• Subject: Carcinogens
• Subject area: Chemistry (natural sciences)
• Age group: (Minimum) 9th grade of primary school (14 years)

Purposes of the lesson

• Students deepen their knowledge of the hazardous properties of substances and how they are labelled, as well as of handling hazardous substances, especially carcinogenic, mutagenic and reprotoxic chemicals (CMR).
• Students supplement their knowledge of cancer and carcinogens (see content of stations).
• Students develop skills in using/working with various data sources (databases, the world wide web, professional literature, etc.) and in presenting or designing short, concise texts on the topic and mini activities.
• Students are trained in collaborative learning and communication and develop critical thinking.

Activities

The goal is to provide key aspects/information about carcinogens within a limited time by rotating through seven stations.

1. What is cancer?
2. Properties of carcinogens
3. Labelling carcinogens
4. Classifying carcinogens
5. Examples of carcinogens and their properties
6. Possible carcinogens in the workplace
7. 12 tips for preventing cancer

Possible variants of implementation

The most basic implementation

The teacher prepares the content and activities at an individual, freestanding station.

Advanced implementation

Preliminary preparation time:
Trios/groups are formed (random or named) that choose topics (choose – draw the order of choosing the station’s theme). Trios/groups prepare the content of the station according to the following criteria:

• Content refinement of the station:
  Based on the prepared content and various sources, they extract key (short, concise) content/information, important and relevant for peers.
• Didactic refinement of the station:
  Students present the content/information in a memorable (“as much and as easily (understandable)”) or interesting way, with educational materials, aids and/or planned activities for a duration of 5 minutes → Preparation of educational materials

Formative implementation

Before implementation, after preparing content for the stations, a peer-analysis of the learning material follows – Trios/groups review the content or learning material for each station (e.g. each group reviews the content of the station with one lower number) and provide feedback (feedback for 5 minutes) on the material’s scope, expertise, transparency, clarity, and usability (for everyone).

Trios/groups return to their stations and, if necessary, try to improve their learning material based on feedback (10 minutes).

Implementation time

• Start of activity:
  Rotation of groups through stations in a clockwise direction.
• Simple implementation:
  Groups rotate through stations at suitable time intervals (e.g. 5 minutes).
• Advanced implementation:
  Every member of the trio has their own colour (e.g. green, blue and red). A chosen colour (determined by the teacher) stays at its station (host) while the other two move on to the next one. In 5 minutes, the station’s host introduces the topic or leads an activity on the topic. In the next round, the host becomes one of the visiting students (different colour), etc. (the rotation lasts 35 minutes + 10 minutes reserve).

Possible content and activities by stations

Station 1: What is cancer?

Question for students:

• How do you understand the disease cancer?
• Do you have any experience with this disease in your extended family?

Cancer is a disease characterized by uncontrolled cell division. Cell division is a normal process in the human body, but only as much as is necessary for the normal, physiological renewal of aging cells. In cancer cells, however, the division goes on unchecked, and due to this uncontrolled division, the mutated cancer cells often grow into surrounding tissue, and can even spread (metastasize) through the blood or lymphatic vessels to distant organs.

What is cancer? General aspects

Cancer is not just one disease but is a name for more than two hundred different diseases, all of which can be classified into several broad groups (carcinomas, sarcomas, leukaemia and lymphomas), depending on the organs in which they occur. The likelihood of developing cancer begins to significantly increase from the age of 45 to 50. According to data from the World Health Organization (WHO), cancer is the second most common cause of death worldwide, right after cardiovascular diseases, with nearly 10 million deaths in 2020. This year, 2.7 million people in the European Union (EU) have been diagnosed with cancer. It is estimated that cancer causes 52% of all work-related deaths in the European Union. Due to exposure to carcinogens at work, approximately 120,000 people are diagnosed with cancer each year, and nearly 80,000 lose their lives.

Questions for students

• What else could be said scientifically about cancer? (Examine a reliable source.)
• Who can get cancer and why?
• How would you complete your notes of what cancer is?

