Risk and ToxicologyRisk and Toxicology

Chapter 18Chapter 18

Smoking in the USSmoking in the US

Smoking is the number one killer in the USSmoking is the number one killer in the US

Worldwide, infectious disease is the number Worldwide, infectious disease is the number one killer. (This includes TB, HIV, malaria, one killer. (This includes TB, HIV, malaria, flu, measles, cholera, and yellow fever.)flu, measles, cholera, and yellow fever.)

One study shows that adolescents who smoke One study shows that adolescents who smoke more than 1 cigarette have an 85% chance of more than 1 cigarette have an 85% chance of becoming smokers.becoming smokers.

RiskRisk

Risk is the possibility of suffering from a Risk is the possibility of suffering from a hazardhazard

A hazard may cause economic loss, A hazard may cause economic loss, environmental loss, injury, disease or deathenvironmental loss, injury, disease or death

Risk = exposure X harmRisk = exposure X harm

HazardsHazards

Cultural – diet, drugs, drinking, driving, criminal Cultural – diet, drugs, drinking, driving, criminal assault, unsafe sex, and povertyassault, unsafe sex, and poverty

Chemical – harmful chemicals in air, water, food and Chemical – harmful chemicals in air, water, food and soil. Most people carry around 500 synthetic soil. Most people carry around 500 synthetic chemicals in their bodies, whose effects are currently chemicals in their bodies, whose effects are currently unknown. (buy organic)unknown. (buy organic)

Physical – ionizing radiation, fire, earthquakes, Physical – ionizing radiation, fire, earthquakes, floods, volcanoes, hurricanes, etc.floods, volcanoes, hurricanes, etc.

Biological – pathogens, pollens, allergens, animals Biological – pathogens, pollens, allergens, animals that bite or sting, parasitesthat bite or sting, parasites

ToxicologyToxicology

Toxicity – measure of how harmful a Toxicity – measure of how harmful a substance is.substance is.

Dose – the amount substance introduced to the Dose – the amount substance introduced to the bodybody

Vector - agent of disease transmissionVector - agent of disease transmission Not all people are affect the same by the same Not all people are affect the same by the same

dosedose

Fig. 16.3, p. 398

VerySensitive

Majorityof population

VerySensitive

0 20 40 60 80

Dose (hypothetical units)

Nu

mb

er o

f in

div

idu

als

affe

cted

BioaccumulationBioaccumulation

Some substances are fat or oil soluble (usually Some substances are fat or oil soluble (usually organic compounds) and can be stored in body organic compounds) and can be stored in body tissues and cells.tissues and cells.

When a substance is ingested in very small When a substance is ingested in very small doses, but is stored in the body, it accumulates doses, but is stored in the body, it accumulates to a higher dose over time (bioaccumulation)to a higher dose over time (bioaccumulation)

BiomagnificationBiomagnification

When a substance that bioaccumulates is When a substance that bioaccumulates is passed up the food chain, each trophic level passed up the food chain, each trophic level receives a higher dose of the substancereceives a higher dose of the substance

This is biomagnificationThis is biomagnification

Animals at the top of the food chain can be Animals at the top of the food chain can be exposed to very high doses and hence are exposed to very high doses and hence are usually affected the most (birds and fish)usually affected the most (birds and fish)

Fig. 16.4, p. 399

DDT in fish-eatingbirds (ospreys)

25 ppm

DDT in largefish (needle fish)2 ppm

DDT in smallfish (minnows)0.5 ppm

DDT inzooplankton0.04 ppm

DDT in water0.000003 ppm,Or 3 ppm

Major BioaccumulantsMajor Bioaccumulants

DDTDDT PCB’s (a class of oily chemicals used in PCB’s (a class of oily chemicals used in

electrical transformers)electrical transformers) Radioactive isotopes (strontium-90)Radioactive isotopes (strontium-90) DioxinDioxin Other organo-chloridesOther organo-chlorides

PoisonPoison

A poison is a substance that has an LDA poison is a substance that has an LD5050 of 50 of 50 or less.or less.

