What risks do these pollutants pose to us?

To determine this we need to understand the following

Risk = Exposure x Harm• Risk

– Possibility of suffering from a hazard that causes harm, disease, economic, or environmental loss

• Risk assessment– Identifying hazards – Determine probability– Assess severity

• Risk Management– Determine seriousness– How can it be reduced?– How much should we spend?

• Probability– Likelihood that an event

or effect will occur

Types of Risks

• Cultural• Physical • Biological • Chemical

Biological Hazards

• Non-transmissible– Not spread through

living organisms– Cannot be spread

between contact– Examples

• Asthma• Heart disease• cancer

• Transmissible– Can be spread through

living organisms– Examples

• AIDS• Malaria• STD

• Viral Diseases– Ability to adapt and

evolve– influenza = largest threat

because it is airborne and highly contagious

• Sexually Transmitted Diseases– 23% of Americans have

an STD and don’t know it

Biological Risks Cause Disease:• Chronic Disease:

– slowly impair body function– Cancers, diabetes, heart disease, obesity

• Acute Disease:– Rapid onset– Ebola, flu

• Infectious Disease:– Caused by pathogens– STDs, flu, cold, viruses, protist infections, fungi

2011 Data

Various Biological Risks

• Will be filled in via class powerpoint slides

Toxicology: The study of chemical risk• Toxicity: measure of harmfulnessChemicals Sources Impact

Neurotoxins Lead, mercury Disrupt nervous system, paralysis, impaired learning

Carcinogens Asbestos, radon, tobacco, PCBs, formaldehyde

Cause cancer and cell damage

Teratogen Thalidomide, alcohol, heavy metals

Impair fetal developmentBirth defects

Allergens Penicillin, codeine, dander Trigger immune response

Endocrine disruptors

Pharmaceuticals, atrazine herbicide, DDT, insecticides, phthalates in cosmetics and plastics

Impair hormone functionsDecrease sperm countGender benders

Toxicology: the study of toxins

• Toxicity – measurement of how

harmful a substance is

• Dose– Amount of a substance

that is absorbed, inhaled, ingested

• What impacts the effect of a toxin?– Size of dose over given

time– Who is exposed to dose

• Genetic makeup• Body detox system

Factors that impact dose:

• Solubility– Water soluble

• Acids, salts

– Oil / fat soluble• Pesticides, PCBs, mercury,

metals

• Persistence– Ability to withstand

breakdown– Persistent Organic

Pollutants• Pharmaceutical medicines• pesticides

• Bioaccumulation– Molecules are absorbed

and stored in organs and tissues of single organism

• Biomagnification– Toxins increase as they

move through food chain

• DDT

Various Chemicals that cause long term harm (poisoning)

• Will be addressed in class PowerPoints

5. Chemical Interactions

• Antagonistic: Decrease in harm when mixed– Chemicals to prevent

anticoagulation– Dimercaprol: treats

arsenic, mercury, lead poisoning

– Bretylium: adrenaline blocker

– Prozac: blocks 5HT receptors

• Synergistic: Combined effect increases harm more than either by themselves– Asbestos + smoking– Smoking and birth

control

Response to Toxins

• Chronic Effect– Permanent and long

lasting• Radium Girls• Smoking• Lead or mercury poison

• Acute effect– Immediate harmful

reaction• Overdose to drugs• Running leads to

increased heart rate

Response = type and amount of health damage due to exposure

QUESTION:

Because there is variation within a population. When we are using risk management, who should we protect? The most sensitive or the average?

Toxicity

Lethal Dose• LD50

– Lethal dose • Amount of chemical needed for

50% of the population of animals in test population to die within 14 days.

• LC50

– Lethal concentration• Concentration needed to cause

death to 50% within 14 days.

• Poison– Chemical with an LD50 of

50mg or less per kg body weight

100

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Dose (hypothetical units)

LD50

DOSE RESPONSE CURVES

Graphs that show the effects of various dosages of a toxin on a group of test organisms.

Nonthreshold dose response

• Any dosage causes harm with an increase in dose.

Threshold Dose Response

• A threshold must be met before detectable harmful effect

• Medicines• Water