Station 2: Properties of carcinogens

Questions for students:

• What does NAPO say about carcinogens?
• Watch NAPO’s film “Danger: Chemicals” and answer to the questions on the observation sheet.
• How can dangerous (toxic, carcinogenic) substances enter the body? Mark it on the diagram!
• What properties of hazardous substances did the filmmakers want to highlight with the excerpts shown?

 

• Are the effects of carcinogens visible immediately?
• What does long-term exposure to a carcinogen mean? What else do we call such exposure to hazardous substances?

Station 3: Labelling carcinogens

Question for students

•  In the NAPO film, you noticed a pictogram. Are you familiar with it?

This is a relatively new pictogram that indicates a particularly dangerous group of substances. It is also called a CMR pictogram (an abbreviation derived from the terms Carcinogenic, Mutagenic substances and substances toxic for Reproduction).

Question for students

• How would you translate CMR into your language?

A carcinogen can be a chemical, physical or biological agent or some other factor that can cause cancer or increase its incidence. Mutagens (mutagenic substances) cause mutations or increase the frequency of mutations. A mutation is a permanent change in the amount or structure of a cell’s genetic material. If these mutations affect germ cells (egg cells or sperm cells), they can be passed on to the offspring. Mutagens can be of physical origin (exposure to ionizing radiation or ultraviolet radiation), chemical origin (exposure to substances such as benzene or formaldehyde), or biological origin (infection with certain biological agents (viruses, bacteria and parasites).

Dangerous substances, such as carcinogens, are not only marked with pictograms, but also with warning words and H and P statements.

What are warning words? These are words that indicate the degree of severity of the hazard to further warn the reader of a potential hazard. Such words are e.g. HAZARD or WARNING in the case of carcinogens of category 1A or 1B or category 2 (you will become familiar with the categories of carcinogens at the next station).

H – statements are Hazard statements and describe the nature of the hazardous substance and appropriately classify it in its class or category with a number. For carcinogens, these statements are e.g.:

H350: May cause cancer.
H350i: May cause cancer by inhalation.
H351: Suspected of causing cancer.

P – statements are Precautionary statements that describe recommended measures when handling a particular hazardous substance to reduce or prevent harmful effects from exposure, use or disposal of the hazardous substance. For carcinogens, these statements are e.g.:

P201: Obtain special instructions before use.
P202: Do not handle until all safety precautions have been read and understood.

Station 4: Classifying carcinogens

Question for students

• Read the text below carefully and answer what is the difference between the European and international (American) systems for classifying carcinogens?

A carcinogen causes cancer or increases its incidence. Substances that have caused benign and malignant formations in animal tests are presumed or suspected human carcinogens unless there is strong evidence that the mechanism of tumour formation is not relevant to humans. Classifying substances as carcinogens is a process through which substances are classified into one of the categories based on the strength and reliability of the evidence. Data for classification are obtained through laboratory testing, computational methods and human experience (epidemiological studies). The classification of hazardous and carcinogenic substances (in accordance with the CLP Regulation) is based on identifying the hazardous properties of these substances (NOT on identifying their risk).

The European Union applies the Classification, Labelling and Packaging Regulation (CLP), which classifies carcinogens based on evidence from reliable studies in humans and animals and, where necessary, additional data. It defines two different categories of hazards:

• Category 1: includes substances known or suspected to be carcinogenic to humans and is divided into two categories:
  • Category 1A: includes proven human carcinogens (epidemiological studies);
  • Category 1B: includes substances known to have carcinogenic potential for humans based on evidence from animals.
• Category 2: includes substances that are suspected of being carcinogenic to humans based on evidence from human and/or animal studies but are not sufficiently convincing to place the substance in Category 1A or 1B.

The International Agency for Research on Cancer (IARC) classifies carcinogens into four or five groups:

• Group 1: the substance is carcinogenic to humans
• Group 2A: the substance is probably carcinogenic to humans
• Group 2B: the substance is possibly carcinogenic to humans
• Group 3: the substance cannot be classified as carcinogenic to humans
• Group 4: substance is probably not carcinogenic to humans

The IARC classification principle is based on evidence of carcinogenic risks from human exposures. Example: a substance that only very slightly increases the likelihood of cancer in humans with long-term exposure to high doses (the evidence for this slight increase is strong) will be classified in Category 1, although under normal use the substance does not pose a high risk.

