Children’s Environmental Health in Michigan

Neurotoxicity: Pesticides

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Of the approximately 890 registered active ingredients in pesticides, EPA considers approximately 140 (over 15%) to be neurotoxicants (GBPSR 2000). Yet, there have been few studies investigating neurotoxicological outcomes associated with childhood exposure to pesticides. A few studies have shown that parental exposure to pesticides in the home is linked to neural tube and other birth defects (Eskenazi et al. 1999). While a few epidemiological studies have been conducted investigating chronic exposure to pesticides in children, the strength of the association is weak, primarily due to small sample sizes and difficulties in assessing exposure (Eskenazi et al. 1999). However, it is also important to note that children are typically not exposed to only one type of pesticide, and multiple exposures may be cumulative (AAP 2003).

Because children spend much of their time close to the ground, they have frequent hand-to-mouth behavior, and unique dietary patterns, children can be exposed to more pesticides in the environment than adults. Semivolatile pesticides can persist on rugs, furniture, stuffed toys, and other absorbent surfaces. Children also have a decreased ability to detoxify and excrete pesticides. They may also be more vulnerable due to rapid growth, development, and differentiation of their vital organ systems (Landrigan, 1999).

Exposure to organophosphate pesticides (OP), organochlorine pesticides (OC), and pyrethroid pesticides have been linked with nuerodevelopmental effects. Exposure to organophosphate pesticides primarily affects the parasympathetic, sympathetic, and central nervous systems (Eskenazi et al. 1999). Acute exposure to OP pesticides in children can result in nausea, vomiting, excessive salivation, lethargy, and muscle weakness (Eskenazi et al. 1999). The effects of chronic exposure to pesticides on a developing child are not definitively established. However, there is a wealth of evidence suggesting that exposure to OP pesticides leads to impairments in neurodevelopment, neurologic functioning, and growth in rodents (Eskenazi et al. 1999; Landrigan et al. 1999). While most studies have focused on the hormone disrupting effects of organochlorine pesticide exposure, there is also evidence that the OC pesticides are neurotoxic (Kamel, Hoppin 2004). Pyrethroid pesticides are generally less toxic to humans than OP and OC pesticides; however, they have also been associated with nervous system effects, particularly at very high exposures (CDC 2005, AAP 2003).

Legislative and regulatory measures exist on the state level in Michigan and in other states to protect human health and the environment. This section will briefly summarize pesticide exposures and associated health effects, present leading policy practices from other states, and recommend steps to minimize childhood pesticide exposure in Michigan.

Contents

Michigan Highlights

Exposure Data

The Michigan Department of Community Health's 2010 report on occupational and non-occupational pesticide illnesses in Michigan provides some indication of pesticide exposure to Michigan children. Approximately 19% of confirmed reported occupational cases were children between the ages of 10 and 19 (MDCH 2010). The report acknowledged, however, "the Michigan occupational pesticide surveillance data are likely a significant undercount of the true number of work-related pesticide poisoning cases in Michigan" (MDCH 2010).

While exposure to antimicrobial pesticides (e.g., sterilizers, disinfectants, and sanitizers) was the most common cause of occupational pesticide illnesses, over half of non-occupational illnesses were due to insecticide exposures (MDCH 2010). Non-occupationally related cases were more commonly reported than occupational cases. The age distribution for confirmed pesticide related illness from non-occupational exposures was 7 weeks to 90 years of age. Approximately 10% of the cases occurred in children ages 1 to 9 years; and approximately 9% occurred in children ages 10 to 19 years (MDCH 2010).

Policy

Michigan statute and regulation define Integrated Pest Management (IPM) as a pest management system that uses all suitable techniques in a total management system to prevent pests from reaching unacceptable levels or to reduce existing pest populations to acceptable levels. Michigan is a national leader in IPM policy because the state requires IPM programs at schools and daycare centers. However, this policy can be improved by requiring the use of "least toxic" pesticides and mandating the use of IPM for outdoor pesticide use. It could also be improved by prohibiting aesthetic/cosmetic pesticide use and prohibiting the use of known mutagenic, carcinogenic, endocrine disrupting, or neurotoxic pesticides.

Background

Sources and Types of Selected Pesticides

A pesticide can be defined as any substance or mixture of substances used to prevent, kill, repel, or mitigate pests (including insects, weeds, molds, rodents, microbes, and others) (Ecobichon 2003). Insecticides are a class of pesticides specifically targeting insects. There are many types of pesticides in use today. This section will focus on only three of the major classes of insecticides: organophosphates, organochlorines, and pyrethrins/pyrethroids. This section will briefly summarize pesticide exposures for those three classes of pesticides, and associated health effects, present leading policy practices from other states, and recommend steps to minimize childhood pesticide exposure in Michigan.

Organophosphate Pesticides

Organophosphate (OP) insecticides are widely used for pest control in the home, lawn, and garden. They are also used in agriculture to treat commercial crops; approximately 37% of registered pesticides used on food are OP (GBPSR 2000). There are approximately 40 different OP pesticides registered for use in the U.S. (CDC 2005). OP pesticides differ in structure and toxicity, ranging from highly toxic to slightly toxic (Nadakavukaren 2000). About 73 million pounds of organophosphate pesticides were used in the United States in 2001 (Kiely et al. 2004). Some common OP pesticides include malathion, chlorpyrifos, methyl parathion, and phosmet. Organophosphate insecticides accounted for approximately 35% of total insecticide use in 2006-2007 (EPA 2011).

