COLUMBIA, S.C. (AP) Bug spray that produces a fog to kill insects is likely to blame for the death of a 10-month-old South Carolina boy, and his 2-year-old brother was critically injured by the fumes, authorities said Monday.

Anderson County Deputy Coroner Don McCown said the boys' mother had been using foggers in their single-wide mobile home in Williamston, in the northwest part of the state, because of an insect problem. Elizabeth Whitfield, 25, called 911 on Sunday afternoon to report her youngest son was having trouble breathing.

Paramedics took all three to a hospital, and Jacob Whitfield was pronounced dead. His brother, Kenneth, was flown to another hospital about 20 minutes north to Greenville, where he remained Monday on a respirator, but was starting to stabilize, McCown said.

Elizabeth Whitfield was coated in chemicals when she first arrived to the hospital and had to remove her clothes and take a shower. She was released Sunday, but was re-admitted to the ER on Monday with breathing problems, McCown said.

Investigators found seven fogger containers. She told authorities she set off three when she began renting a month ago, then continued using them when the insects wouldn't die.

``Most people put these foggers in they do it one time a month or every couple of months. She was using two to three a week,'' McCown said. ``She said she followed the directions, but you have to wonder. We can't attribute it to anything else.''

A single fogger is typically used to treat 6,000 cubic feet and can leave an oily residue on furniture and floors. Directions call for residents to cover all furniture, vacate the home for four hours, then open windows and doors for an hour before returning, he said.

While the pesticides appear to be the cause of death, confirmation through toxicology reports could take eight weeks. Other air quality tests turned up nothing. The baby was otherwise healthy with no signs of abuse or neglect, McCown said.

He said the home was located in a rural area and ``pretty infested with insects, roaches. It was her goal to get rid of all of them.''

``The stuff didn't seem to have too much effect on the bugs,'' he said. ``They're still running everywhere.''

The scent at the home was so strong authorities called in a hazardous materials team before entering. One deputy complained of headaches, McCown said.

Investigators initially focused on a grease fire, but tests showed that didn't play any role in the illnesses, McCown said.

``Right now, we're just concerned about them. We're hoping the 2-year-old can make a recovery and hope the mom will be OK,'' said Sheriff's Sgt. Steve Reeves.

(Copyright 2009 by The Associated Press. All Rights Reserved.)