Grade by Grade
B. Organic Chemistry · Organic Chemistry

Organic Compounds in Society: Benefits, Risks and Taking Action

B1.1 B1.2 A1.3 A1.7 A1.9 A2.1 A2.2About 75 minutes
Learning goals
  • I can assess the benefits and risks of everyday organic compounds, including polymers, food additives, medicines and pesticides, for health, society and the environment.
  • I can use the ideas of hazard, exposure, persistence and bioaccumulation to evaluate a risk.
  • I can evaluate sources of information for reliability and bias.
  • I can create a personal action plan to reduce my use of harmful organic compounds.
  • I can describe careers that use organic chemistry and contributions of Canadian scientists.

Words to know

hazard
The potential of a substance to cause harm.
exposure
How much of a substance reaches a person or organism, and for how long.
risk
The chance that harm will actually happen; it depends on both hazard and exposure.
persistence
How long a substance lasts in the environment before breaking down.
bioaccumulation
The build-up of a substance in an organism's body over time, because it is taken in faster than it is removed.
biomagnification
The increase in concentration of a substance at each higher level of a food chain.
microplastics
Plastic pieces smaller than 5 mm, from broken-down plastic items, fibres or manufactured beads.
green chemistry
Designing chemical products and processes that reduce or eliminate hazardous substances and waste.

Weighing benefits and risks

Organic compounds have transformed life in Canada. Plastics keep food fresh and medical equipment sterile; medicines relieve pain and cure infections; fertilizers and pesticides help farmers grow more food on less land; synthetic fibres keep people warm in a northern winter. Some of the same compounds also cause harm: plastic litter in the Great Lakes, pesticides that affect pollinators, chemicals released near industrial sites.

Scientists, governments and citizens weigh these benefits and risks using a few key ideas:

  • Hazard: can the substance cause harm? (Is it toxic, flammable, carcinogenic?)
  • Exposure: how much reaches people or wildlife, for how long, and by what route (breathing, eating, skin)?
  • Risk = hazard combined with exposure. A very hazardous chemical sealed in a lab has low risk; a mildly hazardous one that everyone breathes every day may have a significant risk.
  • Persistence and bioaccumulation: compounds that last a long time and build up in living things can cause harm far from where they were used, long after.

The idea that the amount matters is old: the 16th-century physician Paracelsus is credited with the saying that the dose makes the poison.

Case 1: Plastics and microplastics

Benefits: light, strong, cheap, waterproof, shapeable, and often lower in transport energy than glass or metal. In hospitals, single-use plastics (syringes, IV bags) prevent infection.

Risks: most common plastics are addition polymers with C–C backbones that do not hydrolyse, so they persist for a very long time. Litter breaks into microplastics, which have been found in the Great Lakes, in Arctic sea ice, in drinking water and in food. Researchers are still studying their effects on health. Burning plastics, especially PVC, can release harmful gases.

Canadian actions:

  • Canada banned microbeads in toiletries such as face scrubs and toothpaste in 2018.
  • The federal Single-use Plastics Prohibition Regulations ban the manufacture and sale of checkout bags, cutlery, certain foodservice ware, ring carriers, stir sticks and straws (with exceptions, for example for people who need flexible straws). These were challenged in court; in January 2026 the Federal Court of Appeal upheld the government's listing of plastic manufactured items as toxic, which the ban is based on.
  • Ontario municipalities run Blue Box recycling, but which plastics are accepted varies, so the resin code alone doesn't tell you if an item is recyclable.
raw materialoil, gas or plantsmonomere.g. ethenepolymere.g. polyetheneproductbag, bottle, toyusedays to decadesrecycle / reuseback to productlandfilllasts very longlitterbreaks intomicroplastics< 5 mm
The life cycle of a plastic product. Most plastics come from fossil fuels, and at the end of their use they are recycled, landfilled or lost as litter. Litter slowly breaks into microplastics; recycling (dashed arrow) returns the material to new products.

Case 2: Pesticides

Benefits: pesticides protect crops from insects, weeds and fungi, increase yields and help prevent diseases spread by insects.

Risks: some are toxic to non-target organisms. DDT, a chlorinated organic compound, is persistent and fat-soluble, so it bioaccumulates and biomagnifies up food chains. It thinned the eggshells of birds of prey such as bald eagles and peregrine falcons. After it was phased out in Canada and the U.S. in the 1970s, these birds recovered. Neonicotinoid insecticides have raised concerns about bees and other pollinators.

Ontario actions: the Cosmetic Pesticides Ban Act (in force since 2009) bans most pesticides for purely cosmetic uses on lawns and gardens. Since 2015, Ontario has regulated the use of neonicotinoid-treated corn and soybean seed.

plankton1×small fishabout 10×large fishabout 100×fish-eating birdsabout 1000×relative concentrationof the chemicalillustrative numbers: real factors depend on the chemical and the food web
Biomagnification of a persistent, fat-soluble chemical such as DDT. Each predator eats many prey, so the chemical becomes more concentrated at each step of the food chain.

