Forensic Chemistry & Toxicology

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FORENSIC CHEMISTRY & TOXICOLOGY By MELCON S. LAPINA, MSCrim 4 th Place, Criminologists Licensure Board Examinations October 1996, Manila

Transcript of Forensic Chemistry & Toxicology

Page 1: Forensic Chemistry & Toxicology

FORENSIC CHEMISTRY & TOXICOLOGY

By

MELCON S. LAPINA, MSCrim

4th Place, Criminologists Licensure Board Examinations

October 1996, Manila

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Forensic Chemistry DefinedForensic Chemistry – that branch of chemistry which deals with the application of chemical principles in the solution of problems that arise in connection with the administration of justices. It is chemistry applied in the elucidation of legal problems.

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Scope of Forensic ChemistryForensic chemistry is not limited to purely

chemical questions involved in legal proceedings. It has invaded other branches of forensic sciences such as but not limited to the following:Legal MedicineBallisticsQuestioned Document ExaminationDactyloscopyPhotography

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Four Stages in the Practice of Forensic Chemistry

1. Collection or reception of specimen to be examined;a. Sufficiency of samplesb. Standard for comparisonc. Maintenance of individualityd. Labeling and sealing

2. The actual examination;3. The communication of results of

examination; and 4. Court appearance

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Six Golden Rules in the Practice of Forensic Chemistry

1. Go slowly2. Be thorough3. Take notes4. Consult others5. Use Imagination6. Avoid complicated theories

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Blood and Blood Stains1. As circumstantial or corroborative evidence

against or in favor of the perpetrator2. For disputed parentage3. Determination of the cause of death the

length of time the victim survived the attack.4. Determination of the direction of escape of

the victim or the assailant.5. Determination of the origin of the flow of

blood.6. Determination of the approximate time the

crime was committed.

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Some Characteristics of Blood1. The circulating tissue of the body2. 1 cc of blood: 5,000,000 red cells.3. Man of average size: about 6 quarts of

blood4. Made up of FORMED ELEMENTS {a. RBC

(Erythrocytes) b. WBC (Leucocytes) c. PLATELETS (Thrombocytes)} and PLASMA (liquid portion of blood; composing about 65% of the total blood volume)

5. Serum – a straw-yellowish liquid that can be seen when blood is allowed to clot.

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Problems in the Study of BloodA. Where blood has to be searched for.B. Collection, preservation and transportation

of specimen suspected to contain blood.C. Does the stain contain blood or another

substance?a. Preliminary Test (a.k.a.: Presumptive or Color

Test) – a positive result is not conclusive that the stain is blood but a negative result is conclusive that the stain is not blood. REASON: Other substances may yield the same reaction as blood. This includes: sputum, nasal secretion, plant juices, formalin, etc.

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1. Benzidine Test: Benzidine Solution & Hydrogen Peroxide (agua oxigenada). A positive reaction is indicated by BLUE COLOR

2. Guaiacum Test (Van Deen’s, Day’s or Schonbein’s Test) – Guaiac & Hydrogen Peroxide. A positive reaction is indicated by BLUE COLOR

3. Phenolphthalein Test (Kastle-Meyer Test) – Phenolphthalein reagent and Hydrogen Peroxide. A positive reaction is indicated by RED/PINK COLOR.

4. Leucomalachite Green Test – Leucomalachite Green Reagent & Hydrogen Peroxide. A positive reaction is indicated by MALACHITE GREEN WITH A BLUISH-GREEN OR PEACOCK BLUE COLOR.

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5. Hemastix Test – designed as a urine dipstick test for blood, the strip can be moistened with distilled water and placed in contact with a suspect bloodstain. A positive reaction is indicated by GREEN COLOR.

6. Luminol Test – its reaction with blood results in the production of light rather than color. By spraying luminal reagent onto a suspect item, large areas can be quickly screened for the presence of bloodstains.

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b. Confirmatory Tests – The actual proof that a stain is blood consists in establishing the presence of characteristic blood pigment, hemoglobin or one of its derivatives. The 3 Confirmatory Tests commonly employed are Teichmann, Takayama and Wagenhaar Tests. They are designed to show the presence of hemoglobin in a suspected bloodstain by the appearance of specific crystals observed under a microscope.

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1. Teichmann or Haemin Crystal Test –DARK BROWN RHOMBIC CRYSTALS OF HAEMIN OR HAEMATIN CHLORIDE (arranged singly or in clusters).

