Basic Chemistry

By Joe O'Connor | May 15, 2004




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Avoid the hazards of chemicals whenever possible

Electrical contractors can find themselves in a variety of environments. But whether you are rewiring a chemical industrial plant or simply working on a residential site using a lubricant to help pull wire, you can be exposed to hazardous chemicals. In fact, all chemicals can be considered hazardous. For example, neither water nor salt are thought of as toxic substances. However, if water is inhaled, it’s deadly. Too much salt can have terrible effects. You need a basic understanding of chemicals, how they might affect the body, and simple precautions that can be taken in the workplace to avoid harmful exposure.

The first step to protection from chemicals is to be aware of the hazards. A Material Safety Data Sheet (MSDS) is a complete description of the chemical with detailed information. A MSDS for each chemical on the job must be available in the work area. To better understand this information, the hazards can be classified into toxins, carcinogens, teratogens, mutagens, corrosives, irritants and sensitizers.

Toxins are poisons. Certain toxins attack a specific part of the body (Nephro-toxins, the kidney; Hepa-toxins, the liver; Neuro-toxins, the nerves and brain, etc.) These are called target organ toxins.

Carcinogens, teratogens and mutagens affect human genes. Their effects may not develop or appear until years later. For example, workers exposed to formaldehyde may develop cancer later in life.

Corrosives and irritants cause damage when they come in contact with the body. Irritants cause damage that is reversible and can be repaired if treated. Exposure to irritants usually results in the inflammation of the skin. Corrosives such as battery acid cause irreversible damage or alteration to skin tissue.

Avoiding chemical hazards is a matter of controlling exposure. If the level of exposure is kept at safe limits, the chemical may not be harmful. The opening of the article noted that even edible substances can become hazardous when limits are not maintained. Safe level limits are identified on MSDS. They are identified as PEL (Permissible Exposure Limit), REL (Recommended Exposure Limit) and/or TLV (Threshold Limit Value). They are usually based on a time-weighted average (TWA). The TWA recognizes that the average worker is on the job eight hours a day, five days per week. During the day, high and low exposures will occur. Short periods of high exposure may be considered safe. The average amount of exposure is controlled. Exposure during the day cannot go above the established limits for more than 15 minutes. There should not be more than four periods during the day where the level is above the limit. There should also be at least a one-hour period between exposures above the limit.

Limits have also been established to identify exposures that are immediately dangerous. They are STEL (Short-Term Exposure Limit) and IDLH (Immediately Dangerous to Life or Health). Never allow exposure to go above these levels.

Engineering controls can be put in place to ensure exposure levels stay within these limits. The best option is substitution. Whenever possible, use a non-hazardous chemical in place of a hazardous one. Ventilation is one of the better options. Most gases and vapors can be reduced to safe levels by general ventilation or air exchange.

Also consider administrative controls. The way you do work or when it is scheduled can have a tremendous impact. Don’t allow silica exposure by wiring while a mason is cutting brick or block in the area. Provide training and institute policies that will reduce exposure. Examples include good housekeeping, washing hands after jobs, no smoking or eating in work areas and monitoring.

As a last resort, control exposure with Personal Protective Equipment (which protects the route of entry). Remember the water example. Certain chemicals will not be hazardous unless allowed to pass into the body in a particular manner. If a chemical is harmful to breathe or inhale, use an appropriate respirator. If the route of entry is through the skin, gloves or other protective clothing should be used. Ingestion or swallowing chemicals should not be overlooked. Although this is not common in the work place, it can be deadly. Even small amounts of certain chemicals may have a harmful effect. Chemicals may pass from the hands to food or cigarettes and into the mouth.

These actions are simple steps that can be taken to protect employees and are a great step toward addressing an overwhelming burden. The National Institute of Occupational Safety and Health (NIOSH) has identified more than 85,000 hazardous chemicals. The Occupational Safety and Health Administration (OSHA) has more than 27 regulations targeting specific substances such as asbestos, formaldehyde and lead. There is a standard for process safety involving chemicals and one for hazardous waste. There are three OSHA tables listing the permissible exposure limits for hundreds of substances. Be sure to consult these regulations for compliance. EC

O’CONNOR is with Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Based in Waverly, Pa., he can be reached at 607.624.7159 or [email protected].


About The Author

Joe O'Connor is with Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Based in Waverly, Pa., he can be reached at 607.624.7159 or [email protected].


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