8.1: Introduction

OSHA Hazard Communication Standard is designed to protect against chemical-source injuries and illnesses by ensuring that employers and workers are provided with sufficient information to anticipate, recognize, evaluate, and control chemical hazards and take appropriate protective measures. This information is provided through safety data sheets (SDSs), labels, and employee training. In order for SDSs, labels, and training to be effective, the hazard information they convey must be complete and accurate. Thus, it is critically important to obtain comprehensive and correct information about the hazards associated with particular chemicals.

Hazard classification is the process of evaluating the full range of available scientific evidence to determine if a chemical is hazardous, as well as to identify the level of severity of the hazardous effect. When complete, the evaluation identifies the hazard class(es) and associated hazard category of the chemical.

Hazard classification does not involve an estimation of risk. The difference between the terms hazard and risk is often poorly understood. Hazard refers to an inherent property of a substance that is capable of causing an adverse effect. Risk, on the other hand, refers to the probability that an adverse effect will occur with specific exposure conditions. Thus, a chemical will present the same hazard in all situations due to its innate chemical or physical properties and its actions on cells and tissues. However, considerable differences may exist in the risk posed by a chemical, depending on how the chemical is contained or handled, personal protective measures used, and other conditions that result in or limit exposure.

Risk is often expressed as the simple equation: Hazard × Exposure = Risk

Construction workers may be exposed to many different hazards in their jobsite. Health hazards in construction fall into four categories: biological, physical, chemical, and ergonomic.

Biological Hazards

Biological hazards are diseases producing agents (pathogens) that can be transmitted to individuals through various routes of exposure (modes of transmission). Exposure to these hazards may result in acute or chronic health conditions. Examples of biological hazards include: Pathogens (bacteria, viruses), fungi, blood and bodily fluids, toxins (harmful substances from plants, animals), environmental hazards (mold, harmful plants, and animal waste).

Physical hazards

Physical hazards are classified as posing the following hazardous effects: explosive; flammable (gases, aerosols, liquids, or solids); oxidizer (liquid, solid or gas); self-reactive; pyrophoric (liquid or solid); self-heating; organic peroxide; corrosive to metal; gas under pressure; or in contact with water emits flammable gas.

Chemical Hazards

Chemical Hazards: There are four basic ways that chemicals can enter your body: direct contact on the skin or eyes, absorption through the skin, accidental ingestion through the mouth, and inhalation through the lungs. Chemicals consist of various types:

Substance – chemical elements and their compounds in the natural state or obtained by any production process, including any additive necessary to preserve the stability of the product and any impurities deriving from the process used, but excluding any solvent which may be separated without affecting the stability of the substance or changing its composition.

Element – the simplest form of matter. There are currently 118 known elements in the periodic table. Examples of elements are aluminum, carbon, chlorine, hydrogen, mercury and oxygen.

Chemical compound – a substance consisting of two or more elements combined or bonded together so that its constituent elements are always present in the same proportions.

Mixture – a combination of a solution composed of two or more substances in which they do not react.

Examples of Exposures and Chemical Hazards refer to any forms of chemicals including medications, solutions, gases, vapors, aerosols, and particulate matter that are potentially toxic or irritating to the body system. Routes of chemical exposure:

• Inhalation: Breathing gases, vapors, particulates, dust, or mist

• Ingestion: Accidentally eating or drinking hazardous substances

• Percutaneous: Permeation or absorbing a substance through the skin; piercing or penetration of skin with needle or other sharp device/instrument (e.g., scalpel or broken glass)

• Dermal: Contact with corrosive or sensitizing materials

Direct Contact = Surface

The cleaners and disin­fectants we work with can burn or irritate the skin and eyes on contact, causing damage on the surface. Dermatitis (inflammation of the skin) and conjunctivitis (inflammation of the eye membrane) are two examples. Skin corrosion is the production of irreversible damage to the skin; namely, visible necrosis through the epidermis and into the dermis, following the application of a test substance for up to 4 hours. Corrosive reactions are typified by ulcers, bleeding, bloody scabs, and, by the end of observation at 14 days, by discoloration due to blanching of the skin, complete areas of alopecia, and scars.

