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Trouble on the Farm
Growing Up with Pesticides in Agricultural Communities

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Chapter 5


Food, water, air, and dust can all be contaminated by pesticides, and are all routes by which children can receive hazardous exposures. Numerous studies have evaluated the degree of pesticide contamination in these environmental media, and some have gone further, to associate pesticides in dust with pesticide residues on children's hands or in their urine. The majority of studies have not involved farm families, but are nonetheless relevant to children's disproportionate exposures. Some small reports do focus on farm children, including migrant farmworkers, and have measured exposures from all of these routes, often finding levels greater than those reported in studies of non-farm families. "Some of the evidence presented in this section comes from early results of the Agricultural Health Study (see box)."

The Agricultural Health Study

"The Agricultural Health Study (AHS), begun in 1993, is a collaborative research project of the National Cancer Institute, the U.S. EPA, and the National Institute of Environmental Health Sciences. It is the largest study to date of farm families." The study has enrolled a cohort of approximately 90,000 people in Iowa and North Carolina. Study subjects include farmer applicators (farmers who apply their own pesticides), spouses of farmer applicators, and commercial pesticide applicators. Many of the families have children, and these children are also being evaluated for exposures and health effects. The study does not include hired farmworkers, who may differ in numerous important ways, including socio-economic status, from farm owners and pesticide applicators.

Exposure assessment in this study includes periodic questionnaires asking about crops grown, pesticide use, agricultural activities, exposures, and general information about children. A sub-sample of the cohort (about 200 families) will undergo measurement of pesticides via all potential routes of exposure, including food and water, inhalation, and skin exposures. Furthermore, biological measurements of pesticide metabolites in blood and urine will be performed on a subset of the study subjects. The cohort will be followed to identify a variety of health outcomes ranging from cancer to neurologic and reproductive problems. [116]

Although very little data from the AHS itself are currently available, small pilot studies have been completed to test methods that are now being applied to the larger cohort. Results of these pilot studies have been published and are discussed in this report. As more data become available from the AHS, we will have some of the information necessary to quantify the excess exposures of farm families.

The cohort under study in the AHS is overwhelmingly white (97 percent). Virtually no Latinos are enrolled. The focus on white farm owner families significantly limits the utility of this large study for predicting exposures to non-white farmworkers. Furthermore, crops grown in different geographic regions have different pesticide use patterns. In Iowa, the major crops are grains, soybeans, and corn, along with hogs and beef cattle, and in North Carolina, crops are similar to those in Iowa but also include tobacco, peanuts, yams, and cotton, as well as poultry. As a result, it may be difficult to generalize the results of this study to states such as Florida, Texas, and California where vegetables and fruits are the primary crops.

Pesticides in Food

"The children became sick when we were picking strawberries and it made them vomit. . .. Much white dust was spotted on the leaves and the fruit as well. Almost all of the people had brought their children. There were between 70 and 100 workers, and each one brought several children. The children started to eat the berries and then they began to vomit. Several of them became sick with vomiting and diarrhea including four of my children. I brought them to the hospital. Almost all the children that were working in the field this day became sick. "
-- Delfina Chavez, Farmworker, Mt. Angel, OR, July 9, 1998

Pesticide residues are widespread in the food supply. Data from the Food and Drug Administration (FDA) for the past nine years show that between 33 and 39 percent of the food supply in any given year contains detectable pesticide residues.[111] Among domestic foods, nearly 46 percent of grain samples, 38 percent of fish and shellfish, 54 percent of the fruit, 36 percent of the vegetables, and 3 percent of the dairy products tested had detectable residues of at least one pesticide, although few of these residues violated legal tolerances.[111]

An average one-year-old's top ten favorite foods are apple juice, grape juice, oats, bananas, milk, apples, orange juice, pears, wheat, and peaches. On a body-weight basis, young children consume these foods at levels from three to twenty-one times greater than the average adult American. FDA monitoring has detected pesticide residues in 50 percent of the samples of these foods, although generally at levels below regulatory tolerances.[71] According to the National Academy of Sciences, diet is an important source of exposure to pesticides, particularly for children, some of whom are exposed to pesticide residues in food above levels considered safe by the federal government.[70]

Several recent studies have detected pesticide residues in food

  • In 1995, the USDA's Agricultural Marketing Service tested nearly 7,000 fruit and vegetable samples and detected residues of 65 different pesticides. Two out of every three samples contained pesticide residues.[112]

