Unit 6: Human Health and Toxicology

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Unit 6 Human Health and Toxicology
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How do we define HEALTH?

• A state of complete physical, mental, and social
  wellbeing
• NOT JUST being free from disease or injury

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Health can be affected by

• Child development
• Lifestyle
• Career
• Trauma
• Income/ Social status
• Education

• Where you live
• Availability of health care
• Culture
• Gender
• Sleep
• Genetics

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Health Care

• Who can we go to in order to maintain our health?
• Medical doctors
• Dentists
• Optometrists
• Psychologists/ Psychiatrists
• Counselors
• Nutritionists
• Personal Trainers
• Chiropractors
• Massage Therapists

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Center for Disease Control Prevention (CDC)

• Part of the Department of Health and Human
  Services
• HQ in ATL
• Study viruses/ bacteria to find vaccines/
  treatments
• Tell us how unhealthy we are and why
• Try to find ways to make Americans more healthy

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?CDC in ATL
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World Health Organization (WHO)

• Part of the UN
• Coordinate efforts to stop the spread of global
  diseases
• Sponsors programs to help prevent and treat
  diseases
• Help develop and distribute vaccines

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Importance of Public Health

• Attempting to stop/ lessen outbreaks of diseases,
  especially ones we can prevent
• Education programs
• Vaccines
• Increase access to health care
• Limit disparity

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Leading causes of death in the US

• Heart disease 597,689
• Cancer 574,743
• Chronic lower respiratory diseases 138,080
• Stroke (cerebrovascular diseases) 129,476
• Accidents (unintentional injuries) 120,859
• Alzheimer's disease 83,494
• Diabetes 69,071
• Nephritis, nephrotic syndrome, nephrosis
  50,476
• Influenza and Pneumonia 50,097
• Intentional self-harm (suicide) 38,364

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The Information Blanket

• Educates mothers about child health
• http//informationblanket.com/

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Epidemiology

• Study of health characteristics, events, or
  patterns within a population
• Studies the cause of diseases
• Abnormal condition affecting the body
• Important because it can help inform public
  health policy

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Causes of disease

• Pollution
• Radiation sickness
• Respiratory disease caused by air pollution
• Has caused an increase in cancer
• Abnormal cell growth

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Causes of disease

• Zoonotics
• Diseases that pass from animals to humans (such
  as Ebola and HIV)
• Bush meat and poaching

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Causes of disease

• Humans are invading previously undisturbed
  habitats and coming into contact with crazy new
  organisms and the diseases they carry
• We dont have immunity to those diseases! (think
  Native Americans and smallpox!)

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Altering Ecosystems

• In the US we have caused the decline of deer and
  mice predators ? more ticks ? more Lyme disease

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Other causes of disease

• Dirty water (cholera, typhoid fever)
• Insects that act as a secondary host (malaria,
  West Nile)
• Undercooked food (salmonella)

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Disease Classification

• Noninfectious Non-communicable, major killer in
  industrialized society often have multiple
  causes
• Cardiovascular disease, Cancer, Sickle-Cell,
  Diabetes, Emphysema, Asthma, Cerebral Palsy

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Disease Classification

• Infectious Can pass from person to person
  caused by a pathogen such as
• Bacteria
• Viruses
• Protozoan
• Parasitic Worms
• Fungus
• Prions

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Transmission

• Vector any organism that carries transmits
  an infectious pathogen into another organism
• Fomite any inanimate object capable of carrying
  an infectious pathogen and transferring it
• Smooth non-porous surfaces transfer pathogens
  more readily than rough porous ones.

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Disease Classification

• Endemic- normal rate of occurrence
• Epidemic- above normal rate of occurrence, an
  outbreak
• Pandemic- worldwide epidemic
• 1918 Flu that killed 21 million people worldwide
• The Black Plague ?

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Disease Classificiation

• Acute- short duration illness or high dose
  exposure. If victim survives initial attack,
  they usually survive (ex influenza)
• Chronic- Long duration illness or low dose
  exposure. Kills you slowly. (ex tuberculosis,
  heart disease, cancer)

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Big 3 Killers

1. HIV- Human Immunodeficiency Virus
2. Infects 5 million/ year kills 3 million/ year
3. Influenza
4. Kills about 1 million/ year
5. Hepatitis B Virus
6. Kills about 1 million/year
7. Damages liver

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What about antibiotics?

