1. Forensic department Luyang Tao
Forensic toxicology
Forensic department
Luyang Tao

2. Toxicology What is toxicology? The study of the effects of poisons.
Poisonous substances are produced by plants, animals, or bacteria.
Phytotoxins
Zootoxins
Bacteriotoxins
Toxicant - the specific poisonous chemical.
Xenobiotic - man-made substance and/or produced by but not normally found in the body.

3. Introduction
Toxicology is arguably the oldest scientific discipline, as the earliest humans had to recognize which plants were safe to eat.
Most exposure of humans to chemicals is via naturally occurring compounds consumed from food plants.
Humans are exposed to chemicals both inadvertently and deliberately.

4. History 2700 B.C. - Chinese journals: plant and fish poisons
B.C. - Egyptian documents that had directions for collection, preparation, and administration of more than 800 medicinal and poisonous recipes.
800 B.C. - India - Hindu medicine includes
notes on poisons and antidotes.
A.D. - Greek physicians classified over
600 plant, animal, and mineral poisons.

5. History 50- 400 A.D. - Romans used poisons for
executions and assassinations.
The philosopher, Socrates, was executed using hemlock for teaching radical
ideas to youths.
Avicenna (A.D ) Islamic authority on poisons and antidotes.
1200 A.D. - Spanish rabbi Maimonides writes
first-aid book for poisonings,
Poisons and Their Antidotes

6. History Swiss physician Paracelsus (1493-1541) credited with being
“the father of modern toxicology.”
“All substances are poisons: there is none which is not a poison. The right dose differentiates a poison from a remedy.”

7. The Dose Makes the Poison
An apparently nontoxic chemical can be toxic at high doses. (Too much of a good thing can be bad).
Highly toxic chemicals can be life saving when given in appropriate doses. (Poisons are not harmful at a sufficiently low dose).

8. Lethal Doses
Approximate Lethal Doses of Common Chemicals (Calculated for a 160 lb. human from data on rats)
Chemical Lethal Dose
Sugar (sucrose) quarts
Alcohol (ethyl alcohol) 3 quarts
Salt (sodium chloride) 1 quart
Herbicide (2, 4-D) one half cup
Arsenic (arsenic acid) teaspoons
Nicotine one half teaspoon
Food poison (botulism) microscopic
Source: Marczewski, A.E., and Kamrin, M. Toxicology for the citizen, Retrieved August 17, 2000 from the World Wide Web:

9. History Spanish physician Orfila (1815) established toxicology as
a distinct scientific discipline.

10. History
20th Century
Paul Ehrlich –developed staining procedures to observe cell and tissues and pioneered the understanding of how toxicants influence living organisms.

11. History
20th Century
Rachel Carson - alarmed public about dangers of pesticides in the environment.

12. Modern Toxicology

13. Toxicology Terms Toxicity - The adverse effects that a chemical
may produce.
Dose - The amount of a
chemical that gains
access to the body.

14. Toxicology Terms Exposure – Contact providing opportunity of
obtaining a
poisonous dose.
Hazard – The likelihood that the
toxicity will be
expressed.

15. Threshold Effects for Dose
Dose-Response Relationships
Is there such a thing as a ‘safe’ dose??
Agent A
Agent B
Response
“NOEL” (No Observable Effect Level)
Dose

16. Fundamental Rules of Toxicology
Exposure must first occur for the chemical to present a risk.
The magnitude of risk is proportional to both the potency of the chemical and the extent of exposure.
“The dose makes the poison” (amount of chemical at the target site determines toxicity).

17. Exposure Concepts Different toxic responses may arise from different:
Routes of exposure.
Frequencies of exposure.
Duration of exposure (acute vs. chronic).

18. Routes of Environmental Exposure
Ingestion (water and food)
Absorption (through skin)
Injection (bite, puncture, or cut)
Inhalation (air)

19. Chemicals, Chemicals Everywhere
Everything in the environment is made of chemicals. Both naturally occurring and synthetic substances are chemical in nature.
People are exposed to chemicals by eating or swallowing them,breathing them, or absorbing them through the skin or mucosa.
People can protect themselves by blocking these routes of exposure.

20. Duration & Frequency of Exposure
Duration and frequency are also important components of exposure and contribute to dose.
Acute exposure - less than 24 hours; usually entails a single exposure
Repeated exposures are classified as:
Subacute - repeated for up to 30 days
Subchronic - repeated for days
Chronic -repeated for over 90 days

21. Exposure to chemicals may come from many sources:
Exposure Concepts
Exposure to chemicals may come from many sources:
Environmental
Occupational
Therapeutic
Dietary
Accidental
Deliberate

22. Children & Poisons

23. Individual Responses Can Be Different
The variety of responses among organisms that get the same dose of chemical is due to individual susceptibility.
Dose and individual susceptibility play roles in all situations involving chemicals, including those making medicine and caffeine.