  • Foods commonly consumed by children are likely to carry more than one pesticide. A 1993 analysis of the FDA monitoring results found 108 different pesticides in 22 fruits and vegetables commonly eaten by children; 42 different pesticides were detected on tomatoes, 38 were detected on strawberries, and 34 were detected on apples.[71] Based on FDA data on U.S.-grown and imported food, the following fruits and vegetables contain the most residues of the most toxic pesticides: strawberries, bell peppers, spinach, cherries, cantaloupes (grown in Mexico), apples, apricots, green beans, grapes (grown in Chile), and cucumbers.[113]

  • Processed baby foods can also contain pesticide residues. According to recent testing, sixteen pesticides were detected in eight baby foods sampled. Five different pesticides were found in pears, four in applesauce, and three in peaches, plums, and green beans. Residue levels were generally below those found in fresh fruits and vegetables.[114]

  • The Agricultural Health Pilot Study, performed on six farms in Iowa and North Carolina, tested food samples collected from the farmhouses for 29 targeted pesticides. Pesticides were detected frequently on foods on these six farms at levels above those reported for the general population. In particular, elevated levels of the pesticide being applied during the monitoring period were detected in the food. The authors conclude that the results show potential dietary exposures above expected values, particularly to pesticides that are currently being applied on the farm and to environmentally persistent pesticides.[115]

Thus the general public is exposed to numerous pesticides in food at levels that can pose a potential risk to a child. There are few data about farm children's dietary exposures to pesticides, although preliminary results from the Agricultural Health Study indicate that exposures to farm children may be higher than to the general public. Anecdotal reports of farm children picking and eating foods directly from the fields are common, although no studies have attempted to measure these exposures.

Pesticides in Drinking Water

"We have to bathe in the irrigation channels by the fields. We know they are filled with pesticides, but we can't live without removing the dirt of our daily work."
-- Anonymous Farmworker, California[117]

". . . all the water that comes from the agro fields . . . it comes right into here . . . every day in our house, our water would usually come out sandy and had a pink color or yellow color. We didn't think anything about it. We would just wonder, ‘Well, gee, what is wrong?' Well, time went on and on. Our water was getting worse. Our sink water would stink like rotten eggs . . . we've had bad water quality."
-- Marta Salinas, McFarland, California[14]

Pesticides have proven to be a pervasive problem in surface waters in many parts of the United States. Because surface waters may be used for drinking, this contamination can be a real threat. Although drinking water problems can be an issue in all parts of the country, agricultural regions are the most heavily impacted. Farm families, because they are more likely to drink from private wells or small water systems, are the most at risk. There are about 54,000 small water systems serving 1,000 or fewer people in the United States, which adds up to approximately 20 percent of the total population. Two-thirds of these systems serve communities with 500 or fewer residents. These small systems are primarily located in rural, often agricultural, areas, and the small utilities often cannot afford the equipment and qualified operators necessary to ensure compliance with safe drinking water standards.[118]

The following examples describe some known water contamination problems

  • In 1992, U.S. EPA reported that 132 pesticide-related compounds, 117 parent pesticides, and 16 pesticide degradates had been found in ground water in 42 states.119 Widely detected pesticides included aldicarb, alachlor, the triazine herbicides, 2,4-D, and nearly a dozen others. The U.S. EPA also has found that one out of every ten public water supply wells is contaminated by at least one pesticide; the EPA infers from these data that nearly 10,000 community drinking water wells and about 440,000 rural domestic water wells contain pesticides, although most do not exceed the EPA's existing drinking water standards.[120]

  • In the period from 19911995, the U.S. Geological Survey (USGS) sampled from 5000 streams and wells and found at least one pesticide in every stream and in at least half of the wells sampled. The triazine herbicides (atrazine and simazine), 2,4-D, and several organophosphates including chlorpyrifos and diazinon were the most commonly detected of the 85 pesticides assayed.[121]

  • A 1997 survey of water contamination found that about 4.3 million Americans in 245 communities are exposed to levels of carcinogenic herbicides in drinking water that exceed the U.S. EPA's benchmark of "acceptable" cancer risk (one excess cancer case in a population of a million).[122] Commonly used agricultural herbicides contaminate the tap water of 374 Midwestern towns. Over ten million Americans in the Midwest and Chesapeake Bay region alone are exposed to herbicides in their drinking water. In addition, up to ten different herbicides and metabolites or derivatives were detected in individual tap water samples.[122]