• Antibiotics are compounds that kill bacteria
• Overusing them! They are in our food and people
  are demanding them when not needed
• People dont take entire prescription
• Travel around and may already have a resistance
• Bacteria reproduce and evolve rapidly (16
  BILLION OFFSPRING in 24 HOURS!)

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What about antibacterial soap?

• Makes things worse!
• You need small doses of bacteria to develop an
  immunity when you get larger doses
• Kids are developing super weak immune systems

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What about vaccines?

• Small doses of living or dead virus injected/
  inhaled to stimulate the bodys immune system
• Give your body info to develop antibodies against
  if you do get the virus later
• Virtually wiped out some diseases!

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But I heard vaccines cause autism

• WRONG!
• The guy that wrote this paper was proven to be a
  fraud- he made up data!
• There is NO LINK between vaccines and autism
  (studies now think autism might be caused by
  illnesses when mothers are pregnant)
• Vaccinate your kids! You cant rely on herd
  immunity (everyone else is vaccinated so Ill be
  okay)

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How can we reduce disease?

• Vaccinate your kids/ yourself
• Reduce poverty (specifically in Africa)
• Increase research on tropical diseases
• Educate people on antibiotics
• WASH YOUR HANDS! ? ? ?
• Reduce antibiotics use in food
• Improve drinking water quality

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Mutagens

• Mutagens are substances capable of inducing
  mutations (changing the nucleotide sequence).
• Mutagens may be chemical, physical or biological
  agents.
• In 1927, X-rays were the first mutagens to be
  recognized.

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Mutagens

• Chemical mutagens include formaldehyde, mustard
  gas, vinyl chloride and many other chemicals.
• Thousands of workers are exposed to mutagenic
  substances in the workplace.
• A mutation can be passed on only if it occurs in
  the sex cells.

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Birth Defects

• Mutations are believed to account for 25 of all
  birth defects.
• Birth defects are the leading cause of infant
  mortality in the US.
• Teratogens are substances that cause birth
  defects.

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Birth Defects

• Men working as painters, farmers, or mechanics -
  jobs involving exposure to solvents and
  pesticides - tend to be at higher risk of
  fathering children with birth defects.
• The most sensitive period for a human embryo is
  during the formation of the organs (from the 18th
  day to the 60th day -gt peak at day 30).

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Types of teratogens Ionizing Radiation

• X-rays -gt central nervous system disorders
• Nuclear fallout -gtmicrocephaly, eye problems,
  mental retardation

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Types of teratogens Pathogenic Infections

• German measles -gt heart defects, deafness,
  cataracts
• Syphilis Herpes simplex 2 -gt microcephaly,
  mental retardation
• Toxoplasmosis -gt fatal legions in the CNS

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Types of teratogens Drugs and Chemicals

• Thalidomide
• a nonprescription sleeping pill used extensively
  in Germany and the UK during the early 1960s
• causes phocomelia (seal limbs) in the babies of
  40 of the women who took thalidomide during
  their 1st trimester

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Types of teratogens Drugs and Chemicals

• Dioxin
• structural deformities, miscarriages
• Methyl mercury
• mental retardation, sensory and motor problems

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Types of teratogens Drugs and Chemicals

• DES (Diethylstilbestrol)
• resembles natural estrogen
• prescribed to prevent miscarriage (it actually
  increased risk)
• in the late 1950s one company urged all pregnant
  woman to take the drug in order to have bigger
  and stronger babies
• 5 million pregnant women used it
• disrupted the endocrine system
• causes vaginal cancer in girls, genital
  abnormalities in boys

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Types of teratogens Drugs and Chemicals

• Cigarette smoke
• low birth weight, miscarriage, still birth
• Alcohol
• mental retardation, growth deficiencies,
  microcephaly, facial irregularities

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Cancer

• Cells that have uncontrollable growth
• 20-25 of all deaths in industrialized countries
• Highest incidence among the elderly 2nd leading
  cause of death among US children age 1-14.

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Environmental Carcinogens

• In 1775, an English doctor, Sir Percival Pott,
  recognized an association between cancer of the
  scrotum and exposure to soot - benzopyrene was
  the carcinogenic agent (the 1st known
  environmental carcinogen)!!!

