National Farm Medicine Center Director Matthew Keifer, M.D., M.P.H., recently traveled to the west African nation of Ghana to develop a pilot-testing program to monitor pesticide applicators for overexposure to the anti-malaria chemicals they apply.
The President’s Malaria Initiative (PMI), credited with dramatic reductions in child mortality in sub-Saharan Africa, selected Keifer to advise on how PMI should monitor, what tools to use, how to train the people running the monitoring program, and how to use the information gathered from the program.
Keifer has worked on similar pesticide applicator monitoring programs in Washington state and Nicaragua. Prior to joining the Farm Center in 2010, Keifer was co-director of the Pacific Northwest Agricultural Safety and Health Center, directing numerous community-based research projects focusing on farm worker health and pesticides. For two years before that, he had served as a pesticide epidemiologist in Nicaragua on behalf of CARE international.
“The President’s Malaria Initiative protects millions of people from one of the world’s most deadly diseases,” said Keifer, who traveled to Ghana in late March. “However, the people who do the day-to-day work of controlling the mosquito vectors which transmit malaria also need protection. The chemicals they use can make them sick, but if we monitor them closely, we can keep them healthy and on the job, saving lives.”
The key to the program will be to monitor blood levels of the enzyme cholinesterase in applicators. Cholinesterase is needed for proper functioning of the nervous systems of humans, animals, and insects. Certain chemical classes of pesticides, such as organophosphates and carbamates, work against undesirable insects by interfering with, or “inhibiting,” cholinesterase. While the effects of cholinesterase inhibiting chemicals are intended for insects, these products can also be toxic to humans.
When human cholinesterase levels are low because of excessive inhibition from pesticides, the nervous system can malfunction, producing pesticide poisoning symptoms such as fatigue, lightheadedness, nausea, vomiting, headaches, and seizures. If levels get low enough, subsequent exposure to organophosphate insecticides can result in death.
The purpose of regular monitoring of cholinesterase levels is to alert the exposed person to any change in the level of this essential enzyme before it can cause serious illness. Ideally, a pre-exposure baseline cholinesterase value should be established for any individual before he or she comes in regular contact with organophosphates and carbamates. Fortunately, the inhibition of cholinesterase can be reversed, and cholinesterase levels will return to normal if pesticide exposure is stopped.
Launched in 2005, the President’s Malaria Initiative is an expansion of U.S. Government resources to reduce the burden of malaria and help relieve poverty on the African continent. PMI is an interagency initiative led by the U.S. Agency for International Development and implemented together with the U.S. Centers for Disease Control and Prevention of the U.S. Department of Health and Human Services.
More than 30 million Africans are protected from malaria year as the result of PMI-supported indoor spraying.
Additional information on pesticides is available through the Pesticide Health Effects Medical Education Database (PHEMED), pesticidemededucation.com, built by Keifer and staff at the National Farm Medicine Center and University of Washington. PHEMED is intended to provide educators of health professionals with materials that can be used to bring the health issues surrounding pesticides into their curriculum by providing ready-made materials for use in lectures and class exercises. There are over 900 active ingredients registered for pesticidal use by the Environmental Protection Agency, and these products range from insect and plant hormone emulators to disinfectants. PHEMED focuses on the most common pesticide groups found in the U.S. and those that cause the most human health issues.