  • A 1994 study found that drinking water is often contaminated with two or more of the common herbicides, atrazine, cyanazine, simazine, alachlor, and metolachlor. In all, some 67 different pesticides and pesticide metabolites have been detected in midwestern sources of drinking water. People in small rural communities, and children in particular, are at high risk; over 400,000 people in 98 rural communities were found to face cancer risks from 10 to 116 times the federal benchmark.[123]

  • The State of California reported that 22 pesticides were detected in a total of 436 groundwater wells in 1996. The most commonly detected compounds were herbicides, and detections were much more frequent in agricultural regions of the state.[124]

Although the average levels of pesticides in water are low, for those families whose water supply is contaminated at levels significantly above the average, drinking water can be a major source of exposure.

In agricultural regions, small water systems and private wells are often shallow and poorly protected, making them more likely to be contaminated with pesticides and other pollutants than larger city supplies. Other small utilities in rural areas may use surface water that is highly vulnerable to pesticide runoff contamination.[120], [121] Small utilities also often lack the economies of scale enjoyed by large utilities, which makes it harder to use more expensive, state-of-the-art water treatment systems capable of removing pesticides. Moreover, in some states, small utilities can get waivers of monitoring requirements or special "variances" or "exemptions" from water treatment requirements that are not generally available to larger water suppliers.[125] As a result of these factors, and the simple fact that agriculture can contaminate local waters, farm families are likely to receive higher exposures to pesticides from drinking water than other households. These exposures may occur from drinking the water, or from bathing or showering because many pesticides are volatile in warm water and can be absorbed through the skin or inhaled in the shower. These routes of exposure should be considered in evaluating total exposures to pesticides.

Pesticides in Outdoor Air, Drift, and Fog

"I believe we here in the colonias are more exposed to the chemicals due to the planes that go by, and they don't care if the wind is strong or if there is no wind. We have been affected some five or six times right here in our house. Once the plane flew over and I think it opened the valve and we were very sick. And the field is very close, then they don't tell us that they are going to spray; they don't take us into account for anything. So I think this needs to change because they are killing us little by little. One of the little ones, when cotton season starts, always sweats and gets a bad rash on the face with lots of pimples. The doctor says it's a skin disease, but he does not say it's the chemicals that are already on his skin . . . The school is very close by, Kelly School, so a lot of children are being affected by the chemicals. "
-- Worker, Hidalgo Park, Public Meeting in Pharr, TX, April 25, 1996

Outdoor air concentrations of pesticides in agricultural regions may be significant, particularly for those applied as a gas for fumigation, by ground broom, or by broadcast spraying. Children who live in agricultural regions may receive airborne pesticide exposures when playing outdoors. Infiltration of homes by outdoor air could also result in airborne exposures inside the home.

Monitoring has revealed that airborne pesticides present a pervasive problem

  • In California, two weeks of ambient air monitoring near sugar beet and potato fields for the fumigant and carcinogen Telone II (1,3-dichloropropene), measured ambient air levels exceeding the federal reference concentration (safe level) for chronic inhalation exposures. Chronic exposure to the levels measured is predicted to result in more than one excess cancer per every five thousand people exposed, far greater than most federal standards for acceptable levels of risk.[126] Even short-term exposures to elevated levels of this chemical may cause respiratory problems.

  • Methyl bromide is an odorless, colorless, acutely poisonous and neurotoxic gas that has also been shown to deplete the ozone layer. Air monitoring near a fumigation chamber where methyl bromide was used revealed exposure levels more than 17 times higher than the California EPA regulatory limit for airborne exposure to this toxicant.[126]

  • In the same study, ambient air levels of the breakdown product of metam sodium, an irritant, acute poison, and developmental toxicant, were over tenfold greater than the reference exposure level for acute eye irritation near fields where soil was being fumigated.[126]

  • A 1996 report by the Environmental Working Group documented elevated air levels of methyl bromide over two-to-three day periods in two residential neighborhoods near California fields. The California state health standard for short-term exposure to methyl bromide is an average of 210 ppb over a 24-hour period, yet peak levels were as high as 665 parts per billion (ppb) in Castroville and up to 1,900 ppb in Ventura, with an average level over the three-day period of 294 ppb. Elevated levels of this fumigant were detected over 400 yards from the application site, six times the allowed buffer zone, in a residential area with a day care center.[127]

