Children living near traditional plantations in Costa Rica are exposed to twice as much of the insecticide chlorpyrifos compared to children living near organic plantations, a study reports. More than half of the 140 studied children who were mostly indigenous Ngäbe and Bribri had higher daily exposures than what is considered safe by U.S. standards. Residential use of the pesticide, which has been linked to neurological effects in children, is banned in the United States, although it is still permitted on some crops. Costa Rica's banana and plantain plantations export products to U.S. and European markets.
Chlorpyrifos treated bags are widely used to protect banana and plantain crops from pests in Latin America and West Africa [Editor's Note: A reference to West African nations using chlorpyrifos was removed on 1/11/2013 because there is no documentation to support it], even in populated areas. The bags coated with the insecticide surround the developing fruit and reduce pest damage. The chemical also contaminates the local air and soil and is tracked by workers into homes.
Chlorpyrifos is an organophosphate insecticide used to control mites on animals, to eradicate termites from buildings and to kill adult mosquitoes (CDC 2009). Although it was banned more than a decade ago for indoor pest-control and all residential uses in the United States due to health concerns, about 10 million pounds are still used on U.S. crops each year, including on corn, citrus trees, cotton and alfalfa (EPA 2002).
Chlorpyrifos is highly toxic to insects, amphibians and fish. In people, it overstimulates the nervous system and can cause nausea, dizziness and confusion in adults.
Pre-birth exposures have been linked to lower birth weights in some but not all studies (Perera et al. 2003, Eskenazi et al. 2004). Children exposed to chlorpyrifos in the womb also are more likely to have mental and motor development delays, higher rates of ADHD at age 3 (Rauh et al. 2006), and lower full scale IQs and working memories through age 7 (Rauh et al. 2011). These neurodevelopmental effects may be caused by potentially irreversible physical changes in children’s brains following exposure (Rauh et al. 2012).
What did they do?
Blue bags treated with cholorpyrifos (CPF) dot the banana and plantain plantations in the Talamanca region of Costa Rica, on the Caribbean coast southeast of San Jose. The area is home to indigenous Bribri and Ngäbe. To gauge children's exposures to the insecticide, researchers compared levels of TCPy – a metabolite and marker of chlorpyrifos exposure – in children from three villages. The banana and plantain villages were near plantations that use CPF-treated bags, while the organic village was near several plantations with little or no insecticide use.
Researchers measured TCPy levels in urine samples collected from 140 children aged 6 - 9 from the three villages. The urinary TCPy levels were then used to back-calculate how much CPF the children had absorbed on average per day. These absorbed daily doses (ADDs) were compared to a reference dose that the U.S. Environmental Protection Agency considers safe for long-term exposures in children. The reference dose is called the chronic population adjusted dose, or cPAD (EPA 2002). To assess environmental exposures, CPF levels also were measured in hand wash and foot wash samples collected from some of the children. Levels also were measured in soil, house dust, mattress dust, drinking water, surface water, and air samples collected from inside or near the children’s homes or near the local school.
What Did They Find?
On average, children in the banana and plantain villages had twice the TCPy levels in their urine with geometric means of 1.6 and 2.0 micrograms per liter (μg/L) compared to children from the organic banana village, who had an average of 0.8 μg/L. Boys living in the plantain plantation also had higher TCPy levels than girls, suggesting that boys spend more time working in the plantation or assisting with other tasks associated with CPF exposure.
Alarmingly, the TCPy levels in urine suggested that more than half of the kids from all three villages exceeded the daily CPF reference dose considered safe by U.S. standards of 0.03 μg/kg/day for chronic exposures in children (EPA 2002). On average, children from the banana and plantain villages absorbed 3 times the reference dose, and those from the organic village absorbed 1.5 times the reference dose. The reference level was exceeded in 97 percent, 82 percent and 68 percent of the individual urine samples from the banana, plantain and organic village children, respectively.
