The dose makes the poison
This presentation is the property of its rightful owner.
Sponsored Links
1 / 17

‘The Dose Makes the Poison’ PowerPoint PPT Presentation


  • 84 Views
  • Uploaded on
  • Presentation posted in: General

‘The Dose Makes the Poison’. Dr Clifford Elcombe University of Dundee and CXR Biosciences. Dose THE KEY CONCEPT in Toxicology. Father of Modern Toxicology PARACELSUS — 1564. “ All things are poisonous, only the dose makes it non-poisonous.” ( Dose alone determines toxicity ).

Download Presentation

‘The Dose Makes the Poison’

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


The dose makes the poison

‘The Dose Makes the Poison’

Dr Clifford Elcombe

University of Dundee

and

CXR Biosciences


Father of modern toxicology paracelsus 1564

Dose

THE KEY CONCEPT in Toxicology

Father of Modern Toxicology PARACELSUS — 1564

“All things are poisonous, only the dose makes it non-poisonous.”

(Dose alone determines toxicity)


The dose makes the poison

  • Toxicology is arguably the oldest scientific discipline, as the earliest humans had to recognize which plants were safe to eat.

  • Approximately 100,000 chemicals currently in use worldwide, 500new chemicals enter the market- place annually.

  • Humans are exposed to chemicals both deliberately and inadvertently. Most exposure of humans to chemicals is via naturally occurring compounds consumed in the diet from food plants.


A selection of natural carcinogens

A Selection of Natural Carcinogens

anise

apples

bananas

brocolli

brussel sprouts

cabbage

carrots

cauliflower

celery

cinnamon

cloves

cocoa

comfrey tea

fennel

grapefruit juice

honey dew melon

horseradish

kale

mushrooms

mustard

orange juice

parsely

parsnips

peaches

black pepper

pineapples

radishes

raspberries

tarragon

turnips


The science of toxicology helps people make informed decisions and balance risks vs benefits

The science of Toxicology helps people make informed decisions and balance RISKS vs. BENEFITS

The study found the highest levels of pesticide residues in peaches, apples, pears…….

AND Spinach.


Hazard and risk

Hazard and Risk

  • Hazard

    • the potential for harm

    • Intrinsic property of the chemical

  • Risk

    • Risk is the chance (probability) that harm will actually occur

    • Hazard x exposure (dose and time)


All interactions between chemicals and biological systems follow a dose response relationship

ALL Interactions between Chemicals and Biological Systems follow a Dose-Response Relationship


Dose response relationship

Dose-Response Relationship

  • The quantitative relationship between the concentration of a xenobiotic in the body and the magnitude of the biological effect it produces.

  • The magnitude of the effect of a xenobiotic is a function of the amount of xenobiotic a person is exposed to (i.e., “The Dose Makes the Poison”).


Dose concepts

Dose Concepts

  • The magnitude of the toxic response is proportional to the concentration (how much) of the chemical at the target site.

  • The concentration of a chemical at the target site is proportional to the dose.

  • Four important processes control the amount of a chemical that reaches the target site.

    • Absorption

    • Tissue distribution

    • Metabolism

    • Excretion


The dose makes the poison

Dose Determines Whether a Chemical Will Be Beneficial or Poisonous

Beneficial DoseToxic Dose

Aspirin300 – 1,000 mg1,000 – 30,000 mg

Vitamin A5000 units/day50,000 units/day

Oxygen20% (Air)50 – 80% (Air)


Dose response relationship the dose makes the poison

Effective Dose

Lethal Dose

100

100

80

80

60

AnimalsKilled (%)

Animals Sleeping (%)

60

LD50

ED50

40

40

20

20

1

2

3

5

7

10

10

20

30

50

100

Phenobarbital(mg/kg) Log Scale

Dose-Response Relationship“The Dose Makes the Poison”


Linearised model

Linearised Model

1,000,000

100,000

10,000

1,000

Risk per 1,000,000

100

10

1

1

100

1,000

10,000

100,000

10

Dose (ppm in diet)

VSD ("virtually safe dose")


Metabolic saturation

Metabolic Saturation!


Concentration analogies

Concentration Analogies

  • one automobile in bumper-to-bumper traffic from Cleveland to San Francisco

  • one minute in two years

  • One Part Per Million is :


Concentration analogies1

Concentration Analogies

  • One Part Per Billion is :

  • one 4 inch hamburger in a chain of hamburgers circling the earth at the equator two-and-a-half times (4x10 9 inches)

  • one second of time in 32 years


Which results in the largest exposure

Which Results in the Largest Exposure?

  • 1000 ng/mL

  • 1 mg/mL

  • 1 ppm

  • 1000 ppb


Resources

Resources

A Journalist's Handbook on Environmental Risk Assessment

http://ruby.fgcu.edu/Courses/Twimberley/IDS3920/main.html

http://www.agius.com/hew/resource/hazard.htm


  • Login