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7/28/2019 General Information on Poisons and Poisoning. Routes of Absorption, Local Effects, Systemic Effects
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GENERAL INFORMATIONSON POISONS AND POISONING.
Routes of absorption
local effects
systemic effects
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WHAT IS A POISON?(from the Latin word - potare - meaning to drink)
Any subs tance that causes harm i f i t gets into the body
Harm can be mild (ex. headache or nausea)
or severe(ex. fits or very high fever),
and severely poisoned people may die.
Poisons can also enter the body: By breathingThrough the skin
By IV injection
From exposure to radiation
Venom from a snake bite
The amount of a chemical substance that gets into the body at one time =
the dose.
A dose that causes poisoning = a poisonous dose or toxic dose.
The smallest amount that causes harm = the threshold dose.
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Depends partly on how long the contact lasts
on how much poison gets into the body, and
on how much poison the body can get rid of during this time.
Exposure may be:
Acute exposure: a single contact that lasts for seconds, minutesor hours, or several exposures over about a day or less
Chronic exposure: a contact that lasts for many days, months oryears. It may be continuous or broken by periods when there is nocontact. Exposure that happens only at work, for example, is notcontinuous.
WHAT IS POISONINGExposure to a poison
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LIST OF POISONSa range of chemicals and their relative toxicity
Chemical Dose Type Target
water 8 kg inorganic nervous system
lead 500 g inorganic nervous system
alcohol 500 g organic kidney/liver
ketamine 226 g drug cardiovascular
table salt 225 g inorganic nervous system
ibuprofen (e.g., Advil) 30 g drug kidney/liver
caffeine 15 g biological nervous system
paracetamol (e.g., Tylenol) 12 g drug kidney/liver
aspirin 11 g drug kidney/liver
amphetamine 9 g drug nervous system
nicotine 3.7 g biological nervous system
cocaine 3 g biological cardiovascular
methamphetamine 1 g drug nervous system
chlorine 1 g element cardiovascular
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Chemical Dose Type Target
arsenic 975 mg element digestive system
bee sting venom 500 mg biological nervous system
cyanide 250 mg organic causes cell death
aflatoxin 180 mg biological kidney/liver
mamba venom 120 mg biological nervous system
black widow venom 70 mg biological nervous system
formaldehyde 11 mg organic causes cell death
ricin (castor bean) 1.76 mg biological kills cells
VX (nerve gas) 189 mcg organophosphate nervous
tetrodotoxin 25 mcg biological nervous system
mercury 18 mcg element nervous system
botulinum (botulism) 270 ng biological nervous
tetanospasmin (tetanus) 75 ng biological nervous system
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Many poisons, however, are substances meant for human food or medicines:
Some mushrooms are poisonous
Drinking water contaminated by agricultural or industrial chemicals Food that has not been properly prepared or handled
Drugs, helpful in therapeutic doses but deadly when taken in excess
ex. Beta blockers, a class of drugs used to treat heart and other
conditions ( angina, high blood pressure, migraine, headache
prevention etc) in excess, they can cause difficulty in breathing,
coma, and heart failure.
ex. Warfarin (Coumadin): a blood thinner used to prevent blood clots,
is also the active ingredient in many rat poisons and may cause
heavy bleeding and death if too much is taken.
ex. Vitamins: especially A and D, taken in large amounts can cause
liver problems
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ROUTES OF ABSORPTION
How a poison gets into the body
By the route of exposure orthe route of absorption.
Through the mouth by swallowing (ingestion) Small children often swallow poison accidentally adults who want to poison themselves may swallow poison.
pesticide poisoning: people eat, drink or smoke after they have been handlingpoisons, without first washing their hands
When poisons are swallowed they go to the stomach and some of them pass throughthe gut walls and into the blood vessels, provoking poisoning.
To stop poisons passing from the gut into the blood:
Vomiting soon after swallowing a poison , the poison may be expelled from the
body before a poisonous dose gets into the blood. give act ivated charc oal because this binds some poisons so that they cannot
pass through the gut walls
give laxat ivesto make the poison move through the gut and out of the body morequickly.
If poisons do not pass through the gut walls, they cannot affect other parts of the bodyand they move along the gut and leave the body in the faeces
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Through the lungs by breathing (inhalation)
gas, fumes,
vapor, smoke,dust or fine spray droplets
may be breathed into the mouth and nose and go down the air passages into the
lungs and into the blood vessels very quickly because the air passages in the
lungs have thin walls and a good blood supply.
Small particles pass into the lungs. Larger particles are trapped in the mouth, throat and nose
and may be swallowed.
Poisons may be breathed
when spraying pecticides or
when ihhaling fumes from oil or gas heaters, cookers, and fires whenthe smoke cannot get outside or if the room does not have a good
supply of fresh air
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Through the skin by contact with liquids, sprays or mistsThe skin is a barrier that protects the body from poisons but
if the chemical is sprayed or splashed onto the skin, or
if people wear clothes soaked with chemical, poisons can pass through the skin.
Quicker passage of the poison
through warm, wet, sweaty skin than through cold, dry skin,
through skin damaged by scratches or burns than through undamaged skin.
The poison mu st be washedoff the skin before a poisonous dose gets into the body.
By injection through the skin From a syringe,
a pressure gun, during tattooing,
by the bite or sting of a poisonous animal, insect, fish or snake.