2. Takayama or Haemochromogen Crystal Test – LARGE RHOMBIC CRYSTALS OF A SALMON-PINK COLOR (arranged in clusters, sheaves and other forms appear within one to six minutes).

3. Wagenhaar Test or Acetone-Haematin – Small dark, circular crystals

4. Spectroscopic Examination – Most delicate and reliable test for presence of blood in both old and recent stains. Uses MICROSPECTROSCOPE: a direct vision spectroscope that fits into the microscope tube in place of the eyepiece. Positive result: OXYHAEMOGLOBIN for recent blood stain; METHAEMOGLOBIN (a converted oxyhaemoglobin owing to exposure to air and light) in old blood stains.

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D. If the stain is that of blood, is it human or animal?

E. - Precipitin Test (human antiserum) – The formation of gray precipitation ring at the interface of the two layers within 20 minutes indicates that the stain is human blood.

F. If the stain is of human blood, did it come from the victim, the accused or from other persons?

This is determined by blood grouping. A-B-O system, which was discovered by Karl Landsteiner in early 1900s, was the first system of blood grouping.

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Summary of the Common Blood Group System

Blood Group Agglutinogen in RBC

Agglutinin in Serum

A A Anti-B

B B Anti-A

AB A & B None

O O Anti- A and Anti-B

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Other Bodily FluidsIt has been found that some individuals

secrete in their fluids – such as: semen, saliva, urine and vaginal fluids and substances, corresponding to their blood groups. Therefore, it is possible to determine the ABO blood group of suspected stains of body fluids from the secretors.

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SEMENSemen refers to the fluid produced by the

male sex organ. It is usually white to yellowish in color, consisting of 2 parts: the seminal plasma or fluid, and the spermatozoa or sperm cells. There are usually 70,000,000 to 150,000,000 sperm cells per milliliter of semen.

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The sperm cells, as seen under a microscope, consist of a head, a neck and a tail approx. 10 X as long as the head. During deterioration the bacteria attacks first the tail, making identification difficult.

The seminal fluid contains certain substances called flavins which help give a yellowish color to semen and cause it to fluoresce under ultra-violet lights.

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Examination of SemenA. Wet Specimen

Normally, suspected semen may be found undried having the alkaline odor characteristics for seminal fluid. In this condition, examination is relatively simple. A drop of fluid (of semen) is paced on a glass slide, and then a drop of distilled water is added. A cover slip is placed over the preparation. The specimen is examined under a high power microscope to determine the presence of sperm cells.

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B. Dried Specimen

1. Physical ExaminationA general visual examination for grayish-

white or yellowish stain is first made. When dry, semen imparts a starchy stiffness to cloth. When inspected under UV light, seminal stain fluoresces. However, this fluorescence is not specific for semen only but may be observed from other materials.

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2. Chemical Examination

There are 3 chemical tests that can be used for seminal stains. They are the following:Florence Test – Dark-brown crystals, rhombic or needle-shaped.Barberio’s Test – Slender yellow-tinted rhomboid needles with obtuse angles.

Acid Phosphate Test – Orange-red pigment.

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The first 2 are based on the formation of characteristic crystals that are observed under the microscope. Acid phosphatase is an enzyme found in both animal and plant cells, but in large concentrations in human semen. REAGENT: Sodium alphanaphthylphosphate and fast blue B dye.

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3. Microscopic Examination

The only specific test for semen is the identification of a sperm cell under a microscope. There are many factors which may affect the detection of sperm cells, making this method difficult. Some of these are nature of cloth in which the suspected stain is found, age of stain, condition to which the stain was exposed and handling of the specimen.

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The presence of sperm cells proves that the stain is of semen. However, with the absence of sperm cells it cannot be concluded that the stain is not of seminal origin. These are some conditions which may lead to non-detection of semen, like ASPERMIA, disorder produced by male organ which produces semen without sperm cells and OLIGOSPERMIA, a semen with a very few sperm cells.

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GUNPOWDER & EXPLOSIVESI. Introduction

In the investigation of crimes involving the use of firearms, law enforcement officers need to know whether a suspect has fired a gun or not and the gunshot range or the approx. distance of the shooter to victim. When a firearm is discharged unburned particles of the gunpowder may escape thru the breech of the gun and deposit on the hands of the shooter, on the clothing of the victim and some may remain in the barrel. These gunpowder residues can be detected by chemical examination.