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Cancer

• Tobacco use is by far the leading cause of cancer
  mortality. Tobacco smoke contains 4,700
  chemicals 43 are known carcinogens (arsenic,
  benzene, radioactive polonium, etc.).

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Cancer

• Aflatoxins are potent carcinogens produced by the
  fungus Aspergillus flavus.
• The fungus grows on peanuts, pistachios, corn,
  rice and certain grains and nuts when
  temperatures and humidity are high.
• Aflatoxins are among the strongest carcinogens
  known!

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Cancer

• Many foods contain anticarcinogenic compounds
  (broccoli, cauliflower, cabbage, kale and
  brussels sprouts contain sulforaphane - one of
  the most potent anticarcinogens known.
• Cooked tomato products, yellow and green
  vegetables, citrus fruits, apricots, cantaloupe,
  brown rice, wheat germ soy products, onions, and
  garlic

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Linking environmental agents to human cancers is
difficult because

• Ethics in human testing
• Long latency periods
• Animal testing is sometimes difficult to apply to
  humans
• Similar chemicals may act very differently
• Chemicals may be transformed by the body (ex.
  nitrite, a food preservative, is transformed by
  the body into nitrosamine, a carcinogen)

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Preventing cancer can be accomplished by

• Decreasing tobacco use
• Decreasing alcohol consumption
• Improving nutritional choices, exercising
  regularly, and maintaining proper body weight
• Avoiding sun exposure and using sunscreen
• Fixing structures with excess radon

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Bioterrorism

• Terrorist act that releases some infectious
  disease into air, water supply, food supply, at a
  large event
• Increasing threat (H5N1 dispute)
• Cheaper and more effective than bombs
• Could spread quickly before anyone knew what
  happened

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What is Risk?

• Risk is the possibility of suffering from harm
  that can result in injury, disease, death,
  economic or environmental damage
• Risk assessment is the scientific process of
  estimating how much harm a particular hazard can
  do to humans
• Risk management involves deciding how to reduce a
  risk to a certain level and the cost

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Risk Analysis

• Identification of hazards and their risks
  (negative or unwanted outcomes)
• Informing people about risk is important
• GREATEST RISK POVERTY

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Probable v Possible

• Risk is defined as a probability
• When we say it is possible a smoker will get lung
  cancer we mean that it might happen.
• Probability gives us a numerical estimate of the
  likelihood of the event happening.

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Risk Perception
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Risk Perception

• We participate in high-risk situations everyday
  that we do not think of as high-risk
• Motorcycling 1 in 50
• Smoking 1 in 300 by age 65
• Hang gliding 1 in 1250
• DRIVING A CAR
• 1 in 3300 WITHOUT a seatbelt
• 1 in 6070 WITH a seatbelt

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Risk Perception

• We are ridiculously afraid of low-risk activities
  because they are perceived as scary
• Getting shot 1 in 28,000
• Nuclear Plant Accident 1 in 200,000
• West Nile Virus 1 in 1 million
• Struck by Lightning 1 in 3 million
• Commercial airplane crash 1 in 9 million
• Snakebite 1 in 36 million
• Shark attack 1 in 281 million

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Risk Perception

• We are more afraid of the unknown or things we
  have no direct control over
• We are afraid of things that are not considered
  voluntary
• We are afraid of catastrophic risks instead of
  chronic risks
• We are worried about unfair distribution of risks

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Toxicology

• Toxicology is the study of toxic substances.
• Toxicants have the ability to harm organs or
  biochemical processes away from the site on the
  body where exposure took place.
• Irritants damage only the tissue they contact.

Poison Ivy Rash ?
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Toxicology Principles

• Anything is dangerous if ingested in a large
  enough quantity.
• How do we know how much exposure causes a harmful
  response?

