The Science:

Additional Definitions:

A chemical is “any element, chemical compound, or mixture of elements and/or compounds:”

Element – the simplest form of matter that cannot be broken down further by chemical means. There are currently 109 known elements in the periodic table. Examples of elements are aluminium, 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 – any combination of two or more chemicals if the combination is not, in whole or in part, the result of a chemical reaction. (Pisaniello & Tepe, 2012, pp. 11-12).

Reactivity – tendency of a material or combination of materials to undergo chemical change under the right conditions (CCPS, 2001, p. 2) 

Energy breaks or makes chemical bonds and depending on its type, heat can be either released (exothermic)  or absorbed (endothermic) (see definitions here)

Toxicity

Toxicity refers to the degree to which a substance can damage an organism, in the context of OHS it is how a substance can impact upon a worker. There are five main routes of exposure for workers:

• Inhalation, through the lungs

• Absorption, through the skin/mucous membranes

• Ingestion, orally

• Injection, into the bloodstream

• Transfer, pregnant women can transfer exposure from the placenta to the baby. (Tranter 2014 p.8-10)

Applying the energy-based classification of hazards,5 chemical hazards may be defined as those where the potentially hazardous energy is released through disruption of the molecular bonding as a result of chemical reaction (usually a reactive chemical hazard) (Pisaniello & Tepe, 2012, p. 12).  Thus, chemical energy is the energy contained within chemical bonds.  

The flash point of a chemical is the lowest temperature where it will evaporate enough fluid to form a combustible concentration of gas. The flash point is an indication of how easy a chemical may burn.  Materials with higher flash points are less flammable or hazardous than chemicals with lower flash points (The Engineering Toolbox ND, Flash Point, viewed 17 January 2015, http://www.engineeringtoolbox.com/flash-point-d_924.html)

Risk Potential:

To fully comprehend chemical hazards and risks in the workplace, a generalist OHS professional requires knowledge of the toxic and physicochemical attributes of the chemical (the hazard), paired with an understanding of the potential for worker exposure to the chemical or its impacts. This understanding must include factors related to acute and chronic exposure, chemical hazard classification systems, and chemical hazard identification, risk assessment and risk communication.

Acute toxicity, which refers to “the adverse health effects following a single or limited number of exposures” can occur as a result of exposure due to equipment failure, inadequate protection during maintenance or cleaning, or improper handling of a chemical. Although the effects of acute exposures are usually obvious within a short period, the effects of exposure to some chemicals such as pesticides may not appear for several days.

Temporary effects of acute chemical exposure may include: skin irritation, headaches and nausea.  

Permanent effects include scars from acid burns. 

Chronic toxicity refers to “the adverse health effects resulting from continuous or intermittent exposure” over a prolonged period, often to relatively low levels of chemical. There may be a latency period of many years before the effects of chronic exposure to a chemical are expressed (Pisaniello & Tepe, 2012, p. 17).  

There are a number of occupations where chemical hazards may be present.  These may include:

• Cleaners

• Truck Drivers

• Steel works

• Manufacturing

• Laboratories

• Aviation

• Emergency services

• Hospitals

Consideration to occupations will need to be made when assessing these hazards in future practice.