Element 7: Chemical and biological agents

 

7.1 Hazardous substances

Forms of chemical agent: dusts, fibers, fumes, gases, mists, vapors and liquids

• Forms of biological agents: fungi, bacteria and viruses
• Difference between acute and chronic health effects
• Health hazard classifications: acute toxicity; skin corrosion/irritation; serious eye damage/eye irritation; respiratory or skin sensitization; germ cell mutagenicity; carcinogenicity; reproductive toxicity; specific target organ toxicity (single and repeated exposure); aspiration hazard.

 

7.2 Assessment of health risks

• Routes of entry of hazardous substances into the body
• The body’s defense mechanisms (superficial and cellular)
• What needs to be taken into account when assessing health risks
• Sources of information:

> Product labels

> Safety data sheets (who must provide them and information that they must contain)

• Limitations of information used when assessing risks to health
• Role and limitations of hazardous substance monitoring.

 

 

7.3 Occupational exposure limits

Purpose of occupational exposure limits

• Long-term and short-term limits
• Why time-weighted averages are used
• Limitations of exposure limits
• Comparison of measurements to recognized standards.

 

 

7.4 Control measures

• The need to prevent exposure or, where this is not reasonably practicable, adequately control it
• Common measures used to control exposure to hazardous substances (‘Ambient factors in the workplace’, ILO Code of Practice – chapters 4.3–4.5)
• Additional controls that are needed for substances that can cause cancer, asthma or genetic damage that can be passed from one generation to another.

 

 

 

 

 

7.5 Specific agents

• Health risks, controls and likely workplace activities/locations where the following specific agents can be found:

> Asbestos (excluding removal and disposal)

> Blood-borne viruses

> Carbon monoxide

> cement

> Legionella

> Leptospira

> Silica

> Wood dust.

 

 

 

 

 

 

 

 

7.1 Hazardous substances

Harmful Chemical and Biological agents/substances

Many things used or made at work could be bad for health. They include solid, liquid, and gaseous chemicals as well as biological agents like bacteria, viruses, and other microorganisms that can cause infections, allergic reactions, or are toxic. Diseases like HIV, Hepatitis, influenza, etc. can be passed from person to person, and diseases like malaria, dengue fever, weil’s disease, etc. can be passed from animals to people.

The agents or substances can be in different forms or spread in different ways, such as dusts, gases, or fumes that are breathed in, or liquids, gels, or powders that come into contact with eyes, mucous membranes, skin, or in some cases are accidentally swallowed. Lastly, some agents can be injected by accident or spread through animal stings, bites, or waste.

Harmful agents or substances can be found in paints, cleaners, water, flour or other dusts, solder fume, air conditioning systems, blood, and waste.

It is possible to avoid getting sick from these things used or made at work. Many things can hurt health, but when they are used right, they almost never do.

Forms of Chemical Agents

Dust – Solid particles made by machines (e.g. from crushing, drilling, grinding, sweeping, or handling of solid materials).

Fume – Solid particles that form when gaseous particles turn into solids. This usually happens after a molten substance has evaporated (for example, when welding) and is often accompanied by a chemical reaction like oxidation. Gases and vapours are not fumes.

Vapour – A solid or liquid at room temperature and pressure that turns into a gas..

Gas – A gas-like substance that is at room temperature and pressure.

Aerosol – Particles, either solid or liquid, that stay in the air for a while. Mists, smokes, fumes, and dusts are all types of aerosols.

Liquid– Flowing freely like water; fluid; neither solid nor gas; made up of particles that can move freely around each other with the slightest pressure. liquid nitrogen.

Fibres– Fibers are structures that look like threads and are thin, long, and flexible.

Forms of Biological Agents

When you get a pathogen inside your body, you get sick. Pathogens are parasites, which means they get their food from the body of the host they are in. You would be the host in this case. Pathogens can also make poisons that can hurt you if they get out. So, what is a pathogen exactly?

You might want to learn more about bacteria, viruses, and fungi, which are three common types of pathogens. These three kinds of living things are all very different..

Bacteria

Bacteria are single-celled organisms that are very small and can be found almost anywhere. There are bacteria on your desk, on your skin, in your body, and even on this computer screen. Most bacteria don’t cause disease. This means that most of the time, they don’t make people sick.

But you can get sick if a bacterium that causes a disease gets into your body. Sometimes the bacteria themselves make you sick, and sometimes a toxin made by the bacteria does. Pink eye and strep throat are two infections that are often caused by bacteria.

Fungus

Mushrooms are a common type of fungus that you probably know. Fungi don’t just come in the form of mushrooms, though. They are actually a whole kingdom of life, and while most of them are harmless to people, a few of them can make people sick.

One example is that athlete’s foot is often caused by the fungus Epidermophyton floccosum. The mushrooms we’re used to are much bigger than this fungus. To see it, you usually need a microscope.

Fungi get the energy they need to live from other living things. Most of the time, they do this by eating the dead parts of plants. In the same way, many dangerous fungi feed on the dead outer layers of our skin. This is what causes athlete’s foot or ringworm symptoms like itching and peeling.

Some fungi, called mycotoxins, also make poisons. The most common way for people to get mycotoxins is by eating poisonous mushrooms by accident.

 

 

Viruses

The smallest common pathogen is a virus. They are so small that many of them can get into bacteria and make them sick. They are different from other diseases because they can’t make more copies of themselves. When a virus gets into a cell, it takes over and uses the cell’s own processes to make more copies of itself. This is called a copy.

A virus can sometimes stay in a cell for a long time before it starts to make copies of itself. This means that you can get sick after being exposed to a virus for a long time. The Chicken Pox is a common viral infection that often stays dormant in the body and isn’t noticed. Varicella zoster stays in your body even after you’ve had Chicken Pox. It stays dormant in your body and can come back to cause shingles in your later years.

