WASHINGTON -- Thirteen U.S. workers were killed on the job each day and roughly 50,000 died from work-related diseases in 2010, a worrisome increase in the long downward trend in fatalities, according to a report issued by the AFL-CIO on Wednesday.

The AFL-CIO, the largest U.S. federation of labor unions, said in its analysis that while the number of workplace deaths has been trending lower for four decades, workers continue to get injured, killed or sick on the job due to weak safety enforcement, soft penalties for offending companies and regulatory inaction by government.

According to the report, 4,690 workers were killed while working in 2010, a 3.1 percent increase from 2009. Bill Kojola, an industrial hygienist with the AFL-CIO's safety and health department, told HuffPost that while the long-term numbers are encouraging, he was alarmed to see the overall number of deaths climb in 2010 when Americans are still underemployed.

Read more: AFL-CIO More Workers Killed On Job While Regulations Languish