24. Types of Toxic Effects Death - arsenic, cyanide
Organ Damage - ozone, lead
Mutagenesis - UV light
Carcinogenesis - benzene, asbestos
Teratogenesis - thalidomide

25. Target Organ Toxicity Central Nervous System – lead
Immune System - isocyanates
Liver - ethanol, acetaminophen
Respiratory Tract - tobacco smoke, asbestos, ozone
Eye - UV light (sunlight)
Kidney - metals
Skin - UV light, gold, nickel
Reproductive System –
dibromochloropropane

26. Mechanistic Toxicology
How do chemicals cause their toxic effects?

27. ? Environmental toxicologists study the
Forensic toxicologists study the application of toxicology to the law. They uses chemical analysis to determine the cause and circumstances of death in a postmortem investigation.
Environmental toxicologists study the
effects of pollutants on organisms, populations, ecosystems, and the biosphere.
Regulatory toxicologists use scientific data to decide how to protect humans and animals from excessive risk Government bureaus such as the FDA and EPA employ this type of toxicologist. ?

28. Regulatory Toxicology
Use data from descriptive and mechanistic toxicology to perform risk assessments.
Concerned with meeting requirements of
regulatory agencies.
Industry/government interactions.

29. Review
Toxicology is the science that studies the harmful effects of overexposure to drugs, environmental contaminants, and naturally occurring substances found in food, water, air, and soil.
Main objectives are to establish safe doses and determine mechanisms of biologic action of chemical substances.
A career in toxicology involves evaluating the harmful effects and mechanisms of action of chemicals in people, other animals, and all other living things in the environment.
This work may be carried out in government, private industry and consulting firms, or universities and other research settings.
Toxicologists routinely use many sophisticated tools to determine how chemicals are harmful.
(e.g.) computer simulations, computer chips, molecular biology, cultured cells, and genetically-engineered laboratory animals .

30. Animals in Research
“Virtually every medical achievement of the last century has depended directly or indirectly on research in animals.”
U.S. Public Health Service

31. Summary Toxicology is a fascinating science that
makes biology and chemistry interesting
and relevant.
Understanding HOW (i.e. mechanism)
something produces a toxic effect can lead to new ways of preventing or treating chemically-related diseases. Animal use in research is essential for medical progress.
Many diseases are the result of an interaction between our genetics (individual variability) and chemicals in our environment.
Toxicology provides an interesting and exciting way to apply science to important problems of social, environmental, and public health significance.

32. The power of EDUCATION

34. For certification as a toxicologist, an individual must possess a Ph.D. or doctorate in one of' the natural, sciences. Undergraduate degrees must also be in these areas (biology or chemistry, usually).
Certification is bestowed by the American Board of Forensic Toxicology, and the expert may use the title of “Diplomate” which must be renewed every three years.

35. A forensic toxicologist is normally presented with preserved samples of body fluids, stomach contents, and organ parts.
They will have access to the coroner's report which should contain information on various signs and symptoms as well as other postmortem data.
The toxicologist needs a through knowledge of how the body alters or metabolizes drugs because few substances leave the body in the same state as they entered.

36. SCREENING TESTS
 Physical tests--boiling point, melting point, density, and refractive index
 Crystal tests--treatment with a chemical reagent to produce crystals
 Chemical spot tests--treatment with a chemical reagent to produce color changes
 Chromatography (thin-layer or gas)--used to separate components of a mixture

37. Forensic Toxicology
Forensic department
Shizhong bian

38. Poisons
"All substances are poisons; there is none which is not a poison.
The right dose differentiates a poison and a remedy."
Paracelsus ( )
Toxicology 3

39. TOXICOLOGY “Science of poisons” Studies chemical effects on life forms
Involves exposure of life forms to outside agents and recording subsequent effects
Exposures can be
occupational or non-occupational
gas station attendant; gas station customer
intentional or non-intentional
cigarette smoker, non-smoker & 2nd hand smoke
toxicology studies involve intentional exposures

40. PRIMARY ROUTES OF EXPOSURE
Ingestion
Inhalation
Absorption
Injection

41. ROUTES OF EXPOSURE Organisms can be “dosed” in 4 ways,
Inhalation - breath
most common, important
OELs based on this
Ingestion - oral, gastrointestinal
poor hygiene often the cause
we “dose” ourselves by ingestion often
Skin absorption/contact
through skin, mucous membrane contact
Injection - through break in skin

42. Ingestion ORAL DOSE Examples
mouth to stomach Generally to the small intestine.
Examples
employee who eats lunch in the work area and ingests inorganic lead that has contaminated a sandwich.
Curious child who puts a toxic substance in his or her mouth out of curiosity
ingestion of residue from chemicals added to our food to kill germs or parasites.

