Deck 11: Environmental Hazards and Human Health

Question 1

What is a toxic chemical ? Distinguish among mutagens teratogens , and carcinogens , and give an example of each. Describe the human immune, nervous, and endocrine systems and give an example of a chemical that can threaten each of these systems. What are hormonally active agents, what risks do they pose, and how can we reduce these risks? Summarize the hazards of mercury in the environment.

Answer 1

Toxic chemicals are agents that could cause harms to humans and other living organisms. Carcinogens, mutagens, and teratogens are three major types of toxic chemicals.
Carcinogens cause cancers. Cancers are diseases in which the cells multiply uncontrollably. The multiplied cells create tumors that can damage the body. People with cancers may die at a much earlier age than expected. Some examples of carcinogens are ultraviolet radiation, PCBs, formaldehyde, benzene, benzene, and arsenic.
Mutagens cause mutations. Mutations are changes in DNA structures. The mutations may be harmless or harmful. The harmful mutations result from change in the DNA structures and change in the functions of the proteins. The mutations may affect the current generation or future generations too. Some examples of mutagens are some chemicals, some forms of radiations, and preservatives in food and drinks.
Teratogens cause harms and birth defects to embryos and fetuses. The affected children may develop a number of problems. The problems and complications that may result include low birth weights, behavioral problems, physical problems, and mental problems. Some examples of teratogens are ethyl alcohol, benzene, formaldehyde, lead, and mercury.
Mercury is a teratogen. Hence, mercury could cause birth defects. Mercury is contained in products such as paints, batteries, and chlorine. Mercury is a very toxic element. Mercury cannot be broken down and degraded. Hence, fish could consume and accumulate great concentrations of mercury in their bodies. People who consume the fish would increase the concentration of mercury in their bodies. These people are at high risk of being harm by mercury.
The immune system consists of cells, such as white blood cells. The white blood cells help the bodies fight off diseases and infections. White blood cells produce antibodies and signal other immune cells to destroy the pathogens. Some toxic chemicals could weaken the immune systems. Weaken immune systems could not protect the bodies against diseases and infections. Chemicals that could weaken the immune systems are methyl mercury, arsenic, and dioxins.
The nervous system consists of the brain, spinal cord, and the peripheral nervous system. The nervous system enables us to respond to environmental stimuli. The nervous system enables us to perform actions. Neurotoxins are toxic chemicals that damage the nervous system. Damaged nervous system would result in problems such as, behavioral changes, learning disabilities, retardation, and death. Some examples of neurotoxins are methyl mercury, arsenic, pesticides, and lead.
The endocrine system is consisted of a network of glands. The glands secrete hormones into the bloodstreams. Hormones are substances that regulate the functions of many organs and organ systems. For instance, hormones could regulate sexual reproduction, growth, learning ability, and development.
Hormonally active agents or HAAs are toxic chemicals that damage the reproductive systems. HAAs could also harm sexual development. People who are exposed to HAAs may have physical disorders or behavioral disorders. Some examples of HAAs are mercury, DDT, aluminum, PCBs, atrazine, and some herbicides.

Question 2

What are the three major risks you face from (a) your lifestyle, (b) where you live, and (c) what you do for a living (whether you work or go to school)? Which of these risks are voluntary and which are involuntary? List the three most important things you can do to reduce these risks. Which of these things do you plan to do?

Answer 2

All our activities have risks. If we smoke cigarettes, we have risks of many health problems. If we do not smoke cigarettes, we have risks of second hand smoke. Second hand smoke is inhaling the smoke of other people. Driving a car presents us with many risks. We could get into a car accident. We expose the environment with greenhouse gas when we drive a car.
Our lifestyle poses us with many known risks and unknown risks. Our eating habits affect our health and the health of other people. If we have health problems, other people would spend the time and energy to take care of us. Hence, all our actions directly and indirectly affect other people.
It is known that exercising benefits our health in many ways. However, it is possible that other people who are in less developed countries may not know the benefits of exercising. They may not be aware of the risks factors involved in their daily routine.
Even when we know the risks factors, we still need to be determined to avoid the risks. First, we must evaluate the risks and compare the risks. Then, we must make a decision. We need to make a conscious effort to avoid the risks. It is possible that many people are not trained with evaluating risks and making the right decisions to avoid the risks.
Being informed about the relevant information would empower us with the ability to evaluate the risks, compare the risks, and make the decisions to avoid the risks. Hence, having the relevant sources of information would help us reduce the risks.

Question 3

How do we perceive risks, and how can we avoid the worst of them?

