Risks and Benefits of Chemicals:
Chemicals are essential to life on Earth.
Humans have developed chemicals to use
for sanitation, preserving foods, treating
diseases, and increasing crop yields
(amount). Although many chemicals are
beneficial, others are harmful to humans
and other organisms.
Risks and Benefits
 The development and use of chemicals
offer both benefits and risks to people,
organisms, and the environment.
 Benefits are how the chemical meets the
needs of society.
 Risks describe how the chemical might
negatively affect the environment or
create unsafe conditions for people.
 The process of weighing the potential
harm of using a new technology against
its benefits is called risk-benefit analysis.
Sanitation
 Sanitation involves all of the methods
used for the removal, treatment, and
disposal of wastes.
 Wastewater treatment is an example of
sanitation.
 Charcoal, a form of carbon, is used to
filter contaminants from water.
 Chlorine is used to kill bacteria and other
microorganisms.
Food Preservatives
 Chemicals used to prevent food spoilage
caused by microorganisms are food
preservatives.
 Salt and vinegar were the first food
preservatives and inhibit the growth of
microorganisms.
 Some chemicals are added to foods to
slow oxidation.
 Oxidation is a chemical reaction that
occurs when a substance reacts with
oxygen.
 Oxidation can cause foods, such as fruits,
to turn brown or black.
 Food preservatives can keep food safe for
use for longer periods of time than food
not treated with preservatives.
 Some people have an allergy for food
preservatives, which is an immune
response to proteins in certain foods.
 A food intolerance is an inability to
digest a food or a food additives.
 To lower the risk of such problems,
companies must list all ingredients on the
label.
Medicines
 In the late 1800’s, a German chemist
isolated and identified the chemical
commonly known as aspirin.
 Today, aspirin is just one of thousands of
chemicals that are used as medicines to
treat diseases from the common cold to
cancer.
Antibiotics
- Antibiotics are a group of medicines
used to kill bacteria that cause
disease.
- Penicillin was the first antibiotic.
- Before antibiotics, a person could die
from an infection caused by a
scratch.
- Today, many different kinds of
antibiotics are used to treat a wide
variety of diseases caused by
bacteria.
Chemicals & Crop Yields
 Two groups of chemicals are used to
increase crop yields: fertilizers and
pesticides
 Fertilizers are chemicals that promote
plant growth and benefit plants.
 However run-off carrying fertilizers into
streams and ponds can cause an excessive
growth of algae that actually harms
ecosystems.
 Pesticides are chemicals designed to kill
organisms that are considered pests.
 Today, about 10 billion kilograms of
pesticides are used each year worldwide.
 The benefit of pesticides is an increase in
crop production.
 However, some pesticides such as DDT,
can have harmful effects on the organisms
they were not intended to kill.
Review Questions:and COACH page 228,1-4
1. What is the benefit of adding chlorine to
water before it is usable?
- To kill bacteria and other
microorganisms.
2. How do food preservatives work?
- Added chemicals make food last longer.
3. Why must all ingredients be listed on
food labels?
- Because people may have a food allergy
or intolerance to an ingredient.
4. What do antibiotics do?
- Antibiotics kill bacteria that cause
disease.
5. Explain the difference between fertilizers
and pesticides.
- Fertilizers promote plant growth and
pesticides kill organisms.
COACH page 228:
1. C
2. D
3. B
4. C
Ticket out the door:
Identify the risks and benefits of at least two
chemicals you use daily.