As a worker do you a TRAINED and COMPETENT employee trained to under the difference between TOXIC and PHYSICAL risks and what it is the difference! The Irony of the new GHS system is no one wants to learn ahead until they have a major incident at work or a serious health risk with staff developing or a legal issue because they are in court for failure to train properly.
Exposure to a toxic substance such as gasoline can affect your health. Since drinking gasoline can cause burns, vomiting, diarrhea and, in very large amounts, drowsiness or death, it is toxic. Some chemicals are hazardous because of their physical properties: they can explode, burn or react easily with other chemicals.
Most people automatically associate chemicals with scientists in laboratories, but chemicals are also found in many of the products we use at work and at home. While they have a variety of beneficial uses, chemicals can also be extremely harmful if they are misused. Chemical hazards and toxic substances pose a wide range of health hazards (such as irritation, sensitization, and carcinogenicity) and physical hazards (such as flammability, corrosion, and explosibility).
An airborne level, typically one-half of the PEL designated in OSHA’s substance-specific standards, calculated as an eight (8)-hour time-weighted average, which initiates certain required activities such as exposure monitoring and medical surveillance.
The exposure limit a worker’s exposure may never exceed.
Sampling and Analytical Error
A statistical estimate of the uncertainty associated with a given exposure measurement.
Short-Term Exposure Limit (STEL)
The average exposure to a contaminant to which a worker may be exposed during a short time period (typically 15 – 30 minutes).
Time-Weighted Average (TWA)
The average exposure to a contaminant over a given period of time, typically 8-hours. For examples of how a TWA is calculated,
Hazardous chemicals must be treated as a risk in the workplace. This includes storing, handling and managing them correctly to avoid harm to workers, members of the public, property and the environment. You should:
· identify the hazardous chemicals in your workplace
· develop a risk management plan
· keep up to date with work health and safety codes of practice and legislation.
It’s very important to put a risk management plan in place whenever employees or employers are required to use, handle or store hazardous chemicals in the workplace.
In GHS chemicals or even CONSUMER products, There are two broad types of hazards associated with hazardous chemicals which may present an immediate or long term injury or illness to people. These are:
Health hazards – These are properties of a chemical that have the potential to cause adverse health effects. Exposure usually occurs through inhalation, skin contact or ingestion. Adverse health effects can be acute (short term) or chronic (long term). Typical acute health effects include headaches, nausea or vomiting and skin corrosion, while chronic health effects include asthma, dermatitis, nerve damage or cancer.
Physicochemical hazards – These are physical or chemical properties of the substance, mixture or article that pose risks to workers other than health risks, as they do not occur as a consequence of the biological interaction of the chemical with people. They arise through inappropriate handling or use and can often result in injury to people and/or damage to property as a result of the intrinsic physical hazard. Examples of physicochemical hazards include flammable, corrosive, explosive, chemically reactive zand oxidising chemicals. Many chemicals have both health and physicochemical hazards.
Toxic materials are substances that may cause harm to an individual if it enters the body. Toxic materials may enter the body in different ways. These ways are called the route of exposure. The most common route of exposure is through inhalation (breathing it into the lungs). Another common route of entry is through skin contact. Some materials can easily pass through unprotected skin and enter the body. Ingestion is another, less common, route of exposure in the workplace. Ingestion often occurs accidentally through poor hygiene practices (e.g. eating food or smoking a cigarette using contaminated hands).
To prevent exposure to a very toxic material, strict control measures are required. Ventilation is a very important control measure for very toxic materials. Well-designed and well-maintained ventilation systems remove the very toxic vapours, fumes, mists or airborne dusts from the workplace before workers are exposed.
By sudden or short term exposures
A one-time exposure to relatively large amounts of the chemical can overwhelm the body. In the workplace this may happen through improper handling of the chemical, or when there is an accidental spill or a leak from a valve or pipe carrying chemicals. It might also happen during maintenance or cleaning of equipment that normally contains chemicals (such as a solvent vat). The ill-health effects caused by one-time, sudden, high exposures are often called “acute toxicity” effects. Some examples of acute toxicity are listed below:
- Inhalation of high concentrations of acid vapours might cause serious burns of the mouth and airways leading to the lungs.
- Skin contact with substantial amounts of certain organic solvents that are absorbed through the skin may cause dizziness and nausea.
- Inhalation of dusts can cause irritation of the respiratory tract, dryness in the throat, and coughing.
By repeated exposures over a long period of time
A repeated exposure over a long period of time can also cause too much chemical to enter the body and produce poisoning. This kind of poisoning occurs because the exposure is repeated day after day over many years. The exposure levels may be too small to cause any acute toxicity. Ill-health effects caused in such situations are often called “chronic toxicity” effects. The following are some examples of chronic toxicity:
- Inhalation of certain acid vapours at concentrations which do not cause acute toxicity may, over long periods of time, cause loss of tooth enamel, eventually leading to extensive tooth decay.
- Inhalation and skin absorption of some organic solvents at concentrations which do not cause acute toxicity may, over long periods of time, cause damage to nerve tissue.
