Organochlorines, Lead, and Mercury in Akwesasne Mohawk Youth. (Children's Health)

Beginning of article

Most humans have detectable body burdens of polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and p,p'-dichlorophenyldichloroethylene (p,p'-DDE), a metabolite of p,p'-dichlorodiphenyltrichloroethane (DDT). Native American communities may be at increased risk of exposure through subsistence-based diets and greater physical contact with contaminated soil and water. In this article we describe the levels of toxicants (PCBs, p,p'-DDE, HCB, mirex, lead, and mercury) among youth 10-17 years old (n = 271) of the Akwesasne Mohawk Nation. Ultratrace, congener-specific PCB analysis of human serum quantitated 83 PCB congeners (plus 18 as pairs/triplets), in addition to p,p'-DDE, HCB, and mirex, and included all major Aroclor-derived congeners typically present in human samples. Twenty congeners (in 16 chromatographic peaks) were detected in 50% or more of the individuals sampled [geometric mean (GM) of the sum of these congeners = 0.66 ppb]. Thirteen congeners (in 10 peaks) were detected in 75% or more of the samples (GM = 0.51 ppb). Of the 20 congeners detected in 50% or more of the samples, 17 had five or more chlorine substitutions. International Union for Pure and Applied Chemistry congeners 118, 101(+90), and 153 were detected in nearly all participants (GM = 0.06 ppb, 0.05 ppb, 0.09 ppb, respectively), p,p'-DDE and HCB were detected in 100% and 98% of the samples (GM: p,p'-DDE = 0.37 ppb; HCB = 0.03 ppb). Mirex was detected in approximately 46% of the samples (GM = 0.02 ppb). No cases of elevated lead level were observed. One participant had a mercury level marginally higher than the U.S. Environmental Protection Agency's current level of concern (0.50 [micro]g/dL). Although differences in analytic methods and participant ages limit comparability, toxicant levels from the Mohawk youth are lower than those associated with severe food contamination (Yusho and Yu-cheng) but similar to other chronically exposed groups. Key words: adolescents, Iroquois, Native American, persistent organic pollutants, polychlorinated biphenyls, toxicants.

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Persistent organic pollutants (POPs) are a group of compounds that includes polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), hexachlorobenzene (HCB), and mirex. These compounds are lipophilic and bioaccumulate (Matthews and Dedrick 1984). They and/or their metabolites have entered the environment and the food chain and can be detected at some level in many, if not all, human populations (Stehr-Green 1989). A major route of POP intake in humans is consumption of contaminated food (Liem et al. 2000; Patandin et al. 1999). In addition, POPs cross the placenta and are transferred through lactation, resulting in exposure to the fetus and to infants. Some PCBs (i.e., the coplanar congeners) resemble 2,3,7,8-tetrachlorodibenzo-p-dioxin (Safe 1994) and produce biologic effects associated with binding to the aryl hydrocarbon (Ah) receptor. In contrast, documented or suspected biologic effects of non-coplanar PCB congeners include disruption of the development and functioning of some endocrine pathways and altered growth, development, and cognitive function in nonhumans and humans (American Council on Science and Health 1997; Brouwer et al. 1999; Carpenter et al. 1998; Schell 1999; Seegal 1996; Swanson et al. 1995).

Previous studies of environmental contamination such as the Exxon Valdez disaster (Palinkas et al. 1992) as well as other work (Akwesasne Task Force on the Environment 1997; Curtis 1992; Grinde and Johansen 1995; Harris and Harper 1997; Hild 1998) have indicated that Native peoples may be differentially exposed to toxicants. They are at particular risk of exposure to environmental contamination because of traditional dietary patterns involving consumption of locally caught fish and riverine species (Sloan and Jock 1990). Also, increased exposure may result from activities involving greater contact with the outdoor environment, such as swimming, wading, hunting, trapping, small-scale farming, and gathering traditional plants for medicines, foods, and other uses (Arquette et al. 2002; Curtis 1992; Sloan and Jock 1990).

The Mohawk Nation, one of the five nations of the Haudenosaunee Confederacy, have long lived, fished, planted, and hunted in the St. Lawrence River valley. The construction of the St. Lawrence Seaway and the St. Lawrence-FDR Power Project in the 1950s has led to substantial industrial development along the St. Lawrence River. The Mohawk Territory of Akwesasne is now adjacent to several industrial complexes, including the General Motors Central Foundry Division, which is a National Priority Superfund Site (Lacetti 1993; U.S. EPA 1984). Also in the vicinity and upriver from Akwesasne are two New York State Superfund sites, the Reynolds Metal Company and Aluminum Company of America aluminum facilities (Fitzgerald et al. 1995, 1998; Lacetti 1993). PCBs and other POPs used during production by all three companies have contaminated the St. Lawrence and its river tributaries (Ecology and Environment, Inc. 1992; Fitzgerald et al. 1995, 1998; RMT 1986; Woodward-Clyde Associates 1991). Some local species of fish, birds, amphibians, and mammals have PCB, p,p'-DDE, HCB, and mirex levels that exceed the U.S. Food and Drug administration's tolerance limits for human consumption (Forti et al. 1995; Lacetti 1993; Skinner 1992; Sloan and Jock 1990). In the past, the Mohawk have relied heavily on locally caught fish and game as sources of protein. In this article we describe the levels of several toxicants in a sample of youth from the Akwesasne Mohawk community. Specific toxicants were chosen for analysis because of community concerns about their effects and their documented presence in the local environment.