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4 Major Hazards

• 1. Cultural hazards
• Unsafe working conditions
• Smoking
• Poor diet
• Drugs/ drinking
• Driving
• Criminal assault
• Poverty
• UNSAFE SEX

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4 Major Hazards

• 2. Physical hazards
• Ionizing radiation
• Fire
• Tornado
• Earthquake
• Volcanic eruption
• Floods
• Hurricanes

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4 Major Hazards

• 3. Chemical Hazards
• Chemicals in the air
• Chemicals in the water
• Chemicals in the ground

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4 Major Hazards

• 4. Biological hazards
• Pathogens
• Bacteria
• Viruses
• Parasites
• Pollen and allergens
• Animals like bees poisonous snakes (on planes)

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Toxicity

• Measure of how harmful a substance is in causing
  injury, illness, or death
• Depends on DOSE (amount that has been inhaled,
  ingested, or absorbed through the skin), age, and
  health of the person/ animal
• Also depends on genetic makeup

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5 factors that affect toxicity

1. Solubility
2. Persistence
3. Bioaccumulation
4. Biomagnification
5. Chemical interactions

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Chemical Interactions

• Can decrease or multiply the harmful effects
• Antagonistic interaction reduces harmful effects
• Synergistic interaction multiplies harmful effects

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Response

• Type and amount of damage resulting from exposure
  to a chemical or other agent
• Acute effect- immediate or rapid harmful reaction
  to exposure (dizziness to death)
• Chronic effect- permanent or long-lasting
  consequence from single dose or repeated
  sublethal doses (organ damage)

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Dose is important

• Dose makes the poison but it is different for
  different people!
• 3 mechanisms to combat harmful effects
• Break down, dilute, or excrete small amounts of
  most toxins
• Enzymes can sometimes repair damage done to DNA
• Cells can reproduce quickly to replace damaged/
  lost cells

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Number of individuals affected
Very Sensitive
Majority of population
Very Sensitive
0
20
40
60
80
Dose (hypothetical units)
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LD50

• Acute toxicity is described by the LD50
• the amount of chemical, administered in one dose,
  that is required to kill 50 of a population of
  test animals within a 14-day period.
• Expressed as (mg of chemical / kg of body
  weight).

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LD50

• Animal testing combined with data from accidental
  poisonings, suicides, murders, industrial
  accidents to estimate lethal doses for humans.
• Testing for subchronic and chronic toxicity is
  more difficult, time consuming, and expensive
  than acute toxicity testing. (involves feeding
  experiments over several months or more, and
  subsequent animal autopsies)

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No threshold
Threshold
Nonlinear dose-response
Nonlinear dose-response
Linear dose-response
Linear dose-response
Effect
Effect
Threshold level
The data collected is plotted on a dose-response
curve. The threshold is the point on the curve
where increasing dosage is beginning to provoke
symptoms
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LD50

• Regulators establish margins of safety - A
  100-fold margin of safety is used for regulatory
  control of toxicants based on two assumptions
• humans are 10 times more susceptible to toxic
  effects than laboratory animals
• children, elderly, and the immunocompromised are
  10 times more susceptible to toxic effects than
  the average healthy adult

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Polychlorinated Biphenyls (PCBs)

• PCBs were first synthesized in 1929.
• Production was halted in the US in 1977.

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Polychlorinated Biphenyls (PCBs)

• Oily liquids to waxy solids.
• Extremely stable substances non-flammable
• Primarily used as insulating liquids in
  electrical transformers and capacitors
• In addition, PCBs were used as plasticizers in
  paints, plastics and rubber products, in
  pigments, dyes, carbonless copy paper and many
  other applications.
• Highly soluble in fat and insoluble in water

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Polychlorinated Biphenyls (PCBs)

• PCBs escape into the environment through
• discharge waste from industries into waterways
• vaporization from paints or landfill burnings
• leaks in industrial equipment, especially
  transformers
• accidental spills or illegal dumping

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Polychlorinated Biphenyls (PCBs)

• PCBs accumulate in fatty tissues (liver, kidneys,
  heart, lungs, brain, and breast milk).
• In 1976, 99 of all breast milk sampled in the US
  contained PCBs.
• Bioaccumulation -gt PCB concentrations in the body
  increase over time.

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DDT in fish-eating birds (ospreys) 25 ppm
DDT in large fish (needle fish) 2 ppm
DDT in small fish (minnows) 0.5 ppm
DDT in zooplankton 0.04 ppm
DDT in water 0.000003 ppm, Or 3 ppm
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PCB health effects

• Miscarriage
• Causes cancer in rats -gt probable human
  carcinogen
• Chloracne -gt acne-like skin disorder caused by
  acute exposure
• Known endocrine disruptor
• Impairs the immune system
• Negative effects on the intellectual development
  of children and adults

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Dioxin (TCDD)

• Dioxins form a large group of chemicals of widely
  varying levels of toxicity - the most dangerous
  being TCDD

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Dioxins

• Dioxins have no industrial uses formed as an
  unwanted by-product of industrial processes.
• In the absence of light TCDD breaks down very
  slowly.

