Section 1 - CHEMICAL PRODUCT AND COMPANY IDENTIFICATION

PRODUCT NAME

WIA 2% THORIATED TUNGSTEN ELECTRODE

NFPA

PRODUCT USE

Used in alloyed tungsten electrode for gas/tungsten arc welding using direct current (DC
electrode negative). GTAW- TIG.

SYNONYMS

"thorium tungsten alloy", "thoriated tungsten electrodeWIG electrode", "tig welding
electrode"

Section 2 - HAZARDS IDENTIFICATION

CANADIAN WHMIS SYMBOLS

EMERGENCY OVERVIEW

RISK

May cause CANCER.

POTENTIAL HEALTH EFFECTS

ACUTE HEALTH EFFECTS

SWALLOWED

  Although ingestion is not thought to produce harmful effects, the material may still be damaging to the health of the individual following ingestion, especially where pre-  existing organ (e.g. liver, kidney) damage is evident. Present definitions of harmful or toxic substances are generally based on doses producing mortality (death) rather than those producing morbidity (disease, ill-health). Gastrointestinal tract discomfort may produce nausea and vomiting. In an occupational setting however, ingestion of insignificant quantities is not thought to be cause for concern.  Not normally a hazard due to physical form of product.  

EYE

  There is some evidence to suggest that this material can causeeye irritation and damage in some persons.  The dust may produce eye discomfort causing smarting, pain and redness.  The material may be irritating to the eye, with prolonged contact causing inflammation. Repeated or prolonged exposure to irritants may produce conjunctivitis.  

SKIN

  The material is not thought to produce adverse health effects or skin irritation following contact (as classified using animal models). Nevertheless, good hygiene practice requires that exposure be kept to a minimum and that suitable gloves be used in an occupational setting.  The material may accentuate any pre-existing skin condition.  The material may cause skin irritation after prolonged or repeated exposure and may produce on contact skin redness, swelling, the production of vesicles, scaling and thickening of the skin.  

INHALED

  The material is not thought to produce adverse health effects or irritation of the respiratory tract (as classified using animal models). Nevertheless, good hygiene practice requires that exposure be kept to a minimum and that suitable control measures be used in an occupational setting.  Persons with impaired respiratory function, airway diseases and conditions such as emphysema or chronic bronchitis, may incur further disability if excessive concentrations of particulate are inhaled.  

CHRONIC HEALTH EFFECTS

  There is sufficient evidence to suggest that this materialdirectly causes cancer in humans.  

  Principal route of exposure is inhalation of welding fumes from electrodes and workpiece. Reaction products arising from electrode core and flux appear as welding fume depending on welding conditions, relative volatilities of metal oxides and any coatings on the workpiece. Studies of lung cancer among welders indicate that they may experience a 30-  40% increased risk compared to the general population. Since smoking and exposure to other cancer-causing agents, such as asbestos fibre, may influence these results, it is not clear whether welding, in fact, represents a significant lung cancer risk. Whilst mild steel welding represents little risk, the stainless steel welder, exposed to chromium and nickel fume, may be at risk and it is this factor which may account for the overall increase in lung cancer incidence among welders. Cold isolated electrodes are relatively harmless.  Welding fume with high levels of ferrous materials may lead to particle deposition in the lungs (siderosis) after long exposure. This clears up when exposure stops. Chronic exposure to iron dusts may lead to eye disorders.  With the exception of two Russian studies that found early signs of  pulmonary fibrosis in some workers exposed to tungsten and tungsten  trioxide most studies have found tungsten to be toxicologically inert.  Prolonged retention of thorium compounds in the body leads to long-term alpha- irradiation of the tissues. Symptoms only appear after a considerable length of exposure, and there are effects to the blood-forming, nervous and immune systems. The bones and the lung may be damaged. Thorium may cause cancer of the liver, throat, bronchi and kidney.  Natural radioactivity from the thorium oxide is considered to be well  below occupational exposure standards. Although thoria is released in  welding and exceeds the recommended threshold value of 0.9 alpha  disintegrations/(min)/m3 at a distance of 6 inches from the arc, levels  measured at the breathing zone of the welder were substantially lower than  this.  An exposure route is the low level ionising radiation from the thoria  content. Anticipated dose rate on handling will not exceed 7.5  microSievert per (working hour).  This means that Annual Limits of Intake  by workers will not exceed the NOHSC Standard of 20 milliSievert per year  as a 5 year average  Workers in plants where thorium oxide is produced have not  experienced either chemical or radiation injury.