Organochlorine Pesticides

Organochlorine (OC) pesticides have a wide array of uses including agricultural, home, garden, and pharmaceutical applications. Like OP pesticides, there are many types of OC pesticides differing in structure, persistence, and toxicity. Due to their health and environmental effects, and their ability to persist in the environment, and build up in the food chain, many types of OC pesticides have already been banned or restricted in the U.S. Previously banned OC pesticides include dichlorodiphenyltrichloroethane (DDT), hexachlorobenzene, mirex, aldrin, dieldrin, and chlordane (CDC 2005). Due to the persistence of these compounds in the environment, contamination from historical uses remains a source of exposure. In addition, there are a number of OC pesticides that are still in use today, including endosulfan (EPA announced a phase out in June, 2010), dicofol (an insecticide), chlorothaionil (the most commonly used fungicide in the U.S.), a form of hexachlorocyclohexane (gamma-hexachlorocyclohexane, used as a treatment for lice and scabies) and commercial uses of pentachlorophenol (used as a fungicide to treat wood) (CDC 2005). In addition, DDT is still used in other countries, and therefore imported food may contain DDT or DDT residue (CDC 2005).

Pyrethrins/Pyrethroids

Like OP insecticides, pyrethrin and pyrethroid pesticides are commonly used in the home and for commercial agriculture. Pyrethrins, a natural extract of dried chrysanthemum flowers, are used for indoor bug bombs and aerosols, and also for anti-lice shampoos. Pyrethroids are synthetic versions of pyrethrins, made to be more potent and longer lasting. Pyrethroids are used in agriculture, gardening, termite control, and head lice and scabies medications (AAP 2003). Both pyrethrins and pyrethroids may be formulated with synergists that increase the toxicity of the pesticide (Beyond Pesticides 2000).

Neurotoxicity and Pesticides

Generalizing about the neurotoxicity of pesticide groups is necessarily difficult. Each distinct pesticide will have unique properties. However, children are typically not exposed to a single pesticide at a time. Given these limitations, the discussion below attempts to explore the issue of accumulative and synergistic toxicities. Children differ from adults in their exposure and vulnerability to pesticides. There are fundamental physiological differences that make children more vulnerable to the effects of pesticide exposure. First, due to immature metabolisms, children are generally less able to detoxify pesticides than adults. Secondly, the course of human development from conception to adulthood is extremely complex. A huge number of biochemical, physical, and organizational processes must be precisely coordinated to assure proper development, the maintenance of health, and to avoid disease. As a result of this complexity, there are numerous opportunities for disruption. Children at particular developmental stages may be uniquely vulnerable to influences that have little impact at other points in their development or as adults. Thirdly, children may be more likely to develop chronic diseases associated with pesticide exposure early in life due to a relatively small time lapse between pesticide exposure and disease initiation (Landrigan et al. 1999, Altshuler, et al. 2003). In addition to physiological differences between adults and children, behavioral differences can also place children at greater risk. Children engage in frequent hand-to-mouth activity and crawl or walk closer to the floor, resulting in the potential for increased exposure through ingestion and inhalation of pesticides applied in or brought in the home.

Of the approximately 890 registered active ingredients in pesticides, EPA considers approximately 140 (over 15%) to be neurotoxicants (GBPSR 2000). Yet, there have been few studies investigating neurotoxicological outcomes associated with childhood exposure to pesticides. A few studies have shown that parental exposure to pesticides in the home is linked to neural tube and other birth defects (Eskenazi et al. 1999). While a few epidemiological studies have been conducted investigating chronic exposure to pesticides in children, the strength of the association is weak, primarily due to small sample sizes and difficulties in assessing exposure (Eskenazi et al. 1999). It is also important to note that children are typically not exposed to only one type of pesticide, and multiple exposures may be cumulative (AAP 2003).

A study of Mexican children exposed to high levels of various agricultural pesticides showed impairment of motor skills, memory, attention, and learning (Guillette et al. 1998). The study compared children in two communities in Mexico with similar genetic, social, and cultural backgrounds. One community lives in the foothills of the Yaqui valley, where there is little exposure to pesticides, and the other group lives in a community in the valley with high levels of agricultural pesticide use. Figure 1 shows examples of the drawings done by children in the two communities. Children in the exposed community showed marked inability to draw recognizable representations of people. They were also found to have diminished stamina, coordination, and memory (Guillette et al. 1998).

Figure 1. Drawings of a person by Mexican Yaqui children, age 5. Children in the valley were exposed to agricultural pesticides, while children in the foothills were not (Guillete et al. 1998).
Figure 1. Drawings of a person by Mexican Yaqui children, age 5. Children in the valley were exposed to agricultural pesticides, while children in the foothills were not (Guillete et al. 1998).

In utero exposure to pesticides may be linked to a number of additional conditions in children. Specifically, researchers have found associations with: limb reduction defects; cryptorchidism, or undescended testes; neural tube defects; heart problems; and impaired fetal growth (Landrigan et al, 2005). Additionally, a 2009 study found a link between seasonal increases in pesticide use and increased birth defects. The study found that the highest rates of birth defects for U.S. babies arise when conception occurs during the spring and summer months, when pesticide use increases and high concentrations of pesticides are found in surface waters (Winchester et al. 1999).

