Biological Hazards

After reading this chapter, you will be able to:

• ➤ Define biological hazards and explain how they affect workers.
• ➤ Explain how biological hazards can be transmitted to workers.
• ➤ Assess the positive and negative impact of science on worker safety.
• ➤ Argue for and against the use of the precautionary principle.
• ➤ Develop a control strategy for a biological hazard using the location of control approach.

In the spring of 2020, the COVID-19 virus brought biological hazards to the forefront of OHS practitioners’ minds. The largest workplace outbreak in Canada occurred at the Cargill meatpacking plant in High River, Alberta, just south of Calgary. Meatpacking entails the slaughter, dismemberment, and packaging of animals. It is a physically demanding job that exposes workers to numerous physical hazards (e.g., sharp objects, repetitive motions) and biological hazards (e.g., blood, feces, and bacteria).

Approximately 2,000 workers were employed at Cargill, including significant numbers of recent immigrants and migrant workers. Migrant workers are an attractive type of worker for meat-processing employers because their work visas effectively tie them to the employers. This makes them less likely to resist low wages and poor working conditions.1 Like most meat-processing plants, to maximize productivity, Cargill’s plant puts workers in close quarters with each other, often with poor ventilation.

In light of the risk posed by COVID-19, Cargill implemented a series of ultimately ineffective COVID-19 protocols (e.g., more cleaning, altered schedules, banning visitors) while initiating an attendance-based bonus program to incentivize workers to come to work every day.2 The first COVID-19 case at the plant was confirmed on April 6. Cargill refused to hold an emergency meeting of the plant’s joint health and safety committee, provide additional distance between workers, or provide more effective personal protective equipment. It also refused to identify infected workers so that close contacts could take precautions. Instead, Cargill implemented temperature checks and symptom screening upon entry to the plant.

By April 13, there were 38 confirmed cases in the plant. Cargill refused a request by the workers’ union for a two-week shutdown, calling it “inflammatory.” The next day government Occupational Health and Safety (OHS) inspectors, fearing for their own safety, performed a plant inspection via online video and declared it as safe as “reasonably practicable.” Union concerns about the quality of this inspection were ignored. On April 18, government officials, including the chief medical officer of health, held a town hall with workers. They declared the plant safe and urged the workers to continue to go to work, even though the provincial health authority knew that 200 workers at the plant had tested positive. The next day the first worker at Cargill (Niep Bui Nguyen, 67) died from COVID-19. Family members of some Cargill employees also became ill. Some of those family members worked in local long-term-care facilities.

The union, barred from Cargill’s meeting, held its own virtual town hall and informed workers about their right to refuse unsafe work. Over the next 24 hours, hundreds of workers invoked that right (i.e., refused to go to work by citing the imminent danger from COVID-19), and Cargill subsequently announced a two-week shutdown. The plant reopened on May 4, the same date that the government linked over 900 COVID-19 cases to the plant. A second worker (Benito Quesada, 51) at Cargill died because of COVID-19 on May 9. A few days earlier the father of a Cargill worker (Armando Sellegue, 71) had also died.3 Eventually, nearly 1,000 Cargill workers tested positive, and over 600 other cases were linked to these workers, which at the time comprised over 25% of Alberta’s confirmed COVID-19 cases.4

The COVID-19 outbreak at Cargill’s High River plant illustrates the potential harm that uncontrolled biological hazards can cause to workers. It also illustrates again the permeable barrier between occupational health and safety and public health. Biological hazards, such as viruses, can be transmitted both inside and outside the workplace. Preventing the spread of diseases caused by biological hazards often requires controls both in the workplace and in the general population.

A useful historical example is cholera. It is a disease caused by exposure to bacteria, often from drinking water (whether at home or work) contaminated by human feces. Cholera can trigger severe diarrhea (10–20 litres per day), which in turn causes dehydration and electrolyte imbalance. Untreated, the disease can be 50–60% fatal. In the Global North, cholera outbreaks have been largely eliminated through water- and sewage-treatment programs as well as surveillance, sanitation regulations (particularly in the food industry), medical care, and, in some cases, vaccination.5 The principles developed to control diseases such as cholera continue to inform our response to biological hazards.

