Organophosphorus pesticide exposure among agricultural workers, their spouses, their children, and consumers: A literature review
Department of Public Health
08 June 2008
Objective: To review research on the exposure of organophosphorous (OP) pesticides among agricultural workers, their spouses, their children, and consumers. OP pesticides are of particular concern because of their acute toxicity and widespread use.
Method: This review included 15 published studies that reported on the exposure to organophosphorous pesticides through surveillance, intervention and epidemiological studies as well as various descriptive articles to gain more insight into OP pesticides, their adverse health effects, how we are ingesting them and if there is a possible solution to this public health dilemma.
Results: The findings indicate that OP pesticides are being ingested into our bodies in great quantities. The mechanism of action is eating foods that are grown with the pesticides, through take home pathways from farmers to their families, or breathing it in the air.
Conclusion/Implications: Exposure to OP pesticides is not only a health concern for the applicators, but also for their families, those living near farms and consumers.
About 70% of insecticides used in theUnited Statesare OP pesticides (Lu et al., 2001 and Loewenherz et al., 1997). The OP pesticides interfere with the nervous system of humans when people are exposed. Agricultural uses of OP pesticides include corn, canola, alfalfa, produce and nuts. People are commonly exposed to OP pesticides through eating fresh vegetables and fruit, contact with surfaces that are pesticide-contaminated, and breathing air near indoor and outdoor applications. Exposure to OP pesticides have been recently documented by U.S. Centers for Disease Control and Prevention (CDC) and academic scientists which show that farmers, their families and consumers have OP pesticides in their urine. Children and infants consume more food per kilogram of bodyweight then adults do and are therefore likely to have a higher concentration of OP pesticides in their systems. Since OP pesticides do not build up in the body fat of humans, it was concluded that there is exposure to these chemicals on a regular basis. This is of public health concern since OP pesticides can cause nausea, headaches, twitching, trembling, excessive salivation, tearing, an inability to breathe because of paralysis of the diaphragm, convulsions and at high doses, death. The purpose of this paper was to examine the exposure and see ways in which prevention of exposure can be demonstrated. In this review, the focused was on studies that demonstrated how the pesticides are getting into our bodies.
To identify studies addressing OP pesticide exposure, PubMed was searched and the Yahoo search engine was utilized using combinations of the keywords organophosphorus pesticides, exposure, organic foods, agricultural, farming, farmers, spouses of farmers, and children of farmers, environment. Information gathered spanned from 1995-2008. Studies were included if they gave insight into the how OP pesticides were being exposed in humans. For example, included were children who ate organic foods versus children who ate conventional and also how pesticides were getting into the household of farmers. Excluded were specific research studies that talk about cancer. However, there was an interesting study on “Pesticides and Parkinson’s Disease- Is there a Link?” which is addressed later in the implications portion of this paper. In all, 19 studies were reviewed and various descriptive articles to gain more insight into OP pesticides, their adverse health effects, and how we are ingesting them as well as a possible solution. My research was divided into two categories (1) exposure of OP pesticides in the home of farmers (2) the exposure of OP pesticides in children.
3.1 Exposure of OP Pesticides in the Homes of Farmers
Pesticides in the home may represent a longer source of exposure than outdoor applications. They may be present in the air, water or dust in or around the surfaces of the home (Hoppin et al 2006). It was hypothesized that children and spouses of farmers are potentially exposed to pesticides indirectly by take-home contamination. This was confirmed by studies conducted by Curl et al., 2002, Arcury et al., 2007 and again by Thompson et al., 2008. Pesticide residue on farm workers clothing, shoes, and skin is brought into the home from the fields and then these residues persist in the indoor environment (e.g., house dust) where they are a potential source of exposure to farm workers families. In a study conducted in 2004 by Coronado et al, workers who mixed, loaded and applied pesticides had less amounts of pesticide residues in their house or vehicle dust than compared with those who did not perform those specific agricultural tasks who surprising had more. Intervention programs to reduce take home pesticide exposure among farm workers and their children failed (Thompson et al 2008). The interpretation of take home pathway of pesticide exposure was unreliable across different analytical methods and laboratories,
Currently there is a study called the Agricultural Health Study which is a prospective cohort of about 90,000 commercial pesticide applicators, farmers and farmers’ spouses being conducted inIowaandNorth Carolinainvolving the National Institute of Environmental Health Sciences and the U.S. Environmental Protection Agency. The project included interviews to obtain information on agricultural practices such as monitoring of pesticide exposures. An Agricultural Health Study conducted in the summer and spring of 2001, tested the urine concentration of 47 fathers, 48 mothers, and 117 children ofIowafarm house holds and non-farm households were screened for specific metabolites (a subset of OP pesticides) that were used extensively inIowafarming. Farm families had higher concentration of some of the metabolites, where some of the other metabolites there was not a difference. Farm children had significantly higher urinary results if fathers had applied the pesticides prior to urinary sample collection (Curwin et al 2007).
3.2 Exposure of OP pesticides in children
Children have a greater vulnerability to the effects of chemical exposure because of their high rate of metabolism, less mature immune systems, and the fact that they tend to eat the foods that have high pesticide residue.
In 1999 Eskenazi et al., conducted a study to discuss the extent of children’s exposure to pesticides and their possible adverse effects as well as investigate exposures to children living in an agricultural area and possible effects on growth, neurobehavioral development, and respiratory disease. It was concluded that more studies were needed to gather more information on the sources, pathways, and levels of pesticide exposure especially of those children at highest risk living in agricultural communities. Later, in another study conducted by Eskensazi et al., 2007 it was concluded that mental development and pervasive problems were found in children exposed to OP.
