Chemicals used in lawn care treatments can enter your body through your skin or eyes or through inhalation, or be transported from your hands to your mouth. Children may ingest treated grass. Pets and wild animals, of course, are also exposed. For most chemicals, there is little evidence about the amount that actually gets into humans as a result of lawn treatments.

The manufacturers of most lawn care chemicals test their products for long-term risks and submit the results to the U.S. Environmental Protection Agency (EPA), which reviews the tests and evaluates the findings. While some chemicals are known to cause allergic reactions in some individuals, evidence indicates that available pesticides and herbicides used in lawn care treatments pose little risk to most individuals as long as they are used according to the directions on their labels.

On the other hand, some pesticides and herbicides have not been evaluated using the most advanced scientific procedures, and it is possible that current procedures cannot detect all possible risks of cancer, mutations, birth defects, reproductive problems, and long-term neurological effects. So you certainly want to make sure that your exposure to chemicals doesn’t exceed what the labels recommend.

You can check on specific pesticides and herbicides with the National Pesticide Information Center (NPIC) to find out what testing data the agency has on possible long- and short-term dangers. The NPIC also provides guidelines for the safe handling and application of control agents—but it will not advise you on what chemicals to use.

It is unclear how great a threat chemical lawn care pesticides pose to the environment. Most of these substances decompose by the time they work their way through lawn turf. Although there may be some runoff from areas with thin grass cover, or driveways and sidewalks where pesticides may be spilled or blown, runoff problems from lawns are usually far less than from agricultural applications. But not enough hard data exist to know the environmental risks from lawn care treatments.

Chemical pesticides are not the only potential environmental contaminant from lawn care treatments. Fertilizers can pollute waterways.

To minimize health risks from all treatment solutions, read the warning labels on the containers; lawn care services will provide copies of labels upon request. Stay off the lawn for at least several hours after it has been treated, until the chemical is dry; some experts recommend 72 hours or more. Make sure your lawn care service posts signs warning that your lawn has been sprayed. But remember that young children and pets can’t read signs.

If a member of your household or a neighbor has a pesticide allergy, insist that your lawn care company not apply pesticides, or notify the neighbor before making treatments. Maryland operates a pesticide allergy registry (phone: 410-841-5710) where pesticide-sensitive individuals can arrange to be listed; pesticide applicators must notify a registered individual before making an application on any property adjacent to the property of the registered person.