Top: A sweatshirt worn under personal protective equipment during a four-hour spray session with fluorescent tracer added to the tank shows areas of contamination.
Bottom: Areas of the neck were contaminated. There was some wind, and the suit did not cover this part of the neck.
Residues in the home are higher where workers delay changing clothes after work.Numerous studies conducted in Washington State and elsewhere have found organophosphate pesticides, such as Lorsban (chlorpyriphos) and Guthion (azinphos-methyl), in dust samples in agricultural workers’ homes.
There is evidence that family members have been inadvertently exposed, as measured by metabolites of these chemicals in the urine of children. New research around the country suggests that low-level exposures to organophosphates can have adverse effects on children’s developing nervous systems. Fortunately, there are ways to reduce the level of agricultural chemicals in workers’ households and keep pesticides from leaving the workplace.
The work-to-home pathway
The work-to-home pathway (sometimes called the take-home pathway) is the term used to describe pesticides inadvertently leaving the workplace through workers’ hair, skin, clothing, tools, or vehicles, resulting in contamination of their homes and family members.
As part of the 1995 Worker’s Family Protection Act, the National Institute for Occupational Safety and Health reviewed all research that assessed work-to-home chemical exposures. They found little information on this exposure pathway in agriculture, compared with other industries. This stimulated a flurry of research throughout the country because of concern about the vulnerability of pregnant women and children. The key findings were:
• Pesticide residues in yard soil and house dust were significantly higher in agricultural families who lived within 200 yards of an orchard than in non agricultural-families who lived more than a quarter of a mile from an orchard. Pesticide residues in household dust (which are not exposed to the usual environmental conditions that would lead to their degradation) were higher than in soil samples.
• Biological markers were used to determine if children were being exposed. Urine samples collected from children demonstrated that pesticide metabolites were more than four times higher in children of pesticide applicators than in children of non-agricultural families. The younger the child, the higher the levels. The further away the home was from an orchard, the less likely that pesticides would be detected in children’s urine samples.
• In an expansion of the former study, researchers conducted more sampling of urine, hand wipes, dust, and indoor surface wipes. The agriculture household dust samples had seven times more pesticide residues than the non-agricultural homes. Children of agricultural workers had five times the urinary metabolite load than their non-agricultural counterparts. Homes within 200 feet of the orchard had higher household dust residues. Pesticide residues were found on some of the children’s hands and on car steering wheels. Researchers in North Carolina found workplace pesticide residues on children’s toys.
• In 2002, workers’ vehicles were established as the transmission route. Residues in house dust and vehicle dust from the same agricultural workers were significantly correlated, regardless of how far the home was from the orchard. Urinary pesticide metabolite levels in adults and children were also correlated.
Children are particularly vulnerable to pesticides. Their chances of exposure are greater because they spend more time on the ground where residues collect and explore their surroundings through hand to mouth activities. They receive a bigger dose than adults because of their rapid metabolism, greater skin surface area per body weight, and pound for pound higher consumption rates of foods and fluids. Finally they are physiologically more vulnerable to the health effects of exposures at these higher doses because their body systems, such as the reproductive and neurological, are still developing. As an example, a child’s underdeveloped liver is less able to break down and detoxify a pesticide.
There is new evidence from three large replicated studies of mothers and their babies in California and
in New York that children exposed to low-level organophosphates during the prenatal period have neurodevelopmental delays. All three studies found an association between maternal and newborn levels of organophosphates and abnormal reflexes at birth. Those with higher levels of exposure showed poorer mental development at age two and three and poorer verbal IQ at three and five year years of age. Using standardized tests, all found various behavioral problems significantly associated with organophosphates, such as attention disorders, hyperactivity, and pervasive development disorders. Whether these findings are temporary or will translate into functional problems later in life is yet unknown.
To identify where best to break the transmission pathway of pesticides from the workplace to home, the Pacific Northwest Agricultural Safety and Health Center (PNASH) has looked at the practices of a small group of thinners and applicators in a large, well-equipped orchard. Almost all the thinners (93 percent) and a majority of the applicators (75 percent) wore their work clothes in the home after work. And, 87 percent of thinners and 69 percent of applicators wore their boots inside as well.
PNASH put a fluorescent tracer in spray tanks as a training tool to show applicators where they were contaminated. After applying four tanks, the applicator’s face and sweatshirt worn under PPE (personal protective equipment) became contaminated (Figure 1). Figure 2 demonstrates contamination of the neck. PNASH is developing a kit and video on how to use the fluorescent tracer as a training tool in the workplace to encourage safer pesticide handling.
A group of researchers in Oregon found that homes where the worker delayed changing clothes by two hours had higher residuals than those that changed right away.
The researchers also studied how well standard household cleaning removed pesticide residues. They cleaned windowsills and floors with Pine-Sol and steam cleaned carpets to remove pesticide residues from workers’ apartments. The levels of pesticide residues were measured in household dust and wipe samples collected before cleaning and again 24 to 48 hours and 12 months later. Steam cleaning carpets brought pesticide residual levels to nondetectable. Linoleum floors were more difficult to clean, but measures to clean windowsills were effective.
More recently, PNASH studied how to keep pesticides from leaving the workplace. The scientists found that the transfer of pesticide residues can be significantly reduced if vehicles are routinely vacuumed at the workplace. Cherry harvesters who vacuumed their vehicles five to eight times over the 50-day study period had eleven times lower residues of azinphos-methyl in their household dust than those who did not vacuum.