Appendix K - Tungsten Information - STATES

More documents

Recommendations

Info

-- -- Entry to and Elimination from the Body Tungsten that enters the body associated with food and drinking water is rapidly taken up into the blood and transported into all parts of the body. It is then eliminated from the body through the urine. Much of the tungsten that did not go into the blood stream from the inhalation or ingestion pathways leaves the body through the feces. A small amount of the tungsten that enters the blood may go into the bones, hair and fingernails and stay there for a while. Some of this tungsten slowly leaves the body through the urine and feces. Tungsten in the blood of a pregnant mother can enter the blood of the fetus in the womb. Tungsten may also enter the milk which could be a route of exposure for breastfeeding infants. Health Effects of Tungsten and Its Compounds The toxicity of tungsten, like any toxin, depends on the route of administration, the chemical form of the metal, the dose, the solubility of tungsten compounds and the duration of exposure. The more soluble tungsten compounds (e.g., sodium tungstate) appear to be more toxic than the insoluble ones (e.g., tungsten carbide and tungsten oxides). Tungsten has no known beneficial effects on human health. Work in occupations with exposures to "hard" metals, which include but are not limited to tungsten, has been associated with a variety of adverse effects. Workers in the hard metal industry where tungsten alloys containing other metals such as such as cobalt breathed air containing tUnf!stenand other substances had elevated levels of pulmonary fibrosis (scaring oflung tissues), and other respiratory effects including asthma, inflammation of tissues of the nose, and lung cancer. Memory loss and impaired vision and hearing have been associated with work in metal industries using tungsten and other metals. It is generally believed that health effects observed in hard metal workers are the result of exposure to cobalt and not tungsten. However, studies conducted in animals that were exposed to tungsten by inhalation or orally also suggest that tungsten metal could be toxic to the respiratory and nervous systems. There are some animal data that suggest that tungsten could cause adverse developmental and reproductive effects. An intermediate duration study in animals indicated that tungsten is toxic to the kidneys. At high concentrations tungsten compounds may cause eye and skin irritation and contact dermatitis. The cancer causing potential of tungsten and its toxicity to the genetic material (genotoxicity) has not been extensively assessed. Sodium tungstate was found to be genotoxic in some test systems and nongenotoxic in some other test systems. In a single study, orally administered sodium tungstate was found not to be carcinogenic in rats. In other studies, soluble tungsten enhanced the carcinogenic potential of other known carcinogens. Tungsten alloy containing nickel and cobalt implanted in the muscle of rats produced cancers at the site of implantation. The cancerous cells metastasized to the lungs. Nickel implanted in rats also produced the same kind of muscle tumor, however, there were no metastases to the lungs. Recent information from Nevada has drawn attention to tungsten's potential toxicity. Data have shown elevated tungsten body burdens in residents of Fallon, NV (http://www.cdc.gov/nceh/clusters/Fallon), increased tungsten content in tree core samples in Sierra Vista, AZ and a childhood leukemia cluster in both communities (and also a nearby military base). Exposures to tungsten have not been conclusively linked to the cancers at either location. This information and the overall limited database on tungsten's toxicity have led the Centers for Disease Control and Prevention's National Center for Environmental Health (NCEH) to recommend tungsten and tungsten compounds for toxicology and carcinogenesis studies (http://ntp.niehs.nih.gov/ntplhtdocs/Chem_Background/ExSumPdf/tungsten.pdf.).Animal studies are now a priority for toxicology testing under the National Toxicology Program. OFFICE OF RESEARCH AND STANDARDS 2
Health Effects of Tungsten and Its Compounds to Children Although all health effects of tungsten observed in adults are of potential concern in children, children sometimes differ from adults in their susceptibility to hazardous chemicals. It is not known whether there is a difference in sensitivity to tungsten between adults and children. Although most of the exposure pathways for children are the same as those for adults, children may be at a higher risk of exposure than adults because of differences in body size, respiration rate, food intake, and increased hand to mouth activity. Tungsten exposure to the mother is also of potential concern to the fetus, as animal studies have shown transfer of tungsten from the mother to the fetus, and possible developmental effects in the fetus. Studies in dairy cows have indicated that tungsten may enter breast milk. Measures to Reduce Risks from Exposure to Tungsten If you live in an area with a high level of tungsten in the water or soil, substituting cleaner sources of water and limiting contact with soil (for example, through use of a dense groundcover or thick lawn) would reduce family exposure to tungsten. By paying careful attention to dust and dirt control in the home (air filters, ftequent cleaning), you can reduce family exposure to contaminated dirt. Some children eat a lot of dirt. You should prevent your children from eating dirt. You should discourage your children ftom putting objects (including their hands) in their mouths. Make sure they wash their hands frequently, especially before eating. It is sometimes possible to carry tungsten ftom work on your clothing, skin, hair, tools, or other objects removed from the workplace, (especially if you work in hard metal or tungsten smelting industries). Reduce exposure of family members by showering and changing clothes before you leave work, and storing your street clothes in separate area of the work place, or laundering your work clothes at home separately ftom other clothes. Medical Evaluation to Determine Exposure to Tungsten You should consult your doctor if you are concerned about your exposure to tungsten. There are laboratories that can measure the amount of total tungsten in the blood, urine, saliva, and feces to determine if exposure to tungsten has occurred. These tests can tell if you have been recently exposed to tungsten. Long-term exposure to tungsten can be measured in hair and nails. Regulatory Measures to Protect Human Health There are few guidelines for tungsten and tungsten compounds set by U.S. federal agencies. In the international community, the old Soviet Union established a 50 ppb (micrograms per liter, ~g/L) drinking water limit. For occupational exposure situations in the US, the National Institute of Occupational Safety and Health (NIOSH) has established a recommended air exposure limit (REL) for tungsten and insoluble tungsten compounds for workers (I O-hour time weighted average concentration) of 5 mg/m3 and a short-term exposure limit (STEL; IS-minute time weighted average) of 10 mg/m3. The Occupational Safety and Health Administration (OSHA) has established permissible occupational air exposure limits (PELs; 8-hour time weighted average) for tungsten of 5 mg/m3(insoluble compounds) and I mg/m3 (soluble compounds) for construction and shipyard industries. OFFICE OF RESEARCH AND STANDARDS 3
Page 1 and 2: NOIJ..VWHO.!lNI N:ilJ..S~Ni1J.. :)1
Page 3 and 4: ERDC/CRREL TR-07-XX March 2007 Fate
Page 5 and 6: iii ERDC/CRREL TR-07 -xx TABLE OF C
Page 7 and 8: v ERDC/CRREL TR-07 -xx Edwards. 16
Page 9 and 10: ATSDR AGENCY FOR TOXIC SUBSTANCES A
Page 11: --.....-- COMMONWEALTH OF MASSACHUS

Appendix K - Tungsten Information - STATES

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?