Organophosphate Pesticides and Neurotoxicity

Exposure to organophosphate (OP) pesticides primarily affects the parasympathetic, sympathetic, and central nervous systems (Eskenazi et al. 1999). Acute exposure to OP pesticides in children can result in nausea, vomiting, excessive salivation, lethargy, and muscle weakness (Eskenazi et al. 1999). The effects of chronic exposure to pesticides on a developing child are not definitively established. However, there is a wealth of evidence suggesting that exposure to OP pesticides leads to impairments in neurodevelopment, neurologic functioning, and growth in rodents (Eskenazi et al. 1999; Landrigan et al. 1999). On a molecular level, OP pesticides function by inhibiting the enzyme acetylcholinesterase in nerve cells. This results in a build-up of the neurotransmitter acetylcholine in the brain, thus causing sensory and behavioral disturbances, impaired coordination, and depressed cognition (AAP 2003). Because of the health risks to children, in 2001, the Environmental Protection Agency (EPA) many major agrochemical producers, including Dow Agrosciences, agreed to stop the sale of chlorpyrifos, an OP insecticide that has been shown to have neurotoxic effects, for residential use (EPA 2000). The ban worked to eliminate: home, lawn and garden uses, termite-control uses in homes, eliminate use of chlorpyrifos in sensitive areas such as daycares, schools, and parks, as well as eliminate or reduce pesticide residues on several foods. It is still commonly used on agriculture, however, and many believe that chlorpyrifos continues to pose an unnecessary risk to farm workers and their children (Earthjustice 2007).

Organochlorine Pesticides and Neurotoxicity

While most studies have focused on the hormone disrupting effects of organochlorine (OC) pesticide exposure, there is also evidence that the OC pesticides are neurotoxic (Kamel, Hoppin 2004). On a molecular level, OC pesticides interfere with the movement of cations across membranes of nerve cells. This can lead to abnormal nerve function, irritability, and possibly seizures (AAP 2003). Common manifestations of acute OC toxicity include impaired sensation, reduced coordination, and impaired mental functioning (AAP 2003). Furthermore, animal studies indicate a link between OC pesticides and developmental abnormalities (AAP 2003).

Pyrethroid and Pyrethrin Pesticides and Neurotoxicity

Pyrethroid pesticides are generally less toxic to humans than OP and OC pesticides; however, they have also been associated with nervous system effects, particularly at very high exposures (CDC 2005, AAP 2003). The primary molecular mechanism of pyrethroid neurotoxicity involves the opening of sodium channels in excited neurons, which can lead to paresthesia, or abnormal skin sensations (CDC 2005). Acute pyrethroid poisoning, while rare, can lead to tremors, salivation, choreoathetosis, and seizures (CDC 2005). Animal studies of gestational and lactational exposure indicate a link with altered neurotransmitter levels and decreased dopamine receptor levels in the brain (GBPSR 2000). Pyrethrins have a similar mode of action as pyrethroids, and exposure to high levels of pyrethrins can similarly cause symptoms such as dizziness, headache, nausea, muscle twitching, reduced energy, changes in awareness, convulsions and loss of consciousness (ATSDR 2003).

Need for Future Research

Although the studies cited above demonstrate some of the hazards of pesticide exposure among children, there is still much left to learn about the neurological effects of pesticide exposure. The National Children's Study (NCS) is a large prospective study to comprehensively evaluate the impacts of environmental exposures, including pesticides, on child development. The study is the largest long-term examination of children's health ever conducted in the United States. It will follow 100,000 children from before birth to age 21 to learn how the environment influences children's health, development, and quality of life. One of the NCS hypotheses to be studied is: "Repeated, low-level exposure to nonpersistent pesticides including carbamates, organophosphates, and pyrethroids in-utero or postnatally increases the risk of poor performance on neurobehavioral and cognitive examinations during infancy and childhood," (NCS 2007). However, this study is in the pilot phase and therefore it will be years and in some cases decades before definitive answers are available. It is important to note that current data on exposures and health impacts suggest there is enough information to act now.

Childhood Exposure to Pesticides

Children can be exposed to pesticides through ingestion, inhalation, or dermal exposure. Direct inhalation of dusts, sprays, or mists can occur during the pesticide application. Following application, exposure may occur through several routes: via ingestion from hand-to-mouth activity during play in an area that was previously sprayed, through dermal exposure due to contact with a treated surface, or through inhalation as the majority of pesticides are volatile compounds that can off-gas even after application. In addition, children can ingest contaminated dust or soil, or unintentionally ingest a pesticide (AAP 2003). Even if a child is not in the direct vicinity of a pesticide treatment, pesticides may drift from a treated application area nearby (such as fields, lawns, or nearby turf).

According to the EPA, there are thousands of reported complaints of off-target spray drift every year (EPA 1999). If a pregnant woman is exposed to certain types of pesticides, the chemicals can cross the placenta, thus exposing the unborn fetus (GBPSR 2000). Pesticide residues are also found in drinking water and in foods, leaving the potential for chronic exposure to a suite of contaminants at low doses.

Primary exposure routes are dependent on the chemical properties of the pesticide of interest. Exposures specific to the classes of pesticides discussed above are presented below.

Childhood exposure to organophosphate pesticides

Because OP pesticides are still used today for residential and agricultural applications, exposure to these pesticides may occur via ingestion, inhalation, or dermal contact (CDC 2005). OP pesticides are responsible for most acute pesticide poisonings in the U.S. (AAP 2003). Children may accidentally ingest these pesticides if the chemicals are not safely contained, and ingestion may also occur via consumption of contaminated foods or soils. Children may inhale spray drift if in the vicinity of application; this may be of particular concern for children of agricultural workers or children residing near agricultural fields. Lastly, dermal exposure may occur through direct contact with the chemicals, or indirectly if a child comes into contact with a contaminated surface during play. There is also significant potential for chronic exposure to OP pesticides; a 2009 study found that, despite being discontinued from use, chlorpyrifos was detected on the floor surfaces of 78% of tested homes (the total sample size was 500) (Stout et al. 2009).

