APES - Chapter 11 Notes

8/12/2019 APES - Chapter 11 Notes

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Chapter 11: Risk, Toxicology, & Human Health

11-1: Risk, Probability, and Hazards

The risk of a particular hazard causing damage to humans or the environment is expressed in terms of proaility!Calculating this proaility is an inexact science "here many variales have to e considered!

Risk managementis the process of determining ho" serious a particular risk is and ho" to go aout #or not go aout$

reducing the risk or preparing for its aftereffects!

Take ird flu for example! %ast year it "as determined that the virus had aout a 1 in 1, chance of mutating into adeadly strain! ' mean, "hat do you do "ith that information( Ho" many resources do you allocate to dealing "ith thepossiility of this turning into a pandemic(

Ho" aout Hurricane )atrina( *hat "as the proaility of a Class + hurricane striking do"nto"n e" -rleans( Ho"many resources should have een reserved for strengthening the flood protection( Ho" many for emergency response('t.s such a tough call ecause people "ill complain if money is spent and the risk is never realized! /eople "ill alsocomplain if the risk actually occurs and not enough "as done to deal "ith the situation!

Risk hazards can e roken do"n into four categories:

1! Cultural hazards: smoking, driving, crime, poverty, unsafe sex0! Chemical hazards: mostly synthetic chemicals in the air, "ater, food, etc!! /hysical hazards: flood, tornado, earth2uake, hurricane, etc!

3! 4iological hazards: pathogens #diseases$, allergens, and killer animals

11-2: Toxicology

Toxicityis a measurement of exactly ho" harmful a sustance is! The toxicity of a sustance is heavily dependent onthe dose, the numer of exposures, and the individual characteristics of the persons exposed! 5ome people arenaturally going to e more sensitive to a toxin than others!

Toxins that are "ater6solule are often less harmful ecause they move through the ody 2uickly and can eeliminated through urination! 7at6solule toxins on the other hand do not dissolve in "ater and are generally storedinside ody fat for a much longer period of time #THC "ould e an example for all you potheads out there$!

'n the environment, the persistenceof the chemical is important to its risk! The longer it takes to reak do"n, themore chance of damaging exposure to humans or "ildlife!

Bioaccumulation occurs "hen certain toxins tend to uild up in specific organs! 7or example, radioactive compoundscollect in the thyroid, elevating the risk of cancer there!

Biomagniication occurs "hen a toxin uilds up in species in the upper trophic levels of a food "e! /ersistent, fat6solule organic compounds are the est candidates for iomagnification!

88T is an example of a chemical that often ecomes iomagnified! 4ecause the chemical is stored in the ody andvery slo" to metaolize, it gets sent right up the food chain! The 88T ends up collecting in the odies of the toppredators and causing side effects like the "eak egg shells that affected ald eagles and ro"n pelicans ack in thedays "hen 88T "as legal in the 9!5! Consult 7igure 1163 on page 01!

n acuteeffect is an immediate physical response to toxin exposure! ;xamples include rashes, s"elling, or somethingmore severe like cardiac arrest!

c!roniceffect is a permanent or long6term response to toxin exposure! n example "ould e permanent raindamage from eating leaded paint chips or emphysema from years of smoking!

-ften chemicals have a synergistic reaction that can multiply the effects of each "hen comined together in the ody!

This is "hy there are drug6drug interaction "arnings on the prescription medication you take! T"o drugs takenseparately may e fine, ut taken together they can have a totally different effect!

asic concept of toxicology is that every chemical has the potential to hazardous if the dose is high enough! ;vensomething as enign as "ater can kill you if you drink too much! *ater poisoning #hyponatremia$ killed a lady inCalifornia a couple of months ago after a radio6station contest to see "ho could drink the most "ater "ithout peeing!College students die every year from alcohol poisoning and people sometimes commit suicide y taking huge amountsof over the counter medication!


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Rememer the units used for chemical concentration: ppm, pp, and ppt!

"#$%stands for median lethal dose, "hich is the amount of a chemical received in one dose that kills exactly += ofthe animals in a test population "ithin a 13 day period!5ometimes the term "&$%is used instead, "hich stands for median lethal concentration!

The legal definition of a poisonis a chemical that has an %8+ of + mg or less per kg of ody "eight!

Chemicals are assigned toxicity ratings ased on their %8+, ranging from supertoxic #dead in one drop$ to essentiallynontoxic #you.d have to drink a lot$

5upertoxic less than 1 drop nerve gas, dioxin, mushrooms

;xtremely toxic less than > drops cyanide, heroin, nicotine

?ery toxic > drops to 1 tsp! morphine, codeine

Toxic 1 tsp! to 1 oz! 88T, sulfuric acid, caffeine

61D1 as a sleep aid and cure for morning sickness forpregnant "oman! 9nfortunately it caused aout 1, irth defectsE the trademark irth defect of thalidomideexposure "as aies orn "ithout the long ones in their arms or legs, causing their extremities to appear like littleflippers!

carcinogen is an agent that causes a cancerous tumor to form! Cancer can e caused y exposure to variouschemicals, radiation, or viruses! ot all cancers are environmentalE many are congenital!


