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... GLOBAL NEWS ... NEWS EXPOSURE TO PESTICIDES times to make sure the results were repro- Health Perspectives 106(6):347-353, June LINKED TO HYPERACTIVITY ducible. They found effects on the 1998). Elizabeth A. Guillette and col- or the past 25 years, tens of millions of endocrine system (thyroid hormone levels) leagues studied two groups of Yaqui Indian Fee in hundreds of cities and towns 294 immune system, and reduced body children living in the Yaqui Valley in north- have been drinking tap water that is weight from mixtures of low levels of — ern Sonora, Mexico. One group of children contaminated with low levels of insecti- 2!dicarb and nitrate, atrazine and nitrate, and _ lives in the lowlands dominated by pesti- cides, weed-killers and artificial fertilisers. atrazine, aldicarb and nitrate together. They _ cide-intensive agriculture (45 or more spray- They not only drink it, they also bathe and observed increased aggression from expo-__ ings each year), and the other group lives in shower in it, thus inhaling small quantities SUT€ to atrazine and nitrate, and from _ the nearby upland foothills where their par- of farm chemicals and absorbing them atrazine, aldicarb and nitrate together. ents make a living by ranching without the through the skin. Naturally, the problem is The Wisconsin research team wrote: "Of use of pesticides. The pesticide-exposed at its worst in agricultural areas. particular significance in the collective work children had far less physical endurance in a The most common contaminants are car- Of Boyd and others, Porter and others, and _ test to see how long they could keep jump- bamate insecticides (aldicarb and others), OY current study is that thyroid hormone _ ing up and down; they had inferior hand-eye the triazine herbicides (atrazine and others) concentration change was consistently a coordination; and they could not draw a and nitrate nitrogen. For years, government eSponse due to mixtures, but not usually to simple stick figure of a human being, which scientists have tested each of these chemi- individual chemicals." In the five-year _ the upland children could readily do. cals individually at low levels in laboratory experiment, thyroid hormone levels rose or Notably, in the Guillette study we find animals—searching mainly for signs of can- fell depending upon the mixture of farm _ this description of the behaviour of pesti- cer—and have declared each of them an Chemicals put into the drinking water. cide-exposed children: "Some valley chil- Dr Porter and his colleagues present evi- dren were observed hitting their siblings dence from other studies, showing that _ when they passed by, and they became easi- numerous farm chemicals can affect the thy- ly upset or angry with a minor corrective roid hormone levels of wildlife and humans. comment by a parent. These aggressive PCBs and dioxins can have similar effects, behaviors were not noted in the [pesticide- they note. Proper levels of thyroid hormone _ free upland] foothills [children]." are essential for brain development of This is a time when Americans are humans prior to birth. Some, though not all, searching for the causes of violence in their studies have shown that attention deficit society. No one seems to be asking whether and/or hyperactivity disorders in children _ pesticides, fertilisers and toxic metals are are linked to changes in the levels of thyroid affecting our young people's mental capaci- hormone in the blood. Children with multi- ty, emotional balance and social adjustment. ple chemical sensitivity (MCS) have abnor- From the work of Warren Porter, Elizabeth mental effects on the nervous, immune and ™al thyroid levels. Furthermore, irritability Guillette and others, it is apparent these are endocrine (hormone) systems (Toxicology and aggressive behaviour are linked to thy- valid questions. and Industrial Health, vol. 15, nos 1&2, roid hormone levels. (Source: By Peter Montague, Rachel's A recent study of four- and five-year-old Environment & Health Weekly, no. 648, 29 children in Mexico specifically noted a April 1999, Environmental Research decrease in mental ability and an increase in Foundation, USA, tel (410) 263 1584, fax aggressive behaviour among children (4/0) 263-8944, e-mail , exposed to pesticides (Environmental website ) "acceptable risk" at the levels typically found in groundwater. Now a group of biologists and medica researchers at the University of Wisconsin in Madison, led by Warren P. Porter, has completed a five-year experiment putting mixtures of low levels of these chemicals into the drinking water of male mice an carefully measuring the results. They reported recently that combinations of these chemicals—at levels similar to those found in the groundwater of agricultural areas 0: the United States—have measurable detri- 1999). Furthermore, they say their research has direct implications for humans. Dr Porter and his colleagues point out that the nervous system, the immune system and the endocrine (hormone) system are all closely related and in constant communica- tion with each other. If any one of the three systems is damaged or degraded, the other two may be adversely affected. The Wisconsin researchers therefore designed their experiments to examine the effects of agricultural chemicals on each of the three systems simultaneously. To assess immune system function, they measured the ability of mice to make anti- bodies in response to foreign proteins. To assess endocrine system function, they mea- sured thyroid hormone levels in the blood. And to assess nervous system function they measured aggressive behaviour in the pres- ence of intruder mice introduced into the cages. They also looked for effects on growth by measuring total body weight and the weight of each animal's spleen. The experiments were replicated many JUNE — JULY 1999 NEXUS <9