounders. RESULTS: Total urinary arsenic concentration was positively associated with the prevalence of T2D and prediabetes: adjusted odds ratios were 1.81 (95% CI: 1.12-2.95) and 2.04 (95% CI: 1.03-4.05), respectively, when comparing the highest (fourth) urinary arsenic concentration quartile with the lowest (first) quartile. Total urinary arsenic was also associated with glycated hemoglobin levels in people with untreated diabetes. CONCLUSION: We found significant associations between arsenic exposure and the prevalence of T2D and prediabetes in the Canadian population. Causal inference is limited due to the cross-sectional design of the study and the absence of long-term exposure assessment.

TITRE: Exposition à l'arsenic et diabète de type 2 : résultats de l'Enquête canadienne sur les mesures de la santé de 2007 à 2009. INTRODUCTION: L'arsenic inorganique et ses métabolites sont considérés comme dangereux pour la santé humaine. Même si plusieurs études ont indiqué des associations entre une faible exposition à l'arsenic et le diabète sucré aux États-Unis et au Mexique, ces associations n'ont pas été étudiées chez les Canadiens. Nous avons analysé l'association entre l'exposition à l'arsenic, mesurée par la concentration d'arsenic total dans l'urine, et la prévalence du diabète de type 2 (DT2) chez 3 151 participants adultes du cycle 1 (2007 à 2009) de l'Enquête canadienne sur les mesures de la santé (ECMS). MÉTHODOLOGIE: La glycémie et l'hémoglobine glycosylée ont été mesurées chez les participants. L'arsenic total a été dosé par une analyse d'urine. De plus, les participants ont répondu à un questionnaire détaillé sur leurs habitudes de vie et leurs antécédents médicaux. Nous avons analysé l'association de la concentration urinaire d'arsenic avec le DT2 et le prédiabète à l'aide d'une régression logistique multivariée ajustée pour les facteurs de confusion potentiels. RÉSULTATS: La concentration urinaire d'arsenic total était positivement associée à la prévalence de DT2 et de prédiabète : les rapports de cotes ajustés étaient respectivement de 1,81 (IC à 95% : 1,12 à 2,95) et de 2,04 (IC à 95% : 1,03 à 4,05) lorsqu'on comparait les concentrations urinaires d'arsenic les plus élevées (quatrième quartile) aux plus faibles (premier quartile). L'arsenic total urinaire était également associé au taux d'hémoglobine glycosylée chez les diabétiques non traités. CONCLUSION: Nous avons noté des associations significatives entre l'exposition à l'arsenic et la prévalence de DT2 et de prédiabète dans la population canadienne. L'inférence causale est limitée car il s'agit d'une étude transversale exempte d'évaluation de l'exposition à long terme.

Exposure of young children to household water lead in the Montreal area (Canada): the potential influence of winter-to-summer changes in water lead levels on children's blood lead concentration.

Drinking water represents a potential source of lead exposure. The purpose of the present study was to estimate the magnitude of winter-to-summer changes in household water lead levels (WLLs), and to predict the impact of these variations on BLLs in young children. A study was conducted from September, 2009 to March, 2010 in 305 homes, with a follow-up survey carried out from June to September 2011 in a subsample of 100 homes randomly selected. The first 1-L sample was drawn after 5 min of flushing, followed by a further 4 consecutive 1-L samples after 30 min of stagnation. Non-linear regression and general linear mixed models were used for modelling seasonal effects on WLL. The batchrun mode of Integrated Exposure Uptake Biokinetic (IEUBK) model was used to predict the impact of changes in WLL on children's blood lead levels (BLLs). The magnitude of winter-to-summer changes in average concentrations of lead corresponded to 6.55 µg/L in homes served by lead service lines (LSL+ homes) and merely 0.30 µg/L in homes without lead service lines. For stagnant samples, the value reached 10.55 µg/L in 'LSL+ homes' and remained very low (0.36 µg/L) in 'LSL- homes'. The change in the probability of BLLs ≥5 µg/dL due to winter-to-summer changes in WLL was increased from <5% (in winter) to about 20% (in summer) in children aged 0.5-2 years. The likelihood of having BLLs ≥5 µg/dL in young children during warm months was reduced by at least 40% by flushing tap-water.