Absorption = Penetration

Some chemicals can pass right through the skin undetected and enter the bloodstream. They are carried throughout the body, causing harm. Broken skin or puncture wounds greatly increase the rate at which chemicals are absorbed. Aspiration means the entry of a liquid or solid chemical directly through the oral or nasal cavity, or indirectly from vomiting, into the trachea and lower respiratory system. An asphyxiant is a vapor or gas that can cause unconsciousness or death by suffocation due to lack of oxygen. When the concentration of a particular gas increases, the fraction of inspired oxygen decreases, causing decreased oxygen in the blood. A decrease in the fraction of inspired oxygen to less than 19.5% causes inadequate oxygen supply within minutes after exposure to a simple asphyxiant, and may result in unconsciousness or death.

Absorption of Chemicals by Your Body

Chemicals can enter your system by being absorbed through the skin. In fact, as the chart below shows, when it comes to absorption through the skin, different parts of your body absorb chemicals at very different rates. (If you are working with chemicals you should wash your hands BEFORE and after using the bathroom!)

Don’t Trust Your Nose. You can’t rely on your sense of smell to protect you from exposure to toxic chemicals. Let’s face it, your nose has some important limitations. Here are the basic ones: Some dangerous chemicals, such as carbon monoxide, are odorless. No nose can smell them. For some chemicals, you can only detect the smell when the toxin is around you in such large quantities that your health is being harmed by it. For example, by the time you can smell ethylene oxide (used in gas sterilizers), you’re already in trouble. Our noses can become accustomed to chemicals. That means that after a while we can’t smell even very powerful odors. For instance, our noses can learn to turn off strong odors like ammonia and bleach.

Ergonomic Hazards

Ergonomic Hazards are the science of fitting jobs to workers instead of trying to get the worker to fit the job. It focuses on designing workstations, tools & work tasks for safety, efficiency and comfort. Ergonomics seeks to decrease fatigue and injuries, along with increasing comfort, productivity, job satisfaction and safety, because work injuries are not inevitable and a well-designed job should not hurt you. Ergonomics is important because when you’re doing a job and your body is stressed by an awkward posture, extreme temperature, or repeated movement your musculoskeletal system is affected. Your body may begin to have symptoms such as fatigue, discomfort, and pain, which can be the first signs of a musculoskeletal disorder.

Musculoskeletal disorders or MSDs are cumulative and chronic injuries of the soft tissue-muscles, tendons, ligaments, nerves, joints, and blood vessels. The body has limits and can fail or wear out when abused or misused. MSDs are defined as injuries to muscles, tendons, ligaments, joints, nerves and discs that are caused or aggravated by our actions and/or environment that does not follow safe and healthy work practices. A well-known MSD is carpal tunnel syndrome which occurs when the nerve, which runs from the forearm into the palm of the hand, becomes pressed or squeezed at the wrist. The carpal tunnel - a narrow, rigid passageway of ligament and bones at the base of the hand - houses the median nerve and tendons. Sometimes, thickening from irritated tendons or other swelling narrows the tunnel and causes the median nerve to be compressed resulting in pain, weakness, loss of grip or numbness in the hand and wrist, radiating up the arm.

Symptoms of MSDs include: pain, weakness, stiffness, sensitivity, swelling, burning sensation, tingling, drowsiness, difficulty moving, clumsiness. Ergonomic risk factors are workplace situations that cause wear and tear on the body and can cause injury. These include repetition, awkward posture, forceful motion, stationary position, direct pressure, vibration, extreme temperature, noise, and work stress. Engineering improvements include rearranging, modifying, redesigning, or replacing tools, equipment, workstations, packaging, parts, or products. These improvements can be very effective because they may reduce or eliminate contributing factors. (For example, if your job requires sitting for long periods of time, having an adjustable seat or foot stool so that your knees are higher than your hips help protect your lower back.)Administrative improvements include changing work practices or the way work is organized, including providing variety in jobs, adjusting work schedules and work pace, providing recovery time (i.e., muscle relaxation time), modifying work practices, ensuring regular housekeeping and maintenance of work spaces, tools, and equipment, and encouraging exercise. Personal Protective Equipment: Safety gear, or personal protective equipment (PPE), includes gloves, knee and elbow pads, footwear, and other items that employees wear.