Many common health problems can be traced back to viruses. Some examples are the flu, the cold, warts, and cold sores. A cold is an infection in the nose and upper airways. There are more than 200 different viruses that can cause colds. But there are only three kinds of viruses that cause the flu: influenza A, B, and C.

Acute and Chronic Health Effects

Acute Health Effect

Acute health effects are bad things that happen to your body quickly after being exposed to high levels or concentrations of harmful substances.

Most of the time, irritations like rashes and dry skin, as well as acute dermatitis, are the first signs of a health problem. Materials that are corrosive can cause burns and break down skin tissue. People may also be very sensitive to something that sends them into anaphylactic shock. Other common acute health effects include metal fume fever and lethal concentration (LC). Another example is fibreglass, which can immediately make your skin red and itchy. In the same way, a very loud noise can cause temporary or even permanent hearing loss right away.

Chronic Health Effect

A negative health effect that lasts for a long time is called a chronic health effect. Most of the time, symptoms don’t go away when the exposure stops. Asthma and cancer are examples of long-term health problems.

Health Hazard Classification

Acute toxicity is when a single dose of a substance is given orally or topically, or when multiple doses are given within 24 hours, or when a person breathes in a substance for 4 hours.

Skin corrosion is when a test substance is put on the skin for up to 4 hours and causes damage that can’t be fixed. This is shown by visible necrosis through the epidermis and into the dermis, which is a sign of irreversible skin damage.

Skin irritation is when a test substance is put on the skin for up to 4 hours and causes damage that can be fixed.

Corrosive chemicals are those that can kill living cells when they come into contact with them. In toxicology, the word “corrosive” usually refers to a substance that, when it comes into contact with the skin, eyes, or lining of the lungs or stomach, causes damage that can be seen. Ulcers, cell death, and scars are all signs of corrosion. In general, corrosive materials have a pH that is very low (acids) or very high (bases) (bases). Most of the time, strong bases are more damaging than acids. Soda hydroxide, also called “lye,” and sulfuric acid are both examples of corrosive materials.

Irritant chemicals are non-corrosive substances that can cause inflammation when they come into direct contact with the tissue in question. Dermal irritation is an inflammatory skin reaction that can be caused by a single or multiple exposures to a physical or chemical agent at the same site.

A sensitizer is something that can cause an allergic reaction in people who are prone to them. Because of this, after a first exposure that makes a person sensitive, subsequent exposures through the skin or through the lungs cause the typical bad health effects of allergic contact dermatitis or asthma (and related respiratory symptoms like rhinitis).

Genotoxicity is a harmful endpoint that can be caused by both somatic mutations and mutations in germ cells. In order to protect human health, it is important to know if a chemical can cause mutations in germ cells, which could affect future generations. Damage to DNA and changes in how genes are expressed can have effects on genes. This change is called mutagenesis. The change in genes is called a mutation, and the thing that makes the change is called a mutagen.

Mutagenicity is the ability of some chemicals to change the DNA in a cell’s nucleus in a way that lets the changes be passed on when the cell divides.

A carcinogen is a substance or group of substances that causes cancer or makes it more likely to happen. For example, asbestos, vinyl chloride, dust from hardwood, mineral oils, etc..

The bad effects that a chemical has on any part of a mammal’s ability to reproduce are called “reproductive toxicity.” It includes all parts of the reproductive cycle, such as damage to the male or female reproductive organs, their function, or their ability to reproduce, as well as death, stunted growth, and structural and functional changes in the offspring that aren’t passed down from the parents.

Specific target organ toxicity – single exposure (STOT-SE) is toxicity to a specific organ caused by a single exposure to a chemical that does not kill the organ. All-important health effects that can hurt function, whether they are temporary or permanent, immediate or delayed.

Specific target organ toxicity – repeated exposure (STOT-RE) means that a chemical makes a certain organ sick when it is exposed to it more than once. All-important health effects that can hurt function, whether they are temporary or permanent, immediate or delayed,

Aspiration is when a liquid or solid chemical goes straight into the trachea and lower respiratory system through the mouth, nose, or through vomiting.

 

7.2 Assessment of health risks

Routes of entry into the Body

Airborne contaminants can be breathed in through the nose or mouth. This is called “inhalation.” Dust, mist, fumes, vapours, and gas are all types of contaminants. The most common way for a chemical to get into the body is by being breathed in.

Absorption is what happens when dangerous chemicals are taken in through the skin or eyes. Some of these chemicals can be solids (like dust and smoke), liquids, gases, or vapours.

Dangerous chemicals are taken in through the mouth during ingestion. These include chemical dusts, particles, and mists that are inhaled through the mouth and swallowed or that have gotten on things like hands, food, and cigarettes that come in contact with the mouth.

Injections can happen when syringe needles are used wrong or when broken glass or other sharp objects that have been contaminated with chemicals are used by accident. Injections can also happen through streams of liquids or gases that are under a lot of pressure.

Defense mechanisms of the Body

Microorganisms would quickly take over the body if it didn’t have ways to fight them off. For these defences to work, the body needs to be alive and working well. Because its defences are no longer working, a dead body starts to rot almost right away.

Organisms that can make you sick are kept out of your body by natural defences and your immune system. (See also Defense Lines.)

The skin, mucous membranes, tears, earwax, mucus, and stomach acid all act as natural barriers. Microorganisms that get into the urinary tract are also washed away by the normal flow of urine.

White blood cells and antibodies are used by the immune system to find and kill organisms that get past the body’s natural defenses.

Most of the time, microorganisms can’t get through the skin unless it is broken (for example, by an injury, insect bite, or burn).

