(Beyond Pesticides, February 17, 2010) In the largest study of its kind, researchers searched hundreds of Salinas Valley, California homes for pesticide compounds sticking to dust layers and discovered widespread residues of 22 residential and agricultural-use products.
The study, “Pesticides in Dust from Homes in an Agricultural Area,” was conducted by an investigator from the California Department of Public Health and researchers with the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) with the University of California, Berkeley. CHAMACOS began recruiting pregnant women in the Salinas Valley for a long-term study of prenatal and infant chemical and allergen exposure in 1999. The center sampled study homes in 1999 and 2000 with a modified vacuum cleaner.
The most common pesticides found were permethrin (467ppb) -a popular insecticide against home insect, and chlorpyrifos (74ppb). The U.S. Environmental Protection Agency (EPA) banned chlorpyrifos for home-use in 2000, but it is still used in agriculture. Other pesticides frequently detected include the herbicide dimethyl tetrachloroterephthalate (DCPA), methomyl, diazinon and a fungicide, iprodione. Household dust concentrations are significantly associated with nearby use of these chemicals on agricultural fields in the month or season prior to sample collection. The study reported that in many cases, homes closer to heavy pesticide zones have higher dust levels of certain chemicals. Other factors contributing to pesticide contaminated household dust levels include temperature and rainfall, farmworkers storing work shoes in the home, housing density, cleaning, and having an air conditioner.
Chlorpyrifos (Dursban) is an organophosphate insecticide linked to many adverse effects. Exposure to low levels of the chorpyrifos during pregnancy can impair learning, change brain function and alter thyroid levels of offspring into adulthood for tested mice, especially females. In 2000, EPA and its manufacturer, Dow AgroSciences, reached an agreement to stop the sale of most home, lawn and garden uses for chlorpyrifos because of its health risks to children. Studies have shown that dust levels of chlorpyrifos decreased after the EPA’s ban, but residues still persist and chemicals can drift into homes from agricultural fields and golf courses. Permethrin, a pyrethroid insecticide, is a possible human carcinogen and exposure is linked to possible endocrine disruption, immunotoxicity, neurotoxicity and reproductive effects.
Toxic pesticides, including those already banned, have been shown to persist in homes. One study’s results indicate that most floors in occupied homes in the U.S. have measurable levels of insecticides that serve as sources of exposure to home dwellers. A California study revealed that children exposed to agricultural pesticides applied near their home have up to twice the risk of developing the most common form of childhood leukemia. In these studies chlorpyrifos continues to be one of the most frequently detected chemical in homes. Significant amounts of pyrethroid pesticides, such as permethrin, have also been found in indoor dust of homes and childcare centers. Homes not associated with nearby agricultural fields have also been found to be contaminated with pesticides. Inner-city homes have also documented the occurrence of pesticide residues in indoor dusts and air samples, including a sampling of homes of pregnant women which found that 75% of their homes were contaminated with pesticides.
Source: The Californian