"My job is to find out what happened and to make sure it never happens again," Robert Eckert told the House Energy and Commerce subcommittee on the first of two days of hearings.
Lead in the paint of some of the 1.5 million toys Mattel recalled in August was 180 times the amount allowed by law, subcommittee documents showed.
The lead levels were 110,000 parts per million when the legal safety ceiling is 600 parts per million.
Eckert outlined Mattel's three-stage lead-paint safety check that subjects products manufactured for Mattel to lead-paint rules throughout the production cycle.
Several subcommittee members complained Mattel blocked congressional staff members from visiting its China plants and talking with plant executives.
"We are all to blame" for a system that allowed children to be exposed to lead-tainted toys, Consumer Product Safety Commission Thomas Moore testified.
Acting agency Chairman Nancy Nord appealed to Congress to increase the agency's budget and authority.
"Our small agency has been ignored by the Congress and the public for way too long," Nord said.