  • Fog samples gathered in suburban Maryland and in agricultural regions of California revealed up to 16 different agricultural pesticides. The pesticides detected included organophosphates, triazines, dinitroaniline (pendimethalin), and chloracetanilides (alachlor, metolachlor). The levels of organophosphates and their oxygen analogues in fog were often two or three times greater than levels reported in rain. The maximum measured level of the highly toxic parathion oxygen analogue (paraoxon) was high enough to cause significant acute cholinesterase inhibition. In addition, volatile, fat-soluble pesticides were found in fog at concentrations far greater than expected.[128] Pesticides in fog can enter the body in numerous ways. The fog vapor and pesticides can be inhaled directly into the lungs, absorbed through mucus membranes, or swallowed.

  • A small Minnesota study found that an application of two herbicides by ground-broom sprayer 50 yards upwind from a farmhouse resulted in a three-to-fourfold elevated concentration of both chemicals in outdoor air adjacent to the farmhouse -- where a child playing in the yard could be exposed to the toxicants. Interestingly, there was also a 50 percent increase in the concentration of one of the herbicides inside the farmhouse.[129]

  • An Israeli study detected small reductions in plasma and whole blood cholinesterase in residents living near fields during spraying season compared with others living further from the fields. The same individuals had normal plasma and whole blood cholinesterase levels off-season. In addition, infirmary records indicated a significant increase in visits for symptoms such as respiratory problems, headache, and eye irritation on days when organophosphates were sprayed.[130] These data indicate that exposures to organophosphate pesticide drift may result in symptoms and slight cholinesterase inhibition in nearby residents.

The potential for children living on or immediately adjacent to fields to be exposed to airborne agricultural pesticides at levels not deemed safe for human exposure must be further investigated and taken into account when evaluating total exposures.

Pesticides in Indoor Air

Pesticides are known to accumulate in indoor air at concentrations one or two orders of magnitude higher than in outdoor air. For farm children, indoor air exposures may include agricultural pesticides never used indoors.

The Non-Occupational Pesticide Exposure Study (NOPES), which focused on adult exposures in non-agricultural families, measured personal exposures to pesticides in household air. Striking results from this survey included significant regional differences, with higher exposures in warmer regions (Jacksonville, Florida) and lower exposures in temperate regions (Springfield and Chicopee, Massachusetts). There was significant seasonal variation in both geographic regions.[7] The average number of pesticides detected in indoor air in households considered to have "high pesticide usage" was eleven, while "medium usage" homes had an average of seven detectable target pesticides, and "low" use homes had an average of five different pesticides detectable in indoor air. As many as 20 different pesticide residues were found in indoor air in homes. The most prevalent pesticides were chlorpyrifos, diazinon, chlordane, propoxur, and heptachlor.[131] Because these pesticides were all once registered for home use (although some no longer are) the residues most likely stemmed from use indoors, sometimes in the distant past. Extrapolation from the NOPES study indicates that, for adults without occupational pesticide exposures, indoor air inside the home may account for as much as 85 percent of the total daily exposure to airborne pesticides.[132]

Pesticides in indoor air tend to concentrate near the floor. Chlorpyrifos, for example, was nearly four times more concentrated at 12-25 cm (about 510 inches) from the floor compared with greater than 60 cm (2 feet) from the floor in a room with a window open for ventilation.[74] This indicates that there is less air mixing near the floor, and that the breathing zone of an infant or crawling toddler is likely to contain a greater concentration of pesticides during certain ventilation conditions than the adult breathing zone. Pesticides in the air can also deposit onto surfaces, including carpets, kitchen counters, and children's toys.[133] Therefore airborne pesticides eventually create tactile exposures through skin contact or children's hand to mouth behavior. The deposited residues, in turn, can become airborne again when dust is stirred up, or through evaporation from surfaces, resulting in a veritable swirl of pesticides throughout the home.

