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Research project: Human exposure and early health alterations Ongoing research, 2003-2004 |
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Identification |
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Ongoing research, 2003-2004 |
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Past
research, 2001-2003 |
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Project summary |
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The overall objectives in the original proposal were: 1. To integrate the human health component into the ecosystem analysis by examining the relationships between diet – synergy of dietary contaminants - lifestyle - early alterations of health and quality of life within target communities. 2. To provide information on the balance between health benefits – health risks associated with fish consumption. 3. To implement intervention, education and resources management by combining local knowledge and scientific data generated from the study. Since the beginning of COMERN, we have pursued these objectives, in collaboration with colleagues from the environmental and education teams, and through our work with communities within the ecosystem case studies: Boreal Forest, Coastal and St. Lawrence. A fourth objective, which seeks to develop a highly sensitive measure of hair Hg, using Laser Ablation with Inductively Coupled Plasma - Mass Spectrometry (LA-ICP-MS), was included in Year 3. This technique will allow us to better understand the relation between dietary input and hair Hg and to identify peak exposures, which are considered to be the most damaging to nervous system functions, particularly in utero. As indicated in the original proposal, a two tiered approach was used: The first step involved dietary evaluation of local and market food and mercury hair measurements for a large number of communities (total population: n = 1002). In the second step, this data was used to target approximately 400 persons from 3 communities for further study of Hg and other contaminants, micronutrients and fatty acids, in relation to neuro-outcomes. The initial communities from the Boreal Forest Ecosystem include anglers from lakes in the Temiscamingue and the Abitibi regions (Québec) and the Innu Nation in Sheshatshiu (Labrador); the Coastal Ecosystem communities are from St-Stephens/St. Andrews and Grand Manan Island of the Bay of Fundy, while the St. Lawrence Ecosystem comprises a cohort of pregnant women living in the Upper St. Lawrence (Lac St-François) and an angler community from the Lac St. Pierre Basin. Research agreements were established with the Aboriginal communities of the Innu Nation and the Passamquoddy. The major findings of the study to date concern relation between environment, diet and exposure, and the relation between exposure and hormonal and placental outcomes for the pregnant women study. Environment, diet and Hg Exposure: Results show that, as expected, there is a direct relation between fish consumption and hair Hg levels for all communities. The originality of the present research is to examine this relationship within the particular ecosystem in order to maximize nutritional input and the use of natural resources, while minimizing toxic risk. The highlights of our findings and how they integrate into the network are presented here. The fish consumption data from the Temiscamingue region, which showed that walleye was the fish the most consumed, was analyzed with respect to Hg levels measured in walleye from the 5 lakes where participants were fishing. Fish Hg data showed highly significant differences in Hg levels, for the same fish species of the same size from difference lakes. Estimated Hg exposure based on fish consumption frequency and fish Hg content from 2 branches of Lake Desjardins showed that if persons ate fish from Lake Desjardins West, their mean Hg intake for the summer months would be 0.09 ?g/kg/day, while from Lake Desjardins East, mean levels would be 0.13 µg/kg/day, surpassing the EPA guidelines of 0.1µg/kg/day. Mean estimates indicate that these guidelines are exceeded during the summer by 34% of adults and 68% of children. For the Abitibi lakes, significant inter-lake differences are also observed for the relation between local fish consumption and hair Hg level, suggesting that there may be differences in Hg in fish in the 3 lakes. Hair mercury levels, adjusted for sex, age and fish consumption, are significantly higher in persons fishing in Lake Duparquet compared to the 2 others. Close collaboration between the health and environment teams, coupled to input from the local authorities and community, will allow us to elucidate these differences and use them for environmental education. For the Innu Nation from Labrador, results from the food frequency questionnaires show that for a large proportion of the community, fish is consumed regularly throughout the year, with higher intake during certain periods of the year, corresponding to the time spent in the summer, spring and winter camps. During these periods, fish can be consumed as much as 3 times a day. Families have their own hunting and fishing territories to which are associated specific levels of fish Hg. Preliminary results from fish collected by the Environmental Team in lakes fished by community members have reveal