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In connection with suspected bombings the lab is requested to detect traces of explosives that may be found in remains of parts of a bomb. Explosives like improvised and manufactured dynamites used in illegal fishing, are also examined.

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II. Description of Gunpowder and Other ExplosivesA. Gunpowder

1. Black powder – first invented; consist of a mixture of carbon (charcoal) 15%, sulfur 10%, & potassium or sodium nitrate 75%.; and

2. Smokeless – which can be either single based; consisting of nitrocellulose and nitroglycerine (glycerol nitrate). Certain inorganic and organic compounds are added as stabilizers.

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B. Types of Explosives

1. Mechanical – such as those caused by expansion of gas producing high pressure beyond capacity of the container.

2. Atomic – resulting from atomic transformations.3. Chemical – produced thru the extremely rapid

transformations of the unstable substances accompanied by the formation of heat.

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C. Classification of ExplosivesThe speed of the chemical reaction or detonation of the explosives determines the classification of explosives as low, initiating or high explosives.

1. LOW explosives are low burning and are used mainly as propellants, like black powder and smokeless powder. Atomic – resulting from atomic transformations.

2. PRIMARY or INITIATING explosives are extremely sensitive to detonation by heat, shock friction and impact. They detonate without burning, like lead oxide and mercury fulminate.

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3. HIGH explosives detonate under the influence of shock of the explosion of a primary explosive.

• Ammonium nitrate – the cheapest and most readily available salt of nitric acid.

• TNT (trinitrotoluene) – the most widely used explosive.

• Nitroglycerine – most widely used commercial explosive.

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• RDX – considered as one of the most important military explosive used today.

• C4 – a plastic explosive which is white and dough like in texture.

• Chloroacetophenone – CN is the principal component in the filler used in tear gas solutions.

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4. Fire Bombs – Molotov cocktail which is an incendiary device, acids mixed with gasoline, alcohol and gasoline, etc.

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C. Distance Determination The process of determining the distance between the firearm and a target, usually based on the distribution of powder patterns or the spread of a shot pattern.

Three Zones of Distance:

a. Those in which the muzzle of the gun was held directly in contact with the body or practically so. (CONTACT WOUNDS).

b. Those in which the muzzle of the gun was held from about 2 inches to 36 inches away.

c. Those in which the muzzle of the gun was held from 36 inches or more.

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CONTACT WOUNDS – Damage (on cloth) is due more to the flame and the muzzle blast than to the penetration of the bullet.

a. Gaping hole where fabric is badly torn,b. Blackened area surrounding the bullet

hole,c. Singeing of the fibers at the entrance,

and d. Presence of partially burned powder

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m

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Distance of 2 to 36 Inches:Smudging and powder tattooing – when the gun is held from about 2 inches to a maximum of 8 inches. Smoke & soot is deposited around the hole of entrance producing a dirty, grimy appearance. Individual specks of tattooing around the hole are visible with the naked eye.

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Distance of 36 Inches: partially burned and unburned powder particles are driven into the surface around the gunshot hole producing a black coarsely peppered pattern called tattooing.

Indication of Suicide or Homicide – The kick of the gun causes the smudge and powder tattooing to be deposited more on one side of the hole than on the other, and the side of the greatest deposit indicates the side on which the sights of the gun were mounted.

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Distance of More than 36 Inches – powder tattooing is seldom seen. Nitrate particles may be present.

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PARAFFIN-DIPHENYLAMINE TESTTo determine whether a person has fired a

gun, the paraffin-diphenylamine test is used. The basis of this test is the presence of nitrates in the gunpowder residue. Warm melted-paraffin wax applied on the hands of the shooter will cause the pores of the skin to open and exude the particles of the gunpowder residue. These particles are collected by the paraffin cast and will appear as BLUE SPECKS, when the diphenylamine reagent is added on the cast. The specks are generally located on the area of the thumb and forefingers.

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The blue colors that appear indicate the reaction of the nitrates with diphenylamine reagent. Thus nitrate from other sources like fertilizers, will give the same reaction. Other substances similar to nitrates known as oxidizers will also react with the reagent in the same way. Thus, the location, distribution and character of the specks are considered to eliminate the other possible sources of oxidizers.

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The FBI employed Neutron-Activation Analysis which is a more specific test. This requires access to a nuclear reactor and facilities for detecting the radiation.

