Diet as a Source of Exposure to Environmental Contaminants for Pregnant Women and Children from Six European Countries
Authors:Eleni Papadopoulou, Line Småstuen Haug, Amrit Kaur Sakhi, Sandra Andrusaityte, Xavier Basagaña, Anne Lise Brantsaeter, Maribel Casas, Sílvia Fernández-Barrés, Regina Grazuleviciene, Helle Katrine Knutsen, Lea Maitre, Helle Margrete Meltzer, Rosemary R. C. McEachan, Theano Roumeliotaki, Remy Slama, Marina Vafeiadi, John Wright, Martine Vrijheid, Cathrine Thomsen, and Leda Chatzi
Persistent organic pollutants (POPs) are toxic compounds that do not degrade quickly. Instead, they remain in the environment for a very long time where they can build up in the food chain. When consumed, they can also accumulate in human bodies and contribute to adverse health effects. Various POPs were introduced in the United States (U.S.) following World War II for use in agricultural, manufacturing and disease control.1 Despite being heavily restricted for the past couple of decades, the persistence of these toxicants continues to pose a hazard to human health.
Examples of POPs, and how they can affect the health of children, include:
- Organochlorine compounds and polybrominated diphenyl ethers (PBDEs), which have been linked to: restricted fetal development, increased harm to the central nervous system, reduced functioning of the immune system, reduced fertility and increased risk for obesity.
- Per- and polyfluoroalkyl substances (PFAS), such as perfluoroundecanoate (PFUnDA), perfluorononanoate (PFNA), and perfluorooctane sulfonate (PFOS), which have been linked to: adverse birth outcomes and are linked to an increased risk of cancer as well as promoting issues associated with the liver.
- Heavy metals, such as mercury (Hg), arsenic (As), and lead (Pb) which are linked to: impaired cognitive, motor and behavioral development.
- Phthalate metabolites (metabolites are by-products produced when compounds are being metabolized in the body), phenolic compounds, and organophosphate pesticide (OP) metabolites, which have been linked to: decreased function of the nervous system.
Today, over 90% of human exposure to these POPs occurs through the consumption of contaminated food.2 POPs enter our everyday diets through: marine and agricultural food chains, food packaging leakage, and also during food processing. Children can experience higher exposure levels to POPs because children eat or take in more than adults do, per pound of body weight. Prenatal exposure occurs because POPs can cross from mother (through her diet) to child through the placenta. POPs can also be passed from mother to child through breast milk, and older children are exposed through their own diet directly.
Children also face more harm from exposure to POPs because their bodies are not finished developing. A fetus or young child’s nervous/neurological, immune, respiratory, and reproductive systems may be in a critical window of development, and particularly vulnerable to harm when faced with exposure.
“Most earlier studies have focused on the dietary determinants of exposure to single contaminants, even though several contaminants frequently share common sources of exposure. Few studies have reported contaminants’ patterns and their association with nutrients and the consumption of specific foods. The identification of such common dietary sources of exposure can assist in designing and delivering effective dietary advice. Dietary recommendations must be balanced between the health risks related to dietary exposure to environmental contaminants and the health benefits of important nutrients.”
This study considered mother-child pairs from across six European countries, specifically 818 mothers and 1,288 children between the ages of 6 and 11 years old.
Diets of all participants were recorded and subsequent blood and urine samples were tested for possible POPs presence.
Researchers categorized blood and urine levels of POPs by seven weekly consumption food groups:
- three of animal origin
- meat and meat products
- fish and seafood
- dairy products
- four of plant origin
- bread and cereals
- variations of dry beans, dry peas, chickpeas and lentils
Mothers were also asked to categorize their children’s dietary habits into one of three categories:
- no organic (grown without pesticide use) food consumption
- once a week or less of organic food consumption
- more than once a week of organic food consumption
Researchers recorded numerous POPs in blood levels of mothers and children, including OP, PBDEs, PCBs, PFAS, and heavy metals as well as urine levels of phthalate metabolites, phenolic compounds, and OP metabolites. The results of children were evaluated in context with the dietary survey.
Mothers who consumed fish more frequently (four or more times a week) demonstrated elevated levels of POPs in blood and urine samples, including a 15% higher presence of PCBs, 42% higher presence of PFUnDA and 487% increase in As levels.
Like mothers, children with high fish consumption (three or more times a week) also had elevated levels of POPs in their samples, with a 23% higher presence of PFNA, 36% increase in PFUnDA, 37% increase in PFOS and >200% increase in Hg and As.
