Risk, Toxicology and Human Health

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Risk, Toxicology and Human Health
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What is Risk

• Risk is the possibility of suffering harm from a
  hazard
• Expressed in terms of probability
• Risk assessment involves using data, hypotheses,
  and models to estimate the probability of harm

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What are the major types of hazards?

• Cultural hazards such as unsafe working
  conditions and poor diet
• Chemical hazards from harmful chemicals in the
  air, water, soil and food
• Physical hazards such as tornadoes, noise and
  fire
• Biological hazards from pathogens, pollen,
  allergens and animals

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What is a poison?

• A poison is a chemical that has an LD50 per
  kilogram of body weight
• The LD50 is the median lethal dose where the
  amount of chemical in one dose kills 50 of the
  animals

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How do scientists determine toxicity?

• Three methods
• Case reports
• Laboratory investigations
• epidemiology
• Dose response curve shows effects of various
  doses of toxic agents

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What are toxic and hazardous chemicals?

• Toxic chemicals are generally defined as
  substances that are fatal to over 50 of test
  animals
• Hazardous chemicals cause harm by
• Being flammable or explosive
• Irritating or damaging the skin or lungs
• Interfering with or preventing oxygen uptake
• Inducing allergy reactions of the immune system

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What are mutagens, teratogens and carcinogens?

• Mutagens are agents that cause random mutations
  or changes in DNA molecules found in cells
• Teratogens are chemicals that cause birth defects
• Carcinogens are chemicals that cause or promote
  growth of malignant tumor, which is cancer

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How do chemicals harm the systems in the human
body?

• Immune system body can not fight off diseases
  and infections
• Nervous system mostly threatened by
  neurotoxins, which attack nerve cells
• Endocrine system messes up the hormones

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Why do we know so little about the effects of
chemicals?

• Under existing laws, chemicals dont need to be
  tested until something bad happens
• Not enough funds, personnel, facilities and test
  animals to provide such information
• We know little about possible interactions with
  other technologies and chemicals or about the
  effects of such interactions on the human body

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What are earthquakes?

• Stress in the earths crust can cause solid rock
  to deform until it suddenly fractures and shifts
  along it which causes an earthquake
• Measuring the magnitude of the earthquake is done
  with the Richter scale

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How can we reduce earthquake hazards?

• Examine historical records and make geological
  measurements to locate active fault zones
• Make maps showing areas in which ground
  conditions are more subject to shaking
• Establish building codes
• Ideally learn to predict them and when they will
  occur

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What are volcanoes?

• Volcanoes can eject ejecta, liquid lava and gases
  (SO2, CO2, etc.)
• Considered bad but provides great scenery and
  fertile soil

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How much ionizing radiation are we exposed to?

• Examples are X-rays, ultraviolet radiation for
  sun, neutrons emitted from nuclear fission and
  fusion and radiation
• Exposed to some ionizing radiation from natural
  background sources
• Most of human-caused exposure (X-rays) are
  unnecessary

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What are the effects of ionizing radiation?

• Genetic damage fro mutations in DNA molecules
• Somatic damage to tissues like eye cataracts
• Alpha particles dangerous when breathed in or
  digested
• Beta particles can penetrate skin

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What are nontransmissible diseases?

• Diseases not caused by licing organisms and that
  do not spread from one to another
• Examples are cardiovascular disorders and diabetes

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What are transmissible diseases?

• Caused by a living organism and can be spread
  from one person to another
• In developing countries infections were
  responsible for 44 of deaths in 1997
• Requires intimate contact with the blood, feces
  or other bodily fluids

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Viral Diseases

• They include influenza or flu, Ebola, rabies, and
  AIDS
• Viruses, like bacteria, can genetically adapt
  rapidly to different conditions.

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How do Viral Diseases Spread?

• Transmitted by the fluids or the air from
  infected person
• Transmitted by the blood or other body fluids of
  an infected person
• Transmitted by animals such as dogs, coyotes,
  skunks, and bats
• Sexually transmitted diseases are passed on
  during sexual activities.

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The Virus Health Threat to humans

• The greatest virus health threat to humans is the
  emergence of new, very virulent strains of
  influenza.
• Only few numbers of antiviral drugs exist because
  most of the drugs kill not only the virus, they
  also kill the cells of its host.

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Major Diseases in Developed Countries

• In developed countries like US, most of people
  died from diseases associated with aging.
• There is chance to prevent 40- 70 of all
  premature deaths if people change their harmful
  lifestyle.
• About 95 of the fund on health care in US each
  year is used to treat rather than to prevent
  diseases.

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Ways to reduce infections and Other Diseases

• Not using antibiotics that have caused widespread
  genetic resistance, coupled with rotating from
  one antibiotic to another.
• Not selling antibiotics without a prescription.
• Educating the public to understand the dangers of
  overuse of antibiotics and the need
• Reducing the use of pesticides to slow the
  increase in numbers of pesticide- resistant
  insects.

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Estimating Risks

• Risk analysis consists of
• Risk assessment
• Comparative risk analysis
• Risk management
• Risk communication.

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Risk Analysis 2

• Risk assessment involves determining the types of
  hazards involved
• Comparative risk analysis summarizes the greatest
  ecological and health risks detected by U.S .
  Environmental Protection Agency
• risk benefit analysis involves estimating
  benefits and the risks involved

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The Greatest Risks People Face

• Poverty is the greatest risk by far
• Poverty can lead to malnutrition, which can bring
  brings down the immunity and makes a path for
  other diseases to come in.
• Also the greatest risks of premature death are
  mostly the result of careless mistakes.

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How do we reduce ones health risks?

• Best way to lower the rate of premature death is
  not to smoke
• Avoid too much sunlight (causes skin cancer)
• Not drinking alcohol or drinking under control
• Control the diet( pay more attention in
  cholesterol and saturated fats)

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Limitations of Risk Assessment and Risk Benefit
Analysis

• Risk assessment is built on uncertainties and
  limitations.
• Risk assessment and risk benefit analysis can be
  made to support almost any conclusion and then
  called scientific decision making.

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The Management for Risks

• Risk management includes the administrative,
  political, and economic actions taken to decide
  whether and how to reduce a particular societal
  risk to a certain level and at what cost.
• Risk management decides which of the risks facing
  society should be evaluated and managed
• Also, it determines how much risk is acceptable,
  and How much money it will take to reduce each
  risk

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How Well Do we Perceive Risks?

• Better quality of education and communication
  about the risks will help brining the publics
  perception of risks closer to risk evaluators.
• It is important to take into account in
  determining the acceptability of a risk and in
  evaluating the possible alternatives

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Bibliography

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Bibliography 2

• www.ssc.wisc.edu/irp/
• maxshouse.com/viral_diseases.htm
• http//www.palisade.com/
• http//www.aon.com/
• www.niaid.nih.gov/factsheets/stdinfo.htm
• edcenter.med.cornell.edu/Pathophysiology_Cases/
  STDs/STD_TOC.html
• ntp-server.niehs.nih.gov