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Common carcinogen categories include:

Cigarettes #63= of cancers$

8iet #06=$

-ccupational exposure #+61+=$

;nvironmental pollutants #161=$

Carcinogens often have a time6lag effect, meaning that the actual occurrence of the cancer may not manifest until

many years after the carcinogen exposure!

The three systems of the human ody most often affected y toxic chemical exposure are the immune, nervous, andendocrine!

The endocrine system is a net"ork of glands that emit hormones "hich control sexual reproduction, gro"th,developmental timing and ehavior!

Certain chemicals, kno"n as hormonally active agents #Hs$ mimic the action of naturally occurring hormones anddisrupt the functioning of the endocrine system!/ossile effects of Hs include accelerated puerty, especially in females, and lo" sperm counts in men! 7or anexpanded #terrifying$ list, consult page 0+$!

11-*: Biological Hazards: #isease in #e(eloped and #e(eloping &ountries

+ontransmissible diseases are those that cannot e passed directly from person to person, such as heart disease,

cancer, diaetes, etc! They.re not contagious!

Transmissible diseases are those that can e passed on from one person to another!

pat!ogenis the infectious agent that causes the disease! The most common pathogens are viruses and acteria,although some protists and parasitic animals also 2ualify!

Rememer that acteria can e killed "ith antiiotics, "hile viruses cannot! Rememer also that natural selection ythe pathogenic acteria against the antiiotics is making these acterial diseases harder and harder to treat!

The (ectoris the means y "hich the pathogen is spread! Common vectors include air, "ater, food, lood, andinsects!

s a country gains "ealth it makes the epidemiological transition! The numer of deaths from transmissile diseasesdeclines "hile the numer of deaths from nontransmissile diseases rises! ' mean, people gotta go one "ay or theother, right(

3= of all deaths in developing countries are from transmissile diseases, compared to only 1= of deaths in developedcountries!

The "orld.s > deadliest infectious diseases are:

1! cute respiratory inections, mostly pneumonia and flu #! million deaths per year$0! #.#c2uired 'mmune 8eficiency 5yndrome$ # million$! #iarr!ealdiseases #0!1 million$3! Tuberculosis#T4$ #1!D million$+! /alaria#1!1 million$D! HepatitisB#1 million$>! /easles#F,$

+e0viruses emerge all the time! ;ola and *est ile are a couple of examples! ;ola is too po"erful to spread veryfarE it incapacitates and kills people too 2uickly for it to spread properly!

The most dangerous viral health threat, though, "ould e a mutated form of the lu! 't is highly contagious andairorne! 8uring the "inter of 11F611, a mutated form of the flu #5panish flu$ infected half the "orld and killed 06 million people! 't "as also a little unusual in that it killed other"ise healthy adults, not Gust children and old folkslike the typical flu! -nce you get the flu there.s little a doctor can do for youE it.s up to your ody.s immune system tofight it off! 5o that.s a little scary!

.T#sare out there! ccording to the author of the ook, 0= of mericans are "alking around "ith an 5T8! 'f they.resho"ing ?altrex commercials on T?, ' guess ' elieve that! '.d also hazard a guess that the figure is higher than 0= ingood old 5outh Carolina! ' think ' read some"here that 5!C! is a syphilis or gonorrhea hoted! -ne or the other!


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-f course His the ig daddy! H'? "asn.t even named until 1F1, right around the time "hen enny Iump died!5ince that time aout million have died, "ith another > million expected to perish "ithin the next 0 years!Currently around 36+ million people are carrying the virus inside their ody! 'n many su65aharan frican countries,et"een 063= of adults are infected "ith H'?! The average life spans in these countries have dropped 16 yearssince 1F! lthough frica is currently the epicenter of '85, 'ndia and 5outheast sia are expected to experience amaGor H'? influx "ithin the next t"o decades!

accinesare the ultimate ans"er to effectively comat viral pathogens! /revious monsters like smallpox and polio

have een virtually "iped out through vigilant vaccination programs! .s malaria rates areack up, ecause the mos2uitoes are ecoming resistant to the pesticides and the protists are ecoming resistant tothe ne" drugs!

7actors that may influence infectious diseases in the future:

'ncreased international air travel makes it easy for a disease to travel half "ay around the "orld in one day!

9ranization makes it easier for diseases to e spread!

Iloal "arming may allo" the insects that carry diseases in tropical areas to survive in temperate areas!

' "as attacked y a s"arm of sian tiger mos2uitoes at ;disto 4each aout + years ago! @ou do not "ant any piece ofthem! ' feared for my life and hid inside the house!

11-$: Risk nalysis

lot of 116+ is a unch of laety6loo ut there are some decent nuggets to take out of there!

Take the perceived risk 2uiz!


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APES - Chapter 11 Notes