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10Epidemiology and Toxicology




According to Valavanidis &Vlachogianni (2010), Carcinogens are substances of particles that when they come into contact with a human being they have the ability to cause cancer. Cancer is a deadly disease in which the normal cells of a human being damaged are not able to u8ndergo the normal programmed cell death. In fact, the cells undergo rapid and fast cell division through mitosis (Kamrin, 2014). The ability to cause cancer is due to the fact that the carcinogens have the ability to distort the structure of the gene and cause a mutation of the cells at the point of direct contact. In addition, carcinogens cause cancer by interfering with the metabolic process of the cells. Since they have the ability to interfere with cellular process, carcinogens interfere with the DNA of the cells resulting in mutation of the cells. Most of the carcinogens are considered as radioactive substances although there are biological and chemical substances that have been proved to be carcinogenic. Due to the wide range of substances that are carcinogenic, different medical authorities and bodies have different ways in which they classify carcinogens. The classification varies depending on the criteria that are used in classifying the substances (Wogan et al., 2004, p.473). The purpose of this essay is to discuss using examples the different classification of carcinogens by different bodies in the world.

Classification of Carcinogens

Different organization the world classify carcinogen different.

International agency for research and cancer

This is an intergovernmental organization under the world healthorganization which has an influence in the classification of carcinogens. The major function of the organization is to identify different causes of cancer among human (Kamrin, 2014). It classifies carcinogens as follows

Group 1: the agent is carcinogenic to human. For example, asbestos

Group 2A: the agents are probably carcinogenic to humans. For example, acrylamide, captafol and dimethyl sulfate

Group 2B: Possibly carcinogenic to humans. For example, Propylene oxide

Group 3: agent not classifiable as carcinogenic to human beings

Group 4: the agent is probably not carcinogenic to humans

Safe Work Australia

This is an Australian organization that is mandated to ensure that the citizens are provided with a health and safer condition for work. In addition, the organization is responsible for work compensation arrangements in Australia. Section 4.76 of the NOHSC: 1008(1999) has classification of substances referred to as carcinogens. The safe work Australia has three major categories of carcinogens

Category 1: this category contains substances that are known to be carcinogenic to human. For example, uranium.

Category 2: these are substances that they should be treated as if they were carcinogenic to humans.

The European Union

According to the directive for dangerous substances and dangerous preparations directive, the European Union has a system for classifying substances considered as carcinogens. According to the European Union, carcinogens are classified into three categories (Kamrin, 2014).

Category 1: contain substances that are known to be carcinogenic to human beings

Category 2: this contain agents that are treated as if they are carcinogenic to human beings

Category 3: these are substances that are a concern on humans due to their carcinogenic effects but there is no adequate information on their assessments ass carcinogenic

American Conference of Governmental Industrial Hygienists

This is an American private organization that is known for publishing different thresholds of different occupational exposures to different chemicals that may appear hazardous to people at their places of work. Therefore, the organization does an assessment of carcinogenicity and classifies carcinogens according to the following groups (Valavanidis &Vlachogianni, 2010).

Group A1: agents confirmed as carcinogenic to human

Group A2: agents suspected to be human carcinogens

Group A3: these are agents that are confirmed as animal carcinogens but have unknown relevance to humans

Group A4: these are substances that are not classifiable are human carcinogens

Group A5: these are agents that are not suspected to be carcinogenic to humans

The united nation classifies carcinogens on the basis that they are either harmful to humans or harmful to experimental animals. This means that substances that are cacogenic to human are classified are human carcinogen whole those which are carcinogenic to experimental animals are treated as probably carcinogen to human although h they wait confirmation.


Carcinogens are compounds that are causative agents of cancer. The carcinogens case cancer by affecting cellular metabolism and affect the normal functioning of the DNA. Different organizations have different classification of carcinogens. However, most of these classifications are based on the fact that some substances are known and confirmed to be carcinogens to humans while some substances are not confirmed to be carcinogenic to humans but their effects is similar as tat of carcinogen since they should be treated as carcinogens. On the otter hand some substances are not known to have any effects on humans are not carcinogenic to humans.