These results suggest that increased fish consumption is positively associated with exposure to a number of POPs.
Fruit consumption is also positively correlated with an increase in OP (pesticide) metabolites in pregnant women and children. Mothers and children who had high fruit intake (more than 18 times per week for mothers, more than 14 times per week for children) showed a positive correlation with an increase in OP metabolites in urine samples.
Children classified by mothers as having more than once a week organic food consumption resulted in urine samples with significantly lower levels of OP metabolites and 8% lower levels of lead (Pb). Organic food consumption by children was more frequent among those with highly educated mothers.
High level of fish consumption by children and mothers in early stages of pregnancy is associated with higher concentrations of POPs accumulating in the body. The researchers estimated that children’s exposure to POPs could be lowered by: pregnant women eating no more than three servings of fish per week, and young children eating no more than two servings of fish per week. The study also suggests that pregnant women and young children who eat a lot of produce can lower their exposure to OPs by eating organic whenever possible.
Despite the findings in this study, fish and produce provide valuable nutrients that are key components of a well-balanced diet for pregnant women and children. The benefits of eating fish and produce, organic or not, likely outweigh the risk of POPs for those consuming a varied and moderate amount of each. However, it is critical that the U.S. government continues to strive for a toxic-free food system.
In 2001, the Stockholm Convention created a framework for the eradication of international POPs usage and finalized a legally binding agreement for countries to minimize their production and distribution of these pollutants. The treaty was signed and ratified by 152 countries in 2004, creating a system to eliminate use of POPs with the ultimate goal of transitioning to safer alternatives.3 The U.S. was among the signatories, and the U.S. Environmental Protection Agency (EPA) regulated the U.S. sale or distribution of the 12 original POPs targeted in the Convention.1 However, the U.S. has not yet ratified the treaty, citing a lack of authority to “implement all of its provisions.”4 In addition,by 2019, the POPs of concern have grown from a list of 12 to 17.2 To best protect the health of our children, the U.S. must update our federal chemical safety and pesticide policies, ratify the Convention and its amendments, and completely phase out all 17 POPs.
The U.S. Food and Drug Administration (FDA) Total Diet Study (TDS) monitors contaminants found on food, including POPs residue. Using the data collected, the FDA is able to estimate the level of exposure people in the U.S. receive to such toxicants annually, utilizing the TDS to inform consumers about food safety and to suggest areas of focus for nutrition programs.7 However, the FDA only updates the list of foods analyzed every 10 years, which appears inefficient in keeping up with ever-changing diets and potential exposures to considerably life-altering pollutants.7 When a tested food item reveals levels of POPs in exceedance of the FDA’s “action level”, it must be removed from the market.8 However, the FDA’s “action level” is too high and not aligned with the health based standards held by the EPA and the Agency for Toxic Substances and Disease Registry (ATSDR).8 This misalignment among the federal agencies jeopardizes food and safety standards in the U.S.
In 2015 the EPA proposed a ban on chlorpyrifos, a widely used agricultural OP associated with brain damage and other harmful effects to children. However, in 2017, under new administration, the EPA reversed course and agricultural workers and consumers are still being unnecessarily exposed to this harmful pesticide. States have now stepped up to protect children. So far Hawaii, California, and New York have issued statewide bans on chlorpyrifos. In the absence of federal action, more states should follow suit.
There are clear gaps in the federal government’s actions to protect children from exposure to POPs. In the meantime, individuals can adopt best practices to reduce exposure to POPs while obtaining the rich dietary benefits of fish and produce. These include: washing produce thoroughly before consumption, checking state, local, and tribal fish consumption advisories to determine the relative safety of local seafood, eating fish no more than twice a week, and if financially feasible--buying organic or using the Dirty Dozen and Clean Fifteen guidelines to prioritize organic purchasing
This study stimulates a larger conversation on issues of environmental justice. Access to a safe and well-balanced diet is influenced by a number of factors, including race, education and socioeconomic standing. Children who eat organic food may have less exposure to some POPs, but organic food tends to be less affordable and less accessible than their conventional counterparts. In addition, some populations, especially marginalized and indigenous populations, are largely or solely dependent upon fish,9 without access to alternative sources of protein. More equitable access to safe and healthy food ensures is needed so that all are able to eat a well-balanced diet while minimizing excess exposure to POPs.