An investigation in Minnesota measured air levels of various pesticides both indoors and outdoors on farms.[129] This study clearly documented "take-home" exposures of pesticides. For example, on "Farm 1A," the farmer sprayed hogs with lindane to control mange. He then visited "Farm 1B" for dinner, still wearing his work clothing. Finally, the farmer went home and changed his clothes. Measurements taken over the three days surrounding the spraying event revealed that the lindane levels in outdoor air on Farm 1A increased by fortyfold, while indoor air levels increased by twenty-four-fold. At farmhouse 1B, about a quarter mile from the site of outdoor spraying, lindane levels in indoor air increased by fourfold. The indoor air levels at farmhouse 1B were likely due to off-gassing of pesticides from the farmer's clothing, while the greater indoor air levels in farmhouse 1A may be due to a combination of infiltration of outdoor air and off-gassing from clothing. In the same study, similar increases in pesticide levels in indoor air were measured following agricultural applications of other insecticides and herbicides. "Background" air levels of various pesticides, including alachlor, atrazine, lindane, and trifluralin, were substantially higher in and near Minnesota farm homes compared with the urban homes in Jacksonville and Springfield studied in the NOPES study. In addition, indoor air levels were up to ten times higher than outdoor air levels for many pesticides; this was generally true even when the pesticide was applied outdoors.

The authors concluded,

This study demonstrates that a direct relationship can exist between outdoor application of a pesticide by a farmer and subsequent elevated indoor air concentrations of the pesticide in his home. The data suggest that transport of residues on the farmer's work clothing and/or track-in on shoes as well as infiltration of aerosol spray drift can be mechanisms contributing to elevated indoor air levels.[129]

The elevated pesticide levels in indoor air, and the documented presence inside farmhouses of pesticides registered for agricultural use only, indicates a source of exposure to a substantial subgroup of children that must be considered when setting pesticide use standards.

Pesticides in House Dust

Dust inside homes is known to collect pesticide residues. These residues may include pesticides used for home pest control, including compounds used years ago which persist in carpets or seep out of foundations that were treated for termites, and those used outdoors that are tracked into the home on shoes. An estimated 31 percent of indoor dust originates in outdoor soil.[134] Researchers estimated that tracking-in of outdoor soil was the principal source of about half of the pesticides detected in the indoor air of one monitored home.135 Whereas pesticides that remain outdoors are generally broken down by sun, rain, and soil microbes, indoors they may accumulate un-degraded in carpets and furniture for years. For small children, house dust is a major route of exposure to pesticides, lead, and allergens.[136]-[138] Because of children's lower body weight and higher dust ingestion, their risk from toxic chemicals in dust is estimated to be at least 12 times greater than that of adults.[137]

A variety of methods have been used to collect and quantify pesticide residues in dust, including modified vacuum cleaners, polyurethane foam rollers, cotton gloves, and bare-hand presses.[139]-[141] A recent publication also demonstrates the validity of sampling dust from used household vacuum cleaner bags.[142] The various methods have been found to be comparable, making it possible to test for pesticide residues in house dust and to quantify the range of concentrations found in homes, particularly in impacted areas such as in agricultural settings.

Homes in Non-Agricultural Areas

Household and yard pesticide use is very common among the general population. A study in Missouri found that 97.8 percent of families use pesticides at least once during the year, and 70 percent of people reported using pesticides in the home or yard during the first six months of a child's life.[143] The commonly used herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), which has been linked in both humans and dogs to non-Hodgkin's lymphoma, can be carried indoors after application on lawns. One investigation revealed that 3 percent of dislodgeable residues of 2,4-D on a lawn was tracked indoors and accumulated in carpet dust.[144] Although 2,4-D and many other lawn and garden pesticides normally break down fairly quickly into less toxic forms from outdoor weathering factors such as wind, rain, sun, and soil microbes, they can linger in the indoor environment for years. Carpets, house dust, and furniture become long-term sinks for pesticides.[132] Calculations based on a single lawn application of 2,4-D indicate that detectable levels of the pesticide can remain in carpet dust up to one year after a one-time outdoor application.[144]

A variety of pesticides have been detected in non-farm homes

  • An in-depth study of a home in San Antonio, Texas, revealed detectable residues of 16 pesticides in the living room carpet. Gradients of many of these pesticides were apparent from the garden onto the front doorstep and into the carpet indicating that the pesticides were likely transported into the home primarily on shoes.[135] Thus, "tracking-in" of pesticides is likely to be fairly common and should be considered for all pesticides which are registered for use on lawns and gardens.