Mucous membranes, like the lining of the mouth, nose, and eyelids, are also good barriers. Mucous membranes are usually covered with secretions that fight off germs. For example, the mucous membranes of the eyes are bathed in tears, which contain an enzyme called lysozyme that kills bacteria and helps keep the eyes from getting sick.

Particles in the air that is breathed in are filtered out by the airways. Mucus coats the walls of the passages in the nose and airways. Microorganisms in the air stick to the mucus, which is then coughed up or sneezed out. Cilia, which look like tiny hairs and line the airways, beat in sync to help move mucus out of the body. Mucus is moved away from the lungs by the cilia, which move it up the airways.

Some of the effective barriers in the digestive tract are stomach acid, pancreatic enzymes, bile, and secretions from the intestines. These things can kill bacteria or stop them from making more of themselves. Peristalsis, which moves bowel contents through the digestive tract, and the normal shedding of cells that line the intestine both help get rid of harmful microorganisms..

There are also several good barriers in the urinary tract. The urethra, which is the tube that drains urine out of the body, protects the bladder. In men, the urethra is long enough that bacteria don’t usually get to the bladder. If they do, it’s usually because a catheter or surgical tool put them there by accident. In women, the urethra is shorter, which sometimes lets bacteria from the outside get into the bladder. When the bladder is empty in both men and women, it flushes out any bacteria that get in.

The Blood

The body also fights infections by making more neutrophils and monocytes, two types of white blood cells that engulf and kill microorganisms that try to enter the body. The increase can happen within a few hours, mostly because white blood cells are released from the bone marrow, which is where they are made. First, the number of neutrophils grows. If an infection doesn’t go away, more monocytes are made. White blood cells go to places where there is an infection through the blood.

Eosinophils are another type of white blood cell. The number of eosinophils goes up during allergic reactions and many parasitic infections, but not during bacterial infections most of the time.

But infections like typhoid fever, viral infections, and bacterial infections that are too strong for the immune system can cause the white blood cell count to drop.

Inflammation

Microorganisms would quickly take over the body if it didn’t have ways to fight them off. For these defences to work, the body needs to be alive and working well. Because its defenses are no longer working, a dead body starts to rot almost right away.

Organisms that can make you sick are kept out of your body by natural defenses and your immune system. (See also Defense Lines.)

The skin, mucous membranes, tears, earwax, mucus, and stomach acid all act as natural barriers. Microorganisms that get into the urinary tract are also washed away by the normal flow of urine.

White blood cells and antibodies are used by the immune system to find and kill organisms that get past the body’s natural defenses.

(See also Overview of Infectious Disease.)

Natural Barriers against Infection

Usually, the skin prevents invasion by microorganisms unless it is damaged (for example, by an injury, insect bite, or burn).

Mucous membranes, like the lining of the mouth, nose, and eyelids, are also good barriers. Mucous membranes are usually covered with secretions that fight off germs. For example, the mucous membranes of the eyes are bathed in tears, which contain an enzyme called lysozyme that kills bacteria and helps keep the eyes from getting sick.

Particles in the air that is breathed in are filtered out by the airways. Mucus coats the walls of the passages in the nose and airways. Microorganisms in the air stick to the mucus, which is then coughed up or sneezed out. Cilia, which look like tiny hairs and line the airways, beat in sync to help move mucus out of the body. Mucus is moved up the airways and away from the lungs by cilia.

Some of the effective barriers in the digestive tract are stomach acid, pancreatic enzymes, bile, and secretions from the intestines. These things can kill bacteria or stop them from making more of themselves. Peristalsis moves the contents of the intestine through the digestive tract. The normal shedding of cells that line the intestine also helps get rid of harmful microorganisms.

There are also several good barriers in the urinary tract. The urethra, which is the tube that drains urine out of the body, protects the bladder. In men, the urethra is long enough that bacteria don’t usually get to the bladder. If they do, it’s usually because a catheter or surgical tool put them there by accident. In women, the urethra is shorter, which sometimes lets bacteria from the outside get into the bladder. When the bladder is empty in both men and women, it flushes out any bacteria that get in.

Most of the time, the vagina is acidic. The vagina is acidic, which keeps bad bacteria from growing and helps keep the number of good bacteria steady.

The Blood

The body also fights infections by making more neutrophils and monocytes, two types of white blood cells that engulf and kill microorganisms that try to enter the body. The increase can happen within a few hours, mostly because white blood cells are released from the bone marrow, which is where they are made. First, the number of neutrophils grows. If an infection doesn’t go away, more monocytes are made. White blood cells go to places where there is an infection through the blood.

Eosinophils are another type of white blood cell. The number of eosinophils goes up during allergic reactions and many parasitic infections, but not during bacterial infections most of the time.

But infections like typhoid fever, viral infections, and bacterial infections that are too strong for the immune system can cause the white blood cell count to drop.

Inflammation

• Any kind of injury, like an infection, causes inflammation in the area that was hurt. Inflammation is a complicated reaction that can be caused by many different things. The damaged tissue releases chemicals that cause inflammation and tell the immune system to do the following:
• Wall off the area
• Attack and kill any invaders
• Dispose of dead and damaged tissue
• Begin the process of repair

However, inflammation may not be able to overcome large numbers of microorganisms.

When there is inflammation, the blood supply goes up, which helps immune cells get to the area that is hurt. Because the blood flow is higher, an infected area close to the skin becomes red and warm. The walls of blood vessels become more porous, which lets fluid and white blood cells get into the affected tissue. The swelling of the inflamed tissue is caused by the extra fluid. The white blood cells attack the microorganisms that are invading and release chemicals that keep the inflammation going.

Other substances cause the tiny blood vessels in the infected area to clot, which slows the spread of the microorganisms and their poisons.