Case 3: Food additives, supplements and medicines

  • Food additives such as preservatives (sodium benzoate), sweeteners and colours are assessed by Health Canada before they are allowed. Preservatives reduce food spoilage and food poisoning. Some people are sensitive to particular additives, which is why ingredients must be listed on labels. The 2018 ban on partially hydrogenated oils (Lesson 6) shows that a permitted ingredient can be removed when evidence of harm grows.
  • Supplements are regulated in Canada as natural health products. "Natural" does not automatically mean safe or effective; look for the eight-digit NPN (Natural Product Number) on the label and for evidence from reliable studies.
  • Medicines such as ASA and acetaminophen relieve pain and fever, but every medicine has risks: too much acetaminophen can seriously damage the liver. Read the label, follow the dose, and dispose of unused medicines through a pharmacy take-back program, never down the drain.

Case 4: Industrial chemicals and communities

Sarnia, on the St. Clair River, is home to one of Canada's largest concentrations of petrochemical plants, sometimes called "Chemical Valley". During the Second World War, the federally created Polymer Corporation began making synthetic rubber there, and the industry grew into a major employer.

Aamjiwnaang First Nation is located right beside many of these facilities. Community members have raised concerns about air pollution and health for many years. In April 2024, after high levels of benzene (a carcinogen, Lesson 4) were measured, Aamjiwnaang declared a state of emergency; the Ontario government ordered a nearby styrene plant to stop operating while the problem was addressed, and the federal government ordered Sarnia-area facilities to reduce benzene leaks. The situation shows why exposure matters: the same chemicals that are useful products can be a daily risk for the people who live closest to where they are made.

Forever chemicals. PFAS (per- and polyfluoroalkyl substances) are organic compounds with many very strong C–F bonds. They resist water, grease and heat, which is why they were used in non-stick coatings, stain repellents, some food packaging and firefighting foams. The same strong bonds make them extremely persistent. In March 2025 the federal government concluded that PFAS as a class (except fluoropolymers) can harm human health and the environment and proposed managing them as toxic substances under the Canadian Environmental Protection Act.

Evaluating information (A1.9)

On topics like these you will find strong opinions online. Ask:

  • Who wrote it, and why? A company selling a product, an advocacy group and a government agency may all present facts selectively.
  • Is it evidence or opinion? Look for data, sample sizes and references to peer-reviewed studies.
  • Is the hazard confused with the risk? "Contains a chemical linked to cancer" says nothing about exposure.
  • Is it current? Regulations change; check the date and the government source (Health Canada, Environment and Climate Change Canada, Ontario ministries).
  • Do several independent, reliable sources agree?

Record your sources with full citations (A1.7) so others can check them.

Worked example

Example 1: Assessing a risk

A family uses a solvent-based paint (containing toluene and other organic solvents) to repaint a basement bedroom in January with the windows closed. Assess the risk and suggest two ways to reduce it.

  1. Hazard: organic solvent vapours can cause headaches, dizziness and nausea, and some are harmful with long exposure. They are also flammable.
  2. Exposure: a small, closed room in winter, so vapour concentrations build up; the person painting breathes them for hours; others may sleep there soon after.
  3. Risk: relatively high, because both the hazard and the exposure are significant.
  4. Reduce it: choose a low-VOC (volatile organic compound) water-based paint; ventilate with a fan and an open window on a mild day; take breaks; keep flames away; let the room air out before sleeping in it.

Moderate-to-high risk because of high exposure; reduce it by lowering the hazard (low-VOC paint) and lowering exposure (ventilation, time).

Worked example

Example 2: Persistence and structure

Use structure to explain why a polyester such as PLA can be composted industrially while polyethene persists for a very long time.

  1. PLA has ester links in its backbone; water (with heat and microbes in an industrial composter) can hydrolyse them, breaking the chain into small molecules.
  2. Polyethene has only C–C and C–H bonds; there are no links that water can attack, and few microbes can digest it.

Ester links can be hydrolysed; an all-carbon backbone cannot, so polyethene persists.

Your personal action plan (B1.2)

Small choices, multiplied across millions of people, make a difference. Examples of actions that reduce harmful organic compounds:

  • Weed by hand or use mulch instead of using herbicides.
  • Bring reusable bags, bottles and containers; avoid single-use plastics when practical.
  • Choose walking, cycling, transit, car-pooling or a fuel-efficient, hybrid or electric vehicle to cut fuel combustion.
  • Take household hazardous waste (paint, solvents, batteries, pesticides) to your municipality's depot, and unused medicines to a pharmacy.
  • Choose low-VOC paints, fragrance-free products if you are sensitive, and cleaning products you actually need.
  • Read labels and look up unfamiliar ingredients in reliable sources.

A good action plan is specific (what, when, how much), realistic, and measurable (how will you know it worked?).

Careers and Canadian contributions (A2.1, A2.2)

Organic chemistry leads to many careers:

  • Pharmacist (university degree in pharmacy and provincial licensing) and pharmaceutical chemist (B.Sc., often a graduate degree), who design and test medicines.
  • Chemical engineer (B.Eng. and P.Eng. licence), who design plants such as those in Sarnia, and process operators and chemical technologists (college diploma programs).
  • Polymer and materials scientists, who develop new plastics, including biodegradable ones.
  • Environmental chemists and toxicologists, who measure pollutants and assess risks for governments and communities.
  • Food scientists and flavour chemists, forensic scientists, and agricultural scientists.