As we saw in Chapter 3, biological hazards are organisms or the products of organisms (e.g., tissue, blood, feces) that harm human health. There are three types of organisms that give rise to biological hazards:

• Bacteria are microscopic organisms that live in soil, water, organic matter, or the bodies of plants and animals. For example, the E. coli bacterium lives in human and animal digestive tracts and some strains can cause food poisoning, infections, or kidney failure when ingested.
• Viruses are a group of pathogens that cause diseases such as influenza (the “flu”) when they enter our bodies.
• Fungi are plants that lack chlorophyll, including mushrooms, yeast, and mould. Many fungi contain toxin or produce toxic substances. For example, stachybotrys chartarum (black mould) produces toxins called mycotoxins that cause nausea, fatigue, respiratory and skin problems, and organ damage when the toxic spores are inhaled.

Insect stings and bites, poisonous plants and animals, and allergens are also biological hazards. Box 6.1 examines how climate change is increasing workers’ exposure to biological hazards.

As with chemical hazards, the nature of biological hazards highlights that the line between occupational health and safety and public health is blurry and easily crossed. Public health protects the health of a community by offering preventative medicine and health education, controlling communicable diseases, maintaining public sanitation, and monitoring environmental hazards. Because bacteria, viruses, and fungi can move from public spaces and private homes to workplaces, public health measures protect workers. Similarly, OHS measures can affect public health because biological hazards can be carried from workplaces to public spaces and private homes.

Consider the Cargill vignette at the beginning of this chapter. The COVID-19 virus was brought into the plant by someone who contracted it elsewhere. It then spread among the workers in the plant. Those workers took it home, infecting their families. Some of those family members might have taken it into other workplaces, including a local long-term-care facility. This example highlights that biological hazards can be very difficult to control because the boundaries of the workplace are more permeable than is the case with physical hazards.

Like chemical hazards, biological hazards can enter our bodies via respiration, skin absorption, ingestion, and skin penetration. There are three main ways that biological hazards that cause disease, such as bacteria and viruses, are transmitted to workers.10Contact transmission means that a worker is exposed to a pathogen through direct contact with someone or something. Contact transmission can also occur when an individual coughs or sneezes and a droplet of mucus (containing the pathogen) is released into the air. This droplet can transmit the pathogen to a new host. It has been generally assumed that droplets do not travel very far (about one metre) and do not stay suspended in the air for very long. COVID-19 revealed that this assumption is not always true (see Box 6.2).

Some pathogens can be transmitted through food, water, or air. This is called vehicle transmission because the food, water, or air acts as a vehicle for the pathogen. For example, aerosols are fine particles that can float through the air for long periods and over long distances, carrying pathogens from a source to a worker. Hantavirus is found in mouse feces. When dried feces are swept up, the virus clings to particles aerosolized by the sweeping. The aerosols are then inhaled by workers, transmitting the virus to them. As we’ll see from Box 6.2, the distinction between droplet and aerosol transmission is not clear in practice.

Vector transmission refers to a pathogen carried to a new host by an animal. Such transmission can be mechanical, meaning that the vector carries the pathogen without itself being infected. For example, a fly landing on feces can carry bacteria from the feces to your sandwich. When you eat the sandwich, you ingest the bacteria. Vector transmission can also be biological, by which the pathogen reproduces within the vector. For example, immature ticks can acquire Lyme disease by feeding on wildlife. Infected female ticks feeding on human blood then transmit the disease to humans.

Our bodies do have mechanisms by which to cope with some biological hazards. For example, our respiratory system has five layers of defence to prevent harmful particles from entering our body, beginning with the hair-like projections (cilia) on the cells that line our airways (which filter out particles) and ending with cells (macrophages) in the air sacs (alveoli) of our lungs that trap and route impurities into the lymphatic system for disposal. Organisms that enter our body are also subject to attack by our immune system. Yet these mechanisms are not effective against every biological hazard or every exposure.

