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Household pesticide use is pervasive. The EPA estimates that approximately 74 million pounds of pesticide active ingredients (7 percent of total conventional pesticide use in the United States) are used in homes and gardens each year.[39] Pesticides used in the home or on the lawn are either applied by commercial pest control and landscape maintenance companies or by homeowners themselves.

A 1992 survey conducted by the EPA found that 85 percent of households nationwide had at least one pesticide product stored in the home. The average number of pesticide products stored in homes is between three and four, and insecticides are the most common type of pesticide used in homes.[40] Of particular concern was the number of households found to still store banned and highly persistent and dangerous pesticides. An estimated one million households still have products containing chlordane; 150,000 still have DDT; 70,000 still have heptachlor, and approximately 85,000 still have Silvex.[41]

Most residents were found to take few precautions, if any, to protect children from exposure to these toxic materials. An estimated 47 percent of households with children under the age of five were found to store at least one pesticide within reach of small children.[42] Only 25 percent of all homes were found to store all pesticides securely.[43] Another survey of household pesticide use among 238 families in Missouri found that 80 percent used pesticides during pregnancy and 70 percent used pesticides during the first six months of a child's life.[44] Sixty-six percent of the households used pesticides more than five times each year.

A recent survey of pesticide use in 51 households in Sarasota County, Florida, found that the most common use of pesticides was direct application to carpets for control of fleas.[45] This is particularly hazardous for children, who spend considerable time at ground level and can inhale pesticides in air and absorb pesticides from the carpet directly through their skin.

State and federal officials evacuated 1,000 people from homes in Mississippi, Alabama, Louisiana, and Arkansas due to unsafe levels of methyl parathion. In addition, twelve businesses have closed, including eight daycare centers, a restaurant, and a hotel. Two unlicensed exterminators had sprayed the chemical in businesses and residences even though it is only registered for agricultural use.[46] The Agency for Toxic Substances and Disease Registry is initiating a study to see whether children exposed to methyl parathion suffer memory loss, behavioral disorders, or other adverse neurobehavioral outcomes.[47]

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Current standards established by the U.S. Environmental Protection Agency to protect children from exposure to hazardous pesticides fail to consider children's cumulative exposure to the same pesticide from multiple sources. Although separate standards exist for minimizing exposure in food and water, for example, none currently take into account that on any given day a child may be exposed to the same pesticide from several sources. With the enactment of the Food Quality Protection Act of 1996, the EPA is now required to consider cumulative routes of exposure to a pesticide when setting tolerances.

Examine the various ways a child can be exposed to chlorpyrifos, the most widely used insecticide in the United States.[77] Under the trade name Lorsban, chlorpyrifos is applied to numerous food crops; under the trade name Dursban, it is widely used around the home and garden. Over 17 percent of U.S. households use chlorpyrifos products, primarily as a treatment for termites underneath homes and buildings, between cracks and crevices for cockroach control, as a fogging agent against fleas, and in pest control strips.[78] Not counting synergists (chemicals added to pesticide products to increase the effect of the pesticide ingredient), chlorpyrifos was the fourth most common insecticide found in U.S. homes in a 1990 EPA survey.[79] Chlorpyrifos is frequently detected in indoor air.[80] Chlorpyrifos residues can remain in homes for years after treatment and, in one study, have actually been found to increase in air over time.[81] Of particular concern is hand spraying of aqueous chlorpyrifos formulations directly to household surfaces for control of fleas. Monitoring of indoor air and surfaces such as carpets after such spraying has detected chlorpyrifos at levels high enough for infants, who spend considerable time crawling on the floor, to absorb a dose five times above levels that cause toxicological effects.[82]

Children are exposed to chlorpyrifos residues in food. According to a 1994 monitoring of ready-to-eat foods conducted by the Food and Drug Administration, chlorpyrifos was the second most commonly detected pesticide in food. The FDA's sample included many foods eaten by infants and children.[83] Chlorpyrifos residues may also appear in drinking water; it has been found in the groundwater of nine states, in the surface water of two states, and in rainwater and fog in California.[86]