Many chemicals released during inflammation activate nerves, resulting in discomfort. Infection is usually accompanied with chills, fever, and muscle aches, which are reactions to the compounds released during inflammation.

Immune Response

When an infection develops, the immune system also produces a number of chemicals and agents tailored to combat the specific germs that have invaded (see Acquired Immunity). Examples are:

• Killer T cells (a type of white blood cell) that can recognize and kill the invading microorganism
• Antibodies that target the specific invading microorganism

Antibodies adhere to bacteria and immobilise them. They kill them directly or assist neutrophils in targeting and killing them.

How effectively the immune system defends the body against each pathogen depends in part on the genetic makeup of the individual.

Assessing Health Risks

A COSHH assessment concentrates on the hazards and risks from hazardous substances in your workplace.

Keep in mind that health risks are not restricted to items labelled “hazardous.” Certain dangerous substances, such as wood dust from sanding or silica dust from tile cutting, can be produced by the procedure you employ.

Identify the hazards

• Identify which substances are harmful by reading the product labels and safety data sheets (SDS)
• If you are in doubt, contact your supplier
• Remember to think about harmful substances produced by your processes, such as cutting or grinding, or to which workers may be otherwise exposed

Decide who might be harmed and how

• How might workers be exposed? Think about the route into the body (whether the substance can be breathed in, get onto or through the skin or can even be swallowed) and the effects of exposure by each of these routes
• Think of how often people work with the substance and for how long
• Think about anyone else who could be exposed
• Don’t forget maintenance workers, contractors and other visitors or members of the public who could be exposed
• Also think about people who could be exposed accidentally, eg while cleaning, or what happens if controls fail

Evaluate the risks and decide on precautions

Once you have carried out a risk assessment and identified which harmful substances are present, and how workers can be harmed, you need to think about preventing exposure.

• Do you really need to use a particular substance, or is a safer alternative available?
• Can you change the process to eliminate its use or avoid producing it? If this is not possible, you must put in place adequate control measures to reduce exposure

The measures you adopt could include the following:

Changing the process to reduce risks

Evaluate whether you can alter your method to lower your exposure risk. Reduce the temperature of a process, for instance, to reduce the amount of vapour released into the air, or use pellets instead of powders since they are less dusty.

Containment

• Enclose the process or activity as much as possible to minimise the escape or release of the harmful substance
• Use closed transfer and handling systems and minimise handling of materials
• Extract emissions of the substance near the source
• Systems of work
• Restrict access to those people who need to be there
• Plan the storage of materials, and use appropriate containers. Check that storage containers are correctly labelled and that incompatible materials, for example acids and caustics, are separated
• Plan the storage and disposal of waste

Cleaning

• Exposure to hazardous substances can occur during cleaning, so plan and organise the workplace so that it can be easily and effectively cleaned
• Smooth work surfaces will allow easy cleaning
• Have the right equipment and procedures to clear up spillages quickly and safely
• Clean regularly using a ‘dust-free’ method – vacuum, don’t sweep

If you have five or more employees, you are required to document your evaluation, but even if you have fewer than five, it makes sense to document the processes you used to identify hazards. Perhaps the most crucial step is documenting the measures you’ve taken to control health risks to your employees.

The risk assessment should be regularly reviewed to ensure that it is kept up to date to take into account any changes in your workplace.

The Law If your organisation uses or generates substances or conducts operations that may be harmful to employees’ health, the law requires you to manage the associated risks. The Control of Substances Hazardous to Health Regulations (COSHH) applies to the majority of dangerous compounds; however, lead and asbestos are governed by distinct regulations, as described further on in this section.

If you manufacture or import chemicals you should look at the European REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) Regulation No 1907/2006.

REACH – European Chemicals Agency (ECHA)

Implementing a Hazard Communication Program

The written program must detail how hazard communication will be addressed at each worksite. It should include:

• An inventory of all hazardous chemicals
• Labeling procedures
• Procedures for maintaining Safety Data Sheets
• Procedures for providing employees with relevant information

Ensure All Chemical Containers Are Labeled

Despite the fact that chemical makers, distributors, and importers are required to mark all exported containers, it is essential to cross-check your inventory to ensure that every chemical is properly labelled. If labelling is performed in-house, verify that the correct format is being used.

Labels must include:

• Product identifier
• Signal word
• Pictograms
• Hazard statements
• Precautionary statement
• Contact information for manufacturer/distributor/importer

Maintain Safety Data Sheets

Every hazardous chemical in the workplace must be accompanied by an employee-accessible SDS. These Safety Data Sheets should be sent automatically by suppliers; if you do not receive one, you must request it immediately.

Safety Data Sheets (SDS) are required by the UK REACH Regulation.

SDS are essential for the safe distribution, handling, and use of chemicals. They ensure that employees who utilise chemicals at work do so safely, without endangering themselves or the environment.

The SDS will contain the information required by the Control of Substances Hazardous to Health Regulations for employers to conduct a risk assessment (COSHH). The SDS is not an assessment on its own. Yet, it will define the hazards, allowing employers to determine the likelihood of their occurrence in the workplace.

SDS are required anytime a hazardous chemical is delivered for workplace use, whether or not it is packaged. If your chemical is not categorised as hazardous but includes trace levels of a hazardous substance, you must additionally provide an SDS.

Generally, an MSDS has 16 sections, each with a fixed heading name. According to the GHS, information in the MSDS should be presented using the following 16 headings:

 

1.Product and Company Identification

2.Hazard(s) identification

3.Composition/information on ingredients

4.First-aid measures

5.Fire-fighting measures

6.Accidental release measures

7.Handling and storage

8.Exposure controls/personal protection

9.Physical and chemical properties

10.Stability and reactivity

11.Toxicological information

12.Ecological information

13.Disposal considerations

14.Transport information

15.Regulatory information

16.Other information.