Materials and Methods

Sample. Present-day Akwesasne is a sovereign nation whose territory lies on both sides of the St. Lawrence River and spans the boundaries of Ontario and Quebec, Canada, and New York State. In 1995, three human health studies were begun under the auspices of the University at Albany's Superfund Basic Research Program (SBRP) and the Akwesasne Task Force on the Environment. Akwesasne is not a federally censused population. Published estimates of the Akwesasne community's population size vary, but recent reports indicate a population of approximately 12,000-13,000 (Akwesasne Task Force on the Environment 1997; Fitzgerald et al. 1998; George-Kanentiio 1995; Goran et al. 1995). Residents of the community live within the boundaries of the Akwesasne Mohawk Nation and in neighboring communities that are part of traditional Mohawk territory, including Bombay, Fort Covington, Hogansburg, Massena, and Rooseveltown, New York, and Cornwall, Ontario.

The target population cannot be defined by a municipal boundary because of the dispersed residence pattern of community residents. The official tribal register also cannot serve this purpose because it lists all Nation members, including those living at very large distances from the source of local contamination (e.g., in New York City). To define the target population with risk of exposure to local contaminants, a panel of Akwesasne community representatives was assembled, and they defined the target population as residents of households within the boundaries of the Akwesasne Mohawk Nation and residents of those Mohawk households in neighboring communities, but no more than 10 miles from the Nation border. All Akwesasne households were enumerated using detailed maps and drive-through surveys by Mohawk data collection staff, all of whom are members of the Akwesasne Mohawk community. These households were contacted to solicit participation in the three SBRP studies. Each household was placed on a list from which a random sample of 50 households were selected, and then each selected household was visited to determine the age, sex, and relationships among household members. When the first 50 households were contacted or were unable to be contacted after repeated attempts, another 50 randomly chosen households were selected and the process was repeated.

When a household was contacted, consent information was explained and eligibility for the three different SBRP studies according to the exclusion criteria was ascertained. To be eligible for this study, the mother/youth pair had to reside in the same household and the youth could not be a twin, have a serious psychologic impairment or problem as determined by a physician or a psychologist, have a serious physical condition as diagnosed by a physician, or have been diagnosed with either fetal alcohol syndrome or fetal alcohol effects. Only one child per household, between 10 and 16.99 years old, was eligible to participate in this study. The oldest eligible child was selected first, but if that child was unwilling to participate, the next oldest was then selected. In 1998, recruitment was expanded because of the small number of age-eligible persons among the households that had been contacted from the randomized lists of households. At this point, all Akwesasne households were included, and volunteers were accepted while all other eligibility criteria were retained. Informed consent was obtained from all participating youths and their parent or guardian, and the study protocols were reviewed and approved by the Institutional Review Board at the University at Albany, State University of New York.

Of the Akwesasne households that met all eligibility requirements, 294 mother/youth pairs participated (138 male and 156 female youth). Of these, 19 dropped out of the study primarily because of an aversion to having their blood drawn, one participant was later found to be ineligible (too young), and three had to be excluded because their blood samples were broken in transit to the lab and they declined to have their blood redrawn. The final sample size was 271 participant pairs, 131 males and 140 females and their mothers.

Interview data collection. Members of the Akwesasne community collected all interview data, and each data collector was trained in measurement techniques specific to this study (anthropometry, interview techniques, and phlebotomy). All data were collected without prior knowledge of the participant's exposure status. Data collection occurred from February 1996 through January 2000.

The youth's mother completed interviews and questionnaires to obtain information about the youth's family background, including breast-feeding history and socioeconomic status, as well as a dietary questionnaire regarding the mother's consumption of locally caught fish and game. However, one participant's mother was deceased and the youth's maternal grandmother, who resided with the youth, completed the questionnaire on breast-feeding history and socioeconomic status, but was unable to complete questionnaires regarding maternal diet during pregnancy.

Laboratory analysis of toxicants. For PCB analysis, two 10-mL and one 5-mL sample of blood were collected from each youth by venipuncture into no-additive (red-top) and ethylenediamine tetracetic acid (EDTA)-additive (lavender-top) glass Vacutainer tubes, respectively. Blood specimens were collected by trained Mohawk staff at each participant's home. The sample was collected within a 5-hr window to minimize the effects of diurnal variation (particularly regarding endocrine assessment). Participants were asked not to eat any locally caught or grown food for 3 days before the collection and not to eat or drink anything after 2200 hr the preceding evening.

After collection, no-additive specimens were allowed to clot for at least 20 min at room temperature and then centrifuged. Aliquots of approximately 5 mL serum were transferred into hexane-washed polytetrafluoroethylene-capped glass vials and stored at -20[degrees]C at the Akwesasne laboratory. Aliquots of approximately 1 mL were transferred to plastic Eppendorf vials and stored at -80[degrees]C for clinical chemistry analyses. EDTA-additive specimens (for lead and mercury analysis) were stored at 4[degrees]C. The blood specimens provided a sufficient volume for at least one PCB/organochlorine (OC) pesticide analysis in addition to a battery of endocrine and clinical chemistry analyses. Universal safety …