They found high levels of common household pesticides in the urine of children with ALL, a cancer that develops most commonly between three and seven years of age.
"In our study, we compared urine samples from children with ALL and their mothers with healthy children and their moms. We found elevated levels of common household pesticides more often in the mother-child pairs affected by cancer," said lead investigator, Dr Offie Soldin, an epidemiologist at Lombardi.
However she cautions, "We shouldn't assume that pesticides caused these cancers, but our findings certainly support the need for more robust research in this area."
During the study, the researchers analysed 41 pairs of children with ALL and their mothers and 41 pairs of healthy children.
The urine samples were collected from all child-mother pairs and analysed by the Centres for Disease Control and Prevention to look for evidence of organophosphates (OP), the chemical name of some household pesticides.
The body breaks down OP into metabolites.
The researchers said pesticides were detected in the urine of more than half of the participants, but levels of two common OP metobolites, diethylthiophosphate (DETP) and diethyldithiophosphate (DEDTP), were higher in the children with ALL.
"We know pesticides - sprays, strips, or 'bombs,' are found in at least 85 percent of households, but obviously not all the children in these homes develop cancer," said Soldin.
"What this study suggests is an association between pesticide exposure and the development of childhood ALL, but this isn't a cause-and-effect finding.
"Future research would help us understand the exact role of pesticides in the development of cancer," she added.
The findings are published in the journal Therapeutic Drug Monitoring.