03. Toxicology - General.ppt

7/23/2019 03. Toxicology - General.ppt

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Introduction to Toxicology

A Brief Introduction to theConcepts of Toxicology

We Will Be UsingThroughout This Course


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Units Used to MeasureChemicals

in the Environment

M ! arts per million

B ! arts per "illion

T ! arts per trillion


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A simple cu"e # cu"ic meter in

volume

#m

#m

#m


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Is formed of #$%%%$%%% cu"es$

# cu"ic centimeter each

#%%cm

#%%cm

#%%cm

#%%cm x #%%cm

x #%%cm $%%%$%%%cc

In # m' "loc(#cc & #ppm


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)ne part per million is

# inch in #* miles

# minute in t+o years

# cent in ,#%$%%%

# ounce of salt in '# tons of potatochips

# "ad apple in -$%%% "arrels of apples


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.ivide each #cc "loc( into

#$%%% "loc(s %/#cm on a side

#cm

#cm

#cm

%/#cm x %/#cm x

%/#cm &%/%%#cm'

In # m' "loc(

%/%%#cm' &

%/%%#cc or#pp"


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)ne part per "illion is

# inch in #*$%%% miles

# second in '- years

# cent in ,#%$%%%$%%%

# pinch of salt in #% tons of potato chips

# lo" in #$-%%$%%% tennis matches # "ad apple in -$%%%$%%% "arrels of

apples


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And divide each %/#cc "loc(into #$%%% "loc(s %/%#cm

on a side

%/#cm

%/#cm

%/#cm

%/%#cm x %/%#cm

x %/%#cm &%/%%%%%#cm'

In # m' "loc( /

%%%$%%%$%%#m' &%/%%%$%%#cc or

#ppt


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)ne part per trillion is

# postage stamp in the area of the city of.allas

# inch in #* million miles 0more than *%%times around the earth1

# second in '-% centuries

# flea on '*% million elephants # grain of sugar in an )lympic si2ed pool

# "ad apple in - "illion "arrels


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Important Concept

)n the left side of the decimal point 0/ 1! # trillion is "igger than # "illion

! # "illion is "igger than # million! # million is "igger than # thousand3

)n the right side of the decimal point 0 / 1! # part per trillion is smaller than # part per "illion

! # part per "illion is smaller than # part per million

! # part per million is smaller than # part perthousand


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Important 4elationship

5or +ater at 6T 0standard temperature7-'oC8 and pressure 7#9 psi81

1 cc = 1ml = 1g


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Which means that

# liter of +ater & # (g

# mg : (g & # ppm

#mm3: liter & # ppm

# mg : liter & # ppm


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Measures of Toxicity

Toxicity of chemicals is determined in thela"oratory

The normal procedure is to expose testanimals! By ingestion$ application to the s(in$ "y inhalation$

gavage$ or some other method +hich introduces

the material into the "ody$ or! By placing the test material in the +ater or air of

the test animals; environment


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Measures of Toxicity

Toxicity is measured as clinical


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Measures of Toxicity@

The Median ?ethal .ose

LD50

The amount 0dose1 of a chemical +hich producesdeath in 9% of a population of test animals to+hich it is administered "y any of a variety of

methods

mg/kg

>ormally expressed as milligrams of su"stance per(ilogram of animal "ody +eight


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Measures of Toxicity@The Median ?ethalConcentration

LC50

The concentration of a chemical in an environment0generally air or +ater1 +hich produces death in9% of an exposed population of test animals in a

specified time frame

mg/L

>ormally expressed as milligrams of su"stance perliter of air or +ater 0or as ppm1


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rimary 4outes of Exposure

to esticidesThere are three primary routes "y +hich

organisms are exposed to pesticides

)ral

.ermal

Inhalation


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rimary 4outes of Exposure@

)ral Exposure

Any exposure to pesticide +hich occurs +hen

the chemical is ta(en in through the mouthand passes through the gastrointestinal tract

.uring oral exposure$ although carried +ithinthe "ody$ the pesticide is still outside of the"ody cavity


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.ermal Exposure

Exposure of the s(in to a pesticide

Most common route of human exposure

With proper hygiene this type of exposure isgenerally not serious unless there is aspecific$ rapid toxicological effect 0often eyeeffects1 +hich is of concern


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Inhalation Exposure)ccurs +hen a pesticide is "reathed into the

lungs through the nose or mouth

6ignificant route of exposure for auaticorganisms

>ot of toxicological concern until it crosses fromthe lung into the "ody 0unless the chemical iscorrosive1


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.uration of Exposure

Three terms are commonly used todescri"e the duration of dose0s1

Acute

Chronic

6u"chronic


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.uration of Exposure@

Acute Exposure

Application of a single or shortterm

0generally less than a day1 dosing "y achemical

If toxic symptoms are expressed$ they arereferred to as symptoms of


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Chronic Exposure

Expression of toxic symptoms only after

repeated exposure to a chemical in dosesregularly applied to the organism for a timegreater than half of its lifeexpectancy



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6u"chronic Exposure

Toxic symptoms are expressed after repeated

applications for a timeframe less than half thelife expectancy of the organism ! "ut moreoften than a single dose or multiple dosesapplied for only a short time



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4emem"er !

