PH161 Unit 1 Intro
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what is environmental health?
Environment: The sum pf all external influences affecting the health and well-being of humans.
Study of chem, phys, and biological environmental agents and the development of prevention/control strtegies and programs
prevent environmental agents from causing harm
Balance of Health
Picture a teeter-totter with human health on one side and disease/injury on the other side. The balancing fulcrum for this teeter-totter, allowing one side to rise and the other to fall, is often the environment. Environmental health processes seek to manipulate the environment so that human health rises and disease and injury decline.Manipulating the environment simply means that we apply controls to sources of pollution, contamination, or harm. For example, we use the environmental control of chlorinating drinking water to kill harmful organisms and keep people from becoming ill. We also put controls on our cars to keep them from spewing out toxic air pollutants that can degrade the air quality and harm human respiratory function. There are several kinds of environmental controls, many of which we will discuss as the semester progresses.
Spaceship earth example
Our planet Earth can be compared to a spaceship because, like the spaceship, it is a self-contained vessel orbiting the sun. It is also a nearly closed system where little gets in or out. The only significant input into our "spaceship" is the energy from the sun in the form of light and heat and the only thing that leaves our atmosphere (other than radio and TV waves and a real spaceship, of course) is the heat that is reflected or radiated from the surface of our planet.Spaceship Earth is composed of all the ingredients to support human life. In a never-ending loop, humans take food, water, air and raw materials from the environment to sustain their lives and produce products like houses and clothing and cars. Some of the resources we need to live2are renewable in that they can be regenerated. Examples of renewable resources are oxygen from plants, fresh water through the hydrological cycle, food crops, and timber. Resources that are considered non-renewable are such things as oil, natural gas, and coal.Unfortunately, human life in our spaceship also creates wastes in the form of sewage, air pollution, water pollution, radiation, and unwanted chemical and solid waste. In the past, we depended on Mother Nature to cleanse herself of these unwanted contaminates. Today, as the human population rapidly increases and our thirst for more and more products grows steadily, we depend on technology and environmental controls to help keep our spaceship clean and healthful.
Environmental hazards that can affect natural settings
- Pollution (contamination) = Biological, chemical, and/or physical agents accumulating in air, water, or soil, and reaching levels capable of causing environmental degradation and injury/illness to plant and animal life forms. Retrogression = Loss of, or backward succession of plant life (flora) due to selective pressure (stress) caused by overgrazing and other harmful human activity.
- Habitat destruction = Loss of animal life (fauna) due to selective pressure on natural areas used for breeding, feeding, or migrating caused by forest removal, draining swamps/wetlands, increased agriculture, damming rivers, and urban development.
- Soil erosion = Loss of topsoil due to overgrazing, improper agricultural practices, and chemical pollution of the soil.
- Deforestation = Loss of woodlands due to forest removal for additional farmland, fuel, and building material.
- Desertification = Creation or enlargement of deserts due to cutting forests, overgrazing, and improper agricultural practices.
- Wetlands destruction = Loss of swamps, bogs, tidal marshlands, estuaries, ponds, river bottoms, and flood plains due to farming, mining, and urban development.
Environmental hazards that affect humans
- Infectious agents = Microbes such as bacteria and viruses that are capable of being spread from one person to another, and that cause illness, death, and epidemics (often of environmental origin through food or the water supply).
- Irritants = Chemical compounds that are capable of causing respiratory disorders when inhaled and chemicals or plants that cause skin irritation. Sulfur dioxide and nitrogen dioxide are common air pollutants (especially in urban areas) that are classified as irritants. Certain workplace chemicals and substances commonly found in our homes (such as formaldehyde that degasses from foam insulation and other materials) are also considered to be irritants.3
- Asphyxiants = Gases that prevent the uptake of oxygen from our lungs into our bloodstream, tissues, and organs. An example of an asphyxiant is carbon monoxide, a compound commonly released from the burning of fossil fuels like the gas in our cars. Carbon monoxide combines with the hemoglobin in our red blood cells and blocks the blood's ability to transport oxygen.
- Respiratory fibrotic agents = Dusts and fibers retained in the lung that cause a fibrotic or scarring response in the lung tissue. Examples of fibrotic agents are asbestos (leads to a potentially fatal condition called asbestosis), coal dust (causes black lung disease or anthracosis, cotton dust (causes brown lung disease or byssinosis), and cellulose (causes sugar cane worker disease or bagassosis).
- Allergens = Pollens, grasses, solvents, metals (especially nickel), etc. that cause allergic reactions in sensitive individuals.
- Metabolic poisons = Arsenic, lead, chromium, etc. that can lead to severe illness and death
- . Physical agents = Unsafe tools and equipment, slip and fall hazards, improper storage, noise, improper lightning, vehicles, and electrical hazards are all considered physical agents that can cause trauma, injury, and/or death.
- Mutagens, carcinogens, teratogens = Radiation, heavy metals (like cadmium), industrial use chemicals (like vinyl chloride and dioxin) can lead to cellular changes, birth defects, and death.
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