43. FOOD CHAIN (ingestion)EXPOSURE
Depending on the chemical,
we could potentially
eat toxic food.

44. Absorption DERMAL EXPOSURE Entering the body through the skin.
Substances that absorb through the skin sometimes further assimilate into the blood system.
some chemicals are not absorbed easily unless the skin is cut
others are absorbed quite readily regardless of the skin’s condition
use of proper gloves prevents skin contact/absorption through the skin

45. Inhalation Breathing what is in the air which travels to the lungs.
lungs are rich in blood vessels
substances inhaled into the lungs often absorbed into the bloodstream
or may cause problems in the lung itself
Warning properties are sensory clues (odor, irritation)
let us know a chemical’s presence in the atmosphere--“rotten egg” smell of H2S
some substances have no warning properties
carbon monoxide

46. Injection Direct chemical access under the skin
Ex. - medical shots, needle sticks
Injection can also occur accidentally.
skin cut by a contaminated can or a piece of glass.
Needle sticks
Powerful means of exposure
contaminant enters the bloodstream immediately.

47. DOSE - RESPONSE 1 Defines a chemical’s toxic potency Related to
Amount of chemical (dose) that enters or contacts the body
That elicits a given response, or reaction occurring after exposure
For a given exposure duration
time is an important factor
Human (or animal) variability (bell curve)

48. Dose-Response (D-R) Relationship
The relationship between the degree of exposure (dose) and the magnitude of the effect (response).
The Occupational Environment -- Its Evaluation and Control 8 8

49. DOSE - RESPONSE 2 Dose-response designations - XYZ (generic)
X = response, effect
L = lethal (death)
T = toxic (toxic effect)
E = effective (a given effect is seen)
Y = method of administration
D = dose (ingested, injected)
C = concentration (inhaled)
Z = magnitude of effect; % of subjects affected
may also be a word such as “lo” (lowest dose to affect)
5 or 50 = 5% or 50% of test animals
Example: LC50 = inhaled dose at which 50% of subjects died

50. Dose-Response Terms 2 TDlo Toxic dose low TClo Toxic concentration low
lowest dose (not inhaled) for effect except radiation
TClo Toxic concentration low
lowest toxic concentration via inhalation
LDlo Lethal dose low
lowest dose to kill 10% of the test population (LD10)
LD50 Lethal dose 50%
administered dose that kills 50% of the test population
LClo Lethal concentration low in air
lowest inhaled concentration to kill a test animal
LC50 Lethal concentration 50%
concentration that kills 50% of the test population 11 10

51. Dose Units
Quantity of chemical per unit mass of body weight (i.e., mg/kg)
Quantity of chemical per unit area of skin surface (mg/m2)
The Occupational Environment -- Its Evaluation and Control 7 7

52. LD50
The dose of chemical that causes death in 50 percent of the test animals.
Approximate oral LD50 in rats often used
PROBABLE ORAL LETHAL DOSE
TOXICITY RATING for a 70 kg PERSON (154 lb)
6 SUPER TOXIC < 5 mg/kg A TASTE (< 7 dps)
5 EXTREMELY TOXIC 5-50 mg/kg BETWEEN 7 dps AND 1 tsp
4 VERY TOXIC mg/kg BETWEEN 1 tsp AND 1 oz
3 MODERATELY TOXIC g/kg BETWEEN 1 oz - 1 pt (1 lb)
2 SLIGHTLY TOXIC 5-15 g/kg BETWEEN 1 pt - 1 qt
1 PRACTICALLY NONTOXIC > 15 g/kg MORE THAN 1 qt (2.2 lb)
The Occupational Environment -- Its Evaluation and Control 12 19

53. LETHAL DOSE - LD50
LD50 for a substance is established by repeated experiments with animals
substance’s effect on humans is extrapolated to determine what the LD50 would be for humans.
results are adjusted to apply to human body weight and similar characteristics.
tests on animals cannot predict the exact effect that the substance will have on a human population
toxic substance often has different effects on different species
In addition, scientists study the effect of a substance on human populations wherever statistics are available.
Another uncertainty - most LD50 data is from acute exposure (single dose) rather than chronic testing

54. TOX. STUDY LIMITATIONS Use of animal data to predict human response
Use of acute exposure data to infer chronic responses in some cases
Unpredictability of D-R relationships
So Safety factors are applied to no-effect dose to determine OELs
1/10, 1/100, or 1/000 of NOEL
What if response is immediate?

