We often think of chemical contamination and pollution as environmental problems. However, for people who study environmental public health, the concern is not only how these issues affect the environment, but how they affect human health.

Environmental public health is a field that encompasses a wide range of topics, including hazards in the natural and human-built world, how people are exposed to these hazards, and how exposures relate to health conditions and diseases.

Throughout this lesson, we will cover various aspects of environmental public health in greater detail. They include:

• Conditions and diseases
• Exposures and risk
• Research
• Community action
• Health policy

Assess your current understanding of how a person's environment affects his or her health. Write down a few statements that describe what you already know about this in the context of these environmental public health topics.

Environmental factors can cause many health problems ranging from mild to fatal. Lack of access to healthy foods and a sedentary lifestyle can lead to obesity and diabetes. Toxic chemicals and air pollution can cause allergic reactions, respiratory problems, cancer, and developmental problems. Some diseases are spread more widely under certain environmental conditions. For example, a warm, wet climate can increase the danger of malaria, caused by a parasite carried by mosquitoes.

In this interactive activity, you'll learn about ways you might be exposed to chemical hazards in plastics, personal care products, food containers, furniture, paint, toys, or contaminated food and water. Click "View" on the left to begin the activity.

After completing the activity, list some possible health effects from exposure to these chemicals.

There are many environmental factors that affect human health, and the changing global climate will only add to them. In this interactive activity, explore some potential effects of climate change on human health. Click "View" on the left to begin the activity.

After completing the activity, describe some of the diseases and conditions that were presented. What environmental factors can lead to these health problems?

While people are often exposed to environmental health hazards, not everyone is at significant risk for health problems. Three fundamental factors influence the risk from environmental exposures:

• The nature of the exposure: The route of exposure (skin contact, respiration, or ingestion) and the amount of exposure affect a person's health risk.
• The timing of the exposure: The duration of exposure and the age of the person when exposed can greatly influence the health risk. A brief exposure to a small amount of environmental toxin may not cause health problems for an adult. However, small, repeated exposures can accumulate over time and cause harm. Fetuses, young children, and teenagers are especially vulnerable because of smaller body size and because their bodies are still developing.
• Genetics: Some people are more susceptible to environmental harm because of their genetic make-up.

Click "View" on the left to watch a video about how arsenic in drinking water can impact health. Note how even low doses of arsenic can cause major problems.

Do you think there is any concentration of arsenic in drinking water that could be considered safe? Why or why not?

In this interactive activity, you'll investigate how air quality is monitored and regulated based on the concentrations of several major air pollutants. Learn how a standardized Air Quality Index warns people about harmful levels of pollution to help them minimize their exposure to unhealthy air.

Click "View" on the left to begin the activity.

After completing the activity, describe how people could lower their exposure to an air pollutant or to one of the other environmental hazards that you learned about earlier in the lesson.

Environmental health research involves the collaboration of scientific researchers from various disciplines, including biology, chemistry, engineering, and statistics. For example, an ecologist looks at the relationship between humans and the natural environment. A toxicologist studies how chemicals affect people. An environmental engineer analyzes contaminants in soil, air, and water. And an epidemiologist studies health patterns to determine how, when, and where diseases occur.

Click "View" on the left to watch two videos about investigations into environmental health issues.

After viewing the videos, choose an environmental hazard and think about how researchers could learn more about it. What studies do you think should be done on the subject?

Environmental health hazards are of particular concern to the communities that are most directly affected. People who live near a toxic waste site, for example, have more exposure to toxins than those who live farther away. Such communities commonly have to take it upon themselves to fight for their environmental rights. Community action can be an effective means to achieving a healthier environment.

Click "View" on the left to watch two videos about people fighting for their health and their environmental rights. Think about the environmental health concerns that each community had and how they took action.

Are there any environmental health issues in your community that you feel strongly about? What action could you and others in your community take to help address these issues?

Governments can take an active role to protect the public health. For example, they can develop and enforce environmental health policies to minimize risks from hazards. These policies might cover what's permissible to emit into the air or water, how water and sewage is treated, and how foods are handled. Keeping everyone well informed about environmental health issues can also help to improve public health.

Click "View" on the left to watch a video about a government effort to provide Mexican communities with safe and clean water.

While we continue to learn more about environmental health hazards and human health risks, the findings are not always cut-and-dried. For example, we know that pesticides have harmful effects on health, but could the benefits of pesticide use outweigh the risks? Are there any safe levels of exposure? Governments are left with the difficult task of deciding how strongly to regulate exposures in order to protect public health.

Click "View" on the left to watch a video about how Halifax, Nova Scotia, became the first major North American city to ban the use of pesticides for lawn or garden use.

How cautious or proactive do you think governments should be when it comes to protecting public health?

In this lesson, you have explored a number of environmental public health topics. Now, choose one environmental health hazard that is of particular interest to you and research it further. It can be a hazard in your community, one covered in the media, or one you learned about in this lesson. Consider the following in your research:

• Conditions and diseases: What health problems are associated with the hazard?
• Exposures and risk: How are people exposed to it?
• Research: What research has been done, or what sort of research do you think should be done?
• Community action: What communities are most impacted, and how could they take action?
• Health policy: What health policies are in place—or should be in place—to protect against the hazard?

To begin, you may want to review your notes. Click "review my work" above and view or print out the screen that pops up. You may also find these websites helpful:

• NIEHS – Environmental Health Topics
• CDC – Environmental Health
• US EPA – Learn the Issues
• WHO – Environmental Health