What are hazardous chemicals? OSHA has defined the term "hazardous substance" as any chemical which poses a physical or a health hazard. For the purposes of the hazard communication standard, a hazardous chemical may be defined as "any chemical which is a physical or health hazard".

Physical hazards - are chemical reactions that could result in a fire, explosion, and/or toxic gas release which cause physical trauma if chemicals are handled or stored improperly.

Health hazards - are health effects (illness or disease) caused directly by the chemicals themselves, not an injury resulting from a reaction. Health hazards, as defined in the HCS means chemicals for which there is statistically significant evidence based on at least one study conducted in accordance with scientific principles, that acute or chronic health effects may occur in exposed employees. Health hazards include chemicals that are carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins, agents which act on the hematopoietic system, and agents which damage the lungs, skin, eyes or mucous membranes. All chemical materials can cause health problems under the wrong conditions.

Forms of Hazardous Chemicals You might think that the chemicals which apply to the rule are those in liquid, gas or particulate form. But, the standard's definition of "chemical" is much broader than that commonly used. According to the HCS, chemicals that apply may exist in one of many forms:

Dusts - are finely divided particles. Example - wood dust.

Fumes - are even smaller particles usually formed when solid metal is heated and vaporized, and then condenses as tiny particles.

Fibers - are similar to dusts but are of an elongated shape. Examples - asbestos and fiberglass.

Mists - are liquid droplets that have been sprayed into the atmosphere.

Vapors - are gases formed when liquid evaporates.

Gases - are substances that are normally airborne at room temperature. A vapor is the gaseous phase of a substance which is a normally a liquid or solid at room temperature.

Solids - such as metal, treated wood, plastic.

Liquids - the most common form in the workplace.

1. The form of the chemical : Is the chemical a solid, liquid, or gas?

2. How the chemical Contacts the body: Is the chemical ingested, inhaled, absorbed, or injected?

3. The amount, or dose, the body receives. How much chemical makes its way into the body?

4. How toxic the chemical is. How poisonous is the chemical?

Routes of Entry Another important task when assessing the workplace for chemical hazards is determine the route(s) of entry the chemicals may take. If we know the route(s) of entry, we can then determine appropriate engineering, administrative, and PPE controls to eliminate or reduce the exposure. The four common routes of entry are:

1. Ingestion Do we eat or drink it?

2. Inhalation Do we breath it in?

3. Absorption Does it pass through the skin, eyes or other membranes?

4. Injection Does it enter through a puncture or cut?

1. Assess the workplace to see which hazardous chemicals are currently being used. Do this by conducting a walkaround inspection and checking records. Use the results of your assessment to create a list of hazardous chemicals. With chemical list in hand, obtain a MSDS for each chemical in preparation for the next step.

2. With each MSDS analyze the hazards presented by each chemical in the workplace. The MSDS is your primary tool to determine the physical and health hazards, routes of entry, toxicity, and other information about each chemical in your workplace.

Engineering Controls. Redesign, replace, substitute chemicals, machinery, equipment to eliminate or reduce the chemical hazard itself. Engineering controls are most effective when the hazard is eliminated or reduced to levels that do not require the use of administrative controls or PPE strategies which are dependent on appropriate behaviors for their success. This strategy seeks to control the hazard at the source by using such methods as total enclosure or substitution of a safer chemical. It also attempts to control the hazardous chemicals along the path by using such measures as ventilation.

Administrative Controls. Change work procedures to reduce the duration, frequency, and severity of exposure to the chemical hazard. The chemical hazard, itself, is not eliminated or reduced using this strategy, only exposure to the chemical hazard. The primary focus is to incorporate safer work practices through written safety policies, rules, supervision and training.

Personal Protective Equipment (PPE). The use of PPE is probably the most common strategy, and in many cases is a mandatory requirement when working with hazardous chemicals. The worker uses protective equipment to set up a barrier between worker and hazard. Once again, the chemical hazard is neither eliminated nor reduced, and a high reliance is placed on appropriate use of PPE for this strategy to be successful.

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