Insecticides for infants?
The use of household insecticides may be hurting more than just mosquitoes and cockroaches
By Mabelle Aban, Contributing Writer
More than a few researchers have noted the apparent rise in the rates of mental retardation, autism, and attention-deficit/hyperactivity disorder in children in the past couple of decades. Although the interplay of a number of factors has been suspected, the possible role of environmental problems in these conditions has been closely studied, especially during pregnancy.
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Dr. Enrique Ostrea, professor of pediatrics at Wayne State University, led a group of researchers (many of whom came from the University of the Philippines Manila-Institute of Child Health and Human Development) to look into the potential effects of fetal exposure to environmental toxicants, particularly pesticides. The study, funded by the United States National Institutes of Health, tried to determine whether infants whose mothers had been exposed to pesticides suffered from immediate and long-term health and development problems. Considered the foremost expert in meconium testing, Ostrea, together with his colleagues, demonstrated in this study that pesticides can also be detected in the meconium.
Preliminary results of the study scheduled to run for five years were presented at a research forum organized by the UP-National Institutes of Health in April.
Pregnant women at midgestation from Malolos, Bulacan, were prospectively recruited for this study. Bulacan was chosen as the study site because it was "an agricultural province" where significant amounts of pesticides are being used. Blood and hair samples from the mothers were obtained at midges-tation. At birth, infant cord blood, hair, and meconium were obtained. All these samples were analyzed for pesticides and heavy metals. A total of 793 infants were enrolled at birth. The study followed 755 of them up to their second birthday.
The toxin found in very high levels among the mothers and infants was not a component of agricultural pesticides, but of household pesticides. Propoxur, the principal ingredient of the insecticide Baygon, was found in 21.2 percent of the meconium samples. Pyrethroids were the second-leading pesticide component, with 2.3 percent.
The presence of these toxicants in cord blood and infant hair was significantly lower. Said Ostrea: "There was significant difference in the prevalence of the pesticides in meconium compared to cord blood or infant hair, indicating that of these three matrices, the best matrix to analyze for fetal exposure is still the meconium."
As for the mothers, the investigators found the highest prevalence of propoxur in maternal hair (21.1 percent), followed by bioallethrin (13.9 percent). The maternal-blood samples showed significantly lower rates for these chemicals. Ostrea said: "If you are trying to test maternal exposure to pesticides during pregnancy, the best is to analyze hair rather than blood."
With regard to "birth weight, length, head circumference, and gestation of those who were exposed and not exposed, we did not see any significant relationship between prenatal pesticide exposure and of the birth outcome, so there was no effect at birth," Ostrea said.
Still, adverse outcomes were seen in the children during follow-up. For instance, the cord-blood samples were examined for t(8;21) translocation, considered a biomarker for leukemia. The rate of this translocation was 10 percent among infants who had tested negative for propoxur exposure, 20 percent for those who had tested positive for propoxur.
Pesticides at home
In a survey, the investigators found that 38.2 percent of households use sprays, specifically Baygon, to eliminate insect problems. Nearly 40 percent of those who admitted to using insecticides were pregnant women.
Ostrea noted that the labels of these sprays had inadequate warnings concerning their appropriate use and the possible risks their use poses on pregnant women. "We have to warn the mothers," he stressed.
He also stressed the importance of following up the infants until they reach school age using "more extensive and sensitive neurobehavioral measures, which are designed to test the developing skills of children at this critical age."
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WATCH WHAT YOU EAT
The presence of pathogenic Yersinia should alert consumers on the importance of food hygiene
News reports of food poisoning are common-in fact we or someone we know may have fallen victim to this nasty problem. We always try to be careful when food that is not cooked at home, and yet, sometimes we couldn't be too sure about the ones that we ourselves prepare. So before any food item reaches our stomachs, how do we know it is clean and free of disease-causing microbes?
One of these "emerging food pathogens" is Yersinia enterocolitica. In a research forum organized by the University of the Philippines Manila-National Institutes of Health in April, Prof. Alice Alma Bungay of the UP Manila College of Public Health discussed the findings of a study on the prevalence of this microbe in a number of Filipino food items.
Yersinia enterocolitica causes a variety of disorders, ranging from nonspecific diarrhea to invasive extraintestinal diseases, said Bungay. It targets the lower digestive tract, where it produces symptoms that resemble those produced by Salmonella. It mimics appendicitis in children. It can also cause enterocolitis and septicemia, which can be fatal.
This organism can be usually found in rodents and farm animals, especially pigs. It can contaminate water and unpasteurized milk. However, vehicles in food-borne outbreaks that have been reported are chocolate milk and even pasteurized milk.
For the study, different food samples were obtained from three Metro Manila public markets considered "class A." Class-A markets are those with the highest number of market stalls, the highest average monthly income, and are most frequently visited by consumers. The food samples included fruits, vegetables, fresh and processed meat (chicken, beef, and pork, including innards), and others (such as noodles and tofu).
Yersinia in food and proper food handling
Out of those 360 food samples collected by the investigators, 20 were found positive for Yersinia spp.-a prevalence rate of 5.5 percent. Yersinia enterocolitica was found in 14 of the samples. Of the 14, three proved positive for the virulent strain. "They are mostly found in the local sources such as longganisa made from ground pork in intestinal casings," said Bungay. "Eleven of the food samples were nonvirulent, but take note, it can be found in chicken innards; two were [from] hotdog samples, two longganisa samples, and one liver sample."
This study showed that Yersinia enterocolitica can be found in food samples commonly consumed by Filipinos, especially those coming from wet markets. This led Bungay to stress that surveillance studies should be conducted on "pork … as reservoirs of infection." She went on to say that the use of an ice box or a refrigerator "does not guarantee complete exclusion and prevention of pathogenic Yersinia," since this microbe can thrive in a cold environment.
She also stressed the importance of proper food handling and processing. Proper hygiene and sanitation should start at the farm, she said, and should be maintained in production sites and public markets, especially with regard to pork and pork products, owing to the risk of cross contamination. And at home, these products should be thoroughly cooked.
M M. Aban
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