Occupational Health Guide (Spanish)

Occupational health deals with the identification, evaluation, and control of workplace hazards that may cause sickness, impaired health and well-being, or significant discomfort among employees. Chemical hazards are one of four general classifications of those hazards. While the other three classifications - physical, biological and ergonomic - are also briefly described. This topic mostly emphasizes issues and concerns related to chemical hazards.

Workplace Hazards
Chemical Hazards
Chemical hazards include excessive airborne concentrations of dust, fumes, smokes, mists, gases, or vapors that can be hazardous through inhalation. This category also includes chemicals that are absorbed through the skin or act directly on the skin or mucous membranes, and chemicals that are ingested. Chemical hazards are often categorized according to their health effects and include irritants, corrosives, sensitizers, carcinogens (cancer-causing agents), reproductive toxins, toxic or highly-toxic agents, hepatotoxins (liver), nephrotoxins (kidneys), neurotoxins (nervous system), blood-damaging agents, asphyxiants, and lung-damaging agents.

Physical Hazards
Physical hazards include noise, temperature and pressure extremes, ionizing and nonionizing radiation, and vibration.

Biological Hazards
Biological hazards include insects, bacteria, viruses, fungi, and other organisms that can cause infection or otherwise adversely affect an employee’s health.

Ergonomic Hazards
Ergonomic hazards include work tasks that require awkward positions and body movements, repeated motions, excessive lifting or reaching, and/or other environmental factors that can lead to impaired health or well-being. Designing tools and job tasks to fit the employee can control ergonomic hazards.

Chemical Hazard Issues and Concerns
Routes of Entry
Hazardous chemicals can gain entry into the body through inhalation, skin absorption, ingestion, or injection. For workplace chemicals, inhalation is the most common mode of entry followed by skin absorption. Ingestion can be a significant entry for hazardous chemicals if poor hygiene practices are followed. To protect employees’ health from inhalation of excessive concentrations of hazardous chemicals, allowable airborne concentration limits have been developed.

Occupational Exposure Limits
Airborne exposure concentration limits have been established using scientific knowledge derived from human and animal studies. The two most common limits have been developed by OSHA and the American Conference of Governmental Industrial Hygienists (ACGIH), and are respectively known as the permissible exposure limits (PELs) and the threshold limit values (TLVs). The PELs and TLVs should not be interpreted as fine lines between safe and dangerous levels. Rather, they are maximum concentration limits, and the best practice is to maintain workplace concentration levels as low as practicable. Also, although exposure limits have been established for hundreds of common workplace chemicals, the majority of chemicals do not have an established occupational exposure limit. For chemicals without established limits, the manufacturer’s recommendations and safety instructions should be followed.

Permissible Exposure Limits (PELs)
PELs are developed by OSHA and are mandatory or enforceable occupational exposure standards. The majority of PELs are based on an eight-hour time weighted average (TWA) exposure concentration. They are usually listed in units of parts per million (ppm) for gases and vapors, and milligrams per cubic meter of air (mg/m3) for dusts, fumes, and mists. For example, the OSHA PEL for ammonia is 50 ppm as an eight- hour TWA, while the PEL for iron oxide fume, a common contaminant of steel welding operations, is 10 mg/m3 as an eight-hour TWA. For certain substances that can cause immediate effects, OSHA has developed ceiling limits. A ceiling limit is the maximum allowable concentration at any time for the hazardous substance.

TLVs are developed by ACGIH and refer to airborne concentrations of substances under which it is believed that nearly all employees may be repeatedly exposed day after day without adverse health effects. Often, the TLV and the PEL are identical for a particular chemical. Like the PELs, the most common TLVs are based upon an eight-hour TWA concentration level, but they also include ceiling limits for certain chemicals. They are also usually given in units of ppm or mg/m3.

Hazard Evaluation
Air Monitoring
In order to determine if employee exposure levels are below applicable occupational exposure limits, air monitoring is usually conducted. Two types of air monitoring commonly conducted in the industrial environment are direct-reading monitoring and full-shift air sampling.

Direct-Reading Monitoring
This type of monitoring is performed with direct-reading instruments or other types of equipment that provide a measurement either instantaneously or in a very short amount of time (e.g., seconds or minutes). An example of a direct-reading instrument used in confined space entry procedures is a four-way meter that detects flammables, oxygen, carbon monoxide, and hydrogen sulfide.

Full-Shift Air Sampling
Full-shift air sampling is usually conducted with a portable air sampling pump and collection medium. The pump is attached to the employee with the collection medium (filter for dusts, sorbent tube for vapors) placed in the employee’s breathing zone. This sampling pump is worn for the full work shift and draws air through the collection medium at a known (calibrated) flow rate. After sampling, the collection medium is sealed and shipped to an accredited laboratory for analysis. By knowing the amount of chemical collected on the filter or tube, and the sampled air volume, an exposure concentration can be determined. This concentration can then be compared with applicable occupational exposure limits.

Hazard Controls
Three primary methods for controlling employee exposure are engineering controls, administrative controls, and personal protective equipment (PPE).

Engineering Controls - Engineering controls are generally the most desirable hazard control method because they eliminate or reduce the hazard. Examples of engineering controls include:
• Eliminating the hazard altogether
• Substituting a less toxic material in place of a highly-toxic material or replacing a volatile solvent with a less volatile solvent
• Changing the process or equipment so there is less employee exposure
• Isolating hazardous processes to certain restricted areas
• Utilizing wet methods to control dusts
• Utilizing ventilation systems

Administrative Controls - Administrative controls can also be an important part of hazard control. They include:
• Training employees
• Establishing and following specific safe work procedures
• Arranging work schedules and allowable employee exposure times
• Conducting air sampling and biological monitoring

PPE - PPE use should be considered the least desirable control method. The major disadvantage of PPE utilization as a method of hazard control is that the hazard is not eliminated. Rather, a protective barrier is placed between the employee and the hazard. If the barrier fails, the employee may be overexposed. Another disadvantage is that wearing PPE can often add to or create additional safety hazards. For example, wearing a full-face respirator and a chemical protective suit can increase the potential for heat stress, increase an employee’s heart and breathing rate and decrease an employee’s visibility and hearing.

OSHA 29 CFR 1910.1000

Additional Resources
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NOTICE: This guide may make reference to the Occupational Safety and Health Administration (OSHA) regulations; however the guide is not legal advice as to compliance with OSHA or other safety laws, codes, or regulations. Compliance with OSHA and other safety laws codes or regulations, and maintaining a safe work environment for your employees remains your responsibility. WCF Insurance does not undertake to perform the duty of any person to provide for the health or safety of your employees. WCF Insurance does not warrant that your workplace is safe or healthful, or that it complies with any laws, regulations, codes, or standards.