Impact of individual and ecological characteristics on small for gestational age births: an observational study in Quebec.

INTRODUCTION: We evaluated associations between ecological variables and the risk of very small for gestational age (VSGA) birth in Quebec in 2000-2008. METHODS: Ecological variables came from the Canadian Community Health Survey, the Canadian census and Quebec's birth registry; individual variables also came from Quebec's birth registry. Odds ratios (ORs) adjusted for mother's age, academic qualification, parity, marital status and country of birth were estimated using multilevel logistic regression (generalized estimating equations method). RESULTS: Births in neighbourhoods with a high proportion of people leading a sedentary lifestyle (OR: 1.07, 95% confidence interval [CI]: 1.01-1.11) and those with a high/middle proportion of residents with food insecurity (OR: 1.09, 95% CI: 1.05-1.15; OR: 1.05, 95% CI: 1.01-1.11) had higher odds of VSGA birth. Those with middle proportion of married residents had lower odds of VSGA birth (OR: 0.94, 95% CI: 0.90-0.98).

TITRE: Incidence des caractéristiques individuelles et des caractéristiques du contexte sur les nouveau-nés de faible poids : une étude d'observation au Québec. INTRODUCTION: Nous avons analysé les liens entre certaines variables contextuelles, certaines caractéristiques des mères et le risque de donner naissance à des nouveau-nés très petits pour l'âge gestationnel (TPAG) au Québec entre 2000 et 2008. MÉTHODOLOGIE: Les variables liées au contexte ont été tirées de l'Enquête sur la santé dans les collectivités canadiennes, du Recensement canadien et du Registre des naissances du Québec. Les variables individuelles provenaient aussi du Registre des naissances du Québec. Les rapports de cotes (RC), ajustés selon l'âge de la mère, la scolarité, la parité, l'état matrimonial et le pays de naissance, ont été évalués au moyen de modèles de régression logistique multiniveau (par des équations d'estimation généralisées). RÉSULTATS: Les naissances survenues dans les quartiers présentant une proportion élevée de résidents sédentaires (RC : 1,07, intervalle de confiance [IC] à 95% : 1,01 à 1,11) et dans les quartiers présentant une proportion moyenne (RC : 1,09, IC à 95% : 1,05 à 1,15) ou élevée de résidents souffrant d'insécurité alimentaire (RC : 1,05, IC à 95% : 1,01 à 1,11) présentaient un risque accru d'être TPAG. Le risque de naissance de nouveau-né TPAG était plus faible dans les quartiers présentant une proportion moyenne de résidents mariés (RC : 0,94, IC à 95 % : 0,90 à 0,98).

Risk of infectious gastroenteritis in young children living in Québec rural areas with intensive animal farming: results of a case-control study (2004-2007).

This study was designed to evaluate the epidemiology of severe gastroenteritis in children living in Québec rural areas with intensive livestock activities. From September 2005 through June 2007, 165 cases of gastroenteritis in children aged from 6 months to 5 years, hospitalized or notified to the public health department were enrolled, and 326 eligible controls participated. The parents of cases and controls were asked questions about different gastroenteritis risk factors. The quality of the drinking water used by the participants was investigated for microbial indicators as well as for four zoonotic bacterial pathogens (Campylobacter spp, Escherichia coli, Salmonella spp and Yersinia spp) and two enteric parasites (Cryptosporidium spp and Giardia spp). From 134 stool specimen analysed, viruses were detected in 82 cases (61%), while 28 (21%) were found with at least one of the bacteria investigated, and five cases were infected by parasites. Campylobacteriosis was the main bacterial infection (n = 15), followed by Salmonella sp (n = 7) and E. coli O157:H7 (n = 5) among cases with bacterial gastroenteritis. No significant difference was found between cases and controls regarding the quality of water consumed; the frequency of faecal contamination of private wells was also similar between cases and controls. Considering the total cases (including those with a virus), no link was found between severe gastroenteritis and either being in contact with animals or living in a municipality with the highest animal density (4th quartile). However, when considering only cases with a bacterial or parasite infection (n = 32), there was a weak association with pig density that was not statistically significant after adjusting for potential confounders. Contact with domestic, zoo or farm animals were the only environmental factor associated with the disease.

