human health and toxicology. major human health issues: focus of epidemiologists: scientists who...

Human Health and Toxicology

Major Human Health Issues:

Focus of Epidemiologists: scientists who investigate the ecology of a disease in a population

ecology of a disease: source, manner in which it is spread, rate of spread, manner of infection, time line of infection, targets of infection

Basic Measures of Human Health

Life Expectancy: How long people are expected to live (average of age of people when they die)

Infant mortality: How many infants in 1000 die before the age of one

Comparison of Human Health in Highly Developed Countries (HDC) and Low Developed Countries (LDC)

HDC (Japan) LDC (Zambia)

Life Expectance

Infant Mortality

WHY?

Health Care

Available Food

Vaccinations

# of Children

Parental Care

$ Spent on Health



Life Expectance ♀- 85 ♂ - 75 ♀- 37 ♂ - 37

Infant Mortality

WHY?

Health Care

Available Food

Vaccinations

# of Children

Parental Care

$ Spent on Health



Life Expectance ♀- 85 ♂ - 75 ♀- 37 ♂ - 37

Infant Mortality 3 per 1000 95 per 1000

WHY?

Health Care

Available Food

Vaccinations

# of Children

Parental Care

$ Spent on Health



Life Expectance ♀- 85 ♂ - 75 ♀- 37 ♂ - 37


WHY?

Health Care Good for All Ages Poor for All Ages

Available Food

Vaccinations

# of Children

Parental Care

$ Spent on Health



Life Expectance ♀- 85 ♂ - 75 ♀- 37 ♂ - 37


WHY?


Available Food Sufficient Insufficient

Vaccinations

# of Children

Parental Care

$ Spent on Health



Life Expectance ♀- 85 ♂ - 75 ♀- 37 ♂ - 37


WHY?



Vaccinations Prevalent Limited

# of Children

Parental Care

$ Spent on Health



Life Expectance ♀- 85 ♂ - 75 ♀- 37 ♂ - 37


WHY?




# of Children 1 or 2 5 – 6

Parental Care

$ Spent on Health



Life Expectance ♀- 85 ♂ - 75 ♀- 37 ♂ - 37


WHY?





Parental Care Focused/High Limited

$ Spent on Health



Life Expectance ♀- 85 ♂ - 75 ♀- 37 ♂ - 37


WHY?





Parental Care Focused/High Limited

$ Spent on Health $550 per year $5 per year

Reasons for Increased Longevity with Development: Sanitation: Decreases spread of disease, especially

those related to human waste (cholera and diarrhea) – prevents the spread of parasites and disease causing microorganisms

Vaccinations: near elimination of disease (mumps, polio, measles)

with increased development the cause of death moves away from infectious disease caused by microorganisms (influenza, tuberculosis, gastritis, cholera) to chronic disease associated with aging (cancer, cardiovascular disease and chronic obstructive pulmonary disease), many of which are preventable by life style choices

Health Issues in HDC:

McDonalds…..obesity and overweight• Overweight: 10 – 15 % over proper weight range –

includes muscle, bone, fat and water • Obese: more than 15% over proper weight range –

usually due to excess fat Proper Weight Range: Body Mass Index –

relationship of a person’s weight and height – BMI = (weight x 740)/(height in inches)2

Compare to accepted standards to determine underweight, healthy weight, overweight or obese

Health Issues in the LDC: mostly due to sanitation, lack of medical

supplies and malnutrition HIV/AIDS

Emerging and Reemerging Diseases

Emerging diseases: cross from other species to the human population

Monkey Pox Asian Bird Flu HIV West Nile Virus Lyme Disease

Reemerging Disease: at one point were under control but are increasing

Tuberculosis, small pox malaria Reasons For Re-emergent Diseases

- decrease in ability to fend off disease (HIV) increased resistance to drugs and treatments

Environmental Pollution and Disease

Cause vs. Association

Cause – direct link between a pollutant and the detrimental effects

Ex: Radon gas and lung cancer

Lead and nervous system degeneration

Association: link between pollutant and disease is less clear due to:- a person’s genetic makeup- diet - levels of exposure (chronic or acute) - other health issues (other diseases or conditions, smoking)- age (children tend to be more susceptible, elderly have weakened immune systems)- local environment

Pollutant: a chemical or waste put into the air, water or soil that makes the environment unfit for living organisms

Toxins vs. Toxicant

Toxin: poisonous substance that is a protein – manufactured by a living organism Ex: poison secreted by the skin of a Poison Arrow Frog, Venom, Poison on Poison Ivy

Toxicant: a man-made chemical that causes biological harm

degrade natural conditions disrupting biological functions and natural cycles

affect human health

Pollutants that cause the most harm are those that persist, bioaccumulate and biomagnify.

Ex: DDT – DichloroDiphenylTrichloroethane – insecticide

used to spray mosquitoes in order to stop the spread of malaria

DDT is consumed by organisms and stored in fatty tissue

In the fatty tissue it slowly degrades into DDE (Dichlorodiphenyldichloroethylene)

DDT and DDE at low levels are not very toxic but both persist, bioaccumulate and biomagnify build up to toxic levels

EX: Eggs of Large Predatory Birds (Bald Eagle) have thin egg shells

Persistence: chemicals that remain in the environment because they are not broken down by natural processes or decomposers – decomposers lack the enzymes necessary for the degradation of the toxicant

Bioaccumulation/Bioconcentrate: pollutants are injested or absorbed by animals or plants and remain in the body

- in animals the pollutants typically are stored in fatty tissue (DDT) or muscle tissue (mercury)

– in plants the pollutants are typically stored in the central vacuole of the cell- at certain levels, the pollutant may not have any noticeable effect, but over time increased accumulation can result in the deterioration of the organism

Biomagnification/bioamplification: organisms in higher trophic levels tend to have higher concentrations of toxic substances in their bodies than lower trophic level organisms

as the toxic substance is consumed by lower trophic levels it is bioaccumulated in the tissues

as the lower trophic levels are consumed, the toxins are stored in the higher trophic levels

since the higher trophic levels consume more and more of the lower trophic level organisms, the level of the toxic substances increases in the tissues

although the levels of the substance are not at toxic levels for the lower trophic organisms, the higher trophic organisms can quickly progress to a toxic state due to the rapid accumulation of the compound

Comparison of Biomass and Biomagnification

Biomagnification of Mercury Mercury mainly enters the environment from the

combustion of fossil fuels also from industrial and chemical waste disposal - Mercury enters water ways by leaching and precipitation

and migrates to the benthic levels. Bacteria in the bottom mud converted it to methyl

mercury, an extremely toxic soluble compound Methyl mercury enters the food chain in the

phytoplankton and is accumulated in the tissues of fish passes up the trophic levels to humans who fish in

contaminated waters.

human health and toxicology. major human health issues: focus of epidemiologists: scientists who...

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