LDLD50 50 stands for the lethal dose in milligrams of stands for the lethal dose in milligrams of a substance that kills 50 percent of the test a substance that kills 50 percent of the test organisms (usually rats and mice) per kilogram organisms (usually rats and mice) per kilogram of body weight. of body weight.

So 50 milligrams of “poison” will kill 50 So 50 milligrams of “poison” will kill 50 percent of organisms weighing 1 kilogram percent of organisms weighing 1 kilogram

Fig. 16.5, p. 400

100

75

50

25

02 4 6 8 10 12 14 16

Per

cen

tag

e o

f p

op

ula

tio

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illed

by

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iven

do

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Dose (hypothetical units)

LD50

Dose-response curveDose-response curve

Different substance act at different rates and at Different substance act at different rates and at different concentrations.different concentrations.

The data of the response tells a lot about the The data of the response tells a lot about the toxicity of a substancetoxicity of a substance

Substances without threshold levels cause Substances without threshold levels cause harm even at small dosesharm even at small doses

Fig. 16.6, p. 401

Eff

ect

Dose

Nonlineardose-response

Lineardose-response

No thresholdE

ffec

t

Nonlineardose-response

Lineardose-response

Threshold

Thresholdlevel

Dose

Toxicity for humansToxicity for humans

Supertoxic – less than .01 – nerve gas, dioxinSupertoxic – less than .01 – nerve gas, dioxin Extremely toxic – less than 5 – nicotine, Extremely toxic – less than 5 – nicotine,

heroin, atropine, potassium cyanide, parathionheroin, atropine, potassium cyanide, parathion Very toxic – 5-50 – morphine, codeine, Very toxic – 5-50 – morphine, codeine,

mercury saltsmercury salts Toxic – 50 – 500 – Lead salts, DDT, carbon Toxic – 50 – 500 – Lead salts, DDT, carbon

tetrachloride, caffeine, sulfuric acidtetrachloride, caffeine, sulfuric acid Moderately toxic – 500 – 5,000Moderately toxic – 500 – 5,000 Slightly toxic – 5,000 – 15,000Slightly toxic – 5,000 – 15,000

Chemical HazardsChemical Hazards

Toxic chemicals are those that are fatal to 50% Toxic chemicals are those that are fatal to 50% of the test population at given concentrationsof the test population at given concentrations

Hazardous chemicals cause harm by:Hazardous chemicals cause harm by: Being flammable or explosiveBeing flammable or explosive Irritating or damaging skin or lungs - acidic/basicIrritating or damaging skin or lungs - acidic/basic Interfering with oxygen uptake - asphyxiantsInterfering with oxygen uptake - asphyxiants Inducing allergic reactionsInducing allergic reactions

NeurotoxinsNeurotoxins

Can effect behavioral changes, learning Can effect behavioral changes, learning disabilities, ADD, paralysis and deathdisabilities, ADD, paralysis and death

ExamplesExamples PCBs - Polychlorinated biphenolPCBs - Polychlorinated biphenol Methyl mercuryMethyl mercury ArsenicArsenic leadlead

MutagensMutagens

Agents (chemicals or other (ionizing Agents (chemicals or other (ionizing radiation)) that cause mutations in DNAradiation)) that cause mutations in DNA

Most mutations are harmless, but mutations in Most mutations are harmless, but mutations in sperm or egg cells can cause genetic defects sperm or egg cells can cause genetic defects like Down’s syndrome, hemophilia, sickle cell like Down’s syndrome, hemophilia, sickle cell anemia, manic depression and thalasseamiaanemia, manic depression and thalasseamia

Mutations in other cells are not inherited, but Mutations in other cells are not inherited, but may still cause harmmay still cause harm

TeratogensTeratogens

Agents (chemicals, viruses, radiation) that Agents (chemicals, viruses, radiation) that cause birth defects while the human embryo is cause birth defects while the human embryo is developing developing

Especially during first trimesterEspecially during first trimester

PCB’s, Thalidomide, Steroid hormones, and PCB’s, Thalidomide, Steroid hormones, and metals (arsenic, cadmium, lead, and mercury)metals (arsenic, cadmium, lead, and mercury)

CarcinogensCarcinogens

Agents that promote growth of malignant Agents that promote growth of malignant tumorstumors