Agroenvironmental determinants associated with the presence of antimicrobial-resistant Escherichia coli in beach waters in Quebec, Canada.

Exposure to microorganisms resistant to antimicrobials may constitute a health risk to human populations. It is believed that one route of exposure occurs when people engage in recreational activities in water contaminated with these microorganisms. The main objective of this study was to explore population-level and environmental determinants specifically associated with the presence of antimicrobial resistant (AMR) generic Escherichia coli isolated from recreational waters sampled from beaches located in southern Quebec, Canada. Water samples originated from the Quebec provincial beach surveillance program for the summers of 2004 and 2005. This study focused on three classes of determinants, namely: agricultural, population-level and beach characteristics for a total of 19 specific factors. The study was designed as a retrospective observational analysis and factors were assessed using logistic regression methods. From the multivariable analysis, the data suggested that the percentage of land used for spreading liquid manure was a significant factor associated with the presence of AMR E. coli (OR=27.73). Conceptually, broad factors potentially influencing the presence of AMR bacteria in water must be assessed specifically in addition to factors associated with general microbial contamination. Presence of AMR E. coli in recreational waters from beaches in southern Quebec may represent a risk for people engaging in water activities and this study provides preliminary evidence that agricultural practices, specifically spreading liquid manure in agricultural lands nearby beaches, may be linked to the contamination of these waters by AMR E. coli.

Association between potential zoonotic enteric infections in children and environmental risk factors in Quebec, 1999-2006.

This study was designed to evaluate the association of potential zoonotic gastroenteritis in children, and specifically giardiasis, salmonellosis and campylobacteriosis, with environmental risk factors in rural areas of Quebec. Notified cases of gastroenteritis in children of 0-4 years of age reported in the period of 1999 through 2006 from municipalities in southern Quebec with <100,000 inhabitants were investigated. Negative binomial regression models accounting for overdispersion and adjusted for clustering were used to estimate relative risks (RR) associated with livestock densities and drinking water quality. Analyses revealed that, during this period, 2500 cases of gastroenteritis were reported in children of 0-4 years, including 819 cases of giardiasis, 690 of salmonellosis and 852 of campylobacteriosis. The incidence rate associated with all potential zoonotic agents reported was 163 cases/100,000 children-years and this was statistically associated with cattle density: RR Quartile 4/Quartile 1 (Q4/Q1) = 1.92, 95% CI = 1.43-2.58. When estimated specifically for each pathogen, incidence rates of giardiasis (RR Q4/Q1 = 1.79, 95% CI = 1.11-2.87), salmonellosis (RR Q4/Q1 = 1.64, 95% CI = 1.15-2.33) and campylobacteriosis (RR Q4/Q1 = 2.43, 95% CI = 1.60-3.68) were also associated with cattle density, with a monotonic increase of RR with increasing animal density. Giardiasis incidence was also positively associated with a poor drinking water quality, although no statistically significant association was found. Our results suggest that, in rural Quebec, bacterial and parasitic enteric infections in young children may be zoonoses related to environmental risk factors and especially cattle production.

Association between indicators of livestock farming intensity and hospitalization rate for acute gastroenteritis.

To evaluate associations between indicators of livestock farming intensity (manure surplus and livestock density) and acute gastroenteritis hospitalization (AGH) rate, we conducted an ecological study on 306 selected agricultural municipalities of Quebec. We estimated the AGH rate for the period 2000-2004 from the Quebec hospital database. Multivariate Poisson regression was used to estimate the strength of association between the farming indicators and AGH with adjustment for confounders. The modifying effect of age and water source was also evaluated. Association between manure and AGH was observed in children, especially those aged 0-4 years for selected zoonotic infections [adjusted hospitalization rate ratio (aHRR) 1.93, 95% CI 1.21-3.09]. The risk ratio was higher for subjects using ground-water source. An increasing HRR trend with each additional level of poultry density was observed in children aged 0-4 years, especially for Salmonella infections. We conclude that livestock farming intensity may be linked to bacterial acute gastroenteritis in children.

