The safety of metam fumigants has been extensively studied and reviewed for decades by regulators around the world charged with protecting human and environmental health. These regulators provide strict directions on how metam fumigants should be applied to minimize human and environmental exposure. The directives include creating buffer zones (areas around a field where the fumigants will not be applied), requirements for posting notices on fields, fumigant management plans, good agricultural practices, worker protections, stewardship and training programs, and emergency preparedness and response measures. These requirements are reviewed on a regular basis and updated as new data becomes available.
Through the effective management and oversight of metam fumigants, the risk of human exposure is effectively managed.
In 2017 the government of Canada concluded the following on metam fumigants and human health:
“….metam sodium and metam potassium are unlikely to affect human health when used according to label directions.”
Science drives the safe use of metam soil fumigants
The U.S. EPA and other regulators around the world continuously review the latest studies to assess the risk of exposure from metam fumigants. These studies determine how metam fumigants might impact human health. Many of these studies include research using laboratory animals such as rodents and exposing them to varying dosages of the pesticide via skin contact, inhaled air or ingested food. During these studies animals are exposed to very small to highly exaggerated doses. The data collected in this research allows scientists to determine how much exposure an animal can have without any adverse effect. With some extrapolation, this level of exposure in animals informs setting allowable exposures for humans.
Those most at risk of exposure are people who apply the fumigant or enter the field after application before the fumigant is fully absorbed and broken down in the soil. Therefore, the EPA and other regulators provide strict directions on how metam is to be applied to prevent bystanders and other workers from exposure. When these directions are followed, the exposure to metam by anyone on or near a field where the fumigants are being applied is minimal.
Additionally, since metam fumigants are only used on soil before crops are planted or after they are harvested, the crops grown in the field are never in contact with metam. As a result, there is little risk of dietary exposure to metam fumigants.
In 2017 the government of Canada concluded the following on dietary exposure:
“Risk from dietary exposure to metam sodium, metam potassium or MITC is not of concern for all registered uses under the current conditions of use.”
Government regulators ensure that each registered pesticide continues to meet the highest standards for safety to protect human and environmental health. Over the years, these standards have become higher as the ability to evaluate potential effects of pesticides has advanced. Pesticides like metam soil fumigants have been effectively used for more than 40 years as part of pest management strategies by growers around the world.