Station 5: Examples of carcinogens and their properties

Question for students

• From the list provided (or at your own discretion), choose one of the carcinogens (e.g. benzene, acrylamide, formaldehyde, asbestos) and, using a safety data sheet or a record of its properties, present the dangers that improper use may pose.

Station 6: Possible carcinogens at the workplace

Questions for students

• Examine the selected workplace and consider what possible carcinogen (chromium, cadmium, benzene, acrylamide, formaldehyde, spent machine mineral oils, diesel engine exhausts, wood dust, asbestos) workers may encounter at this workplace?
• What action should the employer take?
• What action should the worker take?

An example of a workplace in construction with asbestos exposure:

• Asbestos was widely used in buildings and building materials. Activities that crush asbestos-containing materials release asbestos fibres into the air. Individual asbestos fibres cannot be seen or smelled. These fibres can be inhaled unknowingly and then trapped in the lungs or stuck in the gastrointestinal tract.
• With prolonged exposure, asbestos fibres inhaled or ingested may cause inflammation and cancer (lung cancer and mesothelioma). The latent period between exposure and the onset of asbestos-related cancer is very long (from 15 to 50 years).
• In 2005, the European Union banned all use of asbestos and the extraction, production and processing of asbestos products. However, that does not mean that this very harmful material is no longer in our vicinity. On the contrary, it is in many products such as water pipes, steel building frameworks, heating boilers, seals and roofing.
• What must employers do? Before starting construction work, they must determine whether asbestos-containing materials are present on the site. They must examine whether fibres will be released into the air during construction work and strictly follow the applicable regulations. Workers must be informed about the risks and preventive measures. Work should be carried out by qualified workers using appropriate equipment and working techniques.
• What must workers do? They must use the appropriate personal respiratory protective equipment and protective clothing provided by the employer. Asbestos-containing materials must be removed in such a way as to damage them as little as possible.

Questions for students

• What do you do if, as a volunteer, you take part in an environmental cleanup drive and you notice an illegal asbestos-cement roofing dump?
• Consider whether there are buildings in your environment that have roofs made from asbestos cement.

We should not dispose of asbestos products ourselves, but contact authorized contractors who are trained and have appropriate personal protective equipment. You inform the organizers of the environmental protection campaign about the illegal waste dump, who will inform the competent inspection authorities.

Example of a workplace in an auto repair shop and exposure to diesel engine emissions:

• Most hazardous substances are labelled and classified, but there are also carcinogens that are formed as by-products during the work process. Since these are usually not marked and do not have a safety data sheet, special attention should be paid to them. Diesel engine exhaust is a complex mixture of gases, vapours, liquid aerosols and particles. There are relatively large quantities of soot in the exhaust gases, and the mixture contains several carcinogens.
• Short-term exposure to diesel engine exhaust gases may cause eye, nose, throat and lung irritation. Prolonged exposure may increase the risk of developing chronic respiratory diseases, including lung cancer.

Watch the animated film “Napo raises awareness about hidden killers”.

Question for students

• Why do employers need to pay special attention to carcinogens generated as by-products during the work process?

Station 7: Twelve tips to prevent cancer

Did you know that more than 12,000 Slovenians get cancer every year, 5,700 of whom die? Cancer is the second-most common cause of death in Slovenia. The most common cancers in Slovenia are:

• Skin cancer
• Colon cancer
• Rectal cancer
• Lung cancer
• Breast cancer
• Prostate cancer

The above cancers can be associated with an unhealthy lifestyle, e.g. excessive sunbathing, improper diet, smoking and excessive drinking of alcoholic beverages, as well as exposure to carcinogens at the workplace (e.g. exposure to asbestos remains a major problem in building removal, demolition and maintenance procedures).