Effects of electric and magnetic fields from high-power lines on female urinary excretion of 6-sulfatoxymelatonin.

In 1998, the authors studied the effect of residential exposure to electric and magnetic fields from high-power lines on female urinary excretion of 6-sulfatoxymelatonin (6-OHMS) in the Quebec city, Canada, metropolitan area. A sample of 221 women living near a 735-kV line was compared with 195 women the same age living away from any power lines. Participants provided morning urine samples on 2 consecutive days and wore a magnetic dosimeter for 36 consecutive hours to measure personal magnetic exposure. The indoor electric field was assessed by spot measurements. After adjustment for other factors associated with low melatonin secretion, such as medication use or light exposure, nighttime concentration of 6-OHMS was similar in the two groups. When either 24-hour or sleep-time exposure to magnetic field or electric field measurements was used, no exposure-effect relation was evident. However, the trend of decreasing 6-OHMS concentration with age was more pronounced for women living near the lines, as was a lower 6-OHMS concentration in women with high body mass index. Chronic residential exposure to magnetic fields from high-power lines may accentuate the decrease in melatonin secretion observed in some vulnerable subgroups of the population.

Exposure of the Inuit population of Nunavik (Arctic Quebec) to lead and mercury.

The authors conducted a survey during 1992 to evaluate blood levels of lead and mercury in Inuit adults of Nunavik (Arctic Quebec, Canada). Blood samples obtained from 492 participants (209 males and 283 females; mean age = 35 yr) were analyzed for lead and total mercury; mean (geometric) concentrations were 0.42 micromol/l (range = 0.04-2.28 micromol/l) and 79.6 nmol/l (range = 4-560 nmol/l), respectively. Concentrations of omega-3 fatty acid in plasma phospholipids--a biomarker of marine food consumption--were correlated with mercury (r = .56, p < .001) and, to a lesser extent, with blood lead levels (r = .31, p < .001). Analyses of variance further revealed that smoking, age, and consumption of waterfowl were associated with lead concentrations (r2 = .30, p < .001), whereas age and consumption of seal and beluga whale were related to total mercury levels (r2 = .30, p < .001). A significant proportion of reproductive-age women had lead and mercury concentrations that exceeded those that have been reportedly associated with subtle neurodevelopmental deficits in other populations.

Excretion of volatile nitrosamines in a rural population in relation to food and drinking water consumption.

Urinary excretion of volatile nitrosamines was assessed in 59 non-smokers living in a rural county of Québec, Canada. Water and food intakes were measured by means of a 24-hour recall. Nitrates were analyzed in the tap water of all participants (geometric mean=2.0 mg nitrate-N/L) and dietary intakes of nitrate and vitamins C and E were estimated via a validated Canadian food database. Urine was collected over the same 24-hour period and analyzed for nitrates by hydrazine reduction and for volatile nitrosamines by gas-chromatography/mass spectrometry. N-Nitrosopiperidine (NPIP) was found in urine samples from 52 of the 59 subjects. Geometric mean of NPIP urinary excretion was 67 ng/day and maximum value was 1045 ng/day. No other volatile nitrosamine was detected. There was a correlation between urinary nitrate excretion and total nitrate intake (r=0.71, P < 0.001). However, no relationship was found between urinary NPIP excretion and either nitrate excretion, dietary or water nitrate intakes. NPIP excretion was significantly correlated to coffee intake (r=0.40, P=0.002) and this relation was not modified by vitamin intake. We conclude that nitrate intake is not related to nitrosamine excretion in this rural population. The influence of coffee consumption on NPIP excretion deserves further attention.

Sources of nitrate exposure in residents of rural areas in Quebec, Canada.