Childhood exposure to organochlorine pesticides

For the limited number of organochlorine pesticides that are still on the market in the U.S., exposure routes may be similar to those listed above for the OP pesticides. Even though many OC pesticides have been banned, children still have the potential to be exposed to the banned compounds because OC pesticides are highly persistent in the environment. For instance, despite being banned for years, DDT was found in 65% of house dust samples in a 2003 study (Rudel et al. 2003).

In the U.S., diet is the main exposure route for OC pesticides (CDC 2005). OC pesticides bind to soils and sediments, and can make their way into fatty tissues of fish and animals (CDC 2005). Therefore, fatty foods and fish are a primary source of exposure to OC pesticides, while ingestion of contaminated water is a less significant exposure pathway for OC compounds (CDC 2005). Infants can also be exposed to OC pesticides through consumption of breast milk (CDC 2005). In addition to the exposures mentioned above, children can also be exposed to the organochlorine pesticide lindane through direct dermal application for treatment of head lice or scabies (AAP 2003). Lindane is still prescribed for these purposes in Michigan and the U.S. (except California), although all other uses of this organochlorine pesticide have been discontinued.

Childhood exposure to pyrethrin and pyrethroid pesticides

Residential exposure and consumption of contaminated foods are the primary routes of exposure to pyrethroid pesticides in the U.S. and are therefore the leading sources for children. (CDC 2005). Pyrethrin and pyrethroids are also used in head lice and scabies medications. Children may experience dermal exposure and inhalation exposure from direct application of these pesticides (CDC 2005). Pyrethrin and pyrethroids are also commonly used in household insecticide products, pet sprays and shampoos, and mosquito repellents (ATSDR 2003). Additives in compounds containing pyrethrins and pyrethroids have been shown to increase harm to exposed populations. Piperonyl butoxide is a pesticide synergist—a chemical added to enhance the efficacy of the active ingredient—commonly added to pyrethrin and pyrethroids. Piperonyl butoxide acts by inhibiting enzymes in the liver that help detoxify other chemicals; this inhibition may make affected individuals temporarily more susceptible to toxic stimuli than they otherwise would be (Gosselin 1984). Like OP and OC pesticides, pyrethroids are commonly found in household air and dust; permethrin, a common type of pyrethroid, was found in about half of dust samples from tested homes (Rudel et al. 2003). A 2008 study similarly found concentrations of 13 different pyrethroids and their breakdown products in indoor dust collected from homes and childcare centers. In this study, permethrin was found in 100% of dust samples (Starr et al. 2008). A 2009 study found permethrin in 89% of tested indoor dust samples (Stout et al. 2009).

Nationwide Exposure Data

Pesticide Production and Environmental Contamination in the U.S.

National data on background pesticide exposures suggests use of and exposure to these pesticides is widespread, and pesticide residues are reaching our water as well as our food. For example, pesticides were detected in more than 90% of stream samples, and 50% of wells sampled in the U.S. (Stein et al. 2002). Detectable residues of at least one pesticide were found on 72% of fruits and vegetables tested (Stein et al. 2002). Exposure is so ubiquitous that pesticide residues and metabolites are commonly found in human bodies as well. Metabolites of one OP pesticide, chlorpyrifos, were detected in 92% of children in a Minnesota study (Stein et al. 2002).

In addition, three to nine pesticide residues are found in the typical home in the U.S. (Stein et al. 2002). Child daycare centers throughout the U.S. have been found to have pesticide residues (Tulve et al. 2006). Indoor air levels of measured pesticides are typically 10-100 times higher than outdoor levels (Stein et al. 2002). School children typically spend 85% to 90% of their time indoors, mostly at home and at school (Kats 2006). Therefore, the presence of pesticides and possibility of exposure through multiple sources is of concern.

Human Exposure and Body Burden in the U.S.

According to U.S. Poison Control data from 2006, pesticides were the cause of reported exposures for 45,848 children age 5 and under, and were the 8th most commonly reported exposure (following cleaning products, foreign bodies, various medicines, and vitamins) (Bronstein et al. 2007). These data are compiled from real-time data reported by 61 regional poison control centers across the U.S., and are spontaneous, self-reported data (Bronstein et al. 2007). Currently there is no comprehensive national pesticide incident data tracking system; therefore, it is unlikely that these data are inclusive of all accidental pesticide exposures in the U.S. (Levine 2007). Experts believe that there is marked under-reporting of pesticide exposures (Stein et al. 2002).

Monitoring contaminant concentrations in human fluids or tissues, such as blood or urine, can provide a useful snapshot of overall exposure in a population. In the CDC's Third National Report on Human Exposure to Environmental Chemicals, several toxicants were monitored in a representative sample of the U.S. population (CDC 2005). For children (ages 6-19), tested in 2001-2002, pesticides detected in some portion of the population are listed below in Figure 2.

Figure 2. Pesticides detected in urine samples of U.S. children (CDC 2005).
Figure 2. Pesticides detected in urine samples of U.S. children (CDC 2005).

Six organophosphate pesticides were detected in at least 50% of children ages 6-19 years who were tested, suggesting high levels of exposure. For the pesticides 2,4,6-Trichlorophenol (organochlorine), 3,5,6-Trichloro-2-pyridinol (organophosphate), and para-Nitrophenol (organophosphate), children ages 6-11 had higher urine concentrations than the adult population based on 2001-2002 data. The CDC findings also suggest "widespread exposure to pyrethroid insecticides" among children in the U.S. (CDC 2005).

Exposure to pesticides in families of farmers and pesticide applicators is ubiquitous; therefore, this is a subpopulation of particular concern. Twenty-seven percent (27%) of applicators store pesticides in their home, and forty percent of spouses of applicators also helped to mix or apply pesticides (Stein et al. 2002). Almost all clothing (94%) worn for pesticide work is washed in the same machine as other laundry. Over 50% of children 11years of age or older do farm chores (Stein et al. 2002), and therefore may be directly exposed to pesticides. Pesticides may be tracked into homes on the shoes, clothing, and hair of farm workers, and residues may accumulate in house dust, representing a further route of exposure for children of farm workers (Coronado et al. 2006).