5or pesticides ! less is more +hendealing +ith toxicity

The less you need to cause a toxiceffect ! the more toxic the su"stance is

Thus an ?.9%of -9 mg:(g is more toxic

than is one of D$%%% mg:(g


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Words again

Safe

Low Risk


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6ignal Words

The relative acute toxicityof a pesticide is reflectedon the la"el in the form of a

WA4>I>

.A>E4


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6ignal Words@

CAUTI)>


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6ignal Words@

WA4>I>


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6ignal Words@

.A>E4


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)I6)>GGG

?egally defined term ! not Hust anything youdon;t li(e

Any pesticide +ith an ?.9%of 9% mg:(g or less ?a"els must reflect this classification

?a"el must have the signal +ord E4=plus the +ord =

?a"el also must display the s(ull andcross"ones icon


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4elative toxicity

)rganisms can;t differentiate "et+een


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4elative toxicity

Most her"icides act on "iological path+aysnot present in humans

Those approved for use in the 4egion 0muchmore a"out these laterGG1 have ?.9%s of 9%

mg:(g or greater ! they have intermediate orrelatively lo+ toxicity

6ome of the insecticides used are highlytoxic


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4elative toxicity

6ome examples of pesticides and otherchemicals are given to sho+ relative ris( of

pesticides in the environment in +hich +e live This is >)T to triviali2e the pesticides

Al+ays treat them +ith caution and respect

But$ have a realistic recognition of theirrelative ris( in a +orld of ris(s


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4elative toxicity@

Insecticides

TC.. 0.ioxin1 %/# mg:(g

arathion #'/% mg:(g

>icotine 9%/% mg:(g

Car"aryl -D%/% mg/(g Malathion 'D%/% mg:(g


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4elative Toxicity@

er"icides and Additivesmg:(g

arauat J9

-$K. 'D9-$K. 9'-

Triclopyr *'%

Te"uthiuron *KK

.icam"a D9Dexa2inone #$*J%

lyphosate K$'-%

mg:(g

?imonene 9$%%%

Clopyralid F9$%%%6ulfometuron Met// F9$%%%

Ima2apyr F9$%%%

.iesel oil D$'L%

icloram L$-%%5osamine am// -K$K%%

erosene -L$%%%


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4elative Toxicity@

Comparative informationighly toxic chemicals

% ! 9% mg:(g range

0taste # teaspoonful1mg:(g

Botulinus toxin %/%%%%#

.ioxin %/#

arathion #'/% 6trychnine '%/%

>icotine 9%/%

Moderately toxic chemicals

9% 9%% mg:(g range

0teaspoonful # ounce1mg:(g

arauat J9

Caffeine -%%

Car"aryl -D% Malathion 'D%

-$K. 'D9


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4elative Toxicity

Comparative Information6lightly toxic chemicals

9%% ! 9$%%% mg:(g range

0# ounce # pint1mg:(g

-$K. 9'-

Triclpoyr *'%

Te"uthiuron *KK .icam"a D9D

mg:(g

5ormaldehyde L%%

exa2inone #$*J% Asprin #$D%%

Nitamin B' #$D%%

ousehold "leach -$%%%

Ta"le salt '$D9% lyphosate K$'-%

etc/


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4elative Toxicity@

Are all su"stances toxicOPE6G

All are toxic to some uantifia"le degree6ugar has an ?.9%of '%$%%% mg:(g

The foresters favorite ! ethanol has an ?.9%

of only #'$D%% mg:(gEven +ater has a recogni2ed ?.9%of slightly

greater than L%$%%% mg:(g


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4elative Toxicity@

The ?ast Wordesticides are chemicals introduced into the

environment to perform a function

The source of a chemical 0synthetic vs/natural1 is irrelevant +hen considering itstoxicity

esticides should "e treated +ith care andproper respect ! "ut so should householdcleaners$ gasoline and (erosene$ "leaches$paints and all other chemicals

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03. Toxicology - General.ppt