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Titanium Dioxide

10/07/2010

Question:

What effect does titanium dioxide have on the body when ingested from welding metals? What health related issues can it cause? Is it dangerous for you to inhale on a daily basis?

Answer:

There have been animal studies and limited human studies linking ultrafine titanium dioxide with lung cancer, but the evidence is weak. Listed below are two documents that contain relevant information about your question:

Evaluation of Health Hazard and Recommendations for Occupational Exposure to Titanium Dioxide

"NIOSH currently has no recommended exposure limit (REL) for TiO2 and classifies it as a potential occupational carcinogen [emphasis mine]. This recommendation was based on the observation of lung tumors (nonmalignant) in a chronic inhalation study in rats at 250 mg/m3 of fine TiO2 [Lee et al. 1985, 1986a] (Chapter 3)."

The NIOSH report goes on to state, "The National Institute for Occupational Safety and Health (NIOSH) has reviewed the relevant animal and human data for assessing the carcinogenicity of TiO2 and has reached the following conclusions.

"First, the tumorigenic effects of TiO2 exposure in rats appear not to be chemical specific or a direct action of the chemical substance itself. Rather, these effects appear to be a function of particle size and surface area acting through a secondary genotoxic mechanism associated with persistent inflammation.

"Second, current evidence indicates that occupational exposures to low concentrations of TiO2 produce a negligible risk of lung cancer in workers. On the basis of these findings, NIOSH has determined that insufficient evidence exists to designate TiO2 as a 'potential occupational carcinogen' at this time. NIOSH will reconsider this determination if further relevant evidence is obtained. However, evidence of tumorigenicity in rats at high exposure concentrations warrants the use of prudent health-protective measures for workers until we have a more complete understanding of the possible health risks.

"Therefore, NIOSH recommends exposure limits for fine and ultrafine TiO2 to minimize any risks that might be associated with the development of pulmonary inflammation and cancer."

I would say the broader issue is the health effects of welding in general, since the fumes you are exposed to are complex and likely not 100% TiO2.

The abstract for the article, Pulmonary effects of welding fumes: Review of worker and experimental animal studies is a review of existing human (occupational settings) and animal studies which finds the following:

"Pulmonary effects observed in full-time welders have included metal fume fever, airway irritation, lung function changes, susceptibility to pulmonary infection, and a possible increase in the incidence of lung cancer. Although limited in most cases, animal studies have tended to support the findings from epidemiologic studies."

The authors still conclude that not much is known about mechanisms, or how welding may cause disease. I would recommend that you do all you can to minimize your exposure to welding fumes (ensure adequate ventilation). Are there exhaust hoods present where you work? Would management be willing to work with an industrial hygienist and/or an industrial engineer to modify the workstations to minimize your exposures?

Lastly, you could wear respiratory protection. You have already had some exposure, so the key to minimizing your health risks from those exposures is to stop smoking if you're a current smoker, and don't start if you're not. If your company offers them, get a baseline lung function test and have that repeated yearly. If you are very concerned, it may be worth the expense to visit an occupational health physician to get some of these tests and discuss your concerns.

 

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Response by:

J Mac Crawford, PhD, RN J Mac Crawford, PhD, RN
Clinical Associate Professor of Environmental Health Sciences
College of Public Health
The Ohio State University