The public's health is not a priority of current leadership at the U.S. Environmental Protection Agency (EPA).
Consider the case of the insecticide chlorpyrifos (CPF).
Dr. Clif CleavelandCPF is an organophosphate (OP), a group of chemicals initially developed as insecticides before World War II. Noting that OPs were potent nerve toxins, military scientists modified the chemicals for use in warfare. Germany accumulated large stores during the war but did not deploy them. Recent chemical attacks in Syria have been linked to OPs.
OPs act at the intersection of nerve fibers with muscle. Normally, a chemical transmitter is released at the nerve ending and is quickly inactivated by an enzyme. OPs block the enzyme, which leads to prolonged stimulation of muscle fibers by the chemical transmitter. Acute poisoning results in seizures, paralysis and excessive respiratory secretions that may block breathing. OPs are rapidly absorbed through skin, lungs and digestive tract.
OPs are widely used to combat insects and worms in agriculture. Many countries do not regulate use of these pesticides. Agricultural workers and people living close to areas where OPs are applied to crops are at risk of acute poisoning, which kills tens of thousands of people yearly in Third World countries. Acute poisoning of children has resulted from ingesting food that is heavily contaminated with OPs.
In addition to acute toxicity, low-dose exposure to OPs interferes with brain development of fetuses and young children. During this interval, complex changes occur in the brain that will define cognitive and behavioral functions throughout life. OPs are toxic both to nerve cells and surrounding glial cells, which provide structural and nutritional support.
Since its initial marketing in 1965, CPF has become one of the most widely used insecticides in the world. Five U.S. companies produce CPF under a variety of trade names. CPF is applied to croplands by hand-held or large, mechanized sprayers or by aerial spray. CPF is widely used on golf courses.
Concerns about CPF toxicity for infants and children led in 2000 to a ban on most uses within residences.
Studies by Virginia A. Rauh and colleagues at Columbia University's Center for Children's Environmental Health have documented the effects of prenatal exposure to CPF on later brain development. CPF levels were measured in cord blood at birth. MRI scans conducted at ages 6 to 11 years on inner-city children with the higher levels of in-utero exposure showed structural changes in those regions of the brain that regulate cognition and behavior.
The possible toxic effect of chronic, low-concentration exposure to CPF on adult brain function is unsettled. Data from animal studies support toxicity. Parkinson's disease has been linked to sustained, occupational exposure to OP pesticides.
People, especially children, living in agricultural regions of the country along with farm workers who harvest crops sprayed with CPF are particularly vulnerable to toxic exposures to the pesticide.
Further restrictions on CPF use in 2012 limited application to apple trees, established no-spray buffer zones around crops and decreased application rates by aerial application. EPA closely monitored fruits, vegetables and grains for residual amounts of CPF. In 2016 EPA proposed revoking all allowances for CPF residues in food. This would end most agricultural use of CPF. The proposal was scrapped in March 2017.
President Nixon established the EPA in 1970 to clarify often conflicting environmental regulations. EPA assumed responsibility for enforcing the Clean Air Act of 1970, the Pesticide Control Act of 1972 and the Clean Water Act, also of 1972. Other duties were assigned subsequently. A core responsibility of the agency has been protection of human health.
In April 2017, EPA Administrator Scott Pruitt stated a "back-to-basics agenda" that emphasized "the three E's" of environmental protection, economic growth through sensible regulation and engagement with state and local partners. Safeguarding health is no longer mentioned as a priority.
My advice is for pregnant women and young children to consume organic fruits and vegetables, if available and affordable, and to avoid agricultural products from countries where CPF is unregulated. Nonorganic produce should be thoroughly washed to remove any CPF residues. The rest of us should pressure EPA through our congressional representatives to reinstate protection of the public's health as a major responsibility of the agency.
Contact Clif Cleaveland at ccleaveland@epbfi.com.