55. AGENT LD50 (mg/kg)
ETHYL ALCOHOL 7060
SODIUM CHLORIDE 3000
NAPHTHALENE 1760
FERROUS SULFATE 1500
ASPIRIN 1000
FORMALDEHYDE 800
AMMONIA 350
DEXTROMETHORPHAN HYDROBROMIDE 350
CAFFEINE 192
PHENOBARBITAL 150
CHLORPHENIRAMINE MALEATE 118
DDT 100
STRYCHNINE SULFATE 2
NICOTINE 1
DIOXIN
BOTULINUS TOXIN
The Occupational Environment -- Its Evaluation and Control 13 20

56. DOSE - RESPONSE 3 D-R relationship determines relative toxicity rating
Rating Term LD50 LC50
single oral rat 4-hr inhalation rat
mg/kg ppm
1 Super Toxic 5 or less < 10
2 Extremely Toxic
3 Highly Toxic ,000
4 Moderately Toxic 500-5,000 1,000-10,000
5 Slightly Toxic 5,000-15,000 10, ,000
6 Nearly Non-Toxic > 15,000 > 100,000

57. Dose-Response Relationship
The dose-response relationship
(from C.D. Klaassen, Casarett and Doull’s Toxicology, 5th ed., New York: McGraw-Hill, 1996; reproduced with
permission).
% Mortality
Gray Region
Dose (mg/kg)
The Occupational Environment -- Its Evaluation and Control
8.1 25

58. D-R Assumptions Chemical reacts with reactive site to produce effects
Response related to concentration of agent at reactive site
Concentration at site relates to administered dose.
The Occupational Environment -- Its Evaluation and Control 9 9

59. ACUTE vs CHRONIC 1 Acute Acute dose/exposure Acute response/effects
short-term, limited duration usually high level
Acute response/effects
immediate or nearly so
Chronic
Chronic dose/exposure
over time, usually lower level
Chronic response/effects
latent, delayed, long term

60. ACUTE vs CHRONIC 2

61. EXPOSURE LIMITS
Concentrations at or below which it is assumed most healthy workers will not have adverse health affects
Some chemicals/agents may have no safe level
NIOSH position on carcinogens (NPG Appx A)
OELs per chemical may differ--WHAT IS SAFE?
OELs may change with more studies, info
Different types of OELs consider different effects
Look up your chemical’s different OELs, recording source(s)

62. Exposure Limits Summary

63. CHEMICAL INTERACTIONS
Combinations of chemicals can alter the usual effect of the individual chemicals
Additive = 2
toxic chemicals affecting the same organ/system
Synergistic > 2
toxic chemicals enhance each other’s effects
Potentiation > 1
non-toxic chemical increases the toxic effect of a toxic chemical
Antagonism < 2
chemicals hinder the toxic effect(s) of one another or both (i.e., antidote)

64. TOXIC EFFECTS Local vs systemic effects Acute vs chronic effects
Grouped according to target organ, action &/or other factors
Local vs systemic effects
site of contact vs. bloodstream entry, target organ/system
Acute vs chronic effects
now vs. later
Reversible vs irreversible effects
may change w/ exposure duration
Allergic and sensitization effects
antibody development; not D-R dependent
Vary with route & rate of entry, individual characteristics

65. REPRODUCTIVE TOXINS, EFFECTS
Teratogens
physical defects in embryo/fetus
mother is exposed but not necessarily affected
Mutagens
“mutate genes”; permanent DNA changes
inheritable changes (future generations)
exposure to mother or father
usually also carcinogens

66. Threshold Response Non-Threshold NOEL No-observed effect-level
the highest dose in an experiment which did not produce an observable effect
doesn’t mean there was no effect
LOEL Lowest observed effect level
the lowest dose which produced an observable adverse effect
The Occupational Environment -- Its Evaluation and Control 14 11

67. Influencing Factors Concentration Duration and frequency of exposure
Route of entry
Interspecies variation
Intraspecies variation
Environmental factors
Chemical combinations
The Occupational Environment -- Its Evaluation and Control 15 12

68. Intraspecies Variation
Age and maturity
Gender and hormonal status
Genetic makeup
State of health
Overt and covert factors that make us all different, individual, also can affect the way our body responds to exposure 13

