NORA Manufacturing Sector Strategic Goals
9270049 - Titanium Dioxide Quantitative Risk Assessment
Principal Investigator (PI)
Primary Goal Addressed
Secondary Goal Addressed
Attributed to Manufacturing
In response to a request from industry groups, NIOSH is reconsidering whether titanium dioxide (TiO2 ) has the potential to cause cancer in occupational settings. In conjunction with this effort, NIOSH is developing a Current Intelligence Bulletin to describe worker exposures to TiO2, consider the available health effects data, and conduct a quantitative risk assessment using dose-response data in rats. It is anticipated that NIOSH health recommendations will be developed as a result of this effort. One major issue under consideration is the apparent disparity of toxicity of fine versus ultrafine or nanoparticles. The insights from this project are expected to inform other NIOSH research efforts on particulates and nanotechnology.
In response to a request from industry groups, NIOSH is reconsidering whether TiO2 has the potential to cause cancer in occupational settings. In conjunction with this effort, NIOSH is developing a Current Intelligence Bulletin to describe worker exposures to TiO2, consider the available health effects data, and conduct a quantitative risk assessment using dose-response data in rats.
The evidence from a number of studies suggests that the toxicity and carcinogenicity of poorly soluble low toxicity (PSLT) particles, including TiO2, are not substance-specific effects, but are related to the particle surface area dose. In rats chronically exposed to pigment-grade (fine) TiO2, increased lung tumors were observed only at a dose much higher than current exposure limits for TiO2 and other PSLT particles; however, in rats exposed to ultrafine TiO2, lung cancer was elevated at occupationally relevant doses. Epidemiologic studies of titanium dioxide workers have not shown any elevation in lung cancer. In this project, a Current Intelligence Bulletin (CIB) is being developed to summarize the state of knowledge of the health effects of TiO2. The CIB will include the following sections: review and evaluation of the toxicity and epidemiologic studies; review and evaluation of worker exposure data; quantitative risk assessment based on rat in vivo and in vitro dose-response data; and health recommendations.
Although the CIB will focus on TiO2, a number of issues have implications for other aerosols, including the concept of particle surface area dose in health hazard and risk assessments.
The draft CIB, NIOSH internal review process, and review by the NIOSH Office of the Director (OD) were completed in FYs 04 and 05. In FY07 we received comments from external reviewers, and work is ongoing to respond to these comments and prepare the CIB for final NIOSH OD review and publication. This work will complement and inform other institute projects such as ongoing nanoparticle research efforts.
The primary objective of this project is to develop health recommendations for TiO2 and disseminate that information in the form of a NIOSH Current Intelligence Bulletin, which will summarize health effects studies in humans and animals and provide a quantitative risk assessment of TiO2.
This project fulfills one of NIOSH's primary missions – the development of recommendations and then dissemination of this information on occupational hazards. A Current Intelligence Bulletin (CIB) will be developed to summarize the state of the science on adverse health effects and risks to employers and workers who use titanium dioxide (TiO2). The insights gained from this project will aid in our understanding of the occupational health impacts of the entire class of poorly-soluble low toxicity particles.This project contributes to the following sectors:
Strategic Goal 5: Reduce the number of respiratory conditions and diseases due to exposures in the manufacturing sector; and
Strategic Goal 6: Reduce the prevalence of cancer due to exposures in the manufacturing sector.
This project also contributes to the Cross-Sector Programs:
Authoritative Recommendations Program (50%)
Goal 1. Reduce and prevent occupational injuries, illnesses and fatalities by supporting NORA sector and cross-sector programs – specifically, this project will contribute to this goal by providing quantitative risk assessment supporting development of NIOSH authoritative recommendations documents.
Cancer, Reproductive and Cardiovascular Diseases (100%)
Goal 1. Reduce the incidence of work-related cancer.
1.1 Conduct research to reduce work-related cancer.
1.1.1. Conduct analytic epidemiology studies of high-priority, high-feasibility populations and exposures.
1.1.5. Develop methods for quantitative cancer risk asessments, in support of authoritative recommendations for limiting occupational exposures.
This project also contributes to the Coordinated Emphasis Area:
Nanomaterials (50%) Strategic Goals 1 and 2.
Specifically, this project supports
IG2 Toxicity and internal dose
IG2.2 Predictive models for toxicity
IG4 Risk assessment