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LT 7A Active Practice Key
1. Describe the potential risks from exposure to trace amounts of hormone mimics.
 Developmental issues could arise if the hormone is not able to regulate cells as they do normally.
2. Define risk and distinguish between risk assessment and risk management.
 A risk is the probability of suffering harm from a hazard that can cause injury, disease, death, economic
loss, or damage.
 Risk assessment is the process of using statistical methods to estimate how much harm a particular
hazard can cause to human health or to the environment.
 Risk management involves deciding whether or how to reduce a particular risk to a certain level and at
what cost.
3. What is a pathogen?
 A pathogen is an organism that can cause disease in another organism. Examples are bacteria, viruses,
parasites, protozoa, and fungi.
4. Give an example of a risk from each of the following: biological hazards, chemical hazards, physical
hazards, cultural hazards, and lifestyle choices.
 Biological hazard examples are bacteria, viruses, parasites, protozoa, and fungi.
 Chemical hazards from harmful chemicals in air, water, soil, food, and human-made products such as
the BPA from plastic bottles.
 Physical hazards include fire, earthquakes, volcanic eruptions, floods, and storms.
 Cultural hazards include criminal assault.
 Lifestyle choices include smoking.
5. Distinguish among a transmissible disease, and a nontransmissible disease, and give an example of each.
 A nontransmissible disease is caused by something other than a living organism and does not spread
from one person to another. Such diseases tend to develop slowly and have multiple causes. Examples
include cardiovascular (heart and blood vessel) diseases, most cancers, asthma, and diabetes.
 A transmissible disease (also called a contagious or communicable disease) is an infectious disease
that can be transmitted from one person to another. Examples are tuberculosis, flu, and measles.
6. In terms of death rates, what are the world’s four most serious infectious diseases?
 The world’s four most serious infectious diseases are pneumonia and flu (bacteria and viruses),
HIV/AIDS (virus), tuberculosis (bacteria), and diarrheal diseases (bacteria and viruses).
7. Distinguish between an epidemic and a pandemic of an infectious disease.
 A large-scale outbreak of an infectious disease in an area or country is called an epidemic, and a global
epidemic such as tuberculosis or AIDS is called a pandemic.
8.
Describe the threat from malaria for 40% of the world’s people and how we can reduce this threat.

About 1 in five people worldwide, mostly in Africa, are at risk of contracting malaria. Between one to
two million people die from malaria each year. There is no vaccine. Malaria infects red blood cells and
is transmitted by mosquitoes. Draining wetlands and spraying with insecticides decrease the number
of disease-carrying mosquitoes. However, many species of mosquito have become resistant to
pesticides and many of the malaria-causing microbes have become antibiotic-resistant. Ways to
combat malaria include developing new anti-malarial drugs and new mosquito controls, as well as
providing bed nets and window screens. Nutritional supplements (zinc and vitamin A) increase
resistance in children. DDT, while being phased out world-wide, can be cheaply used to spray homes
and greatly reduce the incidence of malaria.
LT 7A Active Practice Key
9. What is a toxic chemical?
 A toxic chemical is one that can cause temporary or permanent harm or death to humans and animals.
10. Distinguish among mutagens, teratogens, and carcinogens, and give an example of each.
 Mutagens are chemicals or forms of radiation that cause mutations, or changes, in the DNA molecules
found in cells, or that increase the frequency of such changes. Most mutations cause no harm but some
can lead to cancers and other disorders. For example, nitrous acid (HNO2), formed by the digestion of
nitrite (NO2 –) preservatives in foods, can cause mutations linked to increases in stomach cancer in
people who consume large amounts of processed foods and wine with such preservatives. Harmful
mutations occurring in reproductive cells can be passed on to offspring and to future generations.
 Teratogens are chemicals that cause harm or birth defects to a fetus or embryo. Ethyl alcohol is a
teratogen. Drinking during pregnancy can lead to offspring with low birth weight and a number of
physical, developmental, behavioral, and mental problems.
 Carcinogens are chemicals, types of radiation, or certain viruses that can cause or promote cancer—a
disease in which malignant cells multiply uncontrollably and create tumors that can damage the body
and often lead to premature death. Examples of carcinogens are arsenic, benzene, chloroform,
formaldehyde, gamma radiation, nickel, PCBs, radon, certain chemicals in tobacco smoke, ultraviolet
(UV) radiation, X-rays, and vinyl chloride.
11. Describe the human immune, nervous, and endocrine systems and give an example of a chemical that can
threaten each of these systems.
 The immune system consists of specialized cells and tissues that protect the body against disease and
harmful substances by forming antibodies that render invading agents harmless. Some chemicals such
as arsenic, methylmercury, and dioxins can weaken the human immune system and leave the body
vulnerable to attacks by allergens and infectious bacteria, viruses, and protozoa.
 Some natural and synthetic chemicals in the environment, called neurotoxins, can harm the human
nervous system (brain, spinal cord, and peripheral nerves). Effects can include behavioral changes,
learning disabilities, retardation, attention deficit disorder, paralysis, and death. Examples of
neurotoxins are PCBs, methylmercury, arsenic, lead, and certain pesticides.
 The endocrine system is a complex network of glands that releases tiny amounts of hormones into the
bloodstreams of humans and other vertebrate animals. Low levels of these chemical messengers turn
on and turn off bodily systems that control sexual reproduction, growth, development, learning ability,
and behavior. Each type of hormone has a unique molecular shape that allows it to attach to certain
cells, using a part of the cell called a receptor, and to transmit its chemical message. In this “lock-andkey” relationship, the receptor is the lock and the hormone is the key. PCBs can affect this system.