Inform and Train Employees

Before beginning work, all personnel must get training on the dangerous chemicals in their work environment.

Evaluate and Re-Assess the Program

Every hazardous communication programme should be assessed periodically to ensure that it stays up-to-date and relevant. When completing an assessment, pay special attention to changes, such as the introduction of new substances and risks.

 

Role of Hazardous Substance Monitoring at the Workplace

To guarantee workers’ safety and well-being, employers should monitor and document their exposure to dangerous chemicals. They should ensure that workers are not exposed to substances in excess of exposure limits and other exposure criteria for evaluating and controlling the working environment. Employers should analyse the exposure of workers to dangerous chemicals based on monitoring data.

Airborne concentrations of hazardous substances should be assessed at all workplaces where this is required to protect the health and safety of employees from inhalation threats.

The aims of this programme should be:

(a) To ensure that the health of the workers is efficiently protected;

(b) To ensure that the preventive actions which have been taken are still effective;

(c) To ensure that the levels, as measured previously, remain unchanged or fall;

(d) To ensure that any changes made in manufacturing processes or work practices will not lead to an excessive exposure to hazardous chemicals;

(e) To promote the implementation of more efficient preventive measures.

7.3 Occupational exposure limits

The role and functions of OELs

It would seem that OELs have a variety of functions in the countries we have studied:

They are used as reference tools for monitoring the systematic management of chemical risks in larger businesses when there is experience and support in-house or through the utilisation of technical assistance from external prevention services/occupational hygiene consultants. This is crucial in industries where hazardous chemicals are used, where substitute is not available, and where gear and process specifications do not eliminate the necessity for monitoring performance criteria. Their use in these circumstances may have some benchmarking value for other workplaces, but it is difficult to discover clear evidence of widespread transfer of best practices.

Its employment as reference tools in monitoring workplace exposures in such organisations is also a helpful sign of adequate risk assessment for regulatory bodies in firms where hazardous chemicals are used and where exposure levels are suspected to be high, where enforcement practices are conducted. Their role in this regard is not strictly pursued everywhere, but their existence is significant and especially valuable for pursuing improvements at the “dirty end” of industrial processes. Compliance with OEL-referenced criteria is a useful indicator of excellent behaviour.

OELs are also helpful reference tools, from a scientific/technical standpoint, for wide scale surveillance of exposure, such as has been conducted in Germany with respect to a variety of substances, and which has contributed to our understanding of the health impacts of exposures.

They play an essential role in informing and educating the public about chemical hazards. In spite of widespread ignorance of their precise meaning (and, in some circumstances, their very existence), they remain an essential reference point and objective benchmark for guiding the discourse on prevention methods. These may also serve as useful “standards” for larger employers to adhere to. While it may be difficult to monitor airborne exposures, the existence of OELs places significant pressure on suppliers to give information on the safe use of hazardous chemical items. As such, they play a part in a variety of risk assessment cycle locations. In addition, they play a significant role in deciding the approach to risk assessment and in alerting employers, workers, and their representatives to the need to take risk management concerns in processes involving the use or substitution of such chemicals seriously. Regarding their employment in this context, however, there is a proviso regarding the necessity for a proper comprehension of their meaning. For instance, persistent conceptions that they represent safe levels or values beyond or below which significantly different consequences occur weaken their function and contribute to their misuse.

They may play a useful role in setting specification standards that can be used to determine risk management issues related to the procurement and installation of new plant, with the proviso that they are properly understood. In some instances where monitoring is highly improbable to begin with, such specifications may eliminate the need for it.

Short-term and Long-term Exposure Limits

WELs are occupational exposure limits established to protect the health of British workers. WELs are time-weighted average concentrations of hazardous compounds in the air, also known as a time-weighted average (TWA). Generally, two time periods are employed:

■ Long-term (8 hours); and

■ Short-term (15 minutes).

Short-term exposure limits (STELs) are established to prevent symptoms, such as eye irritation, that may emerge after a few minutes of exposure.

Time-Weighted Average (TWA)

A time-weighted average (TWA) refers to the average rate at which a worker is exposed to a pollutant or adverse situation (such as noise) over a specified period, such as an 8-hour day or 40-hour work week, without experiencing any harmful effects. Typically, the time-weighted average is computed to ensure that the concentration of a potentially hazardous material throughout an eight- to ten-hour workday does not exceed regulatory or legal limits. Moreover, being below a certain time-weighted average may lower the corrosion rate caused by the presence of those compounds.

The time-weighted average represents the period that employees and equipment in a specific area are exposed to chemical substances when concentration and exposure duration vary. In order to calculate the time-weighted average, variables such as dosage rate, duration, and exposure time are incorporated into the formula. For instance, when a worker is exposed to varied quantities of a chemical vapour over varying time periods, the time-weighted average can be used to calculate the worker’s average exposure to that chemical.

Limitations of Occupational Exposure Limits

OELs are not to be confused with air quality standards, which are intended to protect the general public. Neither should they be used to evaluate exposure outside of the workplace. They cannot be used to compare the levels of toxicity of various drugs. Also, it is important to remember that an OEL is produced for a certain chemical and cannot be applied to another substance.

Workers are rarely exposed to a single dangerous material in the job. Typically, there are several. Hence, the risk management strategies used to keep worker exposure below the OEL for a particular substance are not always efficient in limiting the risks associated with exposure to other compounds present in the working environment.

Certain chemicals’ primary mode of exposure is not inhalation, but rather skin absorption and/or dermal absorption. In these instances, Biological Limit Values are utilised in lieu of (or in addition to) inhalation OEL to estimate the danger to exposed personnel.

A further drawback of an OEL is that its numerical value is based on the level of scientific and metrological information at the time it was established and must be changed if new data becomes available.