- Repeated exposure to dusts containing quartz can cause scar tissue in the lungs. This leads to severe and permanent lung damage.
When considering exposure control measures such as ventilation, there are many considerations, including:
- Toxicity (e.g. LD50, LC50) – this is particularly important for very toxic materials as exposure to VERY small amounts can be harmful or fatal.
- Physical state of the toxic material (e.g. is it a paste? a powder?, a liquid?).
- Chemical properties (e.g. vapour pressure, boiling point, odour threshold, etc.).
- Other potential health effects (e.g. eye or skin irritation?, sensitizer?).
- Potential routes of exposure (inhalation? skin absorption?).
- Quantity used.
- Frequency of use (Once a day? Every day?).
- The job requirements (e.g. how the material is handled).
- Size and layout of the work area.
An assessment of the specific ways that a very toxic material is stored, handled, used, and disposed of is the best way to find out if existing ventilation controls (and other hazard control methods) are adequate.
Generally, with very toxic materials, general (dilution) ventilation does not provide sufficient protection. To prevent a very toxic material from entering the workplace, local exhaust systems are usually required. For larger scale operations, this may require designing the process so that the very toxic material is completely enclosed or isolated from the workplace environment. In other situations, where smaller amounts are used, glovebox isolation units or local exhaust systems are used. Leak detection systems with alarms may be desirable for some situations.
For any of these ventilation systems, particularly ones that deal with very toxic materials, it is important to ensure that:
- Contaminated air does NOT recirculate back into the workspace.
- There is some means of indicating if there is a failure of the system (e.g., alarm system if airflow is compromised).
- Users know how to respond during an emergency or ventilation system failure.
- The protective systems (e.g. ventilation, alarms, etc.) are regularly inspected and maintained by trained individuals who understand the potential hazards and are suitably protected.
In general, when handling very toxic materials:
- Before handling, it is extremely important that engineering controls are operating properly and that required protective equipment requirements and personal hygiene measures are being followed.
- Consider using a closed handling system for processes involving a very toxic material. If a closed handling system is not possible, use the smallest possible amounts in a well-ventilated area separate from the storage area.
- Prevent the release of very toxic vapours, dusts, mists or gases into the workplace air.
- Maintenance and emergency personnel need to be advised of potential hazards.
- Immediately report any leaks, spills or failures of the engineering controls.
- Wear appropriate personal protective equipment to avoid exposure (eye, respiratory or skin) or contact with contaminated equipment/surfaces.
- Never work alone with very toxic materials. Another person must be in view at all times and must be equipped and trained to rescue. Alternatively, precautions such as regular visual checks made by another person or a telephone call-in procedure should be set up to ensure the continued safety of lone workers or workers in remote locations.
- Be alert to the typical symptoms of poisoning and first aid procedures. Report any signs of illness or overexposure immediately to the supervisor. Depending on the material, medical attention for an exposure may be required even if the exposure did not seem excessive. With some materials, symptoms of a severe exposure can be delayed.
- Do not return contaminated or unused material to the original container.
- Ensure containers are clearly labeled and inspect containers for leaks or damage before handling.
- Keep containers tightly closed when not in use.
- To prevent spillage, use proper tools to open containers and to transfer material.
- Pour very toxic liquids carefully from the container to avoid splashing and spurting.
- Maintain good housekeeping (e.g. clean surfaces, no accumulation of dust).
- Avoid any welding, cutting, soldering or other hot work on an empty container or piping until all very toxic liquid and vapours have been cleared.
- For large-scale storage of this material consider the installation of a leak detection system with an alarm.
- Ensure suitable emergency equipment for fires, spills and leaks are readily available.
- In the event of a spill or leak of a very toxic material, evacuate the work space.
- Ensure emergency eyewash/shower stations are readily available and are tested regularly.
Physical and Synergism
Synergism comes from the Greek word “synergos” meaning working together. It refers to the interaction between two or more “things” when the combined effect is greater than if you added the “things” on their own (a type of “when is one plus one is greater than two” effect).
There are several factors which can influence the degree of poisoning caused by a chemical. These are as follows:
- Route of entry into the body
- Amount or dose entering the body
- Toxicity of the chemical
- Removal from the body
- Biological variation
In toxicology, synergism refers to the effect caused when exposure to two or more chemicals at as time results in health effects that are greater than the sum of the effects of the individual chemicals.
When chemicals are synergistic, the potential hazards of the chemicals should be re-evaluated, taking their synergistic properties into consideration.
What are related terms?
In addition to synergism, other terms are used to define the toxicologic interactions.
Additive Effect – This action occurs when the combined effect of two or more chemicals is equal to the sum of the effect of each agents given alone (they do not interact in a direct way); for example:
2 + 2 = 4
This effect is the most common when two chemicals are given together.