Like most workplace hazards, biological hazards can cause both acute and long-term health effects. Acute effects can include immediate or near-immediate injuries, such as allergic reactions and infections. Box 6.3 outlines which workers from which workplaces have been most affected by COVID-19. Biological hazards can also have effects that develop over time. For example, workers who caught COVID-19 sometimes report symptoms long after the acute stage of infection has passed. Other workers report a host of other maladies apparently related to how COVID-19 affects the body’s systems and organs. These maladies include cardiovascular issues (including blood clots and heart attacks), digestive problems, neurological issues, and autoimmune conditions. The ability of workers and employers to recognize and respond to these longer-term effects is impeded by long latency periods, murky causality, and difficulty in observing outcomes.

Biological hazards are recognized, assessed, and controlled using the HRAC process outlined in Chapter 3, including quantifying the frequency, probability, and consequence of exposure. When assessing the probability of harm, it can be useful to give some thought to the biological agents and the contexts in which workers will encounter them.14 Specifically, we should consider an agent’s stability (e.g., ability to reproduce, resistance to disinfectants) as well as how communicable the agent is and the method by which it can be transmitted. It is also useful to think about the physical infrastructure and existing controls as well as whether the work being performed will intensify the exposure (e.g., cleaning mouse droppings aerosolizes the hantavirus).

Similarly, when assessing the potential consequence of exposure to a biological hazard, it can be useful to consider again the agent, the host, and the potential treatments. Biological agents can vary in their virulence and the severity of the resulting illness as well as the required dose for infection. Some workers might be particularly vulnerable to an agent because of health factors (e.g., a compromised immune system, allergies, age, or pregnancy). Finally, agents can differ in terms of the availability and efficacy of preventative measures (e.g., vaccination) and treatments as well as the required emergency response procedures.

Although risk-assessment tools (e.g., the one in Figure 3.2) can improve risk assessment by forcing us to consider all three dimensions of risk, there is a degree of subjectivity to risk assessment. For example, how serious we rate the potential consequences of a hazard reflects our understanding of the hazard and our own risk tolerance. Box 6.4 examines how the social construction of COVID-19 affected how the public assessed the risk that it posed.

Science plays an important role in both injury prevention and compensation. It has identified hazardous chemical and biological agents, determined the mechanism(s) by which these substances cause harm, assessed the risk of harm, and suggested ways to control hazards and treat injuries. It is important for OHS practitioners to understand how scientific conclusions are reached and the limitations of these conclusions.

The scientific method is a process of formulating, testing, and modifying hypotheses. A scientific hypothesis is a proposed explanation of a phenomenon that can be empirically tested to confirm, refine, or refute this explanation. We conduct measurement, observation, and experimentation to gather data that is compared against the hypothesis. If the data agrees with our hypothesis, we may conclude the hypothesis to be true. However, we cannot be certain the results are not the result of chance or a flaw in the method design. In other words, we need to ensure the results are both valid and reliable. Validity means the results of the experiment or observation accurately reflect the real world. For example, a scale measuring weight is valid if it correctly reports your actual weight. Reliability is the degree to which the results would be consistent if the measurement or observation were performed again. The scale in our example would be reliable if it produced the same result every time you step on it (assuming your weight has not changed).

The questions of validity and reliability plague scientific researchers, and achieving them is a key element of the scientific method. They are particularly challenging for the kinds of research usually associated with OHS-related matters because most of those issues involve human behaviour and physiology. When dealing with humans acting in the real world, there are limits to the control we can achieve over the measurement. It is unethical, for example, to intentionally expose someone to a toxic substance to measure its effects. Also, we cannot identify and control all the possible variables that may affect our results.

As a result, we can never be absolutely certain our results are accurate. As a result, scientists are concerned with false positives and false negatives. A false positive result occurs when we conclude a difference or relationship exists when it does not. False negatives occur when we conclude no difference or relationship exists when it does. Scientists tend to be particularly concerned with false positives because of their potential consequences. For example, saying a drug is effective at treating a disease when it actually is not can harm patients by subjecting them to an ineffective course of treatment. False negatives can also have real-life consequences as they may lead to inaction on health threats. The potentially harmful consequences of false positives means scientists are prone to being very conservative in their conclusions.