69. Concentration Units Mass Per Volume Ratio, % volume (ppm = % x 10,000)
mg/m3 milligrams per cubic meter
/m3 micrograms per cubic meter
g/m3 nanograms per cubic meter
Ratio, % volume (ppm = % x 10,000)
PPM- Parts of a substance per million parts of air
(e.g.: 1 inch in 16 miles), 1 minute in 2 years
PPB- Parts of a substance per billion parts of air
(e.g.: 1 inch in miles), 1 second in 32 years
PPT- Parts of a substance per trillion parts of air
(e.g.: 1 inch in 16 million miles, 1 second in 320 centuries 19 16

70. Exposures that Reduce Life Expectancy by 8 Min.
Smoking 1.4 cigarettes
Living 2 months with a cigarette smoker
Eating 100 charcoal-broiled steaks
1 X-Ray (in a good hospital)
Eating 40 tablespoons of peanut butter
Drinking 10, ounce soft drinks from banned plastic bottles
Drinking ounce cans of diet soda containing saccharin
Living 20 years near a polyvinyl chloride plant
Living 15 years within 30 miles of a nuclear-power plant
Wilson, R.: "A Rational Approach to Reducing Cancer Risk." New York Times, July 7, 1978. 21
The Occupational Environment -- Its Evaluation and Control 18

71. TOX. SUMMARY Toxicology continues to evolve, increase in importance
Researching chemical effects
Occupational
Environmental
Medical
Often “educated guesswork”
Essential to continuing health of humanity

72. TOXINS IN OUR BODY THE BRAIN CIRCULATORY SYSEM RESPIRATORY SYSTEMS
HEART
STOMACH
LIVER & KIDNEY
INTESTINE

73. Forensic Science for Educators

74. Presentation Objectives
Forensic Science 101
Teaching forensic science

75. Forensic Science What is it? Components- Applied Science
Legal/Courts & Testimony
Facilities

76. Science and the Law
Scientific Method
Forensic Process
R.I.I.R.

77. Scope of Forensic Science
Criminalistics
Specialities
Medicine
Anthropology
Odontology
Entomology
Others

78. History of Forensic Science
Chinese medicine-6th Century
1839-MJB Orfila, toxicology
Late 1800s-Alexandre Lacassagne, ballistics and bloodstain patterns
1910-Edmund Locard, exchange principle
1924-August Vollmer, LAPD crime lab
1932-FBI Laboratory, fingerprints

79. Forensic Science in USA and china
Federal
State
Local
Private

80. Information from Physical Evidence
Corpus delicti
Modus operandi
Linkage – Locard Exchange Principle
Disproving/Supporting Witnesses’ Statements
Identification of suspects/victims
Provide for investigative leads

81. Forensic Testing Methods
Comparison Testing
Unknown Known or Standard
Evidence “Origin or Source”
Class Characteristics vs.
Individualizing
Characteristics

82. Types of Physical Evidence
Various definitions
“Animal, vegetable or mineral”
Chemical, biological, or microscopic

83. Specific Areas of Forensic Science
Impression Evidence
Fingerprints
Footwear/Tires
Trace Evidence
Hairs
Fibers
Paint
Glass
Chemical Evidence
Drugs
Accelerants
Biological Evidence
Other Areas
Toxicology
Anthropology
Odontology

84. Real CSI….
CS Investigators
Physical Evidence
Forensic Science

85. Teaching Forensic Science
Available resources
Specific useful resources
Practical exercises-
Generally
Today

86. Resources Undergraduate programs American Academy of Forensic Science
Websites of Interest
Forensic Companies
Textbooks
Other Educational Materials
©2004 Marilyn T. Miller

87. Educational Materials
©2004 Marilyn T. Miller

88. Forensic Science in the Classroom
Some states have adopted a
standards-based curriculum
Elective course
11th or 12th Grade
Job shadowing
Post-secondary articulation
©2004 Marilyn T. Miller

89. TN Course Standards Std 1-History Std 2-Careers Std 3-Legal Aspects
Std 4-Safety
Std 5-Collection, Packaging Evidence
Std 6-Lab Capabilities
Std 7-Drug Analysis
Std 8-DNA
Std 9-Lab Instrumentation
Std 10-Technology in the Forensic Lab
Std 11-PE at scene
Std 12-Human features for identification
©2004 Marilyn T. Miller

90. In the Classroom
A wide variety of sections possible with applied science topics
Fingerprints
Bloodstain Patterns
©2004 Marilyn T. Miller

91. Conclusion Fun and exciting exposure to science
Not a replacement for physical science

92. Thanks