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Occupational & Environmental Epidemiology

Toluene Diisocyanate (TDI)

TDI, or toluene diisocyanate, is a chemical used to make many household products, including foam for furniture cushions and some sealants. TDI is released into the environment during some manufacturing activities. The chemical sometimes causes asthma and other health problems in workers who are exposed to it, but little is currently known about possible exposures outside the workplace.

TDI and Respiratory Health in North Carolina (2007-2010)

Following investigations and studies of respiratory health complaints around a foam manufacturing plant in Randolph County in 1995-1999, public health experts from the N.C. Division of Public Health and the federal Agency for Toxic Substances and Disease Registry (ATSDR) worked together on a 2007-2010 public health study about the chemical TDI to see if TDI emissions might be causing health problems in other areas as well. The study staff collected information in five North Carolina communities that were near companies that use TDI and in five communities that were located farther away. By comparing the results from both types of communities, public health experts looked for patterns of community exposure and community health, but not the health of specific individuals.

Three hundred seventy-five adult residents participated in the study. About half lived near TDI sources and half lived in other areas. The study did not include children.

The study team tested air samples for TDI, asked volunteers for a sample of their blood, and asked them questions about their respiratory health. The volunteers were compensated for their time and received the results of their individual tests. Their individual results and personal identifiers were and still are kept strictly confidential. The selected communities were in Catawba, Randolph, Guilford and Mecklenburg counties. The study team held meetings in each community where volunteers were needed. Representatives from companies that use TDI were also invited to these information sessions to answer community questions.

An advisory panel consisting of representatives from the medical, public health, and scientific communities; industry; and the general public, was created to advise the study team on local communications issues related to the study and to ensure open dialogue among the stakeholders.

The study activities began in May 2007. The study staff completed the field work in the communities in January 2008. The data was then analyzed and the report was sent for review by expert scientists outside of the state and federal government. Participants were given their personal test results and the overall study results. The researchers also educated the local medical community on how to interpret individual and overall study results for their patients. While the study did not find a clear scientific connection between living near a TDI-releasing plant and having asthma or other breathing problems, some site-specific differences do call for a closer look at such emissions.

The Community Health Study Report is available in English (PDF) and Spanish (PDF).

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