Further complicating matters is that most research conducted on OHS matters can only identify a correlation between two variables (e.g., exposure to asbestos and lung cancer). Demonstrating that asbestos (rather than some other, unmeasured, substance) causes lung cancer requires more complex research. The lack of clarity around cause also contributes to scientists’ conservatism around findings. Unclear causation also is used by employers and government agencies, such as WCBs, to deny the harmfulness of a substance and the injury claims associated with exposure to it. For example, smoking also causes lung cancer and so, if an asbestos-exposed worker also smokes, it can be much more difficult for them to demonstrate that their cancer was the result of the asbestos exposure. This is a common issue for workers who develop long-latency diseases.

The reason that scientific practices matter to OHS practitioners is that health and safety is contested terrain. As we saw in Chapter 1, the interests of employers and workers don’t always align. While scientific analysis has been immensely helpful to workers seeking to identify chemical and bio- logical hazards or receive compensation for injuries caused by such hazards, employers can use the conservative culture of scientific research to slow or block worker efforts in these regards. As Box 6.5 shows, employers will often exploit such doubt in an effort to block regulation of hazardous substances.

The standards set by scientific research can make it very difficult at times to establish that a chemical or biological exposure is hazardous. Employer use of this conservatism can mean that workers can be exposed to hazards with inadequate information about their effects. By contrast, if those regulating chemical and biological hazards adopted the precautionary principle—where the absence of scientific certainty that a substance was hazardous did not preclude regulating potentially hazardous materials or activities associated with it and the burden of proof fell on those advocating its use—it would be much more difficult for employers to resist this regulation. Box 6.6 considers the precautionary principle in more detail.

As with other workplace hazards, control strategies for biological hazards should be developed with both the mechanism(s) of transmission and the hierarchy of controls in mind. For example, it makes little sense to rely on handwashing to control a virus spread through the air. This approach does not interrupt the mechanism of transmission (i.e., aerosols), and handwashing as a rule (i.e., an administrative control) is subject to frequent failure through non-compliance and error (i.e., not washing thoroughly or long enough).

Successful controls for biological hazards are often so embedded in the world around us that they become effectively invisible. For example, historically, the provision of adequate washing and toilet facilities was an engineering control that significantly reduced worker exposure to many biological hazards. Recent technological improvements, such as automatically flushing toilets and automatic taps, soap dispensers, and towel dispensers, have further limited workers’ contact with bacteria in washrooms. Box 6.7 examines how collective agreements and legislative standards can be employed to control the spread of disease in the workplace.

The process of developing a control strategy for a biological hazard is essentially the same as for any other hazard. As noted above, it is important to be mindful of the mechanism of transmission such that the control can effectively prevent transmission. It can sometimes be easier to categorize controls for biological hazards using the location of control rather than the hierarchy of controls. As set out in Chapter 3, this approach focuses on where and when the hazard is controlled in the context of where the worker is in the production process. In this approach, hazards can be controlled at three locations:

• Control at the source addresses the hazard where it first occurs.
• Control along the path addresses the hazard at some point between its source and when workers encounter it (i.e., it prevents the hazard from reaching the worker).
• Control at the worker implements controls for the hazard only after it reaches the worker.

If, for example, we seek to control the spread of a virus primarily through the air, then we might consider the following controls:

• Control at the source: We might limit access to the worksite and test those permitted to be there to eliminate or radically reduce (through the exclusion of carriers) the virus. If an effective vaccination is available, then we might require workers and visitors to receive it. We might even close the office and have workers perform their jobs from home in order to eliminate the virus from the workplace.
• Control along the path: We might interrupt the transmission of the virus in the workplace through aggressive ventilation and/or air filtration practices.
• Control at the worker: We might require workers to use PPE (e.g., a high-quality mask) to prevent them from inhaling the virus. We might implement a rule that workers who are ill (or have symptoms) are required to work from home for a period of time or until a condition is met (e.g., a negative test result). If there is a vaccine that reduces the severity of the disease caused by the virus, then we might also offer it (see Box 6.8).

