Blog #12 Environmental Hazards and Human Health & Air Pollution

Environmental Hazards and Human Health

This chapter begins by states that we need to consider what risks we take and how serious those risks are and do the benefits of a certain activity outweigh risks? Infectious diseases are caused by a pathogen invading the body and multiplies in its cells and tissue. We face the risk of infectious diseases when when come in contact with people who are already infected with a transmissible disease that can be transmitted from person to person.  There are bacterial diseases such as tuberculosis and measles and bacterial viral diseases like the flu or HIV. In 1900, century infectious disease was the leading cause of death throughout the world. After modern medicine around 1950s, the death rates from infectious diseases has been greatly reduced. The leading cause of death today is a nontransmissible disease, that cannot be transferred from person to person, called cardiovascular disease. Despite a shift from the deaths related to transmissible to nontransmissible diseases, infectious diseases still remains a serious health threat, especially in less-developed countries.

Viral Diseases and parasites kill large numbers of people. A virus can evolve quickly and when not affected by antibiotics and threaten the lives of many people. The flu virus is the biggest killer. The flu is transmitted by the body fluid or airborne emissions of an infected person. After the flu, the second biggest virus is HIV. HIV infects about 2.5 million people each year and the complications resulting from AIDS kill about 2 million people annually. After HIV, the third largest virus is hepatits B virus (HBV). HBV can damage the liver and will kill millions every year. Both HBV and HIV are transmitted through unsafe sex, sharing of hypodermic needles, infected mothers transferring the virus to their child before or during bird and the exposure to infected blood. Health officials are concerned now about the spread of the West Nile virus, the newest avian flu and other emergent diseases (like H1N1). You can reduce your risk of getting an infectious diseases by practicing good hygiene.

The Swine Flu (H1N1) was a virus that caused a pandemic in 2009. By 2010 when WHO claimed H1N1 no longer a pandemic, more than 18,000 people had died. Personally, I worked at a pharmacy during that time period and I remember how intensely everyone wanted to flu vaccine.

What can we do to reduce the incidences of infectious diseases? According to WHO the global death rate from infectious diseases has decreased and is projected to continue dropping. More children are getting immunized with vaccines in less developed countries than previous years, which saves about 10 million lives each year. An important new breakthrough has been the development of oral rehydration therapy that helps to prevent death from dehydration for victims of severe diarrhea, which causes about one-fourth of all deaths of children younger than 5 years old. By implementing the following solutions the WHO estimates that we could save the lives of as many as 4 million children younger than 5 each year: Increase research on tropical diseases and vaccines, reduce poverty, decrease malnutrition, improve drinking water quality, reduce unnecessary use of antibiotics, educate people on antibiotics, reduce antibiotics used on livestock, require careful hand washing by all medical personnel, immunize children, provide oral rehydration, and conduct global campaigns to reduce HIV/AID

Due to the pollution building up in the environment, the concern for chemical hazards in the environment is rising. These chemical can cause cancer, birth defects, disrupt human immune, nervous and endocrine systems. There are three major forms of potentially toxic agents: carcinogens, chemicals that can cause cancer; mutagens, chemicals that can lead to mutagens; and teratogens, chemicals that cause harm or birth defect to the fetus or embryo.

We are exposed to small amounts of potentially harmful chemicals every day in the air we breathe and what we eat and drink. The toxicity of a substance is the measurement of harmfulness and its ability to cause injury, illness or death. A key factor with toxicity is the dse, the amount of the chemical that a person can ingest, inhale or absorb. The dose of the substance that harms the living creature depends on the individual and the chemical. Their response, the damage to health resulting from exposure to a chemical, can be acute or chronic effect. Acute effect is an immediate response and a chronic effect is a permanent long-lasting response.

To determine the toxicity of a particular item a population of live laboratory animals are used to measure doses of a specific substance under controlled conditions. Mice and rats are most commonly used, but other mammals are used as well. Scientist try to find the dose-response curve that determines the lethal dose of a toxins. Some scientist challenge the validity of extrapolating data from test animals to humans. This is because human physiology and metabolism often differ from those of test animals. Others argue that the test work well. However, (thankfully) more humane methods for toxicity testing are becoming available and are being used in replacement of live animals. These include making computer simulation and using tissue cultures of cell and bacteria, chicken egg membranes, and individual animal cells, instead of the whole live animal.