Experimentation indicates that the numerical values of OELs tend to drop with each revision. Sadly, too many of the present OELs are out of date and can no longer be deemed suitable for protecting the health of workers and their offspring.

In all nations, it is acknowledged that small businesses have low awareness and comprehension of OELs and, consequently, limited capacity to implement them effectively in their risk management plans. Compliance with OELs can also have various connotations in different Member States (Walters et al. 2003).

Recognized Standards

In US various terms are used for Occupational Exposure Limits(OELs) –

The Occupational Safety and Health Administration (OSHA) termed it as Permissible Exposure Limits (PELs).

The American Conference of Governmental Industrial Hygienists (ACGIH) termed it as Threshold Limit Value(TLV)

The National Institute for Occupational Safety and Health (NIOSH) terms this as Recommended Exposure Limits (RELs).

The American Industrial Hygiene Association (AIHA) termed it as Workplace Environmental Exposure Limits (WEELs).

In the European Union(EU) it is termed as Indicative Limit Value.

 

7.4 Control measures

Choosing control measures

In order of priority:

1 Eliminate the use of a harmful product or substance and use a safer one.

2 Use a safer form of the product, eg paste rather than powder.

3 Change the process to emit less of the substance.

4 Enclose the process so that the product does not escape.

5 Extract emissions of the substance near the source.

6 Have as few workers in harm’s way as possible.

7 Provide personal protective equipment (PPE) such as gloves, coveralls and a respirator. PPE must fit the wearer.

Control equipment

Control equipment comes in numerous types. It consists of ventilation to extract dust, mist, and fumes; glove boxes and fume cabinets; spray booths and refuges; and fume hoods (clean rooms in dirty work areas). In addition, technologies for sanitising cooling water and the use of water to decrease dust are included. Your provider must supply a “user handbook” for every control equipment. If you do not have one, request one. And if this is not possible, you may want professional assistance. The user manual should provide schedules for inspections, maintenance, and replacement of parts. Specifically, it should include:

■ a description of the system;

■ the daily checks the worker or supervisor needs to carry out, eg the ventilation is turned on, the airflow indicator gives the right reading;

■ the weekly or monthly checks the supervisor or owner needs to carry out, eg of equipment wear and tear, and that short cuts are not creating dangers;

■ details of any thorough examination and test;

■ signs of wear and control failure;

■ a list of replaceable parts;

■ a description of how operators should use the system so it works effectively.

Correct faults in a timely manner. It is useless to conduct checks if no action is taken when something goes wrong. And you are not effectively managing health and safety if the “thorough investigation and test” results in a lengthy list of “activities required.” Maintain simple records of your checks and actions, such as in a logbook, for at least five years.

Staying in control: Checking and maintaining

Once you’ve got control, you need to keep it. As the employer, you must make sure that the control measures (equipment and the way of working) keep working properly.

You should choose someone to oversee the monitoring and maintenance of control measures. It could be you or someone you appoint, so long as they understand their responsibilities and are capable of carrying them out. Specifically, they are “capable” to:

■ check that the process isn’t emitting uncontrolled contaminants;

■ Check that the control equipment continues to work as it was designed;

■ check that workers follow the right way of working.

Two of the most common control measures where maintenance is critical are local exhaust ventilation (LEV) and personal protective equipment (PPE).

Local exhaust ventilation (LEV)

If you use local exhaust ventilation to control exposure, it must be inspected and tested at least once every 14 months, or more frequently if you are using it with one of the processes mentioned in COSHH Schedule 4 Processes.

• Captor Hoods
• Receptor hoods
• Fume Cupboards
• Glove Box

Captor Hood is Use

Many people, e.g. engineers or insurance companies can carry out thorough examination and testing of LEV.

Personal protective equipment (PPE)

Personal protective equipment is frequently incorporated into control methods. This also requires inspection and maintenance, because if it fails, the user will no longer be protected and will be exposed to danger. Both the users and the supervisors need to know precisely what they’re doing.

• Respiratory Protective Equipment-
• Respirators- Filtering face piece respirator, Half mask single/twin cartridge type respirator, Full Face Canister Respirator
• Breathing Apparatus- Fresh Air-hose Breathing Apparatus, Compressed Airline Apparatus, Self-Contained Breathing Apparatus (SCBA)
• Eye Protection- Safety spectacles/ Safety Goggles
• Full body Coveralls, Aprons
• Foot Protection- Safety Gumboots
• Hands and Fingers- Vinyl or Nitrile Gloves or Gauntlets
• Face Protection- Face Shields

 

PPE suppliers and trade associations can tell you about training in how to use it properly. Skills and experience

Competence

Verify that whoever plans, implements, maintains, and tests your control measures is qualified – that they have the required skills, knowledge, and expertise. You can evaluate the competency of equipment and service providers by asking questions like:

■ Have you done this sort of work before?

■ What are your qualifications?

■ Do you belong to a professional organization?

■ Can I speak to previous clients?

You should look for someone who knows your business, has a good track record, and is worth the money.

Worker involvement

Get your workers involved in coming up with control measures to make sure they are right for how they do their jobs. Encourage them to think of ways to make things better and to let you know if they think something is wrong.

Training, instruction and information

Explain the dangers to your workers and anyone else who needs to know. Just giving them a page of written information is not a good idea.

■ Show workers how to use control measures properly, and how to check that they are working.

■ Carry out practice drills for cleaning up spills safely – do this before any spillages happen.

■ If workers need to use respirators, they also need face fitting and training.

■ If they need to use protective gloves, they need to know how to put them on and take them off without contaminating their skin.

