A new US study demonstrates that harmful pesticides can be detected in the body fluids of children who consume conventionally grown foods.
The study was funded by the Environmental Protection Agency (EPA) and involved scientists from Emory University, the Centers for Disease Control & Prevention (CDC) and the University of Washington. The results are published in this month's issue of the Environmental Health Perspectives journal.
The study was conducted over the period of a year and involved children living in suburban areas of Seattle in the state of Washington.
Researchers found that urine and saliva samples of children eating a variety of conventionally grown foods from local supermarkets and grocery stores contained biological markers of organophosphates. These are a particularly nasty family of pesticides whose origins lie in the development of nerve gas during the Second World War.
It was found that when the children were switched to a diet of organic produce, including organically grown fruits, vegetables and juices, the pesticide markers in their urine and saliva disappeared.
The researchers report that once the organic diet was initiated the pesticide markers (malathion and chlorpyrifos) were no longer detecable after only a short period of time.
A total of 21 children, ages 3 to 11, all from local schools took part in the study. After only 36 hours of being on the organic diet the pesticide markers were no longer detectable in any of the children.
Once the childen returned to a conventional diet the pesticide markers were again detectable in urine and saliva samples almost immediately.
The study's authors note that the area in which the children live is affluent but they feel the results would be the same for children in lower income families. The study is now being repeated in the state of Georgia to confirm the findings.
What this study did not investigate was which conventionally grown foods present the greatest risk of pesticide exposure. This is an important issue for consumers since pesticide levels in different foods can vary greatly.
Other studies have looked at this issue. The Environmental Working Group analyzed the results of nearly 51,000 tests for pesticides on fruits and vegetables that the US Department of Agriculture (USDA) and the Food and Drug Administration (FDA) conducted between 2000 and 2005.
The results of this study show fruits fairing particularly badly. Peaches, apples, nectarines, strawberries, and cherries all feature in the top 10 of the most contaminated foods. Bell peppers, celery, and lettuce also appear in the top 10 worst offenders.
The details of the testing make for shocking reading. Of the fruit and vegetables in the top 10, pesticide residues were detected on over 80% of samples tested, apart from lettuce (68.2%). Perhaps even more worrying is the number of different pesticides detected on a single sample. A total of 11 different pesticides were found on a sample of bell pepper and the results show it is not unusual to find more than 5 different pesticides on a whole range of common fruits and vegetables.
At the other end of the scale, onions, avacados, sweet corn, pineapples, and mangoes faired much better with pesticides hardly ever being detected and only a single type being found when they were.
What effect the presence of pesticides may have on children's health at the levels detected in the Seattle study is a contentious issue. Since pesticides such as organophosphates were designed to kill, there is no argument that at higher levels they are very harmful. The question is whether there is a safe level of exposure or whether even small amounts can lead to developmental disorders and disease.
Many researchers believe that pesticides, even in very small amounts, pose serious threats to health, especially in children. Harvard School of Public Health researchers have found that everyday exposures to pesticides can seriously disrupt immune function and therefore increase the potential for the development of allergies, auto-immune conditions and even cancer.
One study reported that pregnant mothers' exposure to pesticides was associated with mental development and pervasive developmental problems in their children at 2 years of age:
Other researchers have concluded that we just don't know what effects pesticide exposure has on children's development and call for much more research:
So it appears clear that more research needs to be focused in this area. For the time being it would seem wise to buy organic whenever possible.