In Ontario, chemists can earn the professional designation P.Chem. through the Association of the Chemical Profession of Ontario.

Canadian contributions: in 1953, Raymond Lemieux and his team at the National Research Council laboratory in Saskatoon achieved the first chemical synthesis of sucrose (table sugar), a landmark in carbohydrate chemistry. Lemieux later led chemistry research at the University of Alberta. The University of Toronto team of Banting, Best, Collip and Macleod isolated insulin, a protein, in 1921–1922, and Sarnia's wartime synthetic rubber industry was a major Canadian achievement in polymer production.

Hands-on activity

Household organic-compound audit and action plan

You need: a notebook or spreadsheet, access to product labels in your home (read only; do not open or mix products), and internet access for research. Grown-up note: cleaning products, solvents and pesticides should stay closed and in their storage place; this activity only reads labels.

  1. Audit: list 10 products that contain organic compounds: for example plastic containers (resin codes), cleaners, paints, lawn and garden products, personal-care products, fuels and medicines.
  2. For each, record: what it is used for, the main organic ingredient or polymer (if listed), the hazard symbols on the label, and how it is disposed of.
  3. Assess: choose the three products you think carry the most risk for your household or the environment. For each, explain the hazard and the exposure in one or two sentences.
  4. Research: for one of the three, find two reliable sources (at least one government source). Cite them fully and note any bias.
  5. Plan: write a personal action plan with three specific, measurable actions (for example: "Replace plastic sandwich bags with two reusable containers starting Monday; count bags saved each week for a month.").

What to look for: a strong plan names a real product and a realistic replacement, explains the chemistry ("PE bags persist because their C–C backbone does not hydrolyse"), and says how success will be measured. Good sources include Health Canada, Environment and Climate Change Canada, Ontario government pages and peer-reviewed articles.

Just for fun

The saying "the dose makes the poison" applies even to water: drinking far too much, far too fast, can be dangerous. Chemistry has no completely safe or completely dangerous substances, only amounts and exposures.

Your turn

1

Explain the difference between hazard and risk, using gasoline as an example.

2

Why do persistent, fat-soluble chemicals biomagnify?

3

Give two benefits and two risks of plastic packaging.

4

Which Canadian regulation banned microbeads, and in what kind of product?

5

State three questions to ask when judging an online claim about a chemical.

6

Name two careers that use organic chemistry and the training each needs.

More practice: warm-up

1

What does "persistent" mean for a chemical?

2

What size are microplastics?

3

What does PFAS stand for?

4

Name one action that reduces herbicide use at home.

5

Which Canadian chemist made the first synthesis of sucrose?

More practice: on your own

1

Use bond strength to explain why PFAS are called "forever chemicals".

2

Why might the same chemical release be a bigger concern for Aamjiwnaang First Nation than for a town 100 km away?

3

A website selling a "chemical-free" cleaner says ordinary cleaners are "full of toxins". Evaluate the claim.

4

Write one specific, measurable action-plan item to reduce fuel combustion.

5

Explain how the 2018 trans fat ban connects to an organic reaction you studied.

Challenge

1

A town must choose between two lawn-care policies: (A) allow a herbicide with low toxicity to mammals but moderate persistence in soil, or (B) ban it and pay for manual weeding and overseeding in parks. Give a structured assessment (benefits, risks, who is affected, evidence needed) and a recommendation.

2

Compare the environmental persistence of nylon-6,6, polyethene and PLA, using the bonds in their backbones.

3

Design a simple investigation (question, variables, method outline and safety) to compare how much microplastic fibre is released when a polyester fleece is washed in cold vs warm water.

Check your understanding

Quiz

1.

Which statement best describes risk?

2.

Why do DDT levels increase up a food chain?

3.

Why are most common plastics persistent in the environment?

4.

Which action is part of a reasonable personal plan to reduce harmful organic compounds?

5.

Which source is likely the most reliable for current Canadian rules on a pesticide?

6.

What chemical feature makes PFAS so persistent?

For parents and teachers

Big ideas (B1.1, B1.2): organic compounds bring great benefits and real risks. Risk depends on hazard and exposure; persistence, bioaccumulation and biomagnification can spread harm. Students should evaluate evidence, recognize bias, and make a realistic personal action plan.

How to help: Do the household audit together. Let your teen lead the label reading, and discuss which actions your family could actually take. Help them find government sources and judge online claims.

Common difficulties:

  • Treating "chemical" as a synonym for "harmful" (everything is made of chemicals).
  • Confusing hazard with risk.
  • Action plans that are vague ("use less plastic") instead of specific and measurable.

Sensitive topic: the Sarnia case involves the health concerns of a real First Nation community today. Discuss it respectfully, as an example of how the location of industry affects who carries the risk, and encourage your teen to read the community's own statements and news from reliable outlets.

Safety: the audit is read-only. Keep cleaners, solvents and pesticides closed, labelled and out of reach of children.