There has been an increase in cases of different illnesses that are associated with the droppings if different animals. Disease causing microorganism prefers or thrive well in areas that are rich in nutrients. This means that for these microbes to multiply and be able to infect their hosts with different kind of diseases, they must be provided with suitable and favorable conditions where they can reproduce. This means that when birds are concentrated in one area. Their droppings act as breeding areas and provides nutrient to different microorganism including fungi, bacteria and viruses. According to Poirier & Feder (2001), Bird’s droppings have been associated with many respiratory disorders especially in individual who get direct contact with the droppings. The birds also carry a number of disease causing agents which they shed with their feathers pausing a health and safety risk to human beings. The damage and diseases caused by the birds and their droppings depend on the number of birds that appear in a certain area (McDermott, 2004, p. 446). This means that the accumulation of bird’s droppings in a street may contribute to health risks. This essay focuses on the link between bird’s droppings and respiratory illnesses that were observed in different individuals involved in cleaning bird’s droppings from the streets for a long period of time. In addition, the essay, will discuss the different ways in which the cleaning of birds droppings can be managed and mitigated in order to reduce the risks of respiratory illnesses.

The link between bird’s droppings and respiratory symptoms in workers

Bird’s droppings are associated with over 60 different illnesses in the world. This is because the droppings of birds are favoring the breeding of different microorganism such as bacteria and fungi that cause different diseases among the workers. Since the birds are found in large numbers in the street, their droppings accumulate and form breeding sites for the microorganisms that cause respiratory illness and the symptoms observed. This implies that when the workers clean the droppings they are likely to come in to contact with the disease causing microorganisms that infect them (McDermott, 2004, p. 480). Chow & Pollock (2011) argues that the health risks that can be caused by the birds droppings are the microorganism that grown in nutrient accumulation areas of the birds drooping, feathers of the birds, and the debris under the roost especially when the roost has been active in the same place for years (Gustin, 2008). In this case, the workers have been cleaning the same place for different years, which means that the roosts in the birds droppings has accumulated fir all those years and has not been able to infect them during the initial years since it was not hazardous by them. After the roost has stayed for the years it became inhabited by fungus that causes airborne diseases. In addition, the birds drooping are full of parasites and diseases causing microorganism that can be transmitted to humans. Microorganisms such as Histoplasma capsulatum are able to rich toxic levels in the soil containing bird’s droppings for several years (Poirier & Feder, 2001, p. 68). This means that the fungus is not able to infect the workers during the initial years as they had not reached a toxic level. After the five years, the levels of the fungus were able to cause disease and the symptoms observed in the workers. Cryptococcis neoformans is also another microorganism that can be found in debris from birds drooping. This bacterium is mainly found in debris that has been contaminated with bird’s droppings (Gustin, 2008). This microorganism is transmitted to its host through respiratory systems. This can explain the fact as to why the different workers had symptoms of respiratory illnesses. These illnesses symptoms could have resulted from the inhalation of disease causing microorganism in the droppings or in the roots and contaminated soil.

Control of Hazard Associated With Birds Droppings

The most common ways in which the microorganism that cause the respiratory symptom are transmitted is through inhalation and contact with the microbes by the cleaners. In order to control the associated health risk, there are different approaches that can be used.

Controlling Aerosolized Dust when removing the droppings from the streets

The best way to reduce the symptoms is to ensure that the fungus and bacteria are not inhaled by the workers. This is done by using means that will reduce the generation of dust during the time if cleaning. Since the dust will be reduced workers will not be able to inhale any disease causing microorganism that are present in the bird’s droppings. According to Salmon & Lickliter (2006), dust generation can be reduced by sprinkling water on the surfaces that contains the birds drooping in order to make the area wet. This reduces the chances of inhaling the fungus. The controlling of aerosolized dust can also be done using a vacuum cleaner that has a high efficiency to absorb contaminated materials such as the bird’s droppings in the streets.

