Toxic Effect of Chemicals
All chemicals have toxic effects at some dose level for some route of exposure. It is therefore wise to minimize exposure to chemicals. Chemicals can have local or systemic effects. Local toxicity refers to the direct action of chemicals at the point of contact. Systemic toxicity occurs when the chemical agent is absorbed into the bloodstream and distributed throughout the body, affecting one or more organs. Toxic effects are also classified as acute or chronic. Acute effects are observed shortly after exposure. Chronic effects result from long term exposures or appear after a latency period.
Routes of Exposure
Dermal Contact: One of the most frequent exposures to chemicals is by contact with the skin. Spills and splash can result in overt contamination of the skin. A common result of skin contact is localized irritation or burns. However, some materials are also absorbed through the skin to produce systemic poisoning. Skin contact hazards are often associated with caustic or acidic cleaners which are highly corrosive to skin tissue on contact or with petroleum base products which are irritating on repeated contact.
Inhalation: Inhalation of toxic vapors, mists gases, or dusts can produce poisoning by absorption through the mucous membrane of the mouth, throat, and lungs and can seriously damage these tissues, by local action. Inhaled gases or vapors may pass rapidly into the capillaries of the lungs and be carried into the circulatory system. The degree of injury resulting from inhalation of toxic substances depends on the toxicity of the material, its solubility in tissue fluids, its concentration, and the duration exposure.
Inhalation hazards are most often associated with gases and volatile products such as adhesives, wood finishes or paint thinners. Dust and non volatile liquids can also present an inhalation hazard. Materials in the form of dusts and particulates can become airborne when transferred from one container to another or by grinding and crushing. Splash created from spills and during vigorous shaking and mixing also results in aerosol formation. Many of the particulates generated during such procedures do not settle out but remain suspended in the air and are carried about by air currents in the room. Some of these particulates are capable of being inhaled and deposited in the respiratory tract. For many operations it is not obvious that an aerosol is being generated and personnel may not be aware that a hazardous situation exists.
Ingestion: Ingestion of toxic materials can occur when contaminated hands come in contact with the mouth or with food items which are placed in the mouth. Food items and utensils themselves can become contaminated when stored near chemicals.
Ocular: The eyes are of particular concern because they are so sensitive to irritants. Ocular exposure can occur via splash or when contaminated hands rub the eyes. Few substances are innocuous in contact with the eyes and a considerable number are capable of causing burns and loss of vision. The eyes are very vascular and provide for rapid absorption of many chemicals.
Safe Handling Practices:
- Read label on the container of the material you are working with. DO NOT USE A MATERIAL IF YOU ARE NOT ABSOLUTELY SURE OF WHAT IT IS
- If you are not sure of the chemical hazards after reading the label contact your supervisor or the Safety Officer to review the Material Safety Data Sheet (MSDS).
- Use protective gloves, goggles etc as instructed on the label. If you do not have these items contact the Safety Officer.
- Determine the amount of ventilation you will need or if respiratory protection may
be required. In general this will depend on the following:
1) The evaporation rate of the product. Flammables have high evaporation rates.
2) The corrosiveness of the fumes (Ammonia, bleach) or the toxicity of the fumes.
3) The length of potential exposure.
4) The open surface area created and method of application. A large surface area would be created by applying a thin coat such as in wood finishing or cleaning. Spray application is more hazardous than brush application.
5) The temperature of the product. Heating will increase evaporation.
IF ADEQUATE VENTALATION IS NOT IN PLACE A SERIOUS HEALTH HAZARD OR EXPLOSION HAZARD MAY BE CREATED.
- If the materials are corrosive, note where the nearest eyewash, shower or other water source is located. Plan how you will quickly flush your eyes or skin if an accident should occur.
- To prevent ingestion always wash your hands when you finish using chemicals. Also rinse your gloves and periodically clean your eye-goggles.
- Store all chemical products at eye level or below. Make sure all containers are resealed after use.
- Gas cylinders must be secure in the upright position at all times and not left free standing.
- If a spill occurs contain the material if safe to do so, evacuate people from the area and contact the Safety Officer. See WCU Emergency Procedures.