To examine the effects of solvent exposure on hearing function, through an audiological test battery, in a population not occupationally exposed to high levels of noise. 

One hundred ten workers from a coating factory were studied. Jobs at the factory were divided into three different levels of solvent exposure. Hearing status was assessed with a test battery including pure-tone hearing thresholds (0.5-8 kHz), high-frequency hearing thresholds (12 and 16 kHz), and dichotic listening measured through dichotic digits test. Multiple linear regression models were created to explore possible association between solvent exposure and each of the hearing outcomes. 

Significant associations between solvent exposure and the three hearing outcomes were found. Covariates such as age, gender, race, and ethnicity were also significantly associated with the studied hearing outcomes. 

Occupational exposure to solvents may induce both peripheral and central auditory dysfunction. The dichotic digits test seems as a sensible tool to detect central auditory dysfunction associated with solvent exposure. Hearing loss prevention programs may use this tool to monitor hearing in solvent-exposed workers. 

Reference:   Fuente A, Slade MD, Taylor T, Morata TC, Keith RW, Sparer J, Rabinowitz PM., Peripheral and Central Auditory Dysfunction Induced by Occupational Exposure to Organic Solvents, J Occup Environ Med. 2009 Sep 25 

From the Escuela de Fonoaudiologia [School of Speech and Hearing Sciences] (Dr Fuente), Medical Faculty, Universidad de Chile, Santiago, Chile; Occupational and Environmental Medicine Program (Mr Slade, Dr Taylor, Ms Sparer, and Dr Rabinowitz), Yale University School of Medicine, New Haven, Conn; Division of Applied Research and Technology (Dr Morata), National Institute for Occupational Safety and Health; and Division of Audiology (Dr Keith), University of Cincinnati, Cincinnati, Ohio.

Growing evidence shows that exposure to lead in the environment is associated with cardiovascular disease, including increased risk of hypertension. However, those studies have looked at lead concentrations in blood, not bone lead, a better indicator of cumulative lead exposure over time. In a new study, researchers at the Harvard School of Public Health (HSPH) and the University of Michigan School of Public Health found that bone lead was associated with a higher risk of death from all causes, particularly from cardiovascular disease. It is the first study to analyze the association between bone lead and mortality.

The study appears online on September 8, 2009, on the website of the journal Circulation and will appear in a later print edition. 

“The findings with bone lead are dramatic. It is the first time we have had a biomarker of cumulative exposure to lead and the strong findings suggest that, even in an era when current exposures are low, past exposures to lead represent an important predictor of cardiovascular death, with important public health implications worldwide,” said Marc Weisskopf, assistant professor of environmental and occupational epidemiology at HSPH and lead author of the study.

Air pollution was the main source of lead in the environment in recent years, though it has been decreasing since leaded gasoline was banned in the U.S. in the mid-1990s. Most of the lead circulating in the body is deposited in bone and remains there for years, unlike blood lead, which has a half life of about 30 days. Since adverse effects from lead on the cardiovascular system would be expected to show up over time, the researchers expected that bone lead would be a better marker of chronic toxicity.

The researchers, led by Weisskopf and senior author Howard Hu, professor of environmental health, epidemiology and internal medicine at the University of Michigan School of Public Health, analyzed data from 868 participants in the Department of Veterans Affairs Normative Aging Study, a study of aging in men that began in 1963. Blood lead and bone lead—analyzed using X-ray fluorescence—were measured for each of the participants. The results showed that the risk of death from cardiovascular disease was almost six times higher in men with the highest levels of bone lead compared to men with the lowest levels. The risk of death from all causes was 2.5 times higher in men with the highest levels of lead compared to those with the lowest levels. The results appeared independent of age, smoking, education, race, alcohol, physical activity, BMI, high density lipoprotein or total cholesterol levels, hypertension or diabetes.

There are a number of mechanisms, such as increased oxidative stress, by which lead exposure may result in cardiovascular mortality, say the authors. They also note that, in addition to high blood pressure, exposure to lead has been associated with widened pulse-pressure (an indicator of arterial stiffening) and heart disease.

Given that bone lead may be a better biomarker of cumulative lead exposure than blood lead, it may be the best predictor of chronic disease from exposure to lead in the environment. “In addition to spurring further public health measures to reduce exposure to lead and to begin monitoring for cumulative exposure, mechanistic and clinical research is needed to determine if opportunities exist to conduct targeted screening and treatment that can further reduce the burden of cardiovascular disease for the millions of adults who have had years of elevated lead exposure in the past,” said Hu.

Reference:    Harvard School of Public Health, Lead in bone associated with increased risk of death from cardiovascular disease in men, Boston, MA, September 9, 2009

EPA to Move Aggressively on Cleanup and HHS to Assist Area Residents with Medical Care  

WASHINGTON – U.S. Environmental Protection Agency Administrator Lisa P. Jackson today announced the agency has determined that a public health emergency exists at the Libby asbestos site in northwest Montana.  Over the past years, hundreds of asbestos-related disease cases have been documented in this small community, which covers the towns of Libby and Troy. The announcement was made today at a joint press conference with Department of Health and Human Services Secretary Kathleen Sebelius and U.S. Sens. Max Baucus and Jon Tester.  

