Anyone who has been plagued with a serious infestation of fleas knows how tenaciously those little critters can withstand the onslaught of chemically treated collars, fine-toothed combs, vacuums, and laundering.

Sooner or later, one is tempted to call out the heavy guns -- powders, sprays, and room foggers that have been laced with flea-poisoning pesticides. A new study now suggests that what a woman eats may affect whether such products also prove toxic to her offspring. Many processed meats have been preserved with nitrites to retard the growth of food-poisoning bacteria.

Last year, a team of West Coast researchers reported finding a link between a pregnant woman's consumption of such nitrite-cured meats -- principally hot dogs, sausages, and bacon -- and her child's risk of pediatric brain tumors. Susan Preston-Martin at the University of Southern California in Los Angeles and her colleagues observed that the children of women who had eaten an average of two helpings of these processed meats daily faced twice the risk of brain cancer of those whose moms had eaten no such foods.

The good news: Diets high in vitamins C and E-potent antioxidants-appeared to block the formation of the nitrogenous compounds responsible for those tumors. If transformation of the sodium nitrite preservative in many cured meats could be ameliorated by those vitamins, might it be fostered by certain other agents? Since Preston-Martin and Janice M. Pogoda of Statology in Truckee, Calif., were investigating a purported link between pesticides and childhood brain tumors, they decided to ask the 440 participants -- half of whom had children with such cancers, the rest mothers of healthy children -- whether they had eaten cured meats during pregnancy.

Carbamates, such as carbaryl, are an active ingredient in many flea and tick products (other than shampoos and dips). Though the Environmental Protection Agency does not consider carbaryl to be a carcinogen, this compound will react with nitrite in a highly acidic environment -- as is found in the stomach -- to form nitrosocarbaryl, notes Pogoda. At least in mice, this compound causes cancer.

In the November Environmental Health Perspectives, she and Preston-Martin indeed find hints of an apparent synergy between pesticide exposure and consumption of cured meats. Explains Pogoda, "We only had eight moms who ate a lot of high-nitrite cured foods while the were pregnant." However, all eight had given birth to a child who ultimately developed brain cancer. Moreover, each had reported using flea powders during pregnancy. About 80 percent of these products contain carbaryl, she notes.

Because the number of women who were ate lots of cured meats was so small, the link remains unproven. However, Pogoda adds, it does look "pretty suspicious."

Related Reading

Pogoda, J.M., and S. Preston-Martin. 1997. Household pesticides and risk of pediatric brain tumors. Environmental Health Perspectives 105(November):1214. 

Preston-Martin, ... and J. Pogoda. 1996. Los Angeles study of residential magnetic fields and childhood brain tumors. American Journal of Epidemiology 143(Jan. 15):105. 

From fleas to brain tumors. Science News 152(Dec. 13):375.  

_____. 1994. Not so hot hog dogs? Science News 145(Apr. 23):264.  

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