Michigan Exposure Data

Pesticide Use and Environmental Contamination in Michigan

Agriculture is the second leading economic sector in Michigan, with $63.7 billion worth of activity in the state. Michigan is home to 53,200 farms averaging 190 acres (Michigan Farm Bureau 2008). Farming and related industries account for about 103,000 Michigan jobs (Michigan Agricultural Experiment Station 2006).

Data from the Michigan Department of Agriculture illustrate the widespread use of pesticides in Michigan. According to 2009 data from the Michigan Department of Agriculture, there are 22,164 applicators certified to apply pesticides in Michigan and 509 applicators registered to apply pesticides in Michigan. Registered applicators cannot use Restricted Use pesticides without the direct supervision of a certified applicator. All pesticides sold, offered for sale, or used in Michigan must be registered with the Pesticide and Plant Pest Management Division, which registered 14,764pesticide products in 2009 (MDA, 2009).

According to 2002 statistics from the U.S. Department of Agriculture (USDA), Michigan ranked 23rd in the U.S. in number of acres (990,827) treated with chemicals to control insects (USDA 2002). Of the 10.4 million acres of farmland in Michigan, approximately 56% are treated with pest-control chemicals (USDA 2002).

According to the National Agricultural Statistics Service (NASS) Agricultural Chemical Use Database, at least 2,951 pounds of active ingredient agricultural chemicals (pesticides) were reported used in Michigan in 2006, including those listed in Figure 3. This is likely an underestimation of pesticide use in the state.

Figure 3. Pesticides used in Michigan in 2006 (NASS 2006).
Figure 3. Pesticides used in Michigan in 2006 (NASS 2006).

# organochlorine

* organophosphate

^ pyrethrin/pyrethroid

These chemicals were applied to some combination of the following crops in 2006: asparagus, sweet corn, winter wheat, snap beans, pumpkins, squash, carrots, cucumbers, and soybeans (National Agricultural Statistics Service Agricultural Chemical Use Database 2006). Data from other years also shows that these chemicals are used on many other crops, including: cherries, asparagus, apples, potatoes, tomatoes, strawberries, grapes, and many more.

Human Exposure and Body Burden in Michigan

The Michigan Department of Community Health's 2010 report on occupational and non-occupational pesticide illnesses in Michigan provides some indication of pesticide exposure to Michigan children. Approximately 19% of confirmed reported occupational cases were children between the ages of 10 and 19 (MDCH 2010). The report acknowledged, however, that "the Michigan occupational pesticide surveillance data are likely a significant undercount of the true number of work-related pesticide poisoning cases in Michigan" (MDCH 2010). For all occupationally-related illnesses, the most common exposure routes were inhalation and dermal exposures.

Inhalation was the most common exposure route for non-occupational cases. While exposure to antimicrobial pesticides (e.g., sterilizers, disinfectants, and sanitizers) was the most common cause of occupational pesticide illnesses, over half of non-occupational illnesses were due to insecticide exposures (MDCH 2010). Non-occupationally related cases were more commonly reported than occupational cases. The age distribution for confirmed pesticide related illness from non-occupational exposures was 7 weeks to 90 years of age. Approximately 10% of the cases occurred in children ages 1 to 9 years; and approximately 9% occurred in children ages 10 to 19 years (MDCH 2010). Additionally, in 2008, the Michigan Poison Control System reported 3,386 cases of pesticide poisoning (MPCS 2008)

It has been noted that children of farm workers are commonly exposed to pesticides through residues tracked into the home (Coronado et al. 2006). According to the Michigan Migrant and Seasonal Farmworker Enumeration Profiles Study, it is estimated that there are approximately 45,800 migrant and seasonal farm workers (MSFWs) in Michigan. The study estimated the number of "children and youth" associated with MSFWs; this category was defined as anyone in the household from less than one year of age through 19 years of age. The category of "children and youth" included both workers and non-workers, but gives some indication of the number of children who may be exposed to agriculturally-related pesticide applications. The study estimated 30,764 "migrant" and 10,274 "seasonal" children and youth. There was an estimated average of 2.54 children per MSFW family (State of Michigan Interagency Migrant Services Committee 2006). The majority of children fell between the ages of 5 and 12 years (Figure 4).

Figure 4. Age distribution of "Children and Youth" associated with MSFW families, subclassified by migrant and seasonal workers (State of Michigan Interagency Migrant Service Committee 2006)
Figure 4. Age distribution of "Children and Youth" associated with MSFW families, subclassified by migrant and seasonal workers (State of Michigan Interagency Migrant Service Committee 2006)

Clearly, the potential for direct exposure to pesticides for Michigan children is high. Furthermore, even if the children themselves are "non-workers," children of agricultural workers are at higher risk for indirect exposure to pesticides through contact with contaminated clothing, elevated pesticide residues in and around the home, and spray drift. Children in the general population have the potential to be exposed to a variety of different pesticides simply by consuming foods with pesticide residues, in addition to coming in contact with pesticides through applications in houses, lawns and gardens, golf courses, and community mosquito control treatments.