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NOTE: The result of this test is not conclusive because it does not always show that nitrates or nitrites were necessary results of discharge of firearms. Other substances yield the same positive reaction for nitrates or nitrites, such as explosives, fireworks, pharmaceuticals, and leguminous plants such as peas, beans, and alfalfa. (People v. Baconguis, 417 SCRA 66, December 2, 2003)

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HAIR IDENTIFICATION1. Hair – An appendage of the skin which

occurs everywhere on the human body except on the palms of the hand and soles of feet. Generally long & stiff. Consists of ROOT, SHAFT & TIP.

2. Cuticle – the outmost covering and consists of one layer of non-nucleated polygonal cells which overlap like the scales of a fish; the free edges of the cells are directed toward the distal end of the hair.

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3. Cortex – the intermediate and the thickest layer of the shaft, and is composed of elongated, spindle-shaped fibrils which cohere; they contain pigment granules in varying proportions depending on a type of the hair.

4. Medulla – the central canal of the hair; it may be empty or may contain various sorts of cells, more or less pigmented.

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5. Continuous Medulla – found in a large number of animals

6. Interrupted Medulla – very often in humans, monkeys, and horses.

7. Micrometer – an instrument attached to microscope and is used to measure the diameter of the hair.

8. Medullary Index - the ratio of the size of the medulla to the diameter of a shaft.

9. Fuzz – Generally short, fine and at times curly and wooly.

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Human vs Animal HairHuman Animal

Air network in fine grains.

Cells invisible without treatment in water.

Value of medullary index is lower than 0.5

Medulla Air network in form of large or small sacks.

Cells easily visible

Value of medullary index is higher than 0.5

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Human vs Animal HairHuman Animal

Fuzz without medulla. Looks like a thick muff 

Pigment in the form of very fine grains.

Cortex Fuzz with medulla. Looks like a fairly thin hollow cylinder Pigments in the form of irregular grains – larger than the human

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FIBER IDENTIFICATIONTypes of Fibersa.Animal – A number of fibers are derived from animal product, the most important being wool, silk, camel’s hair and fur.b.Vegetable – This class includes most of the inexpensive clothing fibers, like cotton, linen, jute, hemp, ramie and sisal.c.Mineral and Synthetics – First provide useful fibers like glass wool and asbestos which is used for safe insulation, while the latter is applied chemistry which produced a number of fibers like rayon, nylon, orlon and Dacron.

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1. Cotton Fibers – Flattened, twisted fibers with thickened edges. Irregularly granulated cuticle. No transverse markings. Fibers show spiral twist. Fibers swell in a solution of copper sulphate and sodium carbonate dissolved in ammonia. It is insoluble in strong sodium hydroxide but soluble in strong sulfuric acid and partially dissolved in hot strong hydrochloric acid.

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2. Flax Fibers – Apex tapering to fine point. Transverse sections are polygonal and show a small cavity. The fibers consist of cellulose and give blue or bluish-red color when treated with a weak solution of potassium iodide saturated in iodine and sulfuric acid. The fibers which show transverse lines and are usually seen in group formation, dissolve in a solution composed of copper sulphate and sodium carbonate in ammonia.

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3. Hemp Fibers – Fibers show transverse lines and consist of cellulose. Large oval cavities are seen in transverse sections. The end is usually blunt, and there is often a tuft of hair at the knots. Stains are bluish-red with phloroglucin, and yellow with both aniline sulphate and weak solution of potassium iodide saturated in iodine with sulfuric acid.

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4. Jute Fibers – Are quite smooth without either longitudinal or transverse markings. The fibers have typical large cavities which are not uniform but vary with the degree of contraction of the walls of the fibers which are lignified. The ends are blunt. The fibers are stained red with aniline sulphate, also with iodine and sulfuric acid.

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5. Wool Fibers – These fibers can easily be distinguished from vegetable fibers since the former show an outer layer of flattened cells and imbricated margins. The interiors are composed of fibrous tissues but sometimes the medulla is present. They do not dissolve in a solution composed of copper sulphate, sodium carbonate and ammonia. Stain is yellow with iodine and sulfuric acid and also with picric acid. Do not dissolve in sulfuric acid. Smell of singeing on burning.

