The Environment is Out to Kill You

• The global disease burden is changing
• Infectious and emergent diseases still kill millions of people
• Conservation medicine combines ecology and health care
• Resistance to drugs, antibiotics, and pesticides is increasing
• Who should pay for health care?

• Prions (Mad Cow, Kreuzfeld-Jacob)
• Viruses (Ebola, AIDS, smallpox, common cold, influenza, herpes)
• Bacteria (cholera, typhoid, plague)
• Protista (malaria, sleeping sickness,
Giardia)
• Fungi (athlete’s foot, yeast infections,
Candida)
• Multicellular Organisms (tapeworms, trichinosis, schistosomes)

• Only known infectious agents without DNA
• Misconfigured protein molecules
• Bind to normal proteins and convert them to misconfigured form
• All known prion diseases attack the brain
• No known cure; invariably fatal; very nasty

• Viruses are non-living but reproducing
• Viruses invade cells and use cell reproduction mechanisms to reproduce
• Retroviruses permanently insert new DNA into cell (AIDS)
• Viruses cannot be attacked in cells
• Being non-living, can’t be killed by antibiotics in blood stream
• Only defenses are immunization or prevention
• Antibiotics do not work against viruses

• Used improperly against viral infections
• Essentially given as placebos
• Sugar pills would be more ethical
• Legitimate users do not use properly
• Used as prophylactic measure in factory farms
• Creation of resistant micro-organisms
• Waste antibiotics get into environment

• How do toxins affect us?
• What Can You Do? Tips for Staying Healthy
• How does diet influence health?

• Allergens (trigger immune response)
• Neurotoxins (damage nervous system: mercury, pesticides, lead)
• Mutagens (alter genes)
• Teratogens (cause birth defects: alcohol, thalidomide)
• Carcinogens (nickel, tobacco, radon)
• Hormone mimics (PCB’s)

• Solubility and mobility determine where and when chemicals move
• Exposure and susceptibility determine how we respond
• Bioaccumulation and biomagnification increase concentrations of chemicals
• Persistence makes some materials a greater threat
• Chemical interactions can increase toxicity

• Metabolic degradation and excretion eliminate toxins
• Repair mechanisms mend damage

• We usually test toxins on lab animals
– “All that proves is rats shouldn’t smoke”
– Reality: Animal tests predict human toxicity well
• There is a wide range of toxicity
• Acute and chronic doses and effects differ
• Detectable levels aren’t always dangerous
– With enough equipment and money, we can detect individual molecules

• Antagonistic (Vitamin A, E against carcinogens)
• Additive (Effects combine)
• Synergistic (Effects multiply: alcohol + drugs, smoking + asbestos)
• Sensitization or Desensitization

• Chemical composition
• Dose
• Acute versus Chronic Exposure
• Solubility and Mobility
• Nature of exposure
• Ability to metabolize, sequester, or excrete
• Tendency to bioaccumulate
• General Health

• Risk perception isn’t always rational
• Risk acceptance depends on many factors
• Some 1:1,000,000 Risks
– Smoking 1.4 cigarettes (cancer, heart disease)
– Two days in large city (air pollution)
– 10 miles by bicycle (accident)
– 1000 miles by jet (accident)
– One chest X-ray (cancer)
– 5 years on boundary of nuclear plant (cancer)
– 100 charcoal broiled steaks (cancer)

• Weapons capable of inflicting large numbers of casualties or affecting a large area in a single event
• Nuclear
• Chemical
• Biological
• Any time you pack a large amount of energy into a small space, you have a potential weapon

• Riot Control (Tear Gas)
• Choking (Cl, phosgene CCl
2
O)
• Blood (HCN)
• Nerve (Sarin)
• Blister (Mustard Gas)
• Hallucinogens (researched, never used)
• Incapacitating (researched, never used)
• Defoliants (Agent Orange, Vietnam)

• World War I
– Tear Gas
– Chlorine
– Mustard Gas
• Japanese in China: 1930's - WWII
• Not used by other parties in WWII
• Yemen 1960's
• "Yellow Rain:" SE Asia, 1970's (Discredited)
• Iraq against Kurds, Iran, 1980's
• US renounced first use but reserves right to retaliate

• Gases disperse too quickly
– Usually delivered as aerosols
– Dependent on weather conditions
– Wind, rain, heat are unfavorable
• Most historical uses against unprotected targets
– Trained soldiers have protection
– Reduces efficiency of both sides
– Psychological effect

• Nerve Agents
– Long Term: Nerve Disorders, Brain Damage
• Blister Agents
– Short Term: Severe Burns
– Long Term: Skin Cancers and Lesions, Lung
Damage
• Most Chemical Agents Easily Decomposed
• Long Term Effects of Low-Level Exposure
Unknown
– Gulf War Syndrome, Agent Orange

• No known modern historical military uses
• US has stated will not use
• Limitations
– Should be self-limiting
– Need fairly quick action
– Anthrax and Smallpox given most speculation
• Plant pathogens
– Wheat Rust, Hoof-and-Mouth
– Drug Interdiction?