Potentiation – This effect results when one substance that does not normally have a toxic effect is added to another chemical, it makes the second chemical much more toxic; for example:
0 + 2 > 2, not just 2
Antagonism – Antagonism is the opposite of synergism. It is the situation where the combined effect of two or more compounds is less toxic than the individual effects; for example:
4 + 6 < 10
Antagonistic effects are the basis of many antidotes for poisonings or for medical treatments. For example, ethyl alcohol (ethanol) can antagonize the toxic effects of methyl alcohol (methanol) by displacing it from the enzyme that oxidizes the methanol
In comparison, a synergistic effect is the situation where the combined effect of two chemicals is much greater than the sum of the effects of each agent given alone, for example:
2 + 2 >> 4 (maybe 10 times or more)
Why does synergism occur?
While the mechanisms of synergism can change from situation to situation, most of the time there appears to be an effect on the enzymes that regulate or influence the way our bodies work.
Our bodies have enzymes that are designed to do specific “jobs”. For example, there is an enzyme that helps break down alcohol – this is why we do not stay intoxicated “forever” after consuming alcohol. These enzymes normally transform (metabolize) the foreign substances (alcohol in this example) into less toxic or non-toxic substances which are eliminated out of the body.
With synergism, an enzyme function could either be inhibited (restricted) or accelerated in some way. Either way, the result is that the chemicals are either “free” or “enhanced” to cause a greater biologic effect in the body.
What are examples of synergism?
There are various examples including:
(a) Carbon tetrachloride and ethanol (ethyl alcohol) are individually toxic to the liver, but together they produce much more liver injury than the sum of their individual effects on the liver.
(b) The much higher incidence of lung cancer resulting from occupational exposure to asbestos in smokers (compared to exposed non-smokers).
(c) The toxicity of some insecticides notably pyrethrin (from chrysanthemums) and synthetic pyrethrins (pyrethroids) can be increased many times by the addition of compounds which themselves are not insecticides. These synergists are sesamin, sesamolin, piperonyl butoxide, MGK-264 (bicycloheptenedicarboximide) and sesamex. Piperonyl butoxide is perhaps the most widely used synthetic pyrethrin synergist. The insecticide activity of pyrethrins increases tenfold when 1 part piperonyl butoxide is mixed with 9 parts pyrethrin. There are no reports available on toxic effects on humans resulting from the exposure to piperonyl butoxide.
(d) Barbiturate drugs have a greater effect on the central nervous system (CNS) by causing CNS depression when taken with general anesthetics, alcohol (acute consumption) narcotic analgesic (pain reliever) and other sedative hypnotic drugs.
Here are some examples of commonly used household products that can damage your health or cause a fire or explosion if used incorrectly:
• cleaning products such as toilet cleaners, disinfectants, mildew remover and chlorine bleach
• art supplies, such as paint thinner and pottery glazes
• garage supplies, such as parts degreasers and cleaning solvents
• office materials, such as photocopier toner
Three main chemical states
All chemicals exist in one of three states: solid, liquid or gas.
•A solid has shape and form, whether it’s a dust particle or a steel pipe.
•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.
Some chemicals move from one state to another with a change in temperature or pressure. Water is a chemical which is normally a liquid but becomes a solid at temperatures below 0 degrees Celsius.
Knowing the physical states of hazardous chemicals is important factor in understanding their health effects. The physical state of a chemical determines which route it may use to enter the body. For example, a gas may easily enter the body by inhalation, while liquids are more likely to be absorbed through the skin. The fact that chemicals may change their state during work processes that involve changes in temperature and pressure makes it all the more important to take all the possible states of a chemical into account.
Common chemical hazards
Specific types of chemicals have been associated with harmful health effects. Common chemical hazards include:
• skin irritation, disfiguring burns, eye injury or blindness caused by corrosive chemical products
•toxic by-products, such as vapours and fumes, caused by mixing incompatible chemicals
•serious burns from flammable solvents that catch on fire
•injury from exploding containers, such as spray cans
•poisoning from accidental swallowing, especially with young children
Controlling chemical hazards in the workplace
•Reduce or eliminate the use of hazardous chemicals whenever possible.
•Maintain adequate ventilation systems to reduce concentrations of airborne chemicals.
•Practicing good personal hygiene (e.g. washing hands) and maintaining regular workplace cleaning routines can reduce the amount of a chemical substance that is absorbed by a worker’s body. Learn how to avoid carrying hazardous substances home.
• Introduce administrative controls to minimize exposure to chemicals (e.g. rotate workers through different jobs or locations, perform maintenance work in off-hours so that accidental release of toxic substances will affect fewer workers).
•Use personal protective equipment and devices.
• Maintain equipment in good order to prevent leaks and breakdowns that may release toxic substances.
Health hazards include skin irritants, carcinogens or respiratory sensitisers that have an adverse effect on a worker’s health as a result of direct contact with or exposure to the chemical, usually through inhalation, skin contact or ingestion.
Physicochemical hazards generally result from a substance’s physical and chemical properties, as is the case with flammable, corrosive, oxidising or explosive substances.
A person conducting a business or undertaking has a primary duty to ensure, so far as is reasonably practicable, that the health and safety of workers and other people are not put at risk from the business’s use, handling or storage of hazardous chemicals.