Recently I have become more aware of how often we test on animals. I think even worse than testing live animals for medical purposes, testing animals for cosmetic purposes is much worse. So I now I only buy from cosmetic companies that are 100% animal friendly.

How do we perceive risk and how can we avoid the worst of them? We need to educate ourselves and become more aware of how lifestyle choices can affect our risks. We can protect ourselves by making the right choices and practicing a safe and healthy lifestyle.

Air Pollution

Atmosphere is the thin blanket of gases surrounding the earth. It is divided into several spherical layers, the two innermost layers are the troposphere and the stratosphere. About 75-80% of the earth’s air mass is found in the troposphere, which is the atmospheric layer closest to the earth’s surface. This layer is extends only about 11 miles above sea level at the equator and 4 miles above sea level over the poles. The second layer is the stratosphere, which extends from 11-30 miles above the earth’s surface. It contains less matter than the troposphere, but the composition is very similar to  the troposphere — with two exceptions, it’s volume of water vapor is about 1/1,000 than of the troposphere and its concentration of ozone is much higher.

Air pollution is the presence of chemicals in the atmosphere in concentrations high enough to harm organisms, ecosystems, or human-made materials or to alter climate. These air pollutants come from natural and human sources. A natural sources would be wind-blown dust, pollution from wildfires and volcanic eruptions. Human inputs of air pollution occur in industrialized and urban areas with higher concentrations of people, cars and factories.

Outdoor pollution can be classified in two categories: primary pollutants – chemicals or substances emitted directly into the air from natural processes and human activities at concentrations high enough to cause harm; and secondary pollutants – when some primary pollutants react with one another and with other natural components of air to form new harmful chemicals. Although air pollution is still a huge problem, the good news is that over the past 30 years the quality of outdoor air in most developed countries has improved greatly. This cleaner air is mostly from enforcing pollution air control laws. However, as a common theme we see within this text, less-developed and people in poverty suffer from outdoor air to breathe. However, the biggest pollution threat to poor people is actually indoor air pollution caused by burning wood, charcoal, coal or dung. Surprisingly to me cigarette smoke is another part of the indoor air pollution problem. I feel like we should have moved away cigarette smoke as an indoor pollution years ago. Outdoor pollution is no longer a problem for just for cities, but it has become a global problem. What are the major air pollutants? Carbon oxides (carbon monoxide and carbon dioxide), nitrogen oxides and nitric acid, sulfur dioxide and sulfuric acid, particulates, ozone, volatile and organic compounds.

Industrial facilities in more developed countries use tall smokestacks to vent the exhausts from burned fuel. These tall smokestacks reduce local air pollution, but they can increase regional air pollution. These acidic substances remain in the atmosphere for 2-14 days and forms wet deposition and  dry deposition. The mixture of the two creates acid deposition, or acid rain. Acid deposition in some regions threatens human health, aquatic life and ecosystems, forests, and human-built structures. But, we can reduce acid deposition. We can work to prevent more acid rain and ‘clean up’ current acid deposition. Prevention comes from reducing coal use, burning low-sulfur coal, increasing use of natural gas and renewable energy resources and removing SO2 particulates and NOx from smokestack gases and remove NOx from motor vehicular exhaust. To aid in the cleanup of pervious acid deposition, we can add lime to neutralize acidified lakes and add phosphate fertilizer to neutralize acidified lakes.

Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer and heart attack, and strokes. Sadly at least 2.4 million people suffer deaths from air pollution each year, mostly occurring in Asia. In the United States the death rate for air pollution ranges from 150,000 to 350,00 yearly. Solutions for stationary source air pollution like industries are as follows: we can prevent more pollution by burning low-sulfer coal or remove sulfur from coal, convert coal to a liquid or gas, or *phase out coal use; to reduce the amount of air pollution we have from industries we can remove pollutants from smokestack gases and/or tax each unit of pollution produced. And, another recurring theme, air pollution can be combated on an individual level.

Two Blog Questions:

  1. Could we completely do away with animal testing and use willing volunteer human participants?

  2. In what ways the the Clean Air Act not fully protecting us from air pollution — why is there still an abundant of air pollution with that law in place.


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