The chances of cancer developing are determined by a sum of interconnected risk factors:

• Environmental factors (biological, chemical and physical)
• Lifestyle (smoking, unhealthy diet)
• Exposure to carcinogens in the working environment
• Hereditary predisposition
• Random

Exposure to an individual risk factor does not mean that every exposed person will definitely get sick, but it does pose a greater chance of falling ill. So, how to avoid cancer? How to reduce cancer risk factors?

Question for students

• Suggest some measures in the fight against cancer! Compare them with the 12 cancer prevention tips described in the leaflet by the Association of Slovenian Cancer Societies.

12 tips on how to reduce your risk of cancer or detect it before problems send you to the doctor

In 1986, experts from the Europe Against Cancer programme, based on previous knowledge of factors in the living and working environments that are associated with the development of cancer and on approaches to reducing the risk of this disease, produced the first version of the European Code Against Cancer. These are tips on how to live to minimize vulnerability and to reduce the population’s rates of cancer morbidity and mortality with the support of the state. New findings on the risk factors of cancer and measures to detect disease as soon as possible led to amendments to the Code first in 1995, then in 2003 and later in 2014.

The fourth, updated version of the Code was produced by experts gathered under the auspices of the International Agency for Research on Cancer, a specialized agency of the World Health Organization.

Following the updated advice not only reduces the threat of cancer, but also other chronic diseases, especially cardiovascular diseases, which are also the most fatal. Taking care of your health is a personal responsibility that is only possible in a country that supports health in all policies, so society’s responsibility should not be ignored in the prevention of cancer and other diseases.

European Code Against Cancer 2014

1. Do not smoke!
   Do not smoke or use tobacco products in any form! Smokers, stop smoking as soon as possible!
   
2. Do not smoke in the presence of others!
   Your smoking can harm the health of the people around you! Do not smoke at home or at work
3. Maintain a healthy, normal weight!
   Obesity increases your risk of colon and rectal cancer, as well as many other cancerous diseases. Maintain a normal weight with a balanced diet comprising plenty of vegetables and fruits! Maintain physical activity!
4. Be physically active every day!
   Limit the time you spend sitting! Take part in various activities (quick-paced walking, running, cycling, swimming, cross-country skiing)!
5. Eat healthy!
   Eat lots of whole grains, legumes, vegetables and fruits! Do not eat too much of high-calorie foods (foods high in sugar and fat) and avoid sweet drinks! Avoid meat products and eat less red meat and foods high in sodium!
6. Limit all types of alcoholic beverages!
   To prevent cancer, it is best not to drink alcoholic beverages at all. If you drink sometimes, then men can have a maximum of two units of alcoholic beverages per day, and women can only have one (the unit contains 10 g of pure alcohol, which is contained in 1 dL of wine, 2.5 dL of beer, 0.3 dL of spirits, or 2.5 dL of must).
7. Expose yourself to the sun as little as possible!
   Use protective clothing, headgear, sunglasses and creams. Be careful to avoid sunburn, especially in children!
   Sunbathing in tanning salons is also dangerous, as the effect is like that of the sun.
8. Protect yourself at work from dangerous substances that cause cancer!
   Get informed about the substances you are dealing with at work!
   Follow the occupational health and safety guidelines!
9. Protect yourself from ionizing radiation!
   Where there is more of the radioactive element radon in the ground, it can penetrate buildings – into living and working spaces. Regular ventilation significantly reduces the concentration of radon in rooms and protects against the development of lung cancer.
10. Women
    Breastfeeding reduces the risk of cancer, so breastfeed your children if possible! Limit your use of hormonal medications to relieve menopausal symptoms, as they are linked to some types of cancer!
11. Make sure your children are vaccinated against:
    Hepatitis B
    Human papillomavirus (HPV) (girls).
12. Participate in organized screening programs!
    After the age of 50, take a test for faecal occult blood, which is offered by the Svit program! Women, visit your gynaecologist regularly for cervical screening! If you receive an invitation for a screening in the Zora program, respond immediately! Women over 50 years of age should schedule a preventive mammogram. If you receive an invitation to the Dora program, respond to the invitation!