Answer 3

Being able to perceive risks and avoid risks are critical in maintaining a healthy life. Often time, people who put themselves at high risks are either not being able to perceive the potential risks or their situations do not allow them to avoid the risks.
Poverty and lifestyle choices could pose major risks that affect people's exposure to toxic chemicals. Poverty is the major factor that put people at high risks. Poor people do not have access to nutritious food, health care, clean water, and helpful information.
People in poverty tend to be less healthy. They are at high risk of consuming water and food that are contaminated with toxic chemicals. In addition, they tend to be less educated. That means they are not knowledgeable about ways to detect the risks, avoid the risks, and improve their living situations.
Lifestyle choices may affect people at higher economic levels. For the most part, people could control their lifestyles choices. They could control what they eat, the activities that they do, and the activities that they choose not to do. Some food choices increase the risks of many health problems.
In addition, some habits increase the risk of premature deaths. For instance, smoking cigarette increase the risk of premature deaths. Nevertheless, many people are addicted to cigarette smoke that they could not avoid smoking even if they realize that cigarette smoking will damage their health.
Being informed is the best way to perceive risks and avoid risks. We could learn about the risk factors and avoid doing activities that put ourselves at higher risks. For instance, suppose we learn that frozen foods contain preservatives. We learn that preservatives are not healthy for us. Then, we change our behavior by not consuming the frozen foods or reduce the consumption of frozen foods.
Even people who are in poverty could avoid doing things that harm their health. For instance, they could clean the water before drinking it if they know unclean water contain parasites and harmful chemicals. Hence, perceiving risks and avoiding risks start with knowing the risk factors and ways to minimize the risk.

Question 4

Define toxicology , toxicity , dose , and response. Explain how the toxicity of a substance can be estimated by using laboratory animals and discuss the limitations of this approach. What is a dose-response curve ? Explain how toxicities are estimated by case reports and epidemiological studies and discuss the limitations of these approaches.

Question 5

Would you support legislation requiring the use of pollution prevention to implement the precautionary principle in deciding what to do about risks from chemicals in the United States (or the country where you live)? Explain.

Question 6

List three ways in which you could apply Concept 11-5 to make your lifestyle more environmentally sustainable while reducing the major risks you face.

Question 7

Are trace levels of toxic chemicals harmful? Discuss the controversy surrounding this question. Why do we know so little about the harmful effects of chemicals? Discuss the use of pollution prevention and the precautionary principle in dealing with health threats from chemicals.

Question 8

What major health hazards do we face?

Question 9

List two questions that you would like to have answered as a result of reading this chapter.

Question 10

Review the Key Questions and Concepts for this chapter on p. 226. Define and distinguish among risk, risk assessment , and risk management. Distinguish between possibility and probability. What is a pathogen ? Give an example of a risk from each of the following: a biological hazard, a chemical hazard, a physical hazard, a cultural hazard, and a lifestyle choice.

Question 11

What is risk analysis? Distinguish among risk assessment, comparative risk analysis, risk management, and risk communication. In terms of premature deaths, what are the three greatest threats that humans face? Summarize the dangers of smoking tobacco products.

Question 12

How can changes in the age structure of a human population increase the spread of infectious diseases? How can the spread of infectious diseases, such as HIV/AIDS, affect the age structure of human populations?

Question 13

How can we estimate the risks from complex technologies? How can we reduce the threats from the use of various technologies?

Question 14

What types of biological hazards do we face?

Question 15

What five factors cause people to misjudge risks? List four strategies that help us to evaluate and reduce risk.

Question 16

Define and distinguish among an infectious disease , a transmissible disease , and a nontransmissible disease , and give an example of each. Describe five possible pathways for infectious diseases. Distinguish between an epidemic and a pandemic of an infectious disease. Describe the causes and possible solutions for the increasing genetic resistance in microbes to commonly used antibiotics.

Question 17

How can we use the three principles of sustain ability to help us in reducing the major risks to our health?

Question 18

What are three actions you would take to reduce the global threats to human health and life from (a) tuberculosis and (b) malaria?

Question 19

What types of chemical hazards do we face?

Question 20

Describe the global threat from tuberculosis. Describe the health threats from the global HIV/AIDS pandemic and the effects it can have on a population. Describe the threats from the hepatitis B, West Nile, and SARS viruses. What are emergent diseases ? Describe the threat from malaria for 40% of the world's people and how we can reduce this threat. List eight ways to prevent or reduce the incidence of infectious diseases.

Question 21

Evaluate the following statements:
a. We should not be overly concerned about exposure to toxic chemicals, because almost any chemical at a large enough dose can cause some harm.
b. We should not worry much about exposure to toxic chemicals, because, through genetic adaptation, we can develop immunity to such chemicals.
c. We should not worry much about exposure to toxic chemicals, because we can use genetic engineering to reduce our susceptibility to the effects of toxic chemicals.

Question 22

How can we evaluate chemical hazards?