Pharmaceutical Use of Pesticides

Concerns about possible health risks from exposure to pharmaceutical lindane prompted the U.S. FDA to issue a public health advisory and a Black Box Warning on lindane in 2003. EPA registration for agricultural use of lindane was voluntarily canceled in 2006. According to the Michigan Department of Community Health (MDCH), "an informal survey of three major commercial pharmacies found at least 2,220 prescriptions of lindane lotion and 4,622 of lindane shampoo filled in 2003 in Michigan. Based on these concerns, several Michigan pediatricians won a prior approval restriction for the Medicaid Pharmacy program, and have succeeded in reducing the monthly average of lindane prescribed from about 230 prescriptions per month in 2004 to 10 per month in the first quarter of 2005" (MDCH 2006).

In 2003 and the first quarter of 2004 the Michigan poison control centers received 22 calls related to lindane use. One exposure resulted in a moderate health effect; the individual washed someone else's hair with lindane shampoo and then developed tachycardia, shortness of breath, and chest pain. There were four exposures resulting in minor effects and twelve with no effect. Four were not followed (minimal clinical effects possible), and one had unrelated effects (lethargy and hallucinations). Most of the calls were due to improper use, which is consistent with other reports. There were 8 (36%) cases of young children accidentally ingesting lindane and 6 (27%) instances where lindane was mistakenly given or taken instead of another medication (MDCH 2006).

Policy Summary and Analysis

Pesticides have been linked to a wide variety of health impacts in humans and animals, including neurotoxicity. Legislative and regulatory measures related to pesticides exist at the state level in Michigan and other states to protect human health and the environment. Herein, best policy practices from other states will be mentioned, and recommendations will be made to help improve children's protection from pesticide exposure in Michigan.

Integrated Pest Management (IPM)

Michigan Policy Highlights

  1. Michigan statute and regulation define Integrated Pest Management (IPM) as a pest management system that uses all suitable techniques in a total management system to prevent pests from reaching unacceptable levels or to reduce existing pest populations to acceptable levels. The five practices and principles of IPM in Michigan include:
  2. Site evaluation, including site description, inspection, and monitoring and the concept of threshold levels.
    • Consideration of the relationship between pest biology and pest management methods.
    • Consideration of all available pest management methods including: population reduction techniques (such as mechanical, biological, and chemical techniques) and pest prevention techniques (such as habitat modification).
    • Pest control method selection, including consideration of the impact on human health and the environment.
    • Continual evaluation of the IPM program to determine the program's effectiveness and the need for program modification.
  3. Michigan legislation requires schools and licensed day care centers to use IPM programs, requires that the Michigan Department of Agriculture develop a model IPM program for schools, and mandates that rooms be free of children for at least four hours post-treatment (MCL § 324.8316).
  4. Michigan regulation requires that pesticide applicators complete training in IPM; and that schools, daycare centers, public buildings, and health care facilities have IPM programs in place (Michigan Administrative Code, regulation No. 637 Pesticide Use).

Analysis and Policy Highlights from Other States

  1. "least toxic" as defined by the California Agricultural Code is: "stressing application of biological and cultural pest control techniques with selective pesticides when necessary to achieve acceptable levels of control with the least possible harm to nontarget organisms and the environment." (Cal. Food & Agr Code § 13182. 11501-11518)
  2. Michigan stands out nationally because it is one of few states to require the use of IPM at schools and daycare centers; however, the definition of IPM in Michigan is weak.

Michigan does not require the use of "least toxic pesticides," as seen in other states such as California (Cal. Food & Agr Code § 13182), Texas (Tex. Occ. Code § 1951.212), and West Virginia (W. Va. Code § 19-16A-4).

Michigan does not require IPM for outdoor use in schools, public buildings, and health care facilities. Maryland, for example, requires the use of IPM on school grounds (Md. AGRICULTURE Code Ann. § 5-208.1).

  1. Oregon requires the use of an IPM program that prohibits the use of pesticides for aesthetic/cosmetic purposes. Additionally, it prohibits pesticides that are known carcinogens, endocrine disruptors, neurotoxicants, and mutagens. (Ore SB 637).
  2. Connecticut prohibits the use of a lawncare pesticide except in the event of a threat to public health (Public Act No. 05-252).

Evaluation and Recommendations for IPM in Michigan

Michigan is a national leader in IPM policy because the state requires IPM programs at schools and daycare centers. However, this policy can be improved by requiring the use of "least toxic" pesticides and mandating the use of IPM for outdoor pesticide use. It could also be improved by prohibiting aesthetic/cosmetic pesticide use and prohibiting the use of known mutagenic, carcinogenic, endocrine disrupting, or neurotoxic pesticides.

Pesticide Use at Schools and Daycare Centers

Michigan Policy Highlights

  1. Integrated Pest Management
    • Please refer to section i.2 above for information about IPM at schools and daycare centers.
  2. Prohibitions on Pesticide Use
    • Michigan regulation restricts the type of pesticides to be used in and around schools and day-care facilities. Neither liquid spray nor aerosol insecticide can be used in a school unless the area is unoccupied by students for at least four hours after the application. It also does not permit outdoor ornamental and turf applications of liquid spray pesticides to be made within 100 feet of an occupied room or building (Michigan Administrative Code, regulation No. 637 Pesticide Use, section 285.637.15).