This is the first time EPA has made a determination under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) that conditions at a site constitute a public health emergency.  This determination recognizes the serious impact to the public health from the contamination at Libby and underscores the need for further action and health care for area residents who have been or may be exposed to asbestos. Investigations performed by the Agency for Toxic Substance and Disease Registry have found the incidence of occurrence of asbestosis, a lung condition, in the Libby area staggeringly higher than the national average for the period from 1979-1998. EPA is working closely with the Department of Health and Human Services, which is making available a short-term grant to provide needed asbestos-related medical care to Libby and Troy residents.  

During her Senate confirmation hearing, Administrator Jackson committed to review the situation at the Libby asbestos site based on current site information, sound science and EPA’s legal authorities. As a result of her review, the Administrator has decided that conditions at the site present a significant threat to public health and that making a public health emergency determination is appropriate.  

“This is a tragic public health situation that has not received the recognition it deserves by the federal government for far too long. We’re making a long-delayed commitment to the people of Libby and Troy. Based on a rigorous re-evaluation of the situation on the ground, we will continue to move aggressively on the cleanup efforts and protect the health of the people,” said EPA Administrator Lisa P. Jackson. “We’re here to help create a long and prosperous future for this town.” She added, “Senator Max Baucus has been a tireless advocate for the people living in Libby and Troy who have confronted this public health tragedy for generations and we commend him for his work. We look forward to working with him and Senator Tester who has been working diligently since being elected to the Senate to bring much needed support to these communities.”  

“Senator Baucus and Senator Tester have powerfully brought the voices of the people of Libby and Troy to Washington so the nation could hear and understand what happened. They refused to give up on finding the best ways to help those who have suffered so much. Today’s announcement reflects our Administration’s concern for the residents of Lincoln County and our intention to act decisively to protect and improve their health and quality of life,’ said Secretary Sebelius. “The Department of Health and Human Services has been working closely with the EPA and the residents of Lincoln County for a number of years to conduct screenings and help provide access to care. Now, we have come together with Senator Baucus and Senator Tester, Administrator Jackson, and agencies across HHS, to offer a new grant to provide short-term medical assistance for screening, diagnostic and treatment services in a comprehensive and coordinated manner in partnership with local officials on the ground in Lincoln County. “  

Sen. Max Baucus, a long-time advocate on this issue, consistently sought out a determination of a public health emergency in this region.  

“This is a great day for Libby. This is a town that was poisoned by W.R. Grace, then had to wait year after year as the last administration failed to determine that public health emergency exists. But today is a new day,” said Sen. Baucus. “Today is the day that Administrator Jackson did the right thing and made this vital determination. Today is the day that Secretary Sebelius declared that people in Libby will get the health care they need. Today is the day that after years of work we were able to succeed in getting this done. Yet, we won’t stop here. We will continue to push until Libby has a clean bill of health.”  

“This is a long-overdue, common-sense decision that will go a long way for Libby and the thousands of folks who were poisoned there,” Sen. Tester said. “This decision will help make quality health care more accessible and it will open the door to get new resources on the ground.  We still have a long way to do right by the folks in Libby.  Working together with the Department of Health and Human Services and the Environmental Protection Agency, we’re making very good progress.”   

Secretary Sebelius tasked two HHS agencies – the Health Resources and Services Administration and the Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry – to help county residents. These two agencies will support a new grant to assist affected residents who need medical care. Local officials are currently putting together a grant proposal that will lay out options for provision of medical care that will work for the residents of Lincoln County. HHS anticipates that this grant can be awarded in August 2009.  

The Libby asbestos site has been on the EPA’s Superfund National Priorities List since 2002, and cleanup has taken place since 2000.  EPA has made progress in helping to remove the threat of asbestos in the land and air, and with it, the increased risks of lung cancer, asbestosis, and other respiratory problems. While EPA’s cleanup efforts have greatly reduced exposure, actual and potential releases of amphibole asbestos remain a significant threat to public health in that area.  

The Libby asbestos site includes portions of the towns of Libby and Troy and an inactive vermiculite mine seven miles northeast of the town. Gold miners discovered vermiculite in Libby in 1881; in the 1920s the Zonolite Company formed and began mining the vermiculite.  In 1963, W.R. Grace bought the Zonolite mining operations. The mine closed in 1990. It is estimated that the Libby mine was the source of over 70 percent of all vermiculite sold in the United States from 1919 to 1990.  

More information: http://www.epa.gov/libby 

EPA, EPA Announces Public Health Emergency in Libby, Montana,  June 17, 2009