Nitrate exposure was investigated in a group of 187 people using well water and living in four areas of rural Quebec (Canada) with intensive agricultural activities. Nitrate intake was evaluated using a 24-h dietary recall and a food frequency questionnaire, in conjunction with a validated food database and measurements of nitrate concentrations in private wells. The total internal dose was estimated by means of the 24-h urinary nitrate excretion, while taking into account risk factors for endogenous nitrate formation. Mean (geometric) 24-h urinary nitrate excretion was 16.9 mg N for the 100 people with low groundwater contamination (mean nitrate concentration=0.18 mg N/l) and 23.3 mg N in the 87 individuals with moderate groundwater contamination (mean nitrate concentration=7.1 mg N/l). A multivariate analysis revealed that dietary nitrate intake during the last 24 h was the principal source of exposure, followed by water intake during the last 24 h. The Quetelet index was also a significant predictor of urinary excretion. The total predictive model explained only 29% of the variability in urinary nitrate excretion (R2=0.286). Neither the inflammatory status as indicated by elevated C reactive protein, the presence of Helicobacter pylori antibodies nor the occurrence of diarrhea during the last 24 h prior to urine collection were associated with urinary nitrate excretion. In conclusion, food and to a lesser extent water contribute to nitrate exposure in this rural setting with moderate water contamination. Better predictors of endogenous nitrate production are needed to improve our ability to model nitrate body burden and estimate associated health risks.

[Study of the incidence of giardiasis in Quebec (Canada) and association with drinking water source and quality]. / Etude de l'incidence de la giardiase au Québec (Canada) et de l'association avec la source et la qualité de l'eau potable.

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.

Comparison between personal exposure to 60 Hz magnetic fields and stationary home measurements for people living near and away from a 735 kV power line.

This study compares stationary home measurements with a personal exposure monitor of 60 Hz magnetic fields in a group of 18 people living near a 735 kV line and 17 people living far away from the line. Most of them were white collar workers who worked during the day. They wore a personal Positron meter for 24 h, while a similar meter was left in their home, away from any appliances. For people living away from the line, the impact of residential activities appeared rather weak when considering the average intensity of the field during the awake period (at home): 0.22 microT for personal exposure versus 0.18 microT for stationary measurements (P = 0.09). The impact of residential activities during the awake period was more detectable when using the percentage of time with exposure above 0.78 microT: median 0.4 for personal vs. 0.0 for stationary measurements (P =.01). The temporal variability of the exposure during the awake period was also significantly higher for personal exposure than for stationary measurements. For people living near the line, the intensity of the magnetic field from the line dominated the personal exposure when considering the mean of measurements and the percentage of time above a threshold. However, the temporal variability was greater for the personal exposure during the awake period. Although limited due to its small sample size, the present study seems to demonstrate the usefulness of considering different indexes of exposure when assessing residential exposure to 60 Hz magnetic fields.

Lead, mercury, and organochlorine compound levels in cord blood in Québec, Canada.

We conducted this study to evaluate blood levels of lead, mercury, and organochlorine compounds in newborns in the Province of Quebec. During 1993 to 1995, we carried out a survey in 10 hospitals located in southern Quebec. During that time, umbilical cord blood samples were obtained from 1109 newborns, and we analyzed each for lead, mercury, 14 polychlorinated biphenyl congeners, and 11 chlorinated pesticides. We used the geometric mean and 95% confidence interval (CI) to describe the results. Mean concentrations of lead and mercury in cord blood were 0.076 micromol/l (95% CI = 0.074, 0.079) and 4.82 nmol/l (95% CI = 4.56, 5.08), respectively. The mean concentrations of total polychlorinated biphenyls (Aroclor 1260) and dichlorodiphenyl dichloroethylene were 0.514 microg/I (95% CI = .493, 0.536) and 0.412 microg/l (95% CI = 0.390, 0.435), respectively. We observed a statistically significant relationship between maternal age and cord blood concentrations of (a) lead, (b) mercury, (c) polychlorinated biphenyls, and (d) dichlorodiphenyl dichloroethylene. In addition, maternal smoking during pregnancy was associated with cord blood lead levels. The cord blood concentrations of lead, mercury, polychlorinated biphenyls, and dichlorodiphenyl dichloroethylene we measured in our study were the lowest levels recently reported in industrialized countries. The results of this study underline the role of public health authorities in the evaluation of biological levels of environmental contaminants among children for the assessment of risk of adverse health effects.