The kids’ environment also was widely contaminated with CPF. In general, the banana village children had more contaminated home environments than the plantain village children. CPF levels in the hand- and foot-wash samples from the banana village also were 3 times higher than in the plantain village. Children from the banana village lived only 16 - 87 yards from the plantation and played in the schoolyard right next to the banana fields. The lower environmental exposures in the plantain village children may be because they lived farther away, a little over a mile from the plantation.
What Does It Mean?
Pesticide exposures higher than recommended by U.S. standards are seen in children who live near plantations in Costa Rica that use insecticides when compared to children near organically farmed plantations. The findings raise concerns about long-term health effects on the youngsters.
The children living in two villages near banana and plantain plantations that use CPF-treated bags had higher exposures than children from a third village with mainly organic fruit production. Alarmingly, more than half of the studied children from all three villages also had calculated daily exposures that are considered unsafe according to U.S. standards.
The findings suggest that CPF-treated bags contribute to chlorpyrifos exposures in local Costa Rican children at levels that may affect their health. Although health effects were not measured directly in the children, previous studies link pre-birth CPF exposures to lower IQ, impaired memory, mental and motor development delays and higher rates of ADHD in children (Rauh et al. 2006, Rauh et al. 2011).
Prior to the 2001 regulatory changes in the United States, TCPy levels in U.S. children were even higher than in the Costa Rican children in the current study. These levels are partly why the U.S. CPF regs went into effect to prevent the use of CPF on various fruits. That year in the United States, CPF was banned for indoor pest-control use, and its use on tomatoes was stopped. Earlier in 2001, CPF was restricted for use on apples and grapes (EPA 2002).
U.S. health studies conducted around the same time reported that mean TCPy levels in 6- to 11-year-olds were 2.9 μg/L in 1999 - 2000 and 2.7 μg/L in 2001 - 2002 (CDC 2009). These levels were 35 - 81 percent higher than those found in the Costa Rican children from the two CPF-exposed villages. Although CPF exposures have likely decreased in U.S. children since 2001, more recent national health study data to confirm this trend have not yet been published.
Children of U.S. farm workers may have had even higher CPF exposures than the Costa Rican kids. A 2000 - 2001 study found TCPy mean level of 7.6 μg/L in farm kids from North Carolina and Minnesota whose fathers applied CPF (Alexander et al. 2006). The levels are 4 - 5 times higher when compared to the children from the Costa Rican study. In 2004, the TCPy mean level of 1.9 μg/L measured in 1- to 6-year-old farm worker children from North Carolina were more similar to Costa Rican children's levels (Arcury et al. 2007).
In addition to concerns about CPF exposure, conventional banana production is rife with other health and environmental concerns. According to BananaLink, a U.K.-based advocacy group, banana workers can work up to 10 - 12 hours a day in blistering heat, without access to clean drinking water or protective equipment to help reduce exposures to agrochemicals. Many workers also do not earn a living wage.
The banana industry uses more agrochemicals than any other industry except for cotton. Pesticides are heavily used to meet consumer demand for perfect, unblemished fruit and because bananas which are mostly grown in large monocultures are highly prone to pests and disease. Pesticides and fertilizers pollute local waterways and can have devastating effects on ecosystems as well as worker health. Deforestation to plant more bananas also can destroy entire ecosystems.
New ways to reduce the need for pesticides and other agrochemicals on banana crops are being developed. Options include planting several varieties of bananas and rotating crops to lessen the chance of pest infestation, using pheromone traps to lure away pests, digging trenches around the banana plants and removing diseased plants by hand to reduce the spread of infestations and disease, and boosting the soil with organic matter and beneficial organisms to strengthen plants and improve soil health (ENDURE 2010).
These and other interventions to reduce CPF exposures in the banana and plantain plantations may ultimately help to protect environmental health, as well as the health of the plantation workers and their children. - Glenys Webster, Wendy Hessler, Environmental Health News