Analysis and Policy Highlights from Other States

  1. Agricultural pesticides can travel substantial distances through the air after application via processes called drift and volatilization, and can pose a public health risk (Lee et al. 2002). Michigan does not have any statewide requirements regarding restricted spray zones (buffers) around school property. Michigan law does have requirements for applicators: "Pesticides shall be applied in a manner that minimizes the exposure of nontarget humans, livestock, domestic animals, and wildlife to pesticides. Unless permitted by the label, an applicator shall take all reasonable precautions that will prevent a pesticide from being applied if unprotected persons are present within the application site or are present in adjacent areas when off-target drift may occur" (MICH. ADMIN. CODE r. 285.637.4(k) (1995). However, buffer zones are recommended around schools to ensure protection against exposures from pesticide drift (Alarcon et al. 2005). Several states require a minimum distance for pesticide application. For example, Arizona prohibits spraying of specific pesticides, including highly toxic pesticides, within 1/4 mile of a school (Arizona Administrative Code, section 3-365(D)). New Jersey prohibits "reasonably foreseeable drift to non-target sites; requires 2-2.5 mile school buffer for treatment of gypsy moths; restricts aerial applications 300 horizontal feet from occupied school" (NJ Pesticide Control Regulations, section 7:30-10.2(f)). Louisiana requires 1,000 feet for aerial spraying of pesticides (Louisiana Administrative Code VII.XXII § 149).
  2. To better protect children's health at schools, it is recommended that the least toxic pesticides be used, when nontoxic methods are impractical or not successful. EPA Toxicity Category I and II pesticides should be avoided if possible (Alarcon et al. 2005). Michigan does not ban any type of pesticide on school grounds, nor does it require records to be kept of pesticide use in schools. California (Cal. Food & Agr Code § 13182), Texas (Tex. Occ. Code § 1951.212), and West Virginia (W. Va. Code § 19-16A-4) require use of least toxic pesticides. West Virginia requires establishment of an IPM program, use of "least hazardous materials," and use of pesticides only when pest infestations are present in schools. West Virginia defines "least hazardous materials" as chemicals falling under the EPA toxicity categories of III or IV, which includes pyrethrin and pyrethroid dusts (W. Va. Code §61-12J-1), although these products may be of potential concern. Connecticut banned the use of "lawn care pesticides" at schools starting in 2008 (Public Act No. 05-252). Massachusetts prohibits outdoor use at schools or day care centers of pesticides considered by the EPA to be carcinogens and only permits use of pesticides considered to present relatively minimal risks in school settings (ALM GL ch. 132B, § 6F and § 6G). Oregon prohibits aesthetic/cosmetic pesticide use and the use of mutagenic, carcinogenic, neurotoxic, and endocrine disruptive pesticides (Ore SB 637).
  3. Michigan does not require a registry of pesticides used at schools, while Connecticut requires records of pesticide use be kept for 5 years, and Louisiana also requires records of use (La. R.S. 3:3383).

Evaluation and Recommendations

Michigan should strongly consider a policy that establishes a buffer zone for agricultural applications around schools. Buffer zones will better protect children's health both outside and inside of school buildings, and several states already require such practices. Michigan should also strongly consider a policy that requires use of "least toxic" pesticides and prohibits the use of the most toxic, particularly those that are neurotoxic, carcinogenic, mutagenic, or endocrine disruptive; several states require such practices. Michigan should prohibit outdoor use of the most hazardous pesticides at schools or day care centers. In addition, Michigan should consider a policy that will require a registry of all pesticides used at schools.

Notification Laws at Schools and Daycare Centers

Michigan Policy Highlights

  1. Michigan legislation (MCL § 324.8316) requires schools and day care centers to create an Integrated Pest Management (IPM) program for the building in order to apply pesticides.
  2. Administrators must notify parents at the beginning of each school year of their right to be informed before pesticides are applied at the school. School administrators are also required to inform parents (via at least 2 ways) of pesticide use 48 hours in advance and to include information about the pesticide application (date, location, and target pests). Posting at entrances is also required (MCL § 324.8316).
  3. Michigan regulations require the school district's administrator to provide annual written information to parents or guardians of students on how to be included on the list for prior notification. During the months when school is not in regular session, school administrators may use a message notification system. In addition, schools must post a sign at the primary point of entry to the building. Posting is required upon completion of the application and must remain for at least 48 hours (Michigan Administrative Code No. 637 Pesticide Use).

Analysis and Policy Highlights from Other States

  1. Michigan policy regarding parental notification of pesticide use inside a school or daycare center parallels those of states that require notification of pesticide use in schools and daycare centers; however, the specific requirements are not fully adequate.
    • Michigan lacks the requirement to provide parents with specific information on the name of the pesticide and its potential health effects.
    • Michigan does not require Material Safety Data Sheet (MSDS) information in parental notifications.
  2. Michigan requirements for sign posting are not fully adequate. Specifically, the following improvements can be made (adapted from Beyond Pesticides, "Model Policy" document):
    • Extend the duration of sign postage on the building because pesticide residues often last longer than 48 hours (current Michigan requirement). For example, Connecticut requires signs to be posted at least 48 hours before application and at least 72 hours after application (ALM GL ch. 132B §6), and New Jersey requires signs to be posted 72 hours before and after application of pesticides (N.J. Stat. § 13:1F-26).
    • Signs should be required at each entrance to the building and at other areas of high traffic such as main bulletin boards (Michigan requires a sign at the primary entrance only).
    • Use of a universal symbol should be required on the sign to indicate that a toxic substance has been used.
    • A larger sign should be required (Michigan currently requires a minimum of 2.5 inches by 2.5 inches).

Evaluation and Recommendations

Michigan stands out nationally with its policy requirements for notification of pesticide application at schools and day care centers. However, these policies can be improved by requiring specific information on the pesticides being used (name, toxicity, MSDS information). In addition, the state can improve the policy regarding notification signs by requiring: extended duration of posting, a larger sign size, posting at each entrance to the building, posting at edges of property under treatment, and use of a universal symbol to indicate a toxic chemical has been used.

General Notification and Surveillance

Although notifying parents of a pesticide application at schools and day care facilities remains the primary focus of state notification legislation, a number of states, including Michigan, have implemented notification laws for other pesticide applications.