Use Protection Materials

The workers should be provided with equipment that will allow them to be protected against inhalation of the fungus and dust containing the fungus. These protective materials include masks that protect the nose and mouth of the workers. In addition, worker should be provided with gloves and gumboots that protect the hands and legs. However, reducing the respiratory symptoms only require protection of the nose and mouths of the cleaners using masks and gloves.

Disinfecting Contaminated Material

It is important to carry out a risk assessment of the areas that the workers are working in order to determine the risk involved. Once the risks have been identifies and the birds droppings have been established to problem contain fungus, the workers can then disinfect the droppings and roots so as to kill the microorganisms in the droppings.

Risk communication to workers

It is the duty of the supervisors to ensure tat workers are aware of any hazards in the working environment inn order to take the necessary causation in cleaning the birds drooping. The workers should be informed of any disturbance of materials that are likely to be contaminated with fungus or any other disease causing microorganisms. This means of communication should be in the form of writing indicating the warning and measures to be taken during cleaning of the bird’s droppings from the streets. On case there are workers who are more likely to get infected as a result of weak immune systems, such workers should seek advice from health car providers before engaging in the cleaning exercise (Salmon & Lickliter, 2006, p. 45)


Birds droppings have been associated with different health problems especially those affecting the respiratory systems. This is because bird’s droppings contain parasites and fungus that are inhaled by humans and cause respiratory illness. When the roots and birds droppings accumulates for a long time in the soil disease causing fungus reach toxic levels that cause diseases to the humans. The droppings they are likely to come in to contact with the disease causing microorganisms that infect them. The health risks that can be caused by the birds droppings are the microorganism that grown in nutrient accumulation areas of the birds drooping, feathers of the birds, and the debris under the roost especially when the roost has been active in the same place for years. Workers who engage themselves in cleaning of bird’s droppings should be made aware of the risks involved. This means that there are various ways that can be used to reduce the risks associated with hazards in bird’s droppings. These control measures include using of water to prevent contaminated dust from being inhaled, wearing protective masks to avoid inhaling the contaminated dusts and communication of risks to workers who are at risk.


Chow, C., & Pollock, C 2011. Heavy metal poisoning in birds. Available at http://thegabrielfoundation.org/wp-content/uploads/2012/11/HeavyMetalToxicosis-in-Birds-LafeberVet.pdf

Gustin, B 2008. Bird Droppings and a Chronic Cough. Available at http://www.toxicologyexpert.net/index.php/Interesting-Cases/bird-droppings-and-a-chronic-cough.html. Accessed on 23/04/2014

Kamrin, M 2014. Carcinogen Classification Schemes. Encyclopedia of Toxicology, pp. 699-704

McDermott, H 2004. Air Monitoring for Toxic Exposures. New Jersey: John Wiley & Sons

Poirier, D., & Feder, K 2001. Dangerous Places: Health, Safety, and Archaeology. Connecticut: Greenwood Publishing Group

Salmon, T., & Lickliter, R 2006. Wildlife Pest Control Around Gardens and Homes. California: UCANR Publications

Valavanidis, A., &Vlachogianni, T 2010. Carcinogenic Chemicals: Classification and Evaluation of Carcinogenic Risk to Humans by International Organizations and the European Union. Science advances on Environment, Toxicology & Ecotoxicology issues. Available at <http://chem-tox-ecotox.org/wp/wp-content/uploads/2010/04/03-Carcinogenic-Chemicals-18_04_2010.pdf>. Accessed on 23rd April 2014.

Wogan, G., N, Hecht, S., Felton, J., Conney, A., &Loeb, L 2004. Environmental and chemical carcinogenesis. Seminar in Cancer Biology, vol.14, no.6, pp. 473-486