Hazardous Chemicals and SDSs
The use of chemicals in the workplace is commonplace and, in most workplaces and tasks. It would be difficult to work a full day without having been in contact with or, using a chemical of some type in a work process.
The rate of new chemical development makes it difficult for government and other agencies track the multitude of new chemicals that are introduced into the market each day. The United States is one of the world leaders in new chemicals development and has more than 85,000 chemicals listed on its inventory of substances that fall under its Toxic Substances Control Act (TSCA).
To put this in context humans have discovered or made 50 million differential chemicals, the vast majority over the last few decades. A new substance is either isolated or synthesised every 2 to 3 seconds, 24 hours a day, seven days a week somewhere in the world and science is constantly playing catch up game trying to determine the effects of these chemicals on the human body. It took 33 years to discover the first 10 million chemicals registered and a mere nine months for the last 10 million.
What is a hazardous substance? The definition below comes from SafeWork Australia.
“Hazardous chemicals are substances, mixtures and articles that can pose a significant risk to health and safety if not managed correctly. They may have health hazards , physical hazards or both.”
Although this is a very broad definition it does give a basis to consider how we handle substances in the workplace. For many people chemicals are something that comes in a bottle or can, with warning labels and first-aid treatment labelling. In construction we need to go a little deeper than this. We need to remember that many of the compounds that we use as well as equipment that we install in workplaces consists of compounds in some form or another. These chemical compounds can be released in hazardous quantities through installation processes including cutting, grinding and heat generation.
Further to this we also need to consider that some substances which are not generally harmful can become harmful when they enter the body through a particular route which the body has no defence An example of this could be something as simple as a vegetable oil which when contacting the skin has no detrimental effects, however, if this is being used in a process that it is atomised into a fine mist, inhalation into the lungs can have serious health implications. The point I am trying to make here is that all substances need to be considered for potential hazards if it has the potential to enter the body.
Before a chemical or substance can affect the body, adversely or otherwise, we must first have an exposure to it. Exposure level depends on the amount of the substance we are exposed to or the period during which it effects the target organ, which can persist after exposure ceases. Another key consideration is the route of entry. The major routes of entry into the body under normal workplace conditions are inhalation, absorption through the skin and, ingestion. Entry methods are;
- Inhalation (breathing in)
- Absorption (through the skin or eyes)
- Ingestion, oral (eating, swallowing)
- Transfer across the placenta to the unborn baby
- Intravenous (injection into the vein)
- Intramuscular (injection into the muscle)
- Subcutaneous (injection under the skin) – common in high pressure injection injuries
- Intraperitoneal (injection inside the membrane that lines the interior wall of the abdomen)
To assess how a chemical affects the human body we need information regarding:
- the substance and its chemical and physical properties
- the biological system affected (i.e. skin, lungs, nervous system, blood and circulatory system, liver, or kidneys)
- the effect or response caused by the substance
- the exposure (dose, time period, situation)
It is for this reason that we require information normally available through Safety Data Sheets (SDS’s), and this is the reason behind the requirement for SDS’s for chemicals in a workplace. To be valid, SDS’s must be not more than five years (60 months) old and specific to the chemical or brand being used. We should always keep in mind that chemicals can be released from the substances that we are working with as a result of work processes and these will not normally be identifiable through SDS’s.
The United States is one of the leading sources of data on toxicology.
Two terms that are commonly used in SDS’s, are LD50 and LC 50.
- LD50 is the abbreviation used for the dose which kills 50% of the test population. Typically, this is determined using rats.
- LC 50 is the abbreviation used for the exposure concentration lethal to half of the test animals.
To control the toxic effects of chemicals, we need to set priorities, goals, and strategies for their management. In workplaces, this may be by setting their own limit values to guide workers. Occupational limit values are based on the best available information from a range of sources including industrial experience, experimental laboratory studies and accidents.
We must remember occupational limits are informed and negotiated compromises, not fixed safety standards.
Other values that we should be aware of are TLV-STEL and TLV-C.
TLV- STEL is the threshold limit value for short-term exposure. This is the limit to which workers may be exposed for a short time (usually 15 minutes) without suffering irritation, long-term irreversible tissue damage or impairment likely to increase accidental injury, affect self-rescue or reduce work efficiency
TLV-C is the threshold limit value – ceiling. This is a concentration that should not be exceeded during workplace exposure.
We should always exercise caution working with chemicals or substances with potential to release chemicals through installation practices such as; grinding, cutting, and drilling, and take measures to protect ourselves. Work practices must follow the hierarchy of controls as legislated by SafeWork in the harmonised legislation. The hierarchy of controls in order of best to least preferred is;
- Elimination: can we eliminate the need for the chemical or the work process that creates an exposure risk?
- Substitution: can we substitute a less hazardous chemical or process into our workflow?
- Isolation: are there measures that we can take to isolate our workers from the exposure?
- Engineering: can we re-engineer a process to minimise or reduce the exposure to a chemical or substance?
- Administrative: administrative controls would include safety data sheets and sufficient and adequate training and instruction on potential exposure and routes of entry to enable the worker to make informed decisions
- PPE: PPE should be the last thing that we rely, on solely. It should be used as an additional control to reduce or limit exposure to the chemical, substance or process that has potential to release the chemicals or substances we are installing.
In summary, chemical exposure is more common than many of us would think. There is insufficient space in this article to cover the effect of chemicals on the human body or introduce terms such as body burden, but I encourage all employers and workers to take chemical safety seriously. Ensure that you have Safety Data Sheets available when working with chemicals which will give further information on the chemical, its impact on the human body and protection methods that need to be taken to protect workers as well as the environment.
Master Electricians Australia maintains a collection of SDS’s for commonly used chemicals in the electrical industry. These SDS’s are available for all members via their ME Safety log in. Our Field Support Advisors (FSA) are also available to assist with any safety questions including help with chemical. Contact MEA on 1300 889 198.
Written by Michael Rogers – Master Electricians Australia