Binding capacity of various fibre to pesticide residues under simulated gastrointestinal conditions.

The purpose of this study was to compare the effect of the nature and quantity of various dietary fibre (cellulose, hemicellulose, pectin, lignin) in diets on the binding capacity to pesticides azinphos-methyl (AZM), chlorpropham (CLP), chlorothalonil (CKL), permethrin (PER) as estimated by solubility under conditions of pH and temperature simulating those in the gastrointestinal tract (incubated at pH 2 for 30 min at 37 degrees C, then at pH 7 for 60 min). The ratios of fibre to pesticides were determined in omnivorous diets. In this model, the binding capacity of lignin was equal to hemicellulose for PER, AZM and CLP, but it was significantly higher for CKL. Hemicellulose bound more CKL, AZM and CLP than did cellulose. Although pectin appreciably decreased all pesticides, its effect was lower than other fibres with one exception--cellulose-CKL. In the presence of equal amounts of fibre, lignin exerted the most significant effect on pesticide solubility. Hemicellulose and cellulose bind to the same extent PER and AZM. The effect of pectin was significant only on CKL and AZM when compared to the control.

Groundwater contamination by nitrates associated with intensive potato culture in Québec.

In rural areas, groundwater contamination by nitrates is a problem related to the spreading of organic and chemical fertilizers by farmers and, to some extent, to effluents from domestic sewage systems. Health effects of groundwater contamination by nitrates have been assessed several times and may lead to important consequences for infants. Following pressures from citizens in 1990, a survey of well water quality around potato fields of the Portneuf county (Québec) found that nitrate contamination was frequently above the 10 mg-N/1 standard. Because this first survey was limited to areas of intensive potato culture, it was not possible to evaluate the real impact on the groundwater quality for the whole county and the subsequent public health intervention was spread over the entire region. A second survey was carried out in 1995 to reevaluate the situation using random sampling methods. This latter study took into account drinking water habits of the population, the relative importance of potato culture as a source of nitrogen loading, the effects of soil types, and waste-water disposal systems as well as land use on nitrate concentration in private well water. The data analysis was carried out by combining GIS and statistical methods to test hypotheses about the spatial relationship linking measured nitrate concentrations with their immediate environment. This paper presents the major findings from this second study which confirm the impact of intensive potato culture on groundwater nitrate concentrations, mainly localized in sandy soil areas within 2 km of fields. Finally, it illustrates the usefulness of GIS to focus public health interventions.

Knowledge, perception and behaviour of the general public concerning the addition of fluoride in drinking water.

A telephone survey was carried out in 1994, in the Quebec City region, among 1006 people living in two municipalities where tap water is fluoridated and 1003 people living in two municipalities where there is no fluoridation. Knowledge of the main benefit associated with the use of fluoride (prevention of tooth decay) in drinking water was not different in fluorated versus non-fluoridated municipalities (20.4% vs 19.4%, p = 0.57). Knowledge of its main disadvantage (increase of dental fluorosis) was very low and similar in both groups (3.1% vs 2.0%, p = 0.11). Opposition to fluoridation was slightly higher in fluoridated areas (22.0% vs 18.3%, p = 0.04), and the use of fluoridated supplements for children was much less important in fluoridated areas (4.4% vs 12.4%, p = 0.001). No changes in the measures of association (odds ratios) were found after adjustment for the different characteristics of the participants (age, family income, education). Opposition to fluoridation was lower among those who believed their tap water was fluoridated (even if not): 19.9% vs 34.5%, p < 0.001. This study demonstrates that there is still need for public health education on the uses of fluorides.

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.