New version page

UT ENS 112 - Chapter 10

This preview shows page 1-2 out of 7 pages.

View Full Document
View Full Document

End of preview. Want to read all 7 pages?

Upload your study docs or become a GradeBuddy member to access this document.

View Full Document
Unformatted text preview:

Environmental Science 112FALL SEMESTER 2018INSTRUCTOR: DR. Adrienne [email protected] 10Environmental Health● Environmental Health is a field that assesses environmental factors that can influence our health and quality of life○ These include both natural and anthropogenic factors● Environmental hazards are categorized into four types○ Physical Hazards■ Arise from natural environmental processes, such as UV radiation from sunlight and natural disasters● Reduced with protective measures, such as sunblock and disaster protection and warning systems○ Chemical Hazards■ Include synthetic chemicals such as pharmaceuticals, disinfectants, and pesticides, and natural toxins like venom○ Biological Hazards■ Result from interactions with other organisms, such as viruses, bacteria, insects, or parasites■ Infectious Disease: are illnesses that can be spread from person-to person■ Vectors are organisms that transfer diseases to their host○ Cultural Hazards■ Occur as the result of our place of residence, socioeconomic status, occupation, or behavioral choices1● Ex: smoking, poor diet, drug use, and workplace hazardsDisease is a major focus of environmental health● Infectious and noninfectious diseases cause the majority of human deaths worldwide● Noninfectious diseases develop without the action of a foreign organism● Infectious Diseases spreads when a pathogenic organism enters a host through the skin, via the respiratory system, or by the consumption of food or water○ Immunization, public sanitation, access to clean water, food security, and public education all help to reduce infectious disease○ Infectious diseases are the second-leading cause of death worldwideToxicology is the study of chemical hazards● Toxicology is the science of examining the effects of poisonous substances on humans and other organisms○ Toxicity is the degree of harm caused by a chemical substance called a toxicant● Any chemical has the potential to be a toxicant, depending on the dose and level of exposure● Environmental Toxicology is the study of anthropogenic chemicals released into the environment that have human health impactsMany Environmental health hazards exist indoors● Cigarette smoke and radon are leading indoor health hazards and the top two causes of lung cancer○ Radon is a radioactive gas that seeps up from certain types of bedrock. It is colorless and undetectable without specialized kits● Asbestos is a substance that was used in the past as insulation in walls and other products and is highly toxic when inhaled● Lead is a heavy metal that, when ingested, damages the brain, liver, kidney, and stomach2○ Lead poisoning has greatly declined since the phaseout of lead- based paint and leaded gasoline in the 1970’s● Polybrominated Diphenyl Ethers (PBDE’s) are compounds used as fire retardants in a variety of products, including electronica, plastics, and furniture○ Act as hormone disruptors, interfering with thyroid hormones○ European Union banned PBDE’s in 2003, but not the USToxic substances and their effects on organisms● The environment contains many natural toxic substances, such as petroleum, radongas, and toxins○ Toxins are toxic chemicals manufactured in the tissues of living organisms, often used as defense against other● We are also exposed to many synthetics chemical substancesSilent Spring began the public debate over synthetic chemicals● Prior to the 1960’s, pesticides were sprayed over residential neighborhoods and public areas, on an assumption that the chemical would not harm people● Rachel Carson published Silent Spring in 1962, using the scientific studies and case histories to demonstrate that pesticides like DDT were harmful to people○ Although the chemical industry challenged the book, public outcry led to the banning of DDT in the United States.● Synthetic Chemicals, such as DDT, take many routes traveling through the environmentNot all toxic substances are synthetic● Many toxic substances exist naturally in the environment and in the foods we eat○ It is a mistake to assume that all synthetics are bad and a natural are goodToxic Substances come in different types● Carcinogens are substances or types of radiation that cause cancer○ Cancer occurs when malignant cells grow uncontrollably, creating tumors and often leading to death3● Mutagens are substances that cause genetic mutations in the DNA of organisms○ Most mutations have little or no effect, but can lead to severe problems like cancer● Teratogens specifically cause birth defects● Neurotoxins such a heavy metals damage the nervous system● Allergens over-activate the immune system, causing an immune response when one is not necessary● Pathway inhibitors block one or more steps in important biochemical pathways○ Cyanide, for example, interrupts the chemical pathways that produce energy in the mitochondria● Endocrine disruptors interfere with the functions of body hormones, either by blocking them, accelerating their breakdown, or mimicking their effectsOrganisms have natural defenses against toxic substances● Organisms have evolved ways to tolerate harmful substances naturally present in the environment to gain an evolutionary advantage○ Skin, scales, and feathers resist uptake from the surrounding environmentIndividuals vary in their responses to hazards● An individual’s sensitivity to a given toxin will vary depending on genetics, overall health, gender, and age○ Those in poorer health, individuals of smaller size, and younger organisms with developing organ systems tend to be more sensitive○ The EPA extrapolates chemical exposure standards for adults down to infants and childrenThe risk of exposure can affect the response● The risk of a hazard also varies according to whether:○ A person experiences high exposure for short periods of time (acute exposure)○ Low exposure for long periods of time (chronic exposure)4Some toxicants persist in the environment● The rate at which a substance degrades in the environment depends on its chemistry and on external factors like temperature, moisture, and sun exposure● We have designed many chemicals, such as those in plastics, to be persistent and resist degradation○ Over time, most toxicants degrade into simpler compounds, called breakdown products, which may be less or equally harmful as the original substanceToxic substances may accumulate and move


View Full Document
Loading Unlocking...
Login

Join to view Chapter 10 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Chapter 10 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?