Conventional fruits are 3.6 times more likely to contain pesticide residues than organic fruit; vegetables contain 6.8 more times. Imported foods contain more residues then domestic samples, regardless of market (Pesticide Data Program, 2007). A research study conducted by theUniversityofWashington(Curt et al., 2003) found that children consuming conventional food had 8.5 times higher average levels of OP pesticides than children eating mostly organic. The research assessed OP pesticide residues in two to five year olds consuming a diet composed of mostly organic foods versus conventional foods. The team found that two to five year olds consuming mostly organic foods over a three day period had much lower mean levels of OP insecticide metabolites in their urine. Children consuming conventional food had 8.5 times higher average levels. Parents kept food diaries. The research team concluded that “The dose estimates suggest that consumption of organic fruits, vegetables and juice can reduce children’s exposure levels form above to below the U.S. Environmental Protections Agency’s current guidelines, thereby shifting exposures from a range of uncertain risk to a range of negligible risk. Consumption of organic produce appears to provide a relatively simple way for parents to reduce their children’s exposure to OP pesticides.” (page 377)
In other study conducted to access if an organic diet would significantly lower exposure to OP pesticides was conducted in 2006 by Lu. A group of 23 elementary school-age students ages 3-11 were enrolled in this study for 15 days. Organic foods were eaten for five days and conventional foods were eaten for ten days. Two spot daily urine samples were collected first thing in the morning and before bedtime for fifteen days. A food diary was kept by the parents. All organic items were purchased by the research staff at a single grocery store. The metabolites from the OP pesticides were undetectable when the children ate the organic foods. When the conventional foods were reintroduced the metabolites were again detectable. The study demonstrated that an “an organic diet provides a dramatic and immediate protective effect against exposures to organophosphorus pesticides that are commonly used in agricultural production. We also concluded that these children were most likely exposed to these organophosphorus pesticides exclusively through their diet” (page 260).
In the early 1990’s little was known about the levels of pesticides in foods we ate. Much new data on pesticide residues in food has emerged as a result of the Food Quality Protection Act (FQPA) in 1996. This bill took into account the susceptibility of infants and children since they consume more food per kilogram of bodyweight then adults do and are therefore likely to have a higher concentration of OP pesticides in their systems. Despite knowing the risk of pesticides there are still many foods that contain high levels of pesticides. Those foods are: apples, pears, peaches, grapes, green beans, tomatoes, peas, strawberries, spinach, peppers, melons, lettuce and various juices. Most of these foods are most commonly eaten by children (Baker et al 2002). The 2002 National Research Council (NRC) report Pesticides in the Diets of Infants and Children concluded that pesticide exposure may account for the increased adverse health events in children. The findings for the OP pesticides exposure in children in the study conducted by Lu in 2006 supports the conclusion made by the NRC in 1993 that the dietary intake of pesticides represents the major source of exposure in infants and young children.
Research on the effects of farm workers has taken place for almost 20 years and yet still much is not certain and unknown. The effects that pesticides have on farm families due to the farmers bringing pesticides home on their skin, trucks, and clothing has only been looked at within the past few years. More research is needed to understand the extent to which pesticides have adversely affected our health. Neurobehavioral performance has been most recently identified with chronic OP exposure (McCauley et al 2006).
Several studies have found that farm homes have higher concentration of pesticides than those homes not having a member in the farming industry (Simcox et al., 1995; Bradman et al, 1997; Lu et al., 2000, 2001 and 2006, Curl et al, 2002; Fenske et al., 2005; McCauley et al., 2006). Pesticide urine concentrations were higher among children of farm workers compared to children of non-farm families (Loewenherz et al, 1997; Lu et al 2004).
In theUnited Statesin 1999 it was recorded that farmers applied approximately 540 million kilograms of pesticides (USEPA 2002). The National Institute for Occupational Safety and Heath (NIOSH) reported to congress in 1995 a concern for pesticide exposure among children of farmers and farm workers. In 1998, the National Resource Defense Council (NRDC) considers pesticides to be one of the highest environmental threats to children’s health.
Research studies have shown that OP pesticides are a public health risk. We do know some of the multiple illnesses caused by OP pesticide exposure; however what we do not know may be more of a concern. More complex surveillance of OP pesticide related illnesses are needed so that we can study and understand the relationship between pesticide exposure and a variety of health effects.
There may be long term effects OP pesticides not present yet to society such as new diseases or unexplained illnesses. For example, Parkinson’s Disease (PD), is a disease of the nervous system and the cause is still unknown. However in 2006 there was research that concluded a relationship exists between PD and pesticides in the study “Pesticides and Parkinson’s Disease-Is There a Link?”(Brown et al, 2006).
An intervention is warranted for the safety of the public’s health to stop the ingesting of pesticides. Interventions such as “vertical farming” would at best alleviate many of the adverse health effects we are seeing by the use of pesticides. Vertical farming is a concept that resides inside urban high rises. It uses greenhouse growing and no pesticides and can supply fruit, vegetables, fish and livestock, allowing cities to become self sufficient and healthier. All foods would be organically grown without fertilizer and free of disease. Moreover, it is estimated that by the year 2050 there will not be enough land to farm to feed all of the people in the world (www.verticalfarm.com).
By converting from “horizontal farming” to “vertical farming”, humanity may never have to worry about:
- running out of arable land
- pesticide ingestion
- concerns about bad weather destroying crops
- natural disasters
Vertical farming is something we should start looking into implementing today. If successfully implemented, it offers promise of:
- urban renewal
- sustainable production of a safe and carried food supply (year round crop production)
- the eventual repair of ecosystems that have been sacrificed for horizontal farming.
Technology to construct vertical farms currently exists. It can be designed to use energy generated from wind power and solar power. It will use less water, with the option of re-cycling it, eliminating the world’s most serious form of pollution – agricultural runoff. The vertical farm aspires to be self-sufficient.
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