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6. Silk Fibers – Manufactured silk is almost structureless, microscopically. Fiber’s stain is brown with iodine and sulfuric acid and yellow with picric acid. They dissolve slowly in a mixture of copper sulphate, sodium carbonate and ammonia.

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7. Linen Fibers – Fibers are straight and tapering to a point. Cortical area shows transverse lines which frequently intersects, simulating a jointed appearance. The medullary region shows a thin dense line. They do not dissolve in concentrated sulfuric acid. If placed in 1% alcoholic solution of fuchsin and then in a solution of ammonium hydroxide, they assume a bright red color.

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Vegetable Vs. Animal FibersTest Vegetable Animal

Ignition Test Rapid combustion, end charred and break sharply; smell of burning wood; vapor turns blue litmus red.

Burn and fuse; smell of burnt hair, fused and globular; fume turns red litmus to blue.

Chemical Tests

Concentrated Nitric Acid

No change in color Turn yellow

Picric Acid Test Cellulose – No change Wool and Silk – Yellow

Million’s Reagent Test Cellulose Fibers – Turn Black

Wool and Silk – Turn Brown

Soaked in Tannic Acid Cellulose Fibers - Black

Wool and Silk – No ChangeHeated with 10%

NaOHCellulose – Not Affected

Wool and Silk – Dissolve

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EXAMINATION OF PAPERObjectives of Comparison with Paper Standards:a.To determine whether the standard is similar to the paper bearing the questioned writing.b.To determine whether a sheet of paper was taken from a particular pad or tablet. c.To show that one document was in contact with another.

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Standards for Comparison

At least five sheets should be submitted for comparison. Each sheet should be identified by writing appropriate case information on the back. In addition there should be included any appropriate information concerning the circumstances surrounding the discovery or location of the sheets.

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Examination by Laba.Physical Test – The following physical characteristics serve to differentiate paper: thickness, measurement of length and width; weight per unit area; color; finish such as bond, laid, smooth or glossy; opacity, capacity of the paper for the transmission of light; folding endurance as determined by instrumentality by the number of alternate folds the paper will stand before breaking; bursting strength as determined by the measurement of the pressure necessary to burst a hole in a sheet of the paper; accelerated aging test performed by means of high temperatures or strong artificial light.

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b. Chemical Test – Chemical test may be conducted to determine the fiber composition, loading materials, and sizing used in the manufacture of the paper. The use of the chemical test causes a small change or alteration in the document; hence, extensive testing may consume a part of the evidence, and the investigator should indicate to the expert the degree to which the testing may be carried.

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1. Sizing Test

By the use of the few drops of chemical reagent, the sizing of two different specimens of paper can be compared. A small perceptible stain results from these tests.

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2. Loading Materials

The test is performed by burning and ashing the greater part of an ordinary sheet of paper, then analyzing the ash. Obviously, where only a limited sample of evidence is available, this test is not recommended.

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3. Fiber Composition

Chemical reagents are applied to small sections of the paper in order to determine the nature of constituents of fibers.

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4. Absorption

Strips of the paper are suspended in liquids to determine either the rate of absorption or the total absorption of the paper.

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c. Watermark – The chief characteristics indicating the source or origin of paper is watermark. It is distinctive mark or design placed in the paper at the time of its manufacture by passing the paper under a “DANDY ROLL”. Several designs are present on the dandy roll, similar to each other, but bearing individual characteristics, particularly if the roll has been subjected to wear or damage. By examining the watermarks, the examiner is able to identify the paper as to the product of a particular manufacturer.

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THE INKS AND APPROXIMATE AGE OF DOCUMENTS

Types of Inksa.Iron Gallotannate Ink – This type of ink has

long been used for entries in record books and for business purposes in general. Iron gallotannate or nutgall inks are true solutions and not merely suspensions of solid coloring matter in liquid form. Hence, the ink is capable of penetration into the interstices of the fibers of the paper, thereby inscribing the writing in the body of the paper and not on the surface alone, thus rendering its removal more difficult.

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b. Logwood Inks – From the wood of the logwood tree, a natural coloring material (haemotoxylin) is obtained by extraction with water. The color of logwood inks depends upon the inorganic salt which is added; but, on drying and standing, they turn black. The addition of chromium salts will yield the deepest black. At the present time logwood inks are practically obsolete, although they are reported to be still in use in Germany.

