Grantee Research Project Results

Final Report: 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: Aja, Hayley
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

Objective:

Project Background:

The Maternal Organics Monitoring (MOM) Study was started in 1999, at the request of the Yukon Kuskokwim Health Corporation (YKHC) Health Board.  Its objective was to determine if the Alaska Native Yupik pregnant population of the Yukon-Kuskokwim Rivers Delta (YKD) was being exposed to man-made contaminants in their traditional subsistence diet.  About 35,000 Yupik residents live in 55 villages in a region of 50,000 square miles, in the delta formed by the Yukon and Kuskokwim in southwest Alaska.  Anthropogenic organohalogen lipophilic contaminants, produced for industrial or agricultural purposes, (e.g., DDT) are produced in the lower latitudes and released into the ocean and atmosphere. They are also found in subsistence marine species around the circumpolar north, and had been found in the blood of other populations of circumpolar women.  They are very slowly metabolized, or broken down in the environment, and are thus both bio-accumulated and biomagnified as they are transferred up the trophic levels of the lipid-rich northern food chain.

The Arctic Council (an international intergovernmental organization consisting of all eight nations with Arctic territories) established a circumpolar program called the Arctic Monitoring and Assessment Program (AMAP).  AMAP was created to monitor maternal and newborn blood for contaminants, and the MOM Study protocol was designed to utilize the same tests, so YK women and newborn infants could be compared to the other circumpolar maternal populations in other Arctic regions.  In addition to the AMAP contaminants, the YK MOM protocol measured maternal blood levels of nutrients found in subsistence wildlife species as well as contaminant levels in the chum and king salmon (the most commonly consumed subsistence species in the YKD) in both the Yukon and Kuskokwim Rivers.

Research Design:

Pregnant women attending their first prenatal visit at the Yukon-Kuskokwim Delta Regional Hospital (YKDRH) Prenatal Clinic were given information on the MOM Study and were offered the opportunity of enrollment.  Participants had 3 extra tubes of blood taken during routine prenatal blood samples and two tubes of umbilical cord blood were taken from the infant during delivery.  They were then sent to the CDC Laboratory in Atlanta for contaminant and micronutrient testing.

After delivery and the maternal six week exam, the maternal health record was reviewed for any problems during pregnancy, labor and delivery. The infant health record was reviewed after the baby reached 12 months of age for a variety of anthropomorphic data, and any health problems during the first year of life.  The contaminant data and the health status of mothers and infants were then analyzed, looking for any associations between contaminants, micronutrients, and positive or negative health effects.  The YK salmon data was also examined to see if trends in tissue levels of contaminants had changed between the first samples in 2001 and the second set of samples in 2010.

Research Objectives:

There are four research objectives of the MOM Study:  1. Determine trends in blood levels of persistent organic pollutants (POPs), metals and micronutrients over the 13 year time interval between the first and final samples, as well as compare them with other circumpolar maternal populations; 2.  Determine any statistical associations between POPs, metals and micronutrients and maternal and infant health outcomes; 3. Determine the impact of prenatal mercury exposure on blood pressure in early childhood, in a group of children born to mothers in earlier MOM Study cohorts; This study proved impossible to complete due to costs of village travel required; 4. Determine the impact of climate warming on POPs levels in salmon tissue over the ten year interval between salmon samples. 

Summary/Accomplishments (Outputs/Outcomes):

Results:

Basic demographic data on the maternal participants is shown in Table 1.  Follow-up information and health record review was possible in 90% of the MOM Study participants.  The remaining 10% had relocated out of the region, and could no longer be contacted.  Only two participants dropped out of the Study, and neither provided a reason.  The average age of participants was 26 years.  The percent of women breast-feeding their infants reflects the cultural practice of transferring a newborn infant to the care of a relative if the family resources will not be adequate to support the infant.  Most of the non-breastfed infants were not raised by the biologic parents.

Table 2 and 3 summarizes basic pregnancy outcome data, and infant growth data.

Table 1

 

Table 2

Table 3

Table 4

 

Table 5 examines the statistical associations between various organic contaminants, with statistically significant associations highlighted in yellow.  The table demonstrates a significant association between almost all the analytes, indicating a common source, in this case, the marine diet.  The single exception is PBDE 47, the most commonly found polybrominated flame retardant (PBFR) in North American blood samples, of every race, sex and age.  The MOM Study cohort has the highest levels, by far, of any maternal population sampled in the AMAP maternal monitoring program.  The levels in the MOM Study participants are at the 50^th percentile of US women of childbearing age, indicating a source in common with lower 48 states, and not the subsistence diet.  This class of compounds is not found the YKD salmon study, although all other analytes are found there.    The PBFRs have been used in countless consumer products, before their tendency to persist in humans and indoor dust was discovered.  Now, the most persistent forms are no longer produced or used, and levels should slowly drop.