Keeping workers healthy

Monitoring exposure

Monitoring usually means taking samples of the air, but it could also mean taking samples of your body, like your breath or urine. Monitoring usually looks at the “Workplace Exposure Limits” (WELs) that the HSE puts out. You shouldn’t go over these limits (see EH40 in “Find out more”).

It is wasteful to try monitoring before you have put any control measures in place (see COSHH essentials sheet G409 www.hse.gov.uk/pubns/guidance/g409.pdf  on air monitoring).

Health checks

If your trade press, HSE, or other information shows that asthma or dermatitis are health problems in your trade, your employees may need special health checks. Most checks are for skin diseases and diseases of the lungs, like asthma.

Find out more

HSE COSHH website: www.hse.gov.uk/coshh/index.htm

A short guide to the Personal Protective Equipment at Work Regulations 1992

Leaflet INDG174(rev1) HSE Books 2005 www.hse.gov.uk/pubns/indg174.pdf

Clearing the air: A simple guide to buying and using local exhaust ventilation (LEV)

Leaflet INDG408 HSE Books 2008 www.hse.gov.uk/pubns/indg408.pdf

EH40/2005 Workplace exposure limits: Containing the list of workplace exposure

limits for use with the Control of Substances Hazardous to Health Regulations 2002

(as amended) Environmental Hygiene Guidance Note EH40 (Second edition)

HSE Books 2011 ISBN 978 0 7176 6446 7

www.hse.gov.uk/pubns/books/eh40.htm

Fire and explosion: A brief guide to DSEAR in the workplace Leaflet INDG370(rev1)

HSE Books 2012 www.hse.gov.uk/pubns/indg370.pdf

Preventing contact dermatitis at work Leaflet INDG233(rev1) HSE Books 2007

www.hse.gov.uk/pubns/indg233.pdf

Read the label: How to find out if chemicals are dangerous Leaflet INDG352(rev1)

HSE Books 2010 www.hse.gov.uk/pubns/indg352.pdf

Respiratory sensitizers and COSHH: Breathe freely – An employers’ leaflet on

Preventing occupational asthma Leaflet INDG95(rev2) HSE Books 1995

www.hse.gov.uk/pubns/indg95.pdf

 

Specific Chemical Agents

Asbestos

Asbestos is the generic name for 6 different naturally-occurring fibrous minerals.

• Asbestos was used in a wide range of products because it could withstand heat and keep things warm. Before 1990, asbestos was mostly used to keep buildings and homes warm and quiet, and to keep fires from starting. Asbestos was used in products made by industry, construction, and business, such as:
• Building materials (roofing shingles, roof sealants, ceiling and floor tiles, paper products and felts, house siding, and asbestos-containing cement and plaster products).
• Friction materials (automobile clutch pads, brake linings, pads and shoes, and transmission parts).
• Fire and heat protection wear.
• Industrial furnaces and heating systems.
• Asbestos textiles (fabrics).
• Heat, electrical, and sound insulation or wrappings.
• Insulation for hot and cold areas.
• Packing materials, gaskets, linings, and coatings.
• Reinforcement of plastic products, thermoset and thermoplastic resins.
• Filler in resins, plastics and caulking and in asphalt road surfacing.

Health Effects of Asbestos

The adverse consequences of long-term asbestos exposure on human health are widely recognised. Asbestos fibres are easily inhaled and transported to the lower lung areas, where they can induce fibrotic lung disease (asbestosis) and alterations in the chest cavity lining (pleura). These conditions can result in diminished respiratory function and mortality. Asbestos fibre inhalation also raises the risk of lung cancer and mesothelioma.

Enlargement of the heart can also occur as an indirect effect from the increased resistance of blood flow through the lungs.

People are more likely to experience asbestos-related disorders if they:

• are exposed to high concentrations of asbestos,
• are exposed for longer periods of time, and/or
• are exposed to asbestos more frequently.

Asbestos Control program

When handling, removing, or disturbing asbestos-containing materials (ACM), or when the presence of ACM is suspected or verified in the workplace, a control programme is required. The objective is to avoid or reduce the emission of asbestos fibres into the air. The employer is responsible for ensuring that the control plan is prepared and implemented in accordance with local government rules.

In general, the control plan should address:

• Containment of asbestos operations.
• Location, type, friability (how easily it crumbles), and condition of ACM in the workplace.
• Controlling of the release of asbestos fibres.
• Reporting procedures for suspected ACM.
• The engineering controls, work practices, hygiene practices, and facilities necessary to control the exposure of a worker to asbestos.
• Providing workers with task-specific work instructions that address both the hazards and the necessary controls.
• Providing, using and maintaining appropriate personal protective equipment and clothing.
• The methods and procedures needed to monitor the concentration of airborne asbestos and the exposure of a worker.
• The methods needed to decontaminate workers clothes, etc.
• The removal and clean-up of asbestos waste and related material.

Blood-Borne Viruses (BBVs)

Blood Borne Viruses (BBVs) are viruses that may be carried by some people’s blood and which may cause severe disease in certain people and few or no symptoms in others. Some of the main BBVs are:

• Hepatitis B, C and D viruses which cause the liver disease hepatitis.
• Human Immunodeficiency Virus (HIV) which causes AIDS (Acquired Immune Deficiency Syndrome) which affects the immune system of the body.

The viruses can also be found in breast milk. Other body fluids or materials such as urine, faeces, saliva, sweat and vomit carry a minimal risk of BBVs unless they are contaminated with blood.

 

Who is at Risk?

Workers in the refuse and recycling industry, laundry workers, laboratory workers, vehicle recovery and repair workers, correctional officers, emergency responders, morticians, hair stylists, beauticians, dentists, needle exchange service workers, plumbers, local authority workers, tattooists, and healthcare personnel may be at risk. The danger of contracting a BBV while doing first aid responsibilities is low, however adequate precautions must be taken.