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c. Nigrosin Ink – This is a water solution of a synthetic black compound prepared from aniline and nitrobenzene. This synthetic type of ink is usually referred to as Nigrosin Ink and Black Aniline Ink. No new compound is formed by oxidation after this ink applied to the paper, so that lines are merely deposited organic solids that were in solution before the ink dried. It should be expected then, that water would affect this ink by re-dissolving the Nigrosin.

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e. Ball Point Ink – Because of the differences in construction of ball point pens, a different type of ink is required. In place of the fluid type ink, a thick pasty substance is used which will be a suitable dye to the ball point but which will not flow readily. The permanency of this ink is not known with any accuracy. It has been noted that many ball point inks have a tendency to fade.

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Comparison of Inks

To determine whether two documents were written with the same type of ink, various physical and chemical methods are available. The inks are compared visually for color. The naked eye, color filters, and infra-red photography usually reveal differences in color. A 5% solution of hydrochloric acid is the most generally used chemical reagent. The reagent may be applied with a sharpened wooden toothpick to a small area of writing.

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Comparison of Inks

When hydrochloric acid is placed on iron nutgall ink, the color disappears and turns to light blue; on logwood ink a red color develops; on Nigrosin or carbon ink there is no reaction. To distinguish Nigrosin from carbon ink, a 10% solution of sodium hypochlorite is used. It should be noted that these reactions sometimes take place over a period of hours. The investigator should test inks only as a screening procedure where a number of suspected documents are available.

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Age of Inks

It may be said, in general, that under ordinary circumstances it is practically impossible to determine the age of inks. A limit can sometimes be placed to the age by the color matching with standards to determine the degree of fading and by chemical reactions which depend on oxidation.

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Age of Inks

The chemical methods are not applicable to Nigrosine and carbon inks, which are not oxidized after being deposited on the paper. In any case, age determination will depend on the composition of the inks, its condition with respect to fluidity and impurities, the nature of the paper used in the writing, and the conditions under which the paper was preserved.

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GLASS FRACTURESDefinition and Composition of Glass

Glass is best described as a supercooled liquid which possesses high viscosity and, hence, rigidity.

Glass is usually composed of oxides such as silica (SiO2), boric oxide (B2O3) and phosphorus pentoxide (P2O5).

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Types of Glass Fractures

a. Radial Fracture – primary fracture resembles the spokes of a wheel radiating outward from the point of impact.

b. Concentric Fracture – secondary fracture having the appearance of circles around the point of impact connecting one radiating crack to the other, thus forming triangular pieces of glass.

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From the study of these two types of fractures (impact) it is possible to derive the following:

1.Point of Impact – The front of the glass can be determined due to the accumulation of dust and dirt on the glass.

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2. Direction of Impact – a bullet will make a clear cut hole in the side of the entrance rather than on the exit side. If a shot is fired perpendicularly it will give a crater of uniform cratings, or flakings. If the shot is fired at an angle from the right, the left exit side of the glass will give more flakings and vice versa. Depression will be produced on the exit side of the glass due to the rebound of the glass. Radial fracture can be felt on the exit side and the concentric fracture on the entrance side.

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3. Cause of Fracture – Fracture due to heat does not exhibit a definite pattern of radial and concentric fractures but are characteristically wavy. They show very little stress lines, whereas fractures due to mechanical means show a definite pattern of radial and concentric fractures.

Determination of the First Shot from a Series of Shots

 The radial fracture of the first bullet hole will end/stop the radial fractures of the succeeding bullet holes.

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Origin of Glass

Comparing fracture pattern is one method for instance in determining if glass fragments found on a suspect’s clothing came from a window at the scene of a burglary. In the analysis of fracture patterns the investigator must consider three dimensional aspects of the evidence. For example, a headlight has a clearly pronounced curved inner surface that may match even if the outer surfaces are broken.

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The analysis of ream marks is related to fracture pattern comparison. Ream marks are present, but not readily visible in drawn glass samples. These ream marks resemble tool marks striations.

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MOULAGE AND OTHER CASTING TECHNIQUES

Criteria of a Good Casting Material 1. Must be readily fluid or plastic when applied.2. Must harden rapidly to a rigid mass 3. Must be deformable nor shrink4. Must be tough5. Must be easy to apply6. Must have no tendency to adhere to the impression7. Should have a fine even composition and surface8. Should not injure the impression9. Should be easily obtainable10.Should be cheap

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The commonly used casting material in the Philippines is plaster of paris. In the U.S., plaster of paris is no longer used. Some of the materials used there are: MikrosilTM , Shoe Print Wax TM, silicon, Bio-Foam®, etc., depending on the manufacturing company.