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Major contributors of dioxin to the environment
include

• Incineration of Municipal Solid Waste
• Incineration of Medical Waste
• Secondary Copper Smelting
• Forest Fires
• Land Application of Sewage Sludge
• Cement Kilns
• Coal Fired Power Plants
• Residential Wood Burning
• Chlorine Bleaching of Wood Pulp
• Backyard burning of household waste may also be
  an important source

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Human exposure

• Most of us receive almost all of our dioxin
  exposure from the food we eat specifically from
  the animal fats associated with eating beef,
  pork, poultry, fish, milk, dairy products.
• Since most of the meats and dairy products we
  consume are not produced locally but have been
  transported hundreds or thousands of miles, the
  majority of our dioxin exposure does not come
  from dioxin sources within our own community. 

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Ukrainian President Viktor Yushchenko(acute
dioxin poisoning resulting in chloracne)
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Lead

• Lead poisoning is entirely preventable, yet it
  is the most common and societally devastating
  environmental disease of young children. -Dr. L
  Sullivan, former Secretary of Health and Human
  Services

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Lead

• In the US, the largest use of lead is for lead
  storage batteries (virtually every car has at
  least 20 pounds of lead in its battery).
• Other lead containing products
• Ammunition
• Brass
• glass TV tubes
• Solder
• Lead-glazed ceramic ware
• Lead-crystal decanters
• Pigments artists paint
• Moonshine (distilled in lead-soldered auto parts)
• Some types of vinyl miniblinds, etc.

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• Lead is found in soil, water, air, and food.
• The amount of lead entering the atmosphere has
  declined sharply since the phaseout of leaded
  gasoline in the mid-1970s (completed in 1995).
• Leaded gasoline is still widely used in other
  countries

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• Many people are exposed to lead in drinking water
  through lead pipes or solder. Now plastic (PVC)
  pipes are used.
• Lead used in soldering the seams of canned foods
  and beverages was once the main source of lead
  intake in the US (banned in 1991).

Original Roman lead pipe
Copper pipe with lead solder
PVC pipe
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Lead

• Lead house paint was used in the US from
  1884-1978 - it is still used to paint bridges,
  ships, and other steel structures.
• House paint is the most important source of lead
  poisoning exposure.
• Infants and toddlers are at highest risk because
  the blood-brain barrier is not fully developed.

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Health effects of lead exposure

• Increased blood pressure
• Anemia
• Miscarriages
• Altered immune function
• Kidney damage
• Injury to the CNS -gt hyperirritablity, poor
  memory, mental retardation, convulsions, coma,
  death
• In children, chronic low-level exposure can
  inhibit intellectual development -gt amount of
  lead in teeth correlates to IQ , learning
  disabilities and drop-out rate.

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Mercury

• Mercury (quicksilver) has been used for more
  than 2500 years.
• Mercurys first medicinal use was for the
  treatment of syphilis in 16th century Europe.

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Mercury

• Mercury is used
• in thermometers, thermostats barometers
• in fluorescent light bulbs
• as a fungicide in paints
• as an alloy in dental fillings
• ritualistic uses
• Coal burning and municipal waste incineration are
  the largest sources of mercury in the atmosphere.
• Gold mining tailings are another important source
  mercury.

CFL
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Mercury

• Mercury caused the Mad Hatters Disease made
  famous in Alice in Wonderland.
• Hat-makers soaked animal hides in mercuric
  nitrate to soften hairs.

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Mercury

• Inorganic mercury (mercury nitrate) can be
  inhaled or absorbed through the skin.
• Inorganic mercury attacks the liver and kidneys.
• Organic mercury (methyl mercury) is much more
  toxic than inorganic mercury.

Methylmercury, an organic mercury compound
released in factory wastewater and the cause of
Minamata disease
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Mercury

• In Minamata Bay, Japan, a plastics factory
  released inorganic mercury into the water from
  1932-68.

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• The inorganic mercury was converted to methyl
  mercury by bacteria in the anaerobic sediments.
• The methyl mercury was biomagnified and caused a
  variety of health effects in cats and then
  humans.
• 1700 people died and 9000 were left with varying
  degrees of paralysis and brain damage.

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