THURSDAY, June 30 (HealthDay News) -- The number of U.S. workers aged 16 and older with elevated blood lead levels has dropped by more than half over the past two decades -- from 14 per 100,000 in 1994 to 6.3 per 100,000 in 2009, a new study reveals.

"Although the prevalence of high blood lead levels has decreased, the health effects from lead exposure are well characterized," researchers from the U.S. Centers for Disease Control and Prevention noted in an agency news release. They point out that, even though ways to cut on-the-job lead exposures exist, "high blood lead levels persist as almost exclusively an occupational health problem" in the United States today.

The analysis of 2008-2009 data from 40 states also showed that elevated blood lead levels were most common among workers in manufacturing (about 72 percent in 2008 and 72.3 percent in 2009), construction (13.2 percent in 2008 and 14.4 percent in 2009) and mining (6.6 percent in 2008 and just over 5 percent in 2009).

When the CDC researchers looked at industry subsectors, they found that those with the highest numbers of workers with elevated blood lead levels included manufacturing of storage batteries, secondary smelting and refining of nonferrous metals, and painting and paper hanging.

The study also found that the number of states with high rates (more than 20 per 100,000) of elevated lead levels among adult workers decreased from six of 17 states in 1994 to three of 40 states in 2009.

The findings are published in the July 1 issue of the Morbidity and Mortality Weekly Report, published by the CDC.

Lead exposure can cause a number of health problems and about 95 percent of all elevated blood lead levels among adults in the United States are work-related, the researchers noted.

The "findings underscore the need for government agencies, employers, public health professionals, health-care providers, and worker-affiliated organizations to increase interventions to prevent workplace lead exposure, and the importance of conducting lead exposure surveillance to assess the effectiveness of these interventions," the authors wrote in the report.

Interventions outlined by the study authors include: developing and distributing educational materials and conducting outreach programs; investigating worksites; providing technical assistance; providing Occupational Safety and Health Administration referrals for consultation and enforcement; and conducting follow-up interviews with doctors, employers and workers.

More information

The U.S. Occupational Safety and Health Administration has more about lead in the workplace.