CEHN Articles of the Month, December 2015 Issue
Effect of Organic Diet Intervention on Pesticide Exposures in Young Children Living in Low-Income Urban and Agricultural Communities
Authors: Asa Bradman, Lesliam Quirós-Alcalá, Rosemary Castorina, Raul Aguilar Schall, Jose Camacho, Nina T. Holland, Dana Boyd Barr, and Brenda Eskenazi
Organophosphate (OP) pesticides are one of the most commonly used pesticides in the world. Although the U.S. Environmental Protection Agency (EPA) phased out the use of many residential OP pesticides during the early to mid 2000’s due to potential health risks in humans, OP pesticides continue to be widely used in agriculture. Pregnant women and children are particularly vulnerable to the effects of OP pesticide exposure. OP pesticide exposure during pregnancy has been linked to several adverse health effects, including reduced birth weight, head circumference, and gestational length in infants, and may cause neurodevelopmental effects in infants and toddlers. The use of OP pesticides in agriculture is particularly concerning given that pesticide residues on food can be ingested, and recent research indicates that a significant amount of OP pesticide exposure in children may be due to dietary sources. Much of this evidence has come from dietary intervention studies in which children given an organic diet demonstrate lower levels of OP pesticide byproducts in their urine than children given a non-organic diet. These organic food intervention studies have been conducted exclusively in suburban and non-agricultural communities, and thus findings may not be representative of children from urban and agricultural communities whose exposure patterns may include higher non-dietary exposures to OPs. Children from low-income, urban families, for example, may experience high exposure to pesticides due to poor housing quality and home pesticide use, and children from agricultural communities tend to be exposed to greater ambient and residential exposure from nearby agricultural applications and from residues brought into the home from farm-working parents. Thus, it is important to examine the impact of dietary intervention in low-income children in urban and agricultural communities to better understand the relative impacts of dietary versus non-dietary pesticide exposure.
To determine the relative contributions of dietary versus non-dietary pesticide exposure in low-income children living in urban and agricultural communities.
Urinary levels of OP pesticide, pyrethroid, and other pesticide byproducts used in homes and agriculture were assessed in a group of 40 Mexican-American children over the course of 16 days. The children were between ages 3-6 and were living in urban and agricultural communities in California. During this 16-day period, children consumed non-organic food for the first 4 days, then organic food for the next 7 days, and then non-organic food for the following 5 days. Urine samples were tested for 23 different types of pesticide byproducts.
While urinary levels of some specific pesticide byproducts did not change, levels of byproducts were generally lower (across all children) for several types of OP pesticides and for one herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), during the organic diet.
This study is the first to examine the relative contributions of dietary versus non-dietary exposures to pesticides in low-income children living in urban and agricultural communities. This study is also the first to find that consumption of an organic diet in children living in urban and agricultural communities reduces urinary levels of several pesticide byproducts. These results suggest that diet is an important source of pesticide exposure in children living in urban and agricultural communities and that organic diet intervention can reduce urinary pesticide levels for several different types of pesticides.
Under the Federal Insecticide, Fungicide and Rodenticide Act of 1947 (FIFRA) all pesticides sold or distributed in the United States are required to be registered by EPA. The agency also, under the Federal Food, Drug, and Cosmetic Act of 1938 (FFDCA), sets acceptable levels (tolerances) for pesticides that will end up in or on food. The Food Quality Protection Act of 1996 amended FIFRA and FFDCA. The statute requires EPA to add an additional ten-fold safety factor to tolerances to specifically account for vulnerabilities associated with pre- and post-natal exposures, unless sufficient reliable data indicates that the tolerance initially established will be safe for children and infants.
Unfortunately, the current regulatory process is not conducive to quick responses to emerging science. For example, chlorpyrifos, an OP pesticide which is toxic to the nervous system, and which has been linked to low birth weights and endocrine disruption, was banned for residential use by EPA in 2000. Since that time, extensive evidence accumulated showing that agricultural use of chlorpyrifos also posed exposure risks that could harm children. However, the proposed rule to ban agricultural use has come a full 15 years later. Quick action in response to sound, peer-reviewed, independent science is necessary to protect children, as is the need to consider all potential exposure sources of pesticides.
Careful consideration of human and environmental health is needed with regard to the use of genetically engineered (GE), pesticide-resistant seeds such as the 2,4-D-resistant corn and soy seeds that the U.S. Department of Agriculture approved last year. Studies show that adoption of GE crops have dramatically increased herbicide use in the US as weeds develop resistance to the herbicides, and scientists estimate that the introduction of 2,4-D resistant crops could lead to as much as a 25-fold increase in 2,4-D use across the country over the next few years.
Lastly, continued and increased support at the federal and state levels is needed for organic and sustainable agriculture. This would not only help organic farmers, but would also increase affordability and accessibility of organic produce for the general public. Ensuring that federal food assistance programs (Supplemental Nutrition Assistance Program Benefits and the Special Supplemental Nutrition Program for Women, Infants, and Children) allow for the purchase of organic--or at least local, in-season, and sustainably-grown foods--at farmers markets and other venues is another way to make organic food more accessible, thereby lowering children’s exposures to pesticide residues on food, as well as their body burdens of many pesticides.