Chlorinated pesticides: threats to health and importance of detection.

Abstract

Although chlorinated pesticides have been mostly banned from use in the United States, their persistent presence in the environment poses an ongoing threat to health. Because of the lipophilic nature of chlorinated pesticides, they are bioaccumulative and difficult to excrete from the body. A select group of these xenobiotics is also associated with a wide range of health problems, identification of which would aid in disease prevention and reversal. Ongoing research by the Centers for Disease Control and Prevention now provides national standards for some of these compounds, allowing the clinician to evaluate levels in a patient. Serum samples are easily obtained and can reveal the presence of these xenobiotics. Eight of the most commonly found and harmful chlorinated pesticides are reviewed in this article, along with the most common sources of exposure and possible action steps. (Altern Med Rev 2009;14(4):347-359)

Introduction

Multiple studies over recent decades have examined the presence of xenobiotic substances in the blood or adipose tissue of a variety of subjects. A number of these compounds, including the chlorinated pesticide dichlorodiphenyltrichloroethane (DDT) and the industrial polychlorinated biphenyl (PCB) compounds, are stored in the fat tissue of the body and, instead of being easily excreted, continue to "bioaccumulate" over time. A portion of these fat-soluble compounds is passed from mother to child; thus, all new life starts with a toxic load. The load is increased incrementally through eating, drinking, and breathing, increasing the total toxin burden during the aging process.

The Environmental Working Group (EWG) (www.ewg.org) funded and published two studies that specifically tested adults and newborns in the United States to see how many toxins were carried. The EWG originally tested nine adults, none of whom worked in industries that would ordinarily expose them to high levels of environmental poisons. (1) The nine adults in the EWG study had an average of 91 of the 210 toxic compounds that were tested present in serum, including an average of 33 PCBs and four chlorinated pesticides.

Since these compounds can be passed from mother to child, the EWG designed another study to measure how many chemicals would be found in a random sampling of cord blood from infants in the United States. The EWG newborn study looked for the presence of 413 different xenobiotic chemicals in the cord blood of 10 infants born in U.S. hospitals in 2004. (2) A total of 287 toxic compounds were found in the cord blood samples, including 147 PCBs and 21 chlorinated pesticides.

While these types of articles are alarming, they do not help the clinician determine whether a patient is carrying an abnormally high load of a particular toxin, or whether the toxin is one that carries documented health risk. To answer the first question, the Centers for Disease Control and Prevention (CDC) has been conducting ongoing studies to identify the toxic burden carried by U.S. residents. They have published three reports to date that are available at http://www.cdc.gov/exposurereport/report.htm. When a new study is...