Chlorpyrifos appears frequently as an illegal residue on foods for which its use is prohibited.[87] The most recent, highly visible case involved chlorpyrifos contamination of Cheerios. In 1994, FDA sampling led to the discovery that a commercial applicator under contract to General Mills, Inc. had illegally treated 21 million bushels of raw oats with chlorpyrifos-ethyl as a substitute for chlorpyrifos-methyl, the formulation of chlorpyrifos legally registered for use on oats.[88] Fifty-five million packages of General Mills cereals made from contaminated oats were eventually landfilled or incinerated.[89]

Both acute and chronic illness are common concerns following exposure to chlorpyrifos. As an organophosphate insecticide, chlorpyrifos is acutely toxic to the nervous system and is associated with numerous poisonings. According to a recent EPA analysis, chlorpyrifos is one of the leading causes of acute insecticide poisoning incidents in the United States.[90] In California between 1984 and 1990, chlorpyrifos was responsible for the highest number of physician reported illnesses related to structural pest control activities.[91] As many as 11,000 children under age five were reported to Poison Control Centers between 1985 and 1992 to have been exposed to chlorpyrifos.[92]

In terms of chronic health effects associated with chlorpyrifos, peripheral neuropathy is of greatest concern. Peripheral neuropathy is a condition involving the nerves of the arms and legs that results in burning and tingling, muscle weakness, and difficulty with coordinated movement. In 1995, the manufacturer of chlorpyrifos, DowElanco, agreed to pay $876,000 for failing to disclose to the U.S. EPA information about adverse effects caused by exposure to chlorpyrifos.[93] The consent agreement covers 327 violations involving claims of neurotoxicity and other health effects associated with chlorpyrifos exposure, including at least 215 personal injury claims between 1984 and 1995.[94]

In January 1997, the EPA completed a review of the potential risks associated with household and termiticide uses of chlorpyrifos. As a result, DowElanco agreed to the EPA's plan for providing safer use of the chemical, including the withdrawal of uses for indoor flea control, indoor total release foggers, pet care, and paint additives.

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Childhood poisonings from pesticide exposure are disturbingly common. According to 1995 data compiled by the American Association of Poison Control Centers, pesticides ranked seventh as the most common cause of poison exposure cases, after cleaning substances, analgesics, cosmetics, and cough and cold preparations. Over 50 percent of the 100,301 pesticide poisoning exposure cases reported in 1995 occurred in children under the age of six.[106] Twenty-four percent of the cases reported to Poison Control Centers received some kind of medical attention, and symptoms were present in 20 percent of all reported pesticide exposure cases.[107] While exposure to pharmaceutical and cleaning substances results in a greater number of poisonings than pesticides, poisoning by pesticides can be more serious. During the seven-year period from 1983 to 1990, pesticide exposure was responsible for a total of 4 percent of the total calls to Poison Control Centers but for 12 percent of the total fatalities in those years.[108]

Insecticides are generally responsible for the greatest number of poisonings from pesticide exposure. In 1993, 54 percent of pesticide poisoning cases in children under six were the result of exposure to insecticides.[109] A review of 37 hospitalized pesticide poisonings among infants and children in Texas revealed that 73 percent of the poisonings were due to ingestion of improperly stored liquid insecticide. Fourteen percent of the cases were due to pesticide absorption from carpets and floors following spraying or fogging inside residences.[110]

Most childhood pesticide poisonings occur at home. In an analysis of pesticide-related calls to Poison Control Centers in Minnesota, researchers found that 85 percent of the calls originated from a residence, and 50 percent of the calls concerned children under the age of three. Seventy-four percent of the cases involved insecticides, and ingestion was the most common route of exposure.[111]

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Among the many trials parents must endure are head lice appearing on their school-age children. Because lice have become more tolerant of insecticidal shampoos and infestation is widespread in some schools, successful treatment requires a combination of practices - daily combing with a special lice-removal comb and hand inspection of the hair. Above all else, elimination of lice requires time and patience.