  • The Non-Occupational Pesticide Exposure Study (NOPES) measured levels of selected pesticides in carpet dust of nine homes. The average number of targeted pesticides measured in carpet dust in any single home was 12, compared to 7.5 pesticides on average in the air samples in the same residences. Many of the less volatile pesticides were not detected in indoor air but were found in carpet dust.7 Older carpets had the highest levels of pesticides, indicating accumulation over time. Numerous pesticides that have been banned in the United States were detected and quantified in carpet dust, particularly in older homes. These included DDT, heptachlor, aldrin, dieldrin, and chlordane.[145]

  • Similar results were found in numerous other small studies in a variety of settings. A small study in the Raleigh-Durham area of North Carolina found a range of 8 to 18 different pesticides in dust in the nine homes sampled. Pentachlorophenol, a wood preservative and endocrine disrupting chemical, was detected in every household sampled, while chlorpyrifos and numerous organochlorine pesticides including DDT were found frequently.[140] Sampling in this study of pesticides in indoor air at 6 inches off the ground (the breathing zone of a crawling toddler) and of pesticides in dust revealed that the dust ingestion of certain pesticides could exceed inhalation exposures for a young child in some of the homes sampled.[132]

  • The Lower Rio Grande Environmental Exposure Scoping study looked for a wide variety of chemicals, including pesticides, in the spring and summer of 1993 in a small number of homes in a farming area.[146] Unfortunately no children were studied during the pilot phase. This study showed that levels of chlorpyrifos measured in indoor air and dust and the levels of a metabolic byproduct of chlorpyrifos in the urine of adults living in the house were highly correlated.[147] Thus in adults, levels of pesticides in indoor air and dust in the home are strong predictors of actual exposure. In children, there is a linear correlation between the concentration of lead in indoor dust and blood lead level.[148] Although the relationship between pesticides in house dust and levels in children's body tissues and urine needs further investigation, the data on lead demonstrate that a toxicant in house dust can get into children's bodies.

  • Evaluations of pesticide levels in carpet dust in 362 homes with children throughout nine states revealed wide variability in the concentrations of pesticides identified. Two pesticides, orthophenylphenol (a fungicide and disinfectant) and chlorpyrifos, were found in the majority of homes sampled (96 percent and 67 percent respectively). While the median concentration of chlorpyrifos measured in dust was not very high (0.54 mg/g), the maximum measured concentration exceeded the median by nearly a thousandfold (324 mg/g). This range of variability was also typical of other insecticides measured in this study, including the organochlorines (DDT and dieldrin), the synthetic pyrethroid (permethrin), and the carbamates (carbaryl and bendiocarb).[149] This study confirms that some children are exposed at levels many times greater than the average child.

  • The California Department of Health Services reviewed an industry study on pesticide absorption from carpets following indoor pesticide use. In the case of propoxur, the estimated exposure for a six-to-nine month old child playing on a carpet after application following the label instructions was above the human Lowest Observable Adverse Effect Level (LOAEL) for acute health effects. For dichlorvos, the predicted dermal exposure to a six-to-nine month old child following application approached the rat oral lethal dose for 50 percent of the animals (LD50). For chlorpyrifos applied similarly, the dermal dose was nearly 90 times the minimal human response level for acute symptoms.[150] Although some of these specific pesticides are no longer used for indoor broadcast applications, these estimates illustrate the significant potential of infant and toddler exposure from contact with pesticides in carpet dust.

Farm Homes

Pesticides used on family farms end up in increased concentrations inside the home, compared with homes in non-agricultural areas, as the following studies show:

  • A study of dust exposures among farm children was carried out in an apple, pear, and cherry-growing area of Washington State.6 A total of 26 farming families, 22 farmworker families, and 11 non-agricultural families participated. All had at least one child between the ages of one and six. Soil from outdoor play areas was sampled, as was household dust from indoor play areas. These samples were analyzed for the presence and concentration of four organophosphate insecticides: azinphos-methyl, phosmet, chlorpyrifos, and ethyl parathion. Residues found in household dust and soil were almost exclusively due to agricultural use, rather than home use of these products. One or more of the four target pesticides was found in 58 percent of the soil samples outside agricultural homes and in only 18 percent of soil samples near comparison homes. At least one of the pesticides was found in 100 percent of the house dust samples from farmworker and farmer homes, and all four of the targeted pesticides were found in 62 percent of farm homes. In comparison, in non-agricultural homes, only 9 percent of dust samples contained all four pesticides. Median indoor pesticide concentrations in house dust were generally 17 to 100 times higher than outdoor soil levels, although both were significantly higher in farm homes. Furthermore, maximum detected concentrations were generally 10 to 100 times greater than the median concentration detected, and the range of detected concentrations was generally much broader in farm homes.

