Several people fell off roofs. Two were caught in a gas explosion. One was a roadside flagger struck by a motor vehicle. Another a worker hit by a falling tree.

The average workers’ comp claim for those and the other 100 most expensive on-the-job injury cases in recent Maine history: just over a half-million dollars.

The Workers’ Compensation Board released a detailed study this week of the most costly cases from 1999 to 2003, a follow-up to a previous five-year study. Executive Director Paul Dionne said it was part of being proactive, highlighting areas that need safety attention and ultimately lowering comp costs.

“We think that this report will give employers and insurance carriers a lot of insight,” he said.

Among the findings:

• Forty-three percent of workers had been on the job less than two years before the catastrophic injury.

• Even though men make up 60 percent of overall paid injury claims, they made up 80 of the 100 most expensive claims.

• The average age of the worker was the same for men and women, 41.

• Costs are rising in a way that can’t be explained by inflation alone. During the first study, from 1994 to 1998, the top 100 cases ranged from insurance payouts of $284,000 to $1 million.

The range this time: $344,000 to $2.9 million.

Researcher Kathleen Schulz, author of the year-long study, said 31 injuries involved the neck or back, 33 the extremities or shoulders. None of the people in the most costly 100 lost their lives at the time of the accident. With death benefits limited, those claims aren’t as expensive as serious injuries where medical bills can run up, Schulz said.

Two died later.

She said the divide in the sexes might be explained, anecdotally, in the occupational split: “Falls from roofs were one of the leading issues. It’s not unusual we’d find more men doing those jobs than women.”

In the average claim – $546,274 – about half that amount went toward medical bills with the other half toward lost wages, legal costs and a settlement. During the last study, about 40 percent went toward medical bills, showing that cost has crept up.

Settlement money has paid for everything from new adaptive homes, new cars, embryonic storage and fertility treatments, according to the report, which was approved by the board on Tuesday.

In one-third of claims, the cases are still open and costs can keep growing.

Steve Minkowsky, the board’s deputy director of benefits administration, said the study raised more than two dozen questions, such as why women’s claims cost less than men’s and why claims were staying open longer. Now, he said, every attempt will be made to find answers.

For a copy of the report, call 287-7067.