The consistent use of common household pesticides can increase a child’s risk of cancer, a new study has found.

According to a study published Monday in the journal Pediatrics, exposure to residential indoor insecticides — but not outdoor insecticides — was strongly associated with an increased risk of childhood cancers.

Researchers say these cancers include leukemia and lymphoma, but they do not include childhood brain tumors.

The study’s lead author Chensheng (Alex) Lu, Ph.D., associate professor of environmental exposure biology at the Harvard T.H. Chan School of Public Health, said while these pesticides are necessary for eliminating household pests, they can be harmful for children.

Childhood Cancers

“Usually pesticides are used in the indoor environment for controlling pest problems, like mosquitos, cockroaches, or bed bugs,” he told Healthline. Lu also noted that pesticides are often used on pets, like cats and docs, for controlling flea problems.

According to the U.S. Environmental Protection Agency (EPA), thousands of children each year are poisoned by common household pesticide products after coming into contact with them and then putting their hands in their mouths.

These products are most often used to kill ants, germs, cockroaches, flies, mice, rats, or termites.

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Examining the Evidence of Increased Risk

Researchers used data from 16 studies that examined possible connections between pesticides and illnesses in children.

The greatest link they found was between childhood exposure to indoor insecticides and the risk of acute leukemia.

The frequency at which these pesticides were used increased a child’s risk for hematopoietic cancers, or those involving cells or tissues in the immune system (or in blood-forming tissues including bone marrow).

The researchers concluded that the cancer risks are related not just to the type of pesticides used but the location of the application.

“Broadcast application, can spraying, or fogger will lead to significant exposures to people who live in the household, schools, etc.,” Lu said. “Some insecticides, such as organophosphates, have been either banned or restricted … due to the known toxicological effects in humans, especially in children.”

A 2010 report found that 28 of the 40 most common pesticides used in schools were probable or possible carcinogens.

The Harvard researchers didn’t find any significant cancer risk for children exposed to pesticides outdoors.

Exposure to herbicides, however, was associated with a slightly higher risk of childhood cancers in general.

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Limiting a Child’s Exposure to Pesticides

Lu says other than in their homes, children could be exposed to pesticides in schools, childcare facilities, parks, or sports fields.

There are things parents can do to limit the multiple areas of potential exposure and the harmful risks associated with them, Lu says.

“Make your homes pest-proof so you do not need to use pesticides at all,” he said. “Talk to schools … about using non-pesticide treatment for pest controls.” 

In California, restrictions are being considered by state legislators on the use of Dow Chemical’s Telone, a gaseous fumigant pesticide that can drift through the air. The pesticide, which is known to cause cancer, is used throughout the state for strawberries, nuts, grapes, carrots, and sweet potatoes.

The California Department of Public Health found the pesticide to be the second-most frequently used pesticide near public schools and that loopholes allow unsafe levels to be used.

“These unscientific and unsafe practices have put California children, especially Latinos, in harm’s way,” Francisco Rodriguez, president of the Pajaro Valley Federation of Teachers, told the Pesticide Action Network.

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