Thorium

SECTION 2: Hazards identification

Flammability Toxicity Mt Body Contact @ Flammability Reactivity Chronic 1 2 3 Fire Diamond Min Low Moderate High Extreme ANSI Signal Word Danger! Explosive Flammable Radioactive wowewveve Emergency Overview * % % ¥ Silvery-white, lustrous, ductile metal. Irritating to skin/respiratory tract. Chronic Effects: radiation disease, fatigue, nausea, teeth/hair loss, damage to blood-forming tissues, blood effects, bleeding. Explosive. Flammable. Reacts with water. Radioactive.

Potential health effects

Target Organs: blood, bone, lungs, lymphatic system, nervous system

Principle Routes of Exposure

inhalation, ingestion, skin contact Acute Effects Inhalation: Particulate/dust is regarded as moderately harmful and the material presents a hazard from repeated exposures over long periods. alpha-Radiation is a densely ionizing source of radiation which kills cells immediately adjacent to the source of contact. Damage may be irreversible. Absorption into the body generally relates to the degree of water solubility - soluble compounds being more likely to enter the bloodstream. Lighter particles may be lodged deep in the alveolar air sacs and remain. Heavier particles may be brought to the throat by ciliary action and subsequently swallowed. Damage depends on the speed of elimination and the susceptibility of the tissue, in which the source is stored, to radioactive damage. Single large doses of radiation may produce radiation sickness. Whole body radiation doses of 2-10 Gray may cause anorexia, apathy, nausea and vomiting which may become maximal within 6-12 hours. An asymptomatic period of 24-36 hours may be followed by blood dyscrasias, (lymphopenia and a slowly developing neutropenia, with thrombocytopenia becoming prominent within 3-4 weeks). Bone marrow depression may reach critical levels with death occurring following overwhelming infection. Copyright © 2006 by Genium Group, Inc. Any commercial use or reproduction without the publisher’s permission is prohibited. Judgments as to the suitability of information herein for the purchaser’ s purposes are necessarily the purchaser’s responsibility. Although reasonable care has been taken in the preparation of such information, Genium Group, Inc. extends no warranties, makes no representations, and assumes no responsibility as to the accuracy or suitability of such information for application to the purchaser’s intended purpose or for consequences of its use. Whole body doses of 4 Gray may produce damage to the intestinal epithelium leading to intractable nausea, vomiting and diarrhoea. Severe dehydration, vascular collapse and death may follow. Regeneration of intestinal epithelium may occur but may be followed by failure of the blood-making (hematopoietic) system within 2-3 weeks. Whole body doses of 6 Gray may be fatal due to gastrointestinal or hemopoietic dysfunction. Survival is inversely related to the dose at 6 Gray or less. Whole body doses of 30 Gray may cause nausea, vomiting, listlessness, drowsiness (with apathy or more severe symptoms such as prostration, tremors, convulsions, ataxia, and death within a few hours). The gonads are particularly radio-sensitive. A single dose of 0.3 Gray may produce temporary sterility in men. In women, loss of fertility may be indicated by loss of menstruation. The material is radiotoxic in the lungs. Eye: Particulate/dust is discomforting and harmful to the eyes. alpha-Radiation produces acute inflammation of the conjunctivae and cornea. The most sensitive part of the eyes is the crystalline lens. Late effects may produce cataracts. A single exposure may be benign for 6 months to several years. Cataract formation begins at the posterior pole of the lens, and continues until the entire lens is affected. The growth of opacity may stop at any point with the growth and degree dependent on dose. Skin: The material may be discomforting and harmful to the skin. Ingestion: The material is toxic if swallowed. The material is radiotoxic principally through the decay isotopes. Considered an unlikely route of entry in commercial/industrial environments. Carcinogenicity: NTP - Not listed; IARC - Not listed; OSHA - Not listed; NIOSH - Not listed; ACGIH - Not listed; EPA - Not listed; MAK - Not listed.

Potential chronic health

Thorium disintegrates with the production of 220Rn, a radon radioisotope, which is an alpha emitter and therefore a radiation hazard. Sorption and re-radiation processes may provide additional sources of exposure. Prolonged retention of thorium compounds leads to long-term alpha- irradiation of the tissues with changes occurring in blood-forming, nervous and reticulo-endothelial systems and functional and morphological damage to bones and lung tissue. Only after considerable periods does such illness become apparent and symptoms characteristic of chronic radiation disease occur; neoplasms may occur and immunological activity may be reduced. Chronic exposure to thorium in patients receiving injections of Thorotrast (a colloidal thorium oxide) for pyelography, has produced tumours at various sites, and confirmed in animal studies. Cancer of the liver, larynx, bronchi and sarcoma of the kidney have been reported. Lack of correlation of amount injected, latency with the development of malignancy may reflect the variable composition of Thorotrast and in particular the number of times thorium was chemically processed to remove radium and other radioactive members of the decay chain. Work experience with thorium and its compounds has been generally good; workers in plants making incandescent Welsbach mantles (99% thorium nitrate) and in plants refining thoria from monazite have not experienced effects attributable to chemical toxicity or radiation injury. Delayed effects of radiation may occur due to single large overexposure or continuing low-level exposures. These may include cancer, genetic effects, a shortened life span and cataracts. Cancer of the hemopoietic system, thyroid, bone and skin are frequently seen. Leukemia is the most common form of malignancy. Lung cancer due to the deposition of radioactive particles in the lungs, may also occur. Genetic effects range from point mutations, severe chromosome damage such as strand breakage, translocation and deletions. If germ cells are involved the effects of the damage might only be seen in following generations.