Table 5

   

Table 6 summarizes the trends, and geometric means in blood metal levels.  The levels of mercury are significantly higher than prenatal populations typically measured in US all-races data, but are not at the EPA level of concern, and reflect the fish and marine mammal intake of the population, rather than point-source contamination from an industry source.  There is, however, a significant association between a maternal mercury level > 5 micrograms/ml, and the risk of developing pregnancy-induced hypertension (PIH).  The levels of mercury have trended down, although the reason for this may be shifts in diet, and not a change in mercury levels in salmon, which has not taken place.  Further studies will be needed to investigate this change.  Levels of cadmium have dropped over the duration of the MOM Study, likely due to the reduction in tobacco use in the prenatal population of the YKD.

Table 6

 

Table 7 summarizes the levels of vitamin D in the maternal participants, taken at entry into prenatal care, and a subset of newborn infants who had cord blood collected at birth.  Due to shortages of resident nursing staff in the delivery room at the YKD hospital, not all infants had cord blood collected, and in addition, some were delivered in referral hospitals. The major finding is that only 28% of YKD MOM Study participants entered prenatal care with levels of vitamin D that are considered “sufficient”.  Of the 78 infants sampled, none were “sufficient, with 53% being “severely deficient” and an additional 38% being “deficient”.  In addition, low vitamin D was associated with a statistically significant risk for a higher hemoglobin A1C on entry to prenatal care.  Association of low vitamin D in cord blood is currently being evaluated as a possible risk factor for dental disease for these infants in the first year of life.  No relationship between low vitamin D and risk of serious infection in the first year of life was noted.  The entire cohort is now being reviewed for evidence of diseases related to insufficient levels of vitamin D

Table 7

Maternal and Infant Levels of Vitamin D in the 2009 – 2012 Cohort, compared with NHANES data for women and children. Vitamin D levels <30nmol/L = severe deficiency; >30 to <50 = deficient; >50 to <75 = insufficient; 75 and above is normal.

Table 8 describes the maternal and newborn levels of Omega-3 Fatty Acids in the cohort of MOM Study participants between 2009 and 2012. 

Table 8

 

Omega 3 Fatty Acid Levels in Maternal and Newborn Blood (2009-2012)

 

Figures 1 and 2 describe the findings of the follow-up salmon tissue study to look at levels of mercury and contaminants in the two major species of wild Pacific salmon that spawn in the Yukon and Kuskokwim Rivers.  Figure 1 shows no significant change in tissue levels, and Figure 2 shows a comparison to similar fish from other regions in the north.

Figure 1

Salmon Tissue Contaminant Levels from 2001 Compared to Levels in 2010, in ppm wet weight

(This graph shows no significant change between salmon of the same species from the same river)

 

 

Figure 2

Contaminant Levels in Fish from Other Regions Compared to YK Salmon

 

 

Conclusions:

Study Conclusions:

• Man-made contaminants from lower latitudes have been transported to the circumpolar north, entered the food chain, and are detectable in bio-samples in the residents.
• The levels in the YKD salmon are lower than fish from other parts of the world.
• The levels of most of the contaminants in YK mothers are statistically similar to pregnant women in Scandinavia, Iceland, and western Arctic Canada, and significantly lower than in Greenland, eastern Arctic Canada, and Russia.
• Contaminant levels have trended lower over the 13 year sampling period of the Mom Study.
• The single exception among the contaminants is the group of chemicals called brominated flame retardants (BFRs).
• BFRs are not associated with salmon or subsistence food but are found in products such as plastics, upholstery, and indoor house dust.
• BFR blood levels in YK mothers are the same as lower 48 women of child-bearing age.
• A significant percent of YK mother’s vitamin D levels when beginning prenatal care are lower than they should be to ensure good bones and general health.  By the end of pregnancy, the blood levels are much lower than needed to ensure the health of the newborn in a majority of the infants tested.
• The traditional diet has many sources of vitamin D, and if YK residents ate as much traditional food as in the past, this would be very likely to improve this deficiency.
• The MOM Study participants showed a strong association between low levels of vitamin D and increased resistance to insulin. This resistance increases the risk for developing type 2 diabetes and associated health risks during pregnancy, in both the mother and her infant.
• An association exists between higher maternal mercury exposure and increased risk for maternal PIH.

Recommendations:

• Consider further investigation of maternal and newborn vitamin D status and implementation of vitamin D supplementation, for mothers during pregnancy, and while nursing, and for infants of mothers discovered to be vitamin D insufficient.
• Possibly further analysis of MOM Study specimens and data for insight into other vitamin D-related health disparities, such as: infection, dental disease, and diabetes.
• Raising community awareness on the sources of vitamin D in traditional foods.
• Long-term monitoring of maternal blood and salmon tissue by using pooled samples, gathered at longer intervals to track trends in contaminant transport.
• Long-term follow-ups of the 400+ mothers and infants to watch for both traditional diet benefits, and any health effects that might be associated with prenatal exposure to contaminants. Although, research in other populations in the north have not shown any effects at the exposure levels seen thus far in the MOM Study.

Journal Articles:

No journal articles submitted with this report: View all 54 publications for this project

Progress and Final Reports:

Original Abstract

2009 Progress Report

2010 Progress Report

2011 Progress Report

2012 Progress Report

2013