An Epidemiologic Study of Time Trends and Health Effects of Persistent Organic Pollutants, Mercury and Micronutrients

EPA Grant Number: R833705
Title: An Epidemiologic Study of Time Trends and Health Effects of Persistent Organic Pollutants, Mercury and Micronutrients
Investigators: Berner, James E.
Institution: Alaska Native Tribal Health Consortium
EPA Project Officer: Klieforth, Barbara I
Project Period: June 1, 2009 through May 31, 2013 (Extended to May 31, 2015)
Project Amount: $948,121
RFA: Issues in Tribal Environmental Research and Health Promotion: Novel Approaches for Assessing and Managing Cumulative Risks and Impacts of Global Climate Change (2007) RFA Text |  Recipients Lists
Research Category: Environmental Justice , Climate Change , Tribal Environmental Health Research , Human Health


This research will address cumulative exposure to multiple environmental stressors in rural Yupik Alaska Natives (AN). The stressors to be investigated are anthropogenic persistent organic pollutants (POPs) and mercury (Hg), accumulated in pregnant Yupik residents through ingestion of traditional subsistence wildlife species, particularly salmon and seals.  This set of stressors may be associated with adverse health outcomes, but the threat of illness caused by the traditional foods that have sustained the Yupik people for thousands of years, and which form a central part of the culture is very threatening to the Yupik worldview.  This has caused some Yupik residents of the Yukon-Kuskokwim River Delta (YKD) to decrease the use of traditional marine subsistence species, and increase western foods where possible, and particularly high sugar and fat containing choices, such as soft drinks, chips, and solid shortening agents.

The concern with safety of traditional foods caused the Alaska Native Tribal Health Consortium (ANTHC) and the Yukon-Kuskokwim Health Corporation (YKHC), the tribal health organizations responsible for health care in the YKD, to initiate a pilot study of maternal and newborn blood levels of POPs, metals, and micronutrients (CDC protocol 2320) starting in 1999. The U.S. Fish and Wildlife Service (FWS) carried out a study in 2001, to determine tissue levels of POPs, heavy metals, omega-3 fatty acids, and selenium in the two most commonly consumed salmon species in the Kuskokwim and Yukon Rivers, which are the drainage for the entire YKD. 


This research will extend and fully analyze a previously obtained data base of human tisse and salmon tissue for POPs, metals, and micronutrients. The expasion of the data base will accomplish the following objectives:

  1. Assure an adequate sample size of Yupik women and infants to document any associations between prenatal exposure to POPs and/or Hg, with adverse health outcomes and document any association between micronutrients and positive outcomes.
  2. Provide a time series in human and subsistence species tissue levels of POPs and Hg to evaluate the impact of climate regime change on ocean and atmospheric current delivery of POPs and Hg from lower latitudes into the Bering Sea, addressing possible climate change impact on subsistence resources and human health.
  3. Provide and communicate risk and benefit data to Yupik residents to enable the development of region-wide strategies and policies to reduce the risk, and inrease the benefits of the traditional diet, which will strengthen that critical component of Yupik culture.

The research hypotheses will specifically address the following required topics:  (a) subsistence resources, (b) subsistence practices, (c) chemical exposures, (d) the differential impact on sensitive sub-populations, and (e) potential impact of climate change on subsistence resources and human health.

The first objective has two parts:  the collection of a representative sample (~40 salmon) of the two most commonly consumed salmon (Chinook salmon [Oncorhynchus tshawytscha] and chum salmon[O. keta]) species in the YKD, and the recruitment of 200 pregnant Yupik women for the human cohort study.



Chinook and chum salmon will be collected at Rampart Rapids, a productive subsistence fishing spot on the Yukon River, and at Bethel on the Kuskokwim River.  At both sites, fish will be collected in cooperation with subsistence users. Fish will be collected using gill nets or fish wheels. Fish will be dissected using clean techniques; samples will be collected and frozen as soon as possible, and the body of the fish will be returned to subsistence users. Twenty fish (10 male, 10 female) of each species will be collected at each sample site. The sample size of 20 fish per species per sampel site should provide sufficient data to characterize the sample variance for comparison to published effect concentrations of organochlorine, metal, and metalloid contaminants. Fatty acids will be measured in muscle tissue. Sampling for Chinook and chum salmon will begin in mid-June. Fish will be weighed, measured, and receive a careful external examination for parasites and abnormalities. Muscle and egg samples for Hg and other metals also will be collected. 