Life Cycle of Head Lice

Mature female lice generally lay their eggs close to the scalp, one egg per hair. (In warm climates, or if the child has a fever, the egg may be laid farther down the hair shaft.) The egg, or nit, is coated with a gluelike substance that cements it to the hair. The eggs hatch within ten to twelve days. Once hatched, females need ten to fourteen additional days to start laying eggs. The approximate total lifespan of a louse is twenty-five days.[136]


Head lice can move rapidly but cannot jump or fly. Most lice are transmitted when an infested person comes into direct contact with other individuals. For example, when children sleep together, enough time is provided for a louse to walk from head to head. Lice and their eggs can also be transferred via infested brushes, combs, caps, hats, scarves, coats, bedding, towels, upholstered furniture, and sponge earpieces on headphones. Head lice cannot live more than twenty hours off the host at room temperature; eggs attached to hairs may remain viable for up to ten days but must find a meal within hours of hatching.[137]


To the untrained eye, nits may be hard to recognize. With a bright light, carefully inspect your child's scalp. A magnifying glass is very helpful. Nits are normally found within a quarter inch of the scalp (although they can be found farther down on the hair shaft). Viable nits are yellowish to gray, darkening to a tan or coffee color as they mature. Empty egg casings are yellow or beige to white. A nit can be easily distinguished from a flake of dandruff or a speck of dust because it will stick to the hair. In other words, if what you see can be easily removed, it is not a nit. The itching associated with head lice arises from the allergic reaction caused by lice saliva. Some people may not experience itching for several weeks.


Successful treatment requires determined parents. Once lice are detected, plan on spending one full day for initial treatment. Thereafter, expect to spend at least one hour per child daily for two weeks. After that, continue to check your child's hair every three to four days for several weeks.

Initial treatment of the child involves a shampoo with water as hot as tolerable, followed by combing of wet hair with a fine-toothed metal lice comb. You can consider using an insecticidal shampoo if the initial infestation is severe. This is not necessary, though. Shampoo, due to the insecticidal properties of soap, is sufficient.[138] (Do not use products containing lindane. It is suspected of causing neurological damage, and lice have become resistant to it.) If using insecticidal shampoo, follow label directions exactly; do not treat for longer periods of time or more frequently than the directions specify. Individuals allergic to ragweed may experience a possible allergic reaction to over-the-counter lice treatments containing pyrethrins, which are derived from chrysanthemum flowers.[139]

Shampoo hair before treatment so insecticide will penetrate lice. Use a basic shampoo without conditioners, detanglers, or silicone. Towel-dry hair before applying the product so the treatment is not diluted. In the last few years, the efficacy of pesticide shampoos against lice has apparently declined, judging by the increasingly common outbreaks of lice and the reported ineffectiveness of over-the-counter treatment products. No good studies of product efficacy in humans have been done in recent years.

After shampooing, comb the hair with the lice comb. You may need to initially detangle with a regular comb. With a towel over your child's shoulders, pass the lice comb through one-inch sections of hair. After each pass, dip the comb in a dish of warm, soapy water to remove the nits. Then manually inspect the hair. The combs, regrettably, are not as effective as hand removal. The only way to eliminate lice is to physically remove all the nits. Be sure to launder towels immediately in hot water, followed by high-temperature drying.

Since head lice wander from head to pillow, headwear, stuffed animals, and such, treating these items at the same time as the initial hair treatment is essential. Clothing, bedding, and other washable items will be successfully deloused by machine-washing with hot water and at least 30 minutes in the dryer on high. Do not forget the cover of the car seat, bike helmet, or sponge earpieces on headphones for computers, cassettes or CD players. Items that cannot be washed or dried can be stored in airtight plastic bags for two to three weeks. Another option is to place items in the freezer for ten hours (space permitting). Remember that head lice do not wander far from the head. A frenzy of laundering, dry-cleaning, washing furnishings and rooms does not substitute for treatment and nit-picking.

For the next three weeks, plan on a daily shampoo, combing, and hand removal of nits. Each morning, place your child's pillowcase and any stuffed animals residing in bed in the dryer for 30 minutes on high heat. (High-temperature heat kills lice.) Use an engrossing arts and crafts project, video, or book to engage your child during the combing process.