Cigarette smoke is a major agent in the USCigarette smoke is a major agent in the US

Usually a lag time of 10 – 40 years from initial Usually a lag time of 10 – 40 years from initial exposure to development of cancerexposure to development of cancer

Usually due to chronic exposureUsually due to chronic exposure

Synthetic ChemicalsSynthetic Chemicals

Many synthetics can harm the brain and spinal cord Many synthetics can harm the brain and spinal cord and peripheral nervesand peripheral nerves

Neurotoxins attack the nerve cellsNeurotoxins attack the nerve cells Chlorinated hydrocarbons (DDT, PCBs, dioxin)Chlorinated hydrocarbons (DDT, PCBs, dioxin) Organophosphate pesticideOrganophosphate pesticide FormaldehydeFormaldehyde Compounds of arsenic, mercury, lead, cadmiumCompounds of arsenic, mercury, lead, cadmium Solvents (trichloroethylene (TCE), toluene and Solvents (trichloroethylene (TCE), toluene and

xylenexylene

Chemicals released each yearChemicals released each year

The US releases more than 1,000 new synthetic The US releases more than 1,000 new synthetic chemicals into the marketplace each yearchemicals into the marketplace each year

99.5% of these chemicals are not regulated by the 99.5% of these chemicals are not regulated by the federal government federal government

Only 2% of 85,000 synthetic chemicals are adequetly Only 2% of 85,000 synthetic chemicals are adequetly testedtested

Chemicals can interact within the body or Chemicals can interact within the body or environment to create new chemicalsenvironment to create new chemicals

The Bodies DefensesThe Bodies Defenses

Immune system - antibodies and cellular Immune system - antibodies and cellular defense - fights against disease and defense - fights against disease and harmful substancesharmful substances

Endocrine system - regulate Endocrine system - regulate hormones/growth and developmenthormones/growth and development Hormone mimics disrupt the endocrine sysHormone mimics disrupt the endocrine sys

Dioxins, PCB’s, DDT, lead, other pesticides Dioxins, PCB’s, DDT, lead, other pesticides (especially chloronated hydrocarbons)(especially chloronated hydrocarbons)

Transmissible diseasesTransmissible diseases

Transmissible diseases are caused by living Transmissible diseases are caused by living organismsorganisms

These infectious agents are spread by air, water, food, These infectious agents are spread by air, water, food, bodily fluid, insects and other vectorsbodily fluid, insects and other vectors

80% of illness in developing countries is from 80% of illness in developing countries is from waterborne infectious diseases (diarrhea, hepatitis, waterborne infectious diseases (diarrhea, hepatitis, typhoid fever, cholera) mainly from unsafe drinking typhoid fever, cholera) mainly from unsafe drinking water and inadequate sanitationwater and inadequate sanitation

7 Deadly Diseases7 Deadly Diseases

According to WHO the seven deadliest infectious According to WHO the seven deadliest infectious diseases are:diseases are:

Acute respiratory infection (pneumonia, flu)Acute respiratory infection (pneumonia, flu) HIV/ AIDSHIV/ AIDS Diarrheal diseasesDiarrheal diseases TB tuberculosisTB tuberculosis MalariaMalaria MeaslesMeasles Hepatitis BHepatitis B

Virus vs. BacteriaVirus vs. Bacteria

Viral diseaseViral disease AIDSAIDS EbolaEbola InfluenzaInfluenza RabiesRabies Avian or bird fluAvian or bird flu West Nile virusWest Nile virus SARSSARS Hepatitus BHepatitus B

Bacterial diseaseBacterial disease Tuberculosis (TB)Tuberculosis (TB) Lyme diseaseLyme disease PneumoniaPneumonia

TuberculosisTuberculosis

A highly infectious bacterial diseaseA highly infectious bacterial disease

It is estimated that between 2006 and 2020 25 It is estimated that between 2006 and 2020 25 million people will die of tuberculosis, most of million people will die of tuberculosis, most of which live in developing countrieswhich live in developing countries

Half of the people infected with TB do not Half of the people infected with TB do not know they have it and can infect another 10-15 know they have it and can infect another 10-15 people on averagepeople on average