In the Washington State study, some agricultural pesticides were detected (albeit at lower concentrations) even in non-farm homes located more than a quarter of a mile from an orchard. This may indicate that drift of agricultural pesticides can contaminate non-farm homes in an agricultural region. It is also notable that almost all of the pesticide handlers in the agricultural families reported using appropriate personal protective equipment and did not bring their personal protective equipment into the home. Nearly all of the pesticide handlers also reported washing the clothing worn under their protective clothing after each pesticide application. Thus, although the pesticide applicators were taking steps to minimize take-home exposures to their families, their children were still at risk from elevated exposures to agricultural pesticides.

  • A small pilot study in Minnesota that tested methods for the Agricultural Health Study evaluated exposures to farmers at four family farms, measuring outdoor and indoor air levels, and analyzing outdoor soil, indoor dust, drinking water, and hand wipes of children. For several herbicides and fungicides, which would never be applied indoors, the indoor air level was up to 10 times higher than outdoor air levels. Furthermore, as in Texas, an increasing concentration gradient was found for numerous pesticides from pathway soil to entryway soil to, finally, carpet dust. Herbicides such as alachlor and atrazine, chlorpyrifos, and DDT were all found on the hands of a three-year-old child.151 These pesticides reflected the pattern found in household dust in that farmhouse, and implied that this child was exposed to agricultural pesticides not registered for home use.

  • An additional report from the Agricultural Health Study in Minnesota, Iowa, and North Carolina reported that house dust levels of herbicides such as alachlor, metolachlor, atrazine, and 2,4-D increased by tenfold to one hundredfold in one home following field applications. Detection frequency of atrazine in house dust on Iowa farms increased from 75 percent to 100 percent during the application season, the median concentration increased tenfold, and the maximum detected concentration increased one hundredfold. When compared to the herbicide levels detected in non-farm homes, farmhouses had significantly greater frequency of detection and elevated concentrations in dust. The authors conclude, "Usage of herbicides and other agricultural pesticides on the family farm may significantly elevate the potential for exposure of young children to these chemicals while growing up on the farm."[10]

Contact with house dust, including inhalation, ingestion, and dermal contact, can be primary routes of pesticide exposure for small children. Extensive experience with lead exposure has conclusively demonstrated that when levels of lead are elevated in household dust and soil, blood levels of this toxicant are also elevated in children.[148], [152]-[156] These multiple and cumulative exposures must be considered when setting pesticide tolerances in order to avoid repeating the mistakes of the past.

Pesticides on Farm Children's Hands

"We think of our children who are at home and about the future of those children. If we do nothing, perhaps they will say 'my parents did nothing, and they could have stopped this.'"
-- Eduardo Montoya, Farmworker[14]

All studies that have investigated dermal exposures to pesticides in adults or children have found that skin contact is a major route of exposure, particularly in children. Numerous pesticides are known to penetrate the skin, so exposures from pesticides on hands would be both oral and dermal.[157] Hands moist with saliva collect more pesticide residue than dry hands.[158] Because young children often have wet, sticky, saliva-moistened hands, they are likely to collect more pesticide from carpets and other surfaces than would be predicted extrapolating from dry-hand presses. Farm children get pesticides on their skin from household pesticides, lawn and garden pesticides tracked into the home, and agricultural pesticides in the soil, or that enter the home through drift or on clothing.

Several small studies have shown that pesticide residues can accumulate on many common objects that children touch

  • A total exposure estimate after broadcast spraying of chlorpyrifos in a three-room residence revealed that the total estimated absorbed dose for an infant in the days following the pesticide application were between 1.2 and 5.2 times the No Observable Effect Level (NOEL), and between 10 and 50 times the human reference dose (RfD). Dermal absorption represented approximately 68 percent of the total projected exposure to an infant.[159]