Additional Advice

Never treat infants with insecticide-based shampoos. Minimize body exposure to insecticide-based shampoos by treating the child's hair in a sink. Children can lie on the kitchen counter with their hair in the sink. This allows use of the spray hose. Do not use a pesticide in the bath or shower. Do not use head lice insecticides preventively. Overuse of insecticides will make lice more resistant to the chemicals.

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What are Hormones?

Hormones are the natural chemical messengers of our bodies. Secreted into our bloodstream in carefully measured amounts by the endocrine glands, these chemicals then bind to special receptors in different parts of the body and thereby control and adjust many body functions. Thyroid hormone adjusts our metabolic rate, thereby affecting appetite, temperature, and even normal turnover of hair and skin. In the fetus, thyroid hormone strongly influences normal brain development. Infants born of mothers with low thyroid hormone levels almost always suffer from severe mental retardation. Estrogen, secreted primarily by the ovaries, influences the menstrual cycle, fertility, pregnancy, and crucial stages in infant development. Testosterone, secreted by the testes and the adrenal glands, influences sperm development, sexual functioning, and even behavior.

There is increasing evidence that some chemicals found in the environment may interfere with our bodies' complex and carefully regulated hormonal messenger system. The significance of this chemical interference is not yet clear. Nonetheless it is important to be aware of emerging science about hormone disruption in order to be prepared to take action.

The DES Story

A synthetic chemical that mimics natural estrogen came into widespread medical use in the 1950s. The chemical, diethylstilbesterol (DES), was widely used as a "morning-after" pill and during pregnancy to prevent miscarriage. In this manner several million women were exposed to a powerful synthetic estrogen. At that time most people did not realize that chemicals can cross the placenta and that what the mother took during pregnancy would actually enter the fetus. It wasn't until the 1970s, after nearly three decades of DES use, that the terrible side effects of the drug began to be recognized.

Girls born of women who took DES as prescribed during pregnancy were born apparently normal. Yet in their teens and twenties many of these girls developed a rare vaginal cancer; others were found to have abnormalities of the reproductive tract.[153] In many cases these DES-daughters were found to be infertile, while those who were fertile were more likely to suffer a miscarriage or an ectopic pregnancy. Other studies have suggested immunologic and neuro-behavioral abnormalities in women exposed to DES in utero.[154] While the effects on the sons of the exposed women have been less clear, there is evidence that they have an increased risk of undescended testicles, have small penises, and poor sperm function.[155]

The lessons of DES are twofold. Both doctors and pregnant women are much more cautious about any drug use during pregnancy because we now know that many chemicals can cross the placenta and that the fetus is more susceptible to adverse effects from exposure than the adult. The second lesson is that synthetic chemicals can mimic natural hormones and can thereby cause severe, unpredictable effects many years, or even a generation, later.

What Chemicals May Be Involved?

Only a small number of chemicals have been conclusively shown to cause adverse effects in humans via an endocrine mechanism. These known human hormone disruptors are DES, DDT, PCBs, and dioxin.[156] DDT is known to mimic estrogen, while its major breakdown product, DDE, interferes with androgen (testosterone) function. Polychlorinated biphenyls (PCBs) have been found to mimic estrogen and interfere with thyroid hormone. Dioxin interferes with sex hormone function via a complex and indirect route.

Pesticides Known or Suspected to be Endocrine Disruptors
2,4,5-T* Amitrole Nitrofen*
2,4-D Atrazine Trifluralin
Alachlor Metribuzin

Benomyl Maneb Vinclozolin
Fenarimol Metiram Zineb
Mancozeb Tributyltin Ziram

Aldicarb Endosulfan Methomyl
Aldrin* Endrin* Methoxychlor
Carbaryl Fenvalerate Mirex*
Chlordane* Heptachlor* Parathion*
Dicofol Kepone* Pentachlorophenol
Dieldrin* Lindane Permethrin
DDT/DDE* Malathion Toxaphene*



Though banned, DDT and PCBs persist in the environment, where they accumulate in the fat of living things. Dioxin has not been banned because it is primarily an unwanted by-product of combustion. Incinerators and paper bleaching processes produce most of the dioxin in our environment today.