Direct ly into th e blo od vessels(quick effect) or
under the sk in into mu sc le or fatty t issues(acts more slowly because it has
has to pass through several layers of tissue before reaching the blood vessels)
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What happens when poison is inside the body
It is carried to the whole body as the blood is pumped round the body by the heart
Some poisons are changed in the body, mostly in the liver, into other chemicals called
metabolites , which are more easily passed out of the body than the original
chemicals.
Unchanged poisons or their metabolites usually leave the body
in the urine : passage of the poison from the blood into urine takesplace in the kidneys
in the faeces : poison may have passed down the gut without beingabsorbed into the blood or it may have been absorbed
into the blood and then passed out into the gut again
in the sweat, or
in the air that a person breathes out : poison from blood intobreathed-out air takes place in the lungs
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THE EFFECTS OF POISONLocal vs Systemic Health Effects
Local effect refers to an adverse health effect that takes place at the point or area
of contact. The site may be skin, mucous membranes, the respiratory tract,gastrointestinal system, eyes, etc.
Absorption does not necessarily occur.
Systemic effect refers to an adverse health effect that takes place at a locationdistant from the body's initial point of contact and presupposes that absorptionhas taken place.
Ex. arsenic effects to the blood, nervous system, liver, kidneys and skin;benzene effects to the bone marrow.
Substances with systemic effects, which are cumulative poisons, often have"target organs" in which they accumulate and exert their toxic effect, which isnot seen until a critical body burden is reached.
Ex. heavy metals such as lead.
When exposure occurs to several substances simultaneously the resultantsystemic toxic effect may be significantly greater in combination than theadditive toxic effect of each substance alone. This is called a synergistic orpotentiating effect
Ex. exposure to alcohol and chlorinated solvents; or smoking and asbestos.
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LOCAL EFFECTSare l imited to the part of the bod y in contact w ith the chemical(the sk in, the eyes, the air passages or th e gut)
It must be washed off straight away
An irritant chemical causes : pain
swelling
itching
watery eyes
irritation of the throat causing coughing
skin rashes
skin burns, like the burns caused by fire, if it is in contact with the skin for a
long time (ex. wearing contaminated clothes for several hours)
A cor ros iveorcaust icchemical very quickly causes painful burns anddestroys the skin ( skin may turn grey-white or brown).
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SYSTEMIC EFFECTSoccur when the amount of a poison absorbed into the body is greater than theamount the body can get rid of, and the poison builds up and reaches the
threshold level.Poisons can :
damage organs such as the brain, nerves, heart, liver, lungs, kidneys, or skin. The most
affected organs are called the target organs.
block messages between nerves.
stop the body working properly, for example, by blocking energy supply or oxygen supply.
On the eyessevere pain if they get into the eyes.
burn the surface of the eye and cause scars or even blindness.
red and watery eyes
bright light will hurt.
Inside the gut the mouth and throat or the inside of the gut may be damaged
Swelling of the throat if is burnt so quickly that he cannot breathe
Vomiting
diarrhoea,
the vomit and faeces may contain blood. belly pain
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Inside the air passages and lungsSome gases and vaporscan irritate the nose, throat and upper air passages and cause
coughing and choking.
the lungs fill with water (lung oedema) very soon after a person breathes in the
substance, or up to 48 hours afterwards.
When people are unconsciousit is very dangerous to try to give them any food, drink or
medicine, becausethe air passage does not close, so there is nothing to stop food, drink or
vomit getting into the lungs and blocking the air passages or causing lung oedema.
At injection sites : into the skinPoisons from insect stings and snake bites may cause pain and swelling where they are
injected, provoking local and maybe systemic effects
Effects on unborn babiesA baby inside the womb can be harmed, most likely during the first three months of pregnancy
when the nervous system and all the major organs begin to form, by some poisonous chemicals
alcohol or smoking during pregnancy
medicines
The parts of the baby usually affected are the bones, eyes, ears, mouth and brain
If the damage is very bad the baby will stop growing and die.
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CONCLUSION :
Before you send a person home always check:
how long ago the exposure to poison happened;
how long it usually takes before the effects of the poison can be seen
check on the person for 12-24 hours to see if any ill effects develop.
In some cases you may need to watch them even longer than that.
Exposure to a chemical does not affect everyone in exactly the same way.
young children and old people are more likely to be severely poisoned thanyoung adults;
people who are not eating well, or are drinking a lot of alcohol or have a
disease, are more likely to be severely poisoned than healthy people
.
Nausea is a sign and vomiting is a symptom of poisoning.
Almost every possible sign or symptom of a poisoning can also be caused bya nonpoison-related medical problem. They can be found in many illnesses
non related to poisoning (stroke, heart attack, stomach ulcers, gallbladder
problems, hepatitis, appendicitis, head injuries, and many others).
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REFERENCES
1. http://www.emedicinehealth.com
2. Management of Poisoning - A Handbook for Health Care Workers(ILO, WHO; 1997 267 pages)
3. http://chemistry.about.com(LIST OF POISONS)
4. Management of poisoning, J. Henry, H. Wiseman, WHO,1997
5. Guidelines for poison control. WHO, 1997
6. Handbook of the acute poisoning - professor A. Monov, Medicine
and physical culture, Sofia, 1987.
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