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Some Techniques in Connection with the Used of Plaster of Paris

1.Hastening – add ½ teaspoonful of table salt to the plaster2.Retarding – add 1 part of a saturated solution of borax to 10 parts of water to be used in making the plaster. One teaspoonful of sugar may also be used.3.Hardening – soak in sodium bicarbonate

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Cast of Human Body1.Negocoll – this is a rubbery gelatinous material made of colloidal and magnesium soaps.2.Hominit – a flesh colored resinous substance used for making positives from negocoll negatives.3.Celerit – a brown colored substance used for backing and strengthening the hominit.

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CHEMICAL DEVELOPMENT OF LATENT FINGERPRINTS

Classification of Crime Scene Prints:

1.Visible print – a print that results after a finger, which has previously touched contaminants as blood, grease or ink touched a clean surface.2.Plastic print – a print that results when a finger touches a plastic material such as wax, soap, or dust, and creates a negative impression of its ridge pattern.3.Invisible print – latent print

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Locating visible or plastic prints at the crime scene normally presents little problem to the investigator, because these prints are usually distinct and visible to the eye. Latent prints, on the other hand, are difficult to locate. They can only be seen after the surface on which they are imprinted has been treated with powders or chemicals.

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In developing latent prints, the investigator is influenced by the kind of surface that is being examined in choosing a developing method. For example, prints on porous evidence such as paper, unfinished wood, cardboard, etc. are normally developed by treatment with a chemical. On the other hand, prints on nonporous evidence such as plastic, glass, metal, foil, etc., are either developed by powdering method or super glue fuming method.

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1. Powdering Method – commonly used materials are black and gray powder.

2. Iodine Fuming – vapors of iodine are brown in color and differentially absorb into the debris forming the print, causing the ridge detail to stand out.

3. Silver Nitrate – the process employs a 0.2 % solution of silver nitrate in distilled water that is used to spray on or saturate the paper, producing silver chloride only in the ridge areas. The paper is exposed to light, and the print turns black.

4. Ninhydrin – develops prints on porous surfaces in violet color.

5. Super Glue – develops prints on nonporous surfaces in white color.

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METALLURGY AS APPLIED TO CRIME DETECTION

Definition:

1.Metallurgy – the art of extracting and working in metals by the application of chemical and physical knowledge.2.Metallography – the branch of metallurgy which involves the study of the microstructures of metals and alloys.

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Application of Metallurgy in Criminal Investigation

1.Robbery (with force upon things) – where entrance is by breaking doors with the use of metallic tools. Traces of these tools can be examined under a metallographic microscope.2.Hit and run cases3.Bomb and explosion4.Nail examination5.Counterfeit coins6.Restoration of serial numbers

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Restoration of Serial Numbers: Principles Behind

When a number or any mark is stamped on metal, the crystalline structure of the metal in the neighborhood of the stamp is disturbed. This disturbance penetrates to an appreciable distance into the substance of the metal, but is not visible to the naked eye once the actual indentations caused by the punch have been removed.

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Restoration of Serial Numbers: Principles Behind

However, when etching fluids are applied to this surface, the disturbed or strained particles of the metal differ in the rate of solubility than those of the undisturbed particles and this difference in solubility makes it possible, in many cases, to restore the numbers to such an extent that they can be read and photographed. In most cases, the criminal restamps the gun with new numbers after filing off the old numbers. By the process of etching, it is found possible to render the original numbers visible.

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1. Cast iron and cast steel – a 10% solution of sulfuric acid and potassium dichromate.

2. Wrought iron and forged irons and steels a. Solution 1: Hydrochloric acid, 80 cc; water,

60 cc., copper chloride, 12.9 gm, alcohol, 50 cc.

b. Solution 2: 15% nitric acid.3. METHOD: Apply with a swab a little of the

acid copper chloride solution (solution 1). Dry with cotton and then apply solution 2. Alternate the swabbing until the numbers appear.

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4. Aluminum – Glycerine, 30 cc., hydrofluoric acid, 20 cc., nitric acid, 10 cc. Due to the dangerous nature of hydrofluoric acid, only experienced chemists should use the solution. An alternate and safer formula is made as follows: Copper chloride, 200 gm., hydrocholoric acid, 5 cc., and water 1000 cc. This reagent gives good results but almost as soon as it is applied, a copper deposit is formed. The copper deposit must be removed as it forms by means of water.

