TMB (3,3",5,5"-Tetramethylbenzidine)

SECTION 2: Hazards identification

CANADIAN WHMIS SYMBOLS EMERGENCY OVERVIEW RISK May cause SENSITIZATION by skin contact. Harmful by inhalation, in contact with skin and if swallowed. Irritating to eyes, respiratory system and skin. Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.

Potential Acute Health Effects

SWALLOWED ■ Accidental ingestion of the material may be harmful; animal experiments indicate that ingestion of less than 150 gram may be fatal or may produce serious damage to the health of the individual. ■ The substance and/or its metabolites may bind to hemoglobin inhibiting normal uptake of oxygen. This condition, known as "methemoglobinemia", is a form of oxygen starvation (anoxia). Symptoms include cyanosis (a bluish discoloration skin and mucous membranes) and breathing difficulties. Symptoms may not be evident until several hours after exposure. At about 15% concentration of blood methemoglobin there is observable cyanosis of the lips, nose and earlobes. Symptoms may be absent although euphoria, flushed face and headache are commonly experienced. At 25-40%, cyanosis is marked but little disability occurs other than that produced on physical exertion. At 40-60%, symptoms include weakness, dizziness, lightheadedness, increasingly severe headache, ataxia, rapid shallow respiration, drowsiness, nausea, vomiting, confusion, lethargy and stupor. Above 60% symptoms include dyspnea, respiratory depression, tachycardia or bradycardia, and convulsions. Levels exceeding 70% may be fatal. EYE ■ This material can cause eye irritation and damage in some persons. SKIN ■ Skin contact with the material may be harmful; systemic effects may resultfollowing absorption. ■ This material can cause inflammation of the skin oncontact in some persons. ■ The material may accentuate any pre-existing dermatitis condition. ■ Open cuts, abraded or irritated skin should not be exposed to this material. ■ Entry into the blood-stream, through, for example, cuts, abrasions or lesions, may produce systemic injury with harmful effects. Examine the skin prior to the use of the material and ensure that any external damage is suitably protected. INHALED ■ Inhalation of dusts, generated by the material, during the course of normalhandling, may be harmful. ■ The material can cause respiratory irritation in some persons. The body's response to such irritation can cause further lung damage. ■ 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.

Potential chronic health

Long-term exposure to respiratory irritants may result in disease of the airways involving difficult breathing and related systemic problems. Skin contact with the material is more likely to cause a sensitization reaction in some persons compared to the general population. There has been some concern that this material can cause cancer or mutations but there is not enough data to make an assessment. Limited evidence suggests that repeated or long-term occupational exposure may produce cumulative health effects involving organs or biochemical systems. Long term exposure to high dust concentrations may cause changes in lung function i.e. pneumoconiosis; caused by particles less than 0.5 micron penetrating and remaining in the lung. Prime symptom is breathlessness; lung shadows show on X-ray. Several epidemiological studies of dye users suggest that there may be an excess mortality from bladder cancer in workers exposed to benzidine-based dyes. Inhalation or absorption through the skin has been recognised as a cause for these tumors. The carcinogenicity risk factor for workers exposed to benzidine is estimated to be 14 times higher than that of the unexposed population. When administered in th diet, benzidine induced urinary bladder carcinomas in dogs and increased the incidence of benign and malignant cholangiomatous tumors and hepatocellular tumors in hamsters of both sexes. When administered by gavage benzidine induced multiple mammary carcinomas in female rats. A survey of benzidine-exposed workers indicated that those with the lower than normal serum properdin levels were more likely to develop bladder tumours. NIOSH recommends that three widely used benzidine-derived dyes, Direct Black 38, Direct Blue 6, and Direct Brown 95, be handled in the workplace as if they were human carcinogens. This recommendation is based primarily upon a preliminary analysis of National Cancer Institute (NCI) data from short-term feeding studies, and on early results from NIOSH field studies. Cancerous and precancerous liver conditions were found in rats, similar to the damage produced by known liver carcinogens. Degeneration of liver cells was found in mice. Although the dyes tested by NCI contained less than 4 ppm residual benzidine when fed to the test animals, greater quantities of benzidine were found in the urine of dosed rats and mice. Caution is also indicated by preliminary results from NIOSH field studies showing that humans working with these same dyes also excrete higher than expected levels of benzidine in their urine. Both laboratory and field studies indicate that these benzidine-derived dyes can be metabolized to benzidine which is present in the urine of animals and humans. Based on the data from the short-term study, NCI scientists believe a cancer causing potential exists upon exposure to the benzidine-derived dyes, most likely through the mechanism of metabolic conversion of the dyes to benzidine in the animal system. Most arylamines are powerful poisons to the blood-making system. High chronic doses cause congestion of the spleen and tumor formation.