levels of mercury ranging from 0.1 to 1.9 ppm for Lake Trout and Northern Pike (Anderson and Robertson, 2002). Hair Hg sequential analysis reflected interlake differences in the relation between local fish consumption and Hg exposure; persons consuming fish from the lakes with the higher fish Hg levels had higher levels of hair Hg. The Food Frequency Questionnaire likewise focused on other country food. These results are important in light of a study, undertaken by University of Prince Edward Island Veterinary College (UPEI) which showed levels above guidelines for cadmium in caribou kidneys and PCB, DDT and dioxin in spring geese. Y3 studies, which will analyze blood levels of these contaminants as well as Hg in the Innu community, will allow us to determine possible interactions between these compounds on neuro-outcomes and health. Although mean hair Hg levels from the communities in the Bay of Fundy were similar to those from the Boreal Forest Ecosystems, maximum levels were much lower, corresponding to differences in types of fish and eating patterns. Hg intake of mercury for each individual was estimated based on the intake of each fish and seafood (fresh or market based) reported in the spring food frequency questionnaire – March, April, May 2002. The top Hg contributor in each season for Grand Manan was haddock; for St Andrews/ St Stephen, canned tuna came on top. The study of pregnant women from the Lac St-François area, where Hg hair and blood levels were very low, revealed that only 27% ate fish from the St. Lawrence and canned and fresh market fish explained most of variance of blood and hair Hg before and during pregnancy. Even at these low levels of Hg exposure, fish eaters had significantly higher levels of hair and blood Hg throughout pregnancy. The highest cord blood levels were observed among those who increased fish consumption during pregnancy. Since canned fish was an important contributor to Hg exposure in both the Bay of Fundy and the Lac St-François communities, we analyzed Hg content in canned salmon, pale and white tuna. The results, which are presented in the Table below, show that the highest values are observed for white tuna and in particular, white tuna in water, for which 20% surpassed the 0.5 ppm limit for commercial fish and half were over 0.4 ppm. In our overall model of factors influencing Hg exposure in Canadians, the consumption of market fish needs to be considered. In the Lac St-François community, 2 women increased their consumption of canned tuna during pregnancy to 1 meal/day. While the population of Lac St-François was a random selection of persons living in the region of the lake, the targeted population from Lac St-Pierre is anglers, with much higher consumption of local fish. Data entry for the Lac St-Pierre anglers is in progress; preliminary results show considerably higher Hg exposure. These results will be analyzed with respect to the data obtained on Hg levels in fish by the Environment Team. Neuro-outcomes: For the 3 communities that were selected for further study of Hg and other contaminants, micronutrients and fatty acids in relation to neuro-outcomes, we have completed the data collection for Lac St-¨Pierre and are currently carrying out the studies in Sheshatshiu and in Abitibi. For the Lac St-François pregnant women study, although total Hg levels were very low, the placental calcium transfer was significantly slower at cord blood levels and preliminary analyses of the relation between Hg and hormonal secretion during pregnancy suggest an inverse relation between maternal blood Hg levels and the thyroid hormone, T3 and a possible additive effect with PCBs. For the study of biomarkers of neurotoxicity, the experimental studies were carried out on offspring behavior of progeny of female rats exposed to MeHg by gavages, before and throughout pregnancy. Results showed increased auditory startle response, memory deficits and a significant decrease in mono-amino oxidase (MAO) activity. The measured values of human platelet MAO activity and affinity are comparable with the literature and suggest that these biomarkers can be evaluated from a small sample of human blood. We have started to develop a new method to measure Hg in human hair samples using Laser ablation technique coupled to an Inductive coupled plasma-mass spectrophotometer. The objective of developing this new methodology is to achieve a resolution of less than 300 um of hair in length which will indicate the daily intake of the individual. We have successfully achieved the required sensitivity and specificity using the appropriate internal and external standards. We are validating the methods using hair samples collected from the communities. |
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link between the COMERN health and applied science research groups: |
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Ecosystemic study:Lakes of the boreal forest Case study 1: Coastal environment of the Bay of fundy Case study 2: The St-Lawrence River |
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COMERN Head Office: Université du Québec à Montréal, President-Kennedy Bldg – Suite PK-7150 C.P.8888, Downtown STA (Qc) H3C 3P8. Phone: (514) 987-3601, Fax : (514) 987-3635 www.unites.uqam.ca/comern -- email: comern@uqam.ca |
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