>> Workplace Hazardous Chemicals

Chemical Hazards

Health hazards can arise from exposure to a large variety of chemical substances. Their toxic properties can harm the body. Chemical hazards take the form of solids, liquids, vapours, gases, dusts, fumes or mists. They can be inhaled, ingested or absorbed into the body.

In order to prevent harm, we need to understand the toxic properties of chemicals. Toxic properties means the ability of the chemical to produce adverse health effects. We also need to know the physical states chemical agents can take during the work process. This can help to determine how they might contact or enter the body and how exposure may be controlled.

Chemicals serve many purposes in the workplace. Some are the raw materials used to make a product. Sometimes the product itself is a chemical. Other chemicals are fuels used to provide energy. Still others are byproducts of a process or are used for other purposes, such as lubrication and cleaning.

Chemicals that may cause an adverse health effect are called toxic. Some chemicals, such as corrosives, can harm the body without being toxic. Hazardous chemicals may also be referred to as hazardous substances or hazardous materials.

A very large number of chemicals are used in workplaces. There are many whose health effects are not entirely known. The problem is all the more difficult because the health effects of some chemicals can be subtle, or may take years to develop. The best policy, therefore, is to regard chemicals as potentially hazardous until their effects are fully known.

The employer, as well as members of joint committees, must know how to recognize, assess and control chemical hazards.
Physical States of Matter

Chemicals exist in one of three states: solid, liquid or gas.

* A solid has shape and form, whether it's a dust particle or an ingot of steel.
* A liquid is a formless fluid. It takes the shape of its container, but doesn't necessarily fill it. Solvents and oils are examples of chemicals in liquid form.
* A gas is a formless substance that expands to occupy all the space of its container. Oxygen and carbon monoxide are examples of chemicals in gaseous form. Gases are usually invisible, but they may be detected in some cases by their taste or smell.

A chemical is described as a solid, liquid or gas according to its state under normal conditions of temperature and pressure. These normal conditions are called room temperature and atmospheric pressure.

Some chemicals move from one state to another with a change in temperature or pressure. Water is a chemical which is normally a liquid. At normal atmospheric pressure, it becomes a solid at temperatures below 0 degrees Celsius. Propane gas is a liquid while it is stored under pressure in a tank, but it becomes a gas when it is released at atmospheric pressure. The product known as dry ice is carbon dioxide. At atmospheric pressure, it becomes a solid at temperatures below -78.5 degrees Celsius. It changes directly into a gas at normal room temperature.

Knowledge of the physical states of hazardous chemicals is important to an understanding of their health effects. The physical state of a chemical determines which routes it may use to enter the body. For example, a gas may easily enter the body by inhalation. Some liquids are more likely to be absorbed through the skin. The fact that chemicals may change their state when subjected to work processes that involve temperature and pressure changes makes it all the more important that all of the possible states be taken into account.