Preventing Infection

The following precautions can help to reduce the risk of infection:

• Avoid all contact with blood or body fluids where possible. Cover breaks in exposed skin by means of waterproof dressings and/or gloves.
• Treat all blood or blood products as if it were infectious.
• Use engineering controls e.g. needle safe systems.
• Use safe work practices e.g. have documented safe practices for handling and disposing of contaminated sharps, handling specimens, handling contaminated laundry, items and surfaces etc.
• Wear appropriate Personal Protective Equipment (PPE) to avoid contamination e.g. gloves, goggles or visor, disposable clothing protection such as aprons.
• Make hepatitis B vaccinations available to those at risk.
• Ensure emergency procedures and post-exposure plans are in place for those who experience an exposure incident e.g. needlestick injury.
• Follow good basic hygiene practices such as hand washing before and after glove use and avoid hand to mouth or eye contact.

Carbon Monoxide :- Carbon monoxide is a toxic, odourless, tasteless, and colourless gas. It is a gas that is non-irritant, lighter than air, and very little soluble in water.

Owing to these features plus the fact that it might be produced unintentionally by incomplete combustion (due to a lack of oxygen), it is commonly known as a silent killer. It is extremely combustible and is also known as carbonic oxide or coal gas.

Carbon monoxide is an important industrial gas with numerous applications in the production of bulk chemicals, such as the production of acetic acid.

As a common industrial danger, carbon monoxide is produced by the incomplete combustion of any carbon-based fuel. Coal, gasoline, diesel, liquefied petroleum gas (LPG), natural gas, and wood are examples of carbon-based fuels.

Employees at risk are those working:

• In locations where there is faulty or inefficient fuel-burning equipment, for example, heaters, furnaces, vehicles, engines, generators, leaking chimneys or vents.
• You are most at risk from carbon monoxide exposure if you are working in a place where there is a petrol or diesel driven generator or other engine driven appliance, gas heater or other unflued appliance;
• In the vicinity of appliances which have poorly maintained, damaged, blocked or sealed flues. Heavy condensation in the area and / or staining of the flue is a sign of possible carbon monoxide exposure;
• With fuel burning powered appliances and tools which generate carbon monoxide.
• Workers using gasoline, diesel, or gas-powered tools/appliances such as concrete cutting saws, power floats, floor grinders, small mobile plant, diesel forklift trucks, compressors, and generators in poorly ventilated places or enclosed spaces are susceptible to carbon monoxide poisoning;
• In the cab of vehicles with defective exhaust systems;
• Directly with carbon monoxide gas in industrial applications.

Occupations which may be at risk of exposure to carbon monoxide include:

• Security guards / watchmen;
• Construction workers;
• Fire fighters;
• Garage mechanics;
• Toll booth attendants;
• Truck drivers;
• Welders;
• Multi-storey or underground car park attendants;
• Roll on – Roll off (Ro-Ro) workers / dockers.

Health effects of Carbon Monoxide

The effect is proportional to the amount and duration of exposure to the petrol. Carbon monoxide poisoning is reversible if detected in time. Long-term exposure to low concentrations of carbon monoxide may cause heart disease and nerve damage.

Carbon monoxide is a reproductive poison of category 1. This indicates that the material is recognised to be hazardous to human reproduction; exposure of pregnant women to carbon monoxide may result in reduced birth weight, cardiomegaly (enlarged heart), delays in behaviour development in neonates, and damage to children’s nervous systems. The normal concentration of carbon monoxide in the air we breathe is unlikely to be harmful.

How to prevent Carbon Monoxide exposure?

• You can reduce the chances of carbon monoxide exposure in your workplace if you:
• Check your workplace to see if you have any equipment, tools or appliances that produce carbon monoxide.
• Do not use petrol / diesel powered engines or tools in poorly ventilated areas, inside buildings or in partially enclosed areas unless:

– The engines can be located outside with at least a metre of clear space all around, in order to ensure adequate ventilation. Ensure that the engine is also situated away from air intakes, for instance air conditioning intakes and air vents;

– An effective ventilation system that will remove carbon monoxide from work areas has been installed.

• Ensure appropriate hazard warning labels are placed on any equipment, tools or appliances likely to produce carbon monoxide.
• Change from petrol / diesel powered equipment to equipment powered by electricity, batteries or compressed air, provided it can be used safely.
• Maintain and service equipment and appliances. Ensure that equipment is installed and maintained by a competent person.
• Ensure that existing vents are working and are not blocked.
• Educate workers about carbon monoxide exposure, ensure that they know how to recognise the symptoms and signs of exposure.
• Ensure that only authorised personnel operate any equipment, tools or appliances that are likely to produce carbon monoxide and that those personnel have adequate instruction, information and training.
• If there is a chance of being exposed to the gas, install carbon monoxide monitors with audible alerts or offer personal carbon monoxide monitors. Such monitors should not be utilised in place of safe working practises, as well as for equipment use and maintenance, but rather as a backup.
• Give personnel with the personal protective equipment they need to perform their jobs in environments where carbon monoxide may be present, such as self-contained breathing apparatus for firefighters.

Cement

Concrete and mortar are both made of cement, which can lead to major skin issues like dermatitis and burns. Determine which tasks will involve the use of cement-based goods. Particularly at danger are workers who handle or mix cement powder or use wet mortar and cement. Look for any skin or allergy issues you may already have, as this work may make them worse. Follow the below-listed control measures.

Cement powder is also a respiratory irritant. The dust produced while cutting, drilling etc dried concrete and mortar can cause more serious lung disease.

Skin problems are not just a nuisance, they can be very painful and sometimes debilitating. Cement and cement-based products can harm the skin in a number of ways.

The nature of wet cement is rather alkaline. If it is pressed up against the