We do not know for sure how many other chemicals may have effects on our hormones. At this time there is no series of tests that chemicals can undergo to determine if they may disrupt hormones. The EPA is working to establish such a series of tests, but the tests will not be widely used for several years. Meanwhile, individual scientists are reporting that a number of other common chemicals may have effects on hormones, particularly on estrogen. The suspect chemicals include a fairly long list of common pesticides, as well as chemicals used in plastics. Many plasticizers, including the alkyl phenols, bisphenol A, and the phthalates, all of which are in widespread use today, have been shown to interact with the estrogen receptor. Many of these chemicals have also been shown to stimulate growth of estrogen-sensitive breast cancer cells in the laboratory. Although these chemicals are all weaker, molecule for molecule, than natural estrogen, there is some cause for concern and a clear and urgent need for more information.

Industrial Chemicals Known or Suspected to be Endocrine Disruptors
Bisphenol A Manganese
Butylhydroxyanisole (BHA) Mercury
Cadmium Polybrominated biphenyls (PBB's)
Dioxins Polychlorinated biphenyls (PCB's)
Furans Penta- to Nonyl-phenols
Hexachlorobenzene Phthalates
Lead Styrene

Polychlorinated Biphenyls (PCBs) and Children

The presence of significant levels of contamination in the Great Lakes ecosystem, and the presence of adverse health effects in animals feeding on fish from these lakes, raises the question of what human health effects may arise from eating Great Lakes fish. A study designed to answer this question was initiated in the early 1980s. A group of new mothers who ate fish from the Great Lakes either just prior to pregnancy or during pregnancy were selected. New mothers who were similar to the fish eaters in most other ways but who ate no Great Lakes fish were used as a comparison group. Maternal blood and breast milk, as well as umbilical cord blood samples, allowed the researchers to accurately measure levels of PCBs in the mothers and infants. The infants were then followed with examinations just after birth, at seven months, at four years, and most recently at eleven years of age.

As infants, the exposed children were smaller and had disproportionately small head size compared to expectations for their age and birthweight, as well as compared to the average head size of the unexposed infants.[157] At seven months the exposed infants had less preference for novelty and had deficits in visual recognition memory. [158] At four years of age the exposed children remained thinner and had lower activity levels compared to the unexposed children; the effect on activity level was particularly correlated with postnatal PCB exposures via breast milk.[159] Even at eleven years there were significant neurological differences between the exposed and unexposed children. Compared with the unexposed children, the most highly exposed children were three times as likely to have low average IQ scores and twice as likely to be at least two years behind in reading comprehension.[160]

The results of these studies in the Great Lakes region are consistent with other studies done in the U.S. and throughout the world on children exposed to PCBs.[161] Because PCBs are known to interfere with thyroid hormone, and because thyroid hormone is critical for normal fetal brain development, it is not surprising that this class of hormone-disrupting chemicals would be responsible for such significant health effects in exposed children. Although the health effects of PCBs are not yet as well understood as the effects of lead, they are similar chemicals in certain respects: both persist in the environment and in the body; both are easily passed from mother to fetus; and both interfere in significant ways with the normal and full development of the human brain.

Future Directions

Hormones regulate the basic functions of our lives and are particularly critical in ensuring reproductive function and proper growth and development. Interference with the normal hormone balance would be a very serious problem with implications for human reproduction, fetal development, neurobehavioral function, and cancer causation. A few chemicals are now known to interfere with hormones. Fortunately most of these are banned, though they persist in our environment. Two major questions must be answered: How many of the chemicals in our environment can affect hormone systems? And are the observed increasing trends in breast, prostate, and testicular cancer as well as the possible declining trend in sperm counts and increasing incidence of male genital abnormalities due to exposure to hormone disruptors? Much more scientific work needs to be done in this emerging area of research. Only after science has clarified some of these important questions can we say how great a threat endocrine disruptors may be for our own and future children.

last revised 11/25/1997

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