It could be a father hugging his children after a day's work in the tobacco field, or pesticide residue on his clothing washed with family laundry. Maybe it was children playing in farming fields outside their homes.

A new study suggests all could be factors in high levels of pesticide exposure detected in children of migrant workers in Eastern North Carolina, where an estimated 21,000 people in the heart of the state's agriculture industry work in vast fields of tomatoes, cucumbers and other produce.

Educating workers and pushing for more enforcement of safety laws are central to protecting workers and their children from chemicals, experts say.

"We know that exposure to these pesticides creates all kinds of problems, we just don't know exactly how much," said Thomas A. Arcury, lead researcher for a study conducted by the Wake Forest University School of Medicine and published in the American Journal of Industrial Medicine.

The study analyzed urine samples from 60 children between the ages of 1 and 6 who lived with migrant farm workers in six North Carolina counties in 2004. The study looked for specific metabolites the body produces after being exposed to pesticides.

The study found the metabolite level in the North Carolina children was generally higher than the national averages of slightly older children, the only comparison data available, and the same as or higher than levels found in similar studies in Washington state, California, Texas and Oregon.

Scientists weren't sure whether the levels were high enough to cause harm, the study said.

Researchers concluded the results "are of concern," because exposure to pesticides has been linked to health issues ranging from nausea to cancer, problems in lung and brain development, and even death.

"This information is helpful, but it's only a snapshot at a particular time," said Allan Noe, spokesman for CropLife America, a trade group of pesticide manufacturers. He noted that some of the national comparison data go back to 1999.

But advocates said the study would be helpful in pressuring officials to focus on enforcement of safety rules, said Fawn Pattison, executive director of the Agricultural Resources Center, a nonprofit that supports the use of nontoxic pesticides in North Carolina.

"It certainly informs policy makers, and the officials charged with regulating this industry, about dealing with the health and environmental questions that are exposed by this research," Pattison said.

Programs to educate farmworkers and farmers about pesticide safety have been under way for years, but with the recent surge in immigration, advocates say the need to educate workers has increased. North Carolina saw its illegal immigrant population grow 43 percent to 300,000 from 2000 to 2004, according to the Pew Hispanic Center.

Concern has heightened since three workers for Ag-Mart, which grows tomatoes in Eastern North Carolina, had babies with serious birth defects. A state report released in May said pesticide exposure may have caused the defects.