TuberculosisTuberculosis

Population growth, urbanization, and air travel have Population growth, urbanization, and air travel have increased contact with TBincreased contact with TB

Luckily four inexpensive drugs in combination can Luckily four inexpensive drugs in combination can cure 90% of cases, but the drugs must be taken every cure 90% of cases, but the drugs must be taken every day for 6-8 monthsday for 6-8 months

Because symptoms disappear after a few weeks, Because symptoms disappear after a few weeks, many patients stop taking the medicationmany patients stop taking the medication

TuberculosisTuberculosis

The incidence of TB has increased due to The incidence of TB has increased due to Increased size in populationIncreased size in population Increased number of elderly in the populationIncreased number of elderly in the population PovertyPoverty World travelWorld travel TB bacterium have developed resistance to TB bacterium have developed resistance to

antiobioticsantiobiotics Weakened immune systems (from AIDS and other Weakened immune systems (from AIDS and other

diseases)diseases)

MalariaMalaria

Symptoms come and go and include: fever, Symptoms come and go and include: fever, anemia, enlarged spleen, severe abdominal anemia, enlarged spleen, severe abdominal pain, headaches, extreme weakness to other pain, headaches, extreme weakness to other diseasesdiseases

Kills about 1.5 million each year, most under 5Kills about 1.5 million each year, most under 5

Caused by parasitic protozoa (Caused by parasitic protozoa (PlasmodiumPlasmodium) ) passed on typically by passed on typically by AnophelesAnopheles mosquitoes mosquitoes

Reduction in MalariaReduction in Malaria

Incidences of malaria were temporarily Incidences of malaria were temporarily decreased during the mid 1900’sdecreased during the mid 1900’s Draining wetlands/swampsDraining wetlands/swamps Spraying DDT to kill mosquitosSpraying DDT to kill mosquitos Use of drugs to kill parasite in patientsUse of drugs to kill parasite in patients Increased awareness of symptoms for early Increased awareness of symptoms for early

treatmenttreatment

Unfortunately, since 1970 malaria has risen due to Unfortunately, since 1970 malaria has risen due to genetic resistance and deforestationgenetic resistance and deforestation

West Nile VirusWest Nile Virus

Transferred to humans by mosquitosTransferred to humans by mosquitos It arrived in the US in 1999 (estimated)It arrived in the US in 1999 (estimated) Since then has spread coast to coast and Since then has spread coast to coast and

infected more than 1.2 million peopleinfected more than 1.2 million people

SARSSARS

Severe acute respiratory syndromeSevere acute respiratory syndrome

First appeared in 2002 in ChinaFirst appeared in 2002 in China Flu-like symptoms that can quickly turn to Flu-like symptoms that can quickly turn to

pneumonia (and death)pneumonia (and death) Spread quickly in 2003, but was contained by Spread quickly in 2003, but was contained by

WHO and other local agenciesWHO and other local agencies

Lyme DiseaseLyme Disease

Spread by deer ticksSpread by deer ticks Bacteria that attacks the nervous systemBacteria that attacks the nervous system The bite from the tick leaves a red bulls-eye The bite from the tick leaves a red bulls-eye

target on the skintarget on the skin With immediate antiobiotics the effects are With immediate antiobiotics the effects are

minimalminimal

PovertyPoverty

This is the greatest risk humans faceThis is the greatest risk humans face

Other than poverty, most people face the greatest risk Other than poverty, most people face the greatest risk from their lifestyle choicesfrom their lifestyle choices

Avoid risk – no smoking, avoid excess sun, low to Avoid risk – no smoking, avoid excess sun, low to zero alcohol consumption, reduce cholesterol and zero alcohol consumption, reduce cholesterol and saturated fats, eat a variety of fruits and vegetables, saturated fats, eat a variety of fruits and vegetables, exercise, lose excess weight, and use safety exercise, lose excess weight, and use safety equipment (seatbelts, helmets, life jackets, etc)equipment (seatbelts, helmets, life jackets, etc)

The EndThe End

Stay healthyStay healthy

Live longLive long

Enjoy life!Enjoy life!