All chemical analyses will be conducted at a USFWS contract laboratory, and all analytical methods, quality assurance, and quality control procedures will meet USFWS contractual standards.

Among Yupik residents of YKD, the prevalence of type 2 diabetes is 20/1000 population. The risk of type 2 diabetes mellitus (DM) is higher in U.S. NHANES III participants with higher POPs exposure, and the possible association between YK maternal POPs levels and risk for DM will be examined. In addition, all complications of pregnancy including preterm delivery is 14.7/1000 births. Each maternal participant will undergo a complete standard prenatal history and physical examination and a 2-page subsistence-focused dietary survey. The participants will have blood drawn to determine levels of POPs, Hg, and omega-3 fatty acids with the same venipuncture as the initial prenatal lab studies.

After delivery a maternal record review will be carried out and a data abstraction form will be completed. After the infant is 12 months old a medical record review and data abstraction form are competed. The two prior maternal and infant cohorts will be combined with the 200 additional women and infants recruited in this project. The total of approximately 550 women and infants will be examined by a within cohort comparison for any increased risk for adverse outcome with POPs and/or Hg exposure in the highest quartile of exposure, compared with the lowest quartile. Confounders such as smoking, alcohol use, obesity, and famiy history will be statistically analyzed. The approximately 350 infants who will be between 4-8 years old during the grant period will be evaluated as a cohort to look at blood pressure in relation to prenatal Hg exposure, adjusting for family history or other risk factors, such as extreme prematurity.

Expected Results:

The primary results of the research will be:  (1) new salmon contaminant and nutrient data; (2) new human tissue contaminant, Hg, and nutrient data; (3) new pediatric blood pressure data; and (4) new subsistence dietary data for YK mothers. The benefits will be:

  1. The first risk assessment of exposure to POPs and Hg from dietary sources for any AN population.
  2. The first time trend data on human tissue levels of POPs and Hg for any ethnically specific U.S. population.
  3. The first region species-specific salmon POPs and Hg time trend data in the Bering Sea.
  4. The first risk assessment in any Native American children for chronic disease related to prenatal dietary exposure to Hg, or DM in AN women related to POPs exposure.

These benefits will allow the State of Alaska, ANTHC and the YKHC to formulate subsistence diet risk reduction strategies to take advantage of any health benefits associated with micronutrients. This would allow specific strategies to reduce exposure for the sensitve subpopulations of AN, including infants, female children, and women who are planning pregnancy, already pregnant, or at risk for pregnancy. Such strategies could include reduction in certain foods that might include items such as salmon eggs, and eating larger and older marine mammals. It might include increasing land mammal intake, increasing salmon intake, and limiting use of seal oil. Findings of risk of higher blood pressure in children exposed to higher levels of prenatal Hg would warrant a blood pressure surveillance protocol for all Y-K children, something not now done routinely.

Finally, salmon tissue POPs and Hg reflects the levels in the trophic levels at which they feed, and at the lowest levels, these lower level organisms reflect the seawater POPs and Hg levels. Seawater receives river and atmospheric deposition, and there is concern that the recent increase in global mean temperature has increased volatilization of POPs, and air current transport to northern latitudes. Increased river discharge in mild and lower latitudes has increased from increased precipitation secondary to more frequent El Nino events. Thus, it is quite possible that the time trend in salmon may show increases in toxaphene, Hg, and PBDEs, all of which are rising in the Western Arctic. Findings like these, if present, would encourage both human health and wildlife agencies in the United States, Canada, and internationally to advocate forcefully for more stringent, effective controls on production and release of these compounds and for institutionalization of measures to reduce global warming. The data gained in the research will be shared with the YKHC, villages, state and federal wildlife and human health agencies, and the Arctic Monitoring and Assessment Program's (AMAP) Human Health Assessment Group (HHAG).

Publications and Presentations:

Publications have been submitted on this project: View all 54 publications for this project

Relevant Websites:

Alaska Native Tribal Health Consortium: Community Environment and Health Exit

Progress and Final Reports:

  • 2009 Progress Report
  • 2010 Progress Report
  • 2011 Progress Report
  • 2012 Progress Report
  • 2013
  • Final Report