Similar to the chemical warfare agents produced during World War II, organophosphates (OPs) are some of the most common, and most toxic insecticides used today, adversely affecting the human nervous system even at low levels of exposure.
Organophosphates and Neurological Development in Children
Research shows a range of neurodevelopmental problems associated with prenatal and early childhood exposure:
Fruits and vegetables that are commonly eaten by children, including peaches, apples, grapes, green beans, and pears, are among the foods most commonly contaminated with organophosphates. (source: WhatsOnMyFood.org)
Developing youngsters are the most susceptible to OPs. Children can be exposed to OPs through the air, food, dust and soil, and even pets. Children of farmworkers and children in agricultural areas are among the most exposed to OPs, although urban children are also at risk.
Among the most acutely toxic pesticides, most organophosphates are classified by the U.S. Environmental Protection Agency as highly or moderately toxic. They interfere with the nervous system by inhibiting an enzyme called acetylcholinesterase. Under normal conditions, acetylcholinesterase controls nerve impulses--sending chemical signals to halt the nerve impulse at the appropriate time. When organophosphates impede this process, the nervous system becomes severely overstimulated, resulting in immediate neurological dysfunction.
Symptoms of acute exposure include nausea, headaches, twitching, trembling, excessive salivation and tearing, inability to breathe because of paralysis of the diaphragm, convulsions, and at higher doses, death.
Longer term, lower dose exposure to organophosphate pesticides is linked to a number of health problems:
Since the advent of chemical warfare during World War II, organophosphorous compounds have become widely available as pest-control agents. Because of their relatively low cost and ability to be applied on a wide range of target insects and crops, OPs have become the most widely used class of insecticides in the United States. Organophosphates are also among the most common active ingredients in pesticides poisonings.
OPs of primary concern include: azinphos-methyl, chlorpyrifos, diazinon, dichlorvos, dimethoate, ethephon, malathion, methamidophos, naled, and oxydemeton-methyl. Detailed information on specific OP pesticides is available in Pesticide Action Network’s internet database.
Many metabolites (or breakdown products) of organophosphates are more toxic than the primary chemicals themselves--making them acutely lethal to sensitive species like amphibians, says a 2007 USGS study:
Because organophosphates share a common toxicity mechanism, exposure to several OP insecticides and their breakdown products could intensify their toxic effects. Heavy organophosphate use in California is thought to contribute to the decline of several local frog species. The National Marine Fisheries Service concluded that the use OPs threatens endangered salmon species in the Pacific Northwest.
Some organophosphates travel long distances and persist in cold climates. Researchers have detected OPs in Arctic and sub-Arctic environments:
A number of less-toxic alternatives to organophosphate pesticides are currently available and in use around the country and around the world. The University of California produced a special report on the use of OP alternatives in California. These alternatives include:
Research & Factsheets