MEXICO — At one time, lead paint seemed like a dream product. Thanks to the magic of chemistry, lead paint went on rich and thick, resisted corrosion, expanded and contracted with the temperature, and fought mold and mildew.

Today, lead paint’s legacy looks more like a peeling, toxic mess.

“It looks like a pretty good product,” Peter Crockett, executive director of the Maine Labor Group on Health, said of lead paint. “But it kills people.”

On Thursday, Crockett traveled to Mexico to teach local contractors how to safely work on houses and other buildings that contain lead paint. The Renovation, Repair and Paint Course lasted eight hours, and showed contractors how to safeguard against lead poisoning at every step of the construction process, from setup to cleanup.

The RRP Course is required for contractors under the Environmental Protection Agency’s Renovation, Repair and Painting Rule, which went into effect in April 2010. According to the law, contractors and landlords must be certified by the EPA if they plan to renovate, repair or paint pre-1978 homes, child care facilities or schools. Lead paint was banned from all household paints in 1978.

Since 2010, Crockett has certified thousands of contractors and landlords across Maine. When he teaches the class, Crockett tries to simplify the complex federal law to small-scale contractors who may have never given a passing thought to the dangers of lead paint.

“For the Pete the Painters out there that have never had any remediation training, or never worried about dust control, there’s a bigger learning curve,” Crockett said. “They’re more nervous or apprehensive.”

Most of the contractors in Crockett’s class run their own businesses and regularly work on houses and other structures built well before 1978. All watched attentively as Crockett demonstrated how to test paint samples for lead, seal doors and windows to prevent the spread of lead dust, and to use high-efficiency particulate air filters on power tools.

Allan Sparks of Rumford said he’s eager to work within the framework of the new law, given the number of old buildings he works on and his concern for the health of his clients.

“It definitely will affect how I work, mainly because the structures in the area are older structures,” Sparks said. “I want to make sure that I’m complying with the rules.”

Although the lead paint law went into effect more than two years ago, many insurance companies and developers are now starting to get serious about requiring subcontractors to get RRP certification, Crockett said.

“It’s not necessarily ‘Here’s your ticket from the federal government,'” Crockett said. “It’s ‘No, I can’t hire you because you’re not certified.'”

Once a contractor becomes certified, he or she will have to follow the letter of the law when they work on any pre-1978 home, school or child care facility with lead paint. In some cases, that will require several extra hours of preparation and cleanup.

Not following the law could have devastating consequences, particularly for children. If exposed to lead at an early age, children may experience learning disabilities, behavioral problems and a reduced IQ. In adults, low-level lead exposure can cause high blood pressure and hypertension. In high doses, lead can lead to hallucinations, coma or death.

Lee Merrill of Peru isn’t willing to take any chances. The sole proprietor of Lee’s Home Improvements, Merrill sees it as his responsibility to protect the health of his clients — even if it means more time spent on the job site.

“If you leave that site and leave something that’s contaminated, you’re going to poison the people that are there,” Merrill said. “It’s not fair to the kids and the people there.”