When it is not possible to ensure that a biological hazard has been controlled at the source, it might make sense to implement a series of controls that provides workers with layers of protection. For example, we might increase ventilation, restrict access to the workplace, and require masking and/or vaccination.

Biological hazards are often more challenging to recognize, assess, and control. In some cases, they are normalized (e.g., daycare workers get sick) and ignored. In other cases, biological hazards are less readily observed, and the level of complexity involved in their interactions with the human body is greater. Further, health effects may only develop from prolonged exposure, or the disease may have a long latency period. Often, pinpointing the cause of a disease can also be difficult due to exposure to multiple hazards, a lack of knowledge about what we are exposed to in the workplace, and the lack of a clear boundary between work-related and environmental exposures.

As a result, this area of OHS relies heavily on science to understand the effects of biological hazards. Nevertheless, the nature of scientific practices often results in overly conservative conclusions when assessing the risk these hazards pose to workers. Issues with such scientific conventions can be compounded by employers’ long-standing efforts to deny the existence of chemical and biological hazards and avoid taking action to control them. As a result, there is strong evidence suggesting that current protections are inadequate and systematically under-protective of workers. Even if the precautionary principle is not a legal requirement in Canadian workplaces, this dynamic makes a strong argument for adopting the principle for moral reasons when it comes to chemical and biological hazards.

Such an approach would have helped to prevent over 1,000 workplace infections, 600 related infections in the community, and three deaths linked to the Cargill meatpacking plant outbreak in 2020. A popular explanation of the size of the Cargill outbreak is that, in the spring of 2020, COVID-19 was new and poorly understood, and thus the company was operating in uncharted territory. In this view, there was really nothing that it could have done to prevent the outbreak. Yet, in hindsight, we can see that Cargill and the government were presented with many opportunities to limit the outbreak. Yet they prioritized maintaining production over protecting workers’ safety. Subsequent outbreaks at other plants and, indeed, at the same Cargill plant a year later, when much more was known about COVID-19, reinforce the view that such outbreaks were cases of profit trumping safety rather than innocent errors made in novel circumstances.

Write a definition for each bold italic word in this chapter.

Select a workplace with which you are familiar and identify a job task performed by a worker that exposes them to a biological hazard. For example, you might select a kitchen at a restaurant or a child-care facility.

Using the HRAC process set out in Chapter 3, perform a hazard assessment for this task. Your completed assessment should include:

• ➤ A description of the workplace and the work being assessed.
• ➤ A description of the hazard, which injury it might cause workers, and the mechanism of the injury.
• ➤ The risk of injury that the hazard poses to the workers, including probability, exposure, and consequences.
• ➤ Three ways to control the hazard. For each potential control, identify which kind of control it is on the hierarchy of controls, how it would be implemented, and the expected cost and effectiveness of the control.
• ➤ A recommended control or controls based on your analysis, including a justification for why you recommended this control instead of the other options that you developed.

Briefly discuss with a partner or write 250-word responses to the following questions:

1. What are the three mechanisms of transmission for biological hazards? Which do you believe you are most likely to encounter in the future?
2. What would be the most effective control for a highly contagious, aerosolized virus?
3. Why are biological hazards normalized in the workplace? Who benefits from this normalization, and who bears the costs?
4. Which specific factors need to be considered while doing a risk assessment for biological hazards?
5. How does the scientific method both help and hinder the recognition of biological and chemical hazards?

Write 250-word responses to the following questions:

1. What are two biological hazards that you have faced in a workplace? Describe each, including the potential health effects.
2. Which of these hazards posed the highest risk to you and why?
3. Did your employer control these hazards? If so, then how? How could your employer have made the work safer?
4. Do you think that these hazards and the controls that your employer used would have stood up to a worker’s refusing unsafe work?
5. Which strategies did (or could) you or other workers use to make the work safer?