Michigan Policy Highlights

Michigan regulation requires pesticide applicators to post a sign for 24 hours when using a broadcast, space, or foliar application for turf or ornamental purposes. In addition, the regulation requires a sign at the primary point of entry to a public building, health care facility, daycare center, or school for 48 hours after a pesticide is applied. In addition, a commercial applicator is required to make a "reasonable effort" to provide prior notification of broadcast or foliar applications to persons who own or reside on property that is within the target area or to their authorized representatives (Michigan Administrative Code No. 637 Pesticide Use).

Analysis and Policy Highlights from Other States

  1. States that have enacted legislation that expands or is more comprehensive than Michigan policy include California, Connecticut, Montana, and New York.
    • California requires pesticide application notification signs in both Spanish and English before use in public parks or "public rights of way" (Cal Food & Agr Code § 12978).
    • California requires commercial pesticide applicators to notify the owner and tenant of property on which pesticides are to be used of what pesticides will be used and a warning about the toxic nature of pesticides (Cal Bus & Prof Code § 8538).
    • New York requires public notice of commercial pesticide application be given and remain for at least 24 hours after application and that a copy of the pesticide's label be provided to the owner of the property on which pesticides are to be applied (NY CLS ECL § 33-1003).
    • New York and Montana state law expressly authorize localities to have more stringent notification laws (NY CLS ECL § 33-1004 & Mont. Code Anno., § 80-8-120), while Connecticut requires written notice of pesticide use, to those who request it and live within 100 yards of a property undergoing pesticide use (Conn. Gen. Stat. § 22a-66a).
  2. States that have more stringent notification requirements for aerial spraying include:
    • Maine, which requires public notice be given at least 14 days before aerial pesticide spraying, and requires the notice include the name of the pesticide to be used (22 M.R.S. § 1471-R).
    • New Hampshire, which requires written notice be provide to all residences in an aerial spraying zone (RSA 430:34-a), and prohibits spraying in sensitive areas (schools, day care centers, athletic fields, etc) and during times when children are traveling to and from school.
  3. Every state should implement a pesticide poisoning surveillance system (Alarcon et al. 2005). California requires physicians to report suspected pesticide poisonings (Cal Health & Saf Code § 105200).

Evaluation and Recommendations

Michigan is among a number of states to require notification for pesticide use in communities. However, the state should consider expanding its policy for better public health protection. Such measures can include bilingual signage, written notification to residents near pesticide applications, and provision of public notice sufficiently prior to applications. Although Michigan has a pesticide poisoning surveillance system, poisonings are known to be greatly underreported. Without a reinforcing system to encourage physicians to report these incidences they have little incentive to spend the time doing so.

Sensitivity Registries

Michigan Policy Highlights

Michigan regulation maintains a voluntary pesticide notification registry that informs those with "medically documented condition[s]" that pesticide use will be occurring on property adjacent to theirs. To be on the registry, one must apply annually with a physician's certification (Michigan Administrative Code No. 637 Pesticide Use).

Analysis and Policy Highlights from Other States

Like Michigan, Colorado and Washington have pesticide sensitivity registries, where those who are certified by a physician as sensitive to pesticide use receive prior notification before pesticide use in their area.

Evaluation and Recommendations

Michigan is one of few states to require a sensitivity registry, but in order to increase the effectiveness and accessibility of this registry, Michigan should drop the onerous requirement of annual physician certification of sensitivity.

Cosmetic or Ornamental use of Pesticides

Michigan Policy Highlights

No Michigan policy met our specific criteria.

Ontario Policy Highlights

According to the Toronto Star, Ontario joined Quebec in banning the sale and cosmetic use of pesticides. More than 80 ingredients and 250 pesticides products have been prohibited following full implementation of the ban in spring 2009 (Babbage 2009).

Evaluation and Recommendations

Michigan should adopt a ban of pesticides for cosmetic use while allowing towns and cities to enact even stricter pesticide laws.

Pharmaceutical Use of Pesticides

Michigan Policy Highlights

  1. No Michigan policy met our specific criteria to address pharmaceutical uses of pesticides. Michigan does require prior approval under Medicaid for lindane prescriptions, but not for patients with private insurance.
  2. The Michigan Department of Community Health does not recommend the use of lindane to treat scabies or head lice patients in part because of “recent concerns of drug resistance and severe adverse reactions, including death” (MDCH 2004, MDCH 2005).
  3. The Michigan House of Representatives passed HB 4402 in March 2009 to prohibit use of lindane for treatment of lice and scabies unless applied under the direct supervision of a physician. The bill was referred to the Michigan Senate but not action was taken.

Analysis and Policy Highlights from Other States

  1. California is the only state to ban the pharmaceutical use of lindane. Bills in Illinois and New York have not yet succeeded in their legislatures.
  2. At least 16 states have some Medicaid restrictions for lindane. Aside from California, which has a complete ban on lindane, Arkansas has the strongest state Medicaid requirements: the recipient cannot be under 13 years of age, the quantity dispensed is limited, it cannot be prescribed more than once every 180 days, and the patient must have two trials with safer treatments for lice or one trial with a safer treatment for scabies (Arkansas Department of Human and Health Services, 2006).

Evaluation and Recommendations

Michigan should continue to pursue a phase-out of pharmaceutical products containing pesticides linked to neurotoxicity (or require strict physician supervision) and should also encourage the use of safer alternatives.

Summary of Recommendations for Pesticide Policy in Michigan

To reduce health hazards posed to children by exposure to pesticides, Michigan should strongly consider adopting the following policies:

Prior notification time requirement exceptions could include licensed professionals working in industries such as agriculture in which reaction to pests are time sensitive.

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