  • A recent study revealed that children's toys can accumulate pesticide residues and may represent significant sources of exposure.[133] The investigators sprayed chlorpyrifos inside a home according to the label directions, and after the recommended airing period placed plush and plastic toys in the room. The toys were tested for pesticide residues periodically over a two week period. Chlorpyrifos accumulated on both types of toys, apparently due to absorption from the air into the plastic and felt materials. A multi-pathway exposure estimate (not including food and water ingestion) based on the scenario of a three-to-six year-old child playing in the room one week after an application of the pesticide revealed a total exposure estimate more than 20 times greater than the U.S. EPA reference dose. A child in this environment would receive about two-thirds of their total dose from hand-to-mouth exposure, about one third from skin penetration, and a small amount from inhalation. Label instructions regarding reentry times into indoor environments after pesticide applications are based on the period of time needed for air levels (in the adult breathing zone) to decrease to "safe" levels. These reentry times do not account for the fact that pesticide vapors can be more concentrated near the floor, and for the deposited pesticides on surfaces that can result in dermal exposures to children.

  • A small study of children from middle class non-farm families in North Carolina found that there is a strong correspondence between pesticide concentrations detected on children's hands and levels found in carpet dust in the home. Among the four child participants, between one and six different pesticides were recovered by hand rinse sampling. Pesticides detected on children's hands included chlordane, heptachlor, pentachlorophenol, chlorpyrifos, and dieldrin. It is notable that several of these were banned but are still persistent in the indoor environment, and still causing exposures to children.[140]

  • In a small study in Minnesota, hand wipes of farm children taken in the days following pesticide application by the father revealed significant residues of the same pesticides that the father had recently applied on the farm. Similar pesticides and quantities were found on children's hands on sequential days, and particular residue profiles were found consistently in different families. On three farms, investigators detected a total of 17 different pesticides on the hands of non-working children ranging from age 3 to age 15.[160] Eight pesticides, including alachlor, atrazine, 2,4-D, dicamba, pentachlorophenol, chlorpyrifos, propoxur, and DDT were all found on the hands of one three-year-old child living on a farm. On another farm, a four-year-old and an eight-year-old child also had residues of nine pesticides detected on their hands.[160]

  • In an in-depth investigation of four Iowa family farms, there were significant differences between pesticide detections during the application season as opposed to during a non-application period, even when the pesticides were applied miles from the farmhouse. A total of five herbicides and eight insecticides were detected on the hands of wives and children who were not directly involved in farm work during the application season.[161] An average of more than two pesticides was detected per hand wipe and concentrations were higher compared to the average of 0.4 pesticides detected per wipe during the non-application season. Strong correlations were observed between levels of individual pesticides in indoor air, carpet dust, on food preparation surfaces, on the mother's hands, and those levels on the child's hands. One three-year-old child had atrazine and metolachlor on his hands after his father applied these herbicides on the farm. Both pesticides were also found in the carpet dust. It is clear from this study that pesticide use by a family member outside the home can result in elevated levels of the pesticide inside the home, and ultimately result in exposures to family members.

  • In a pilot study of ten homes and one day-care center in the San Joaquin valley, researchers from the California Department of Health Services demonstrated the feasibility of performing high quality testing of farmworker homes for pesticide residues. Approximately 50 pesticides were used within one mile of the town during the months preceding the testing. Samples of house dust were collected, along with hand wipe samples from the toddlers in each family. An accompanying questionnaire obtained information about pesticide use in the home, parental occupation, and the child's activities.[11] Although home pesticide storage and use appeared generally to be lower among farmworkers, pesticide loading in house dust was generally greater. A total of 12 different pesticides were detected in the house dust samples. Two pesticides, diazinon and chlorpyrifos, were found on the hands of three out of the five farmworker children sampled, at levels as high as 100 nanograms. None of the children in non-farmworker homes had detectable pesticide residues on their hands. A screening risk assessment revealed that the diazinon exposures to two of the farmworker children could exceed the U.S. EPA's chronic reference dose from hand-to-mouth exposure alone. The reference dose is set at a level that is predicted to cause no long-term health effects, so any exceedance constitutes a risk.

All of the studies concerning residues of pesticides on children's hands and toys have been small, mostly pilot investigations involving only a few families. The California farmworker pilot study revealed concentrations of organophosphate pesticides on the hands of toddlers that have potential toxicological significance. The knowledge that agricultural pesticides can be brought into the home, accumulate in carpet dust, and end up on children's hands should be considered when evaluating cumulative exposure and risk from pesticides, even those not registered for household use.

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