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5. Copper, brass, German silver, and other copper alloys – Ferric chloride, 19 gm, hydrochloric acid, 6 cc., and water, 100 cc. Since the reagent is slow in its action, it is recommended that “retaining wall” method should be employed. The reagent can remain for 24 hours.

6. Stainless steel – Use dilute sulfuric acid or 10% hydrochloric acid in alcohol.

7. Lead (Motor car batteries, etc.) – Glacial acetic acid, 3 parts, hydrogen peroxide, 1 part.

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8. Zinc – 10% sodium hydroxide solution. The “retaining wall” method is recommended.

9. German silver – Ferric chloride syrupy solution, 25% concentrated hydrochloric acid, 25%, and water 50%.

10. Tin – 10% hydrochloric acid.11. Silver – Concentrated nitric acid solution.12. Gold and platinum – Aqua regia.13. Wood – Erased numbers and figures on wood can

also be treated and excellent results have been obtained by subjecting the suspected areas to a jet of steam. Liquid that is SYRUPY is sweet or thick like syrup; a SYRUPY quality of behavior is sentimental in an irritating way.

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PETROGRAPHY AS APPLIED TO CRIME DETECTION

Petrography is that branch of geology which deals with the systematic classification and identification of rocks, rock forming minerals, and soils. This definition has been construed to cover not only the study of soils and other mineral substances, but also dust and dirt, safe insulations, ceramics, and other such materials, both natural and artificial.

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Soil

Soil as evidence has been overlooked by most investigators probably because it is such a commonplace substance is more or less taken fro granted. Researchers have shown that soils are greatly diversified and vary considerably over the surface of the earth, not only from widely separated points but also from points quite close together.

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1. Alluvial Soil – its particles may be derived from almost infinite number of sources, and since the action of water and wind would in a few cases be identical over long periods of time in different spots, great variations in composition would be expected.

2. Colluvial Soil – soil in which some movement and intermingling of parts has occurred would be expected to be less variable.

3. Sedentary Soil – least variable

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Constituents of Soil

a.Primary Minerals – undecomposed rock fragments ranging from stones down thru pebbles, sand, and silt.

b.Clay Minerals – may be found in nearly all soils and is the major constituent of most heavy soils. It imparts to a soil cohesiveness and plasticity, and becomes hard and adherent on heating.

c. Organic Constituents – organic matter is one of the most variable of all soil constituents and is of peculiar importance in the identification of soils.

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Dust and Dirt  

Dust and dirt has been described as “matter in the wrong place”.

Classification of Dust

1.Dust deposited from the air 2.Road and footpath dusts 3. Industrial Dusts4.Occupational Dusts

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ARSONThe Technical Aspect of Arson Cases

A.Burning or combustion is the rapid oxidation of substances accompanied by the generations of heat and light. Burning occurs only when three essential ingredients are present: FUEL, OXYGEN & HEAT. Obviously, to create a fire three must be present combustible materials. It may be solid, liquid or gas. Strictly speaking, only gases burn. The solids and liquids must be heated to liberate flammable gases. The gases in turn must be raised to the proper temperature of the fuel to the kindling point. Finally, there must be a supply of oxygen since burning is a process of oxidation. Oxygen may be supplied from the air or from oxidizing agents.

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B. Without fuel; the elimination or exclusion of oxygen; or when the heat is sufficiently low enough is not capable of maintaining the process of combustion; burning will be extinguished.

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The Triangle of Fire

Fuel, heat and oxygen are known as the fire triangle. All three must be present in order for them to produce fire. Solids and liquids do not burn, only gases burn. It is heat that converts solids and liquids to flammable gases. In the case of gasoline and other volatile liquids, the surface of the liquid is constantly liberating flammable gases. It is only these gases that burn.NOTE: For burning to continue, there must be the fourth element, i.e., uninhibited chain reaction.

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Other Factors Involved in Burning

a.When a combustible material ignites, combustion continues only as long as the heat remains above the ignition temperature. The heat may com from external source or more commonly from the burning material. The temperature at which the ignition takes place depends on the materials and the length of time that it is exposed to a temperature higher than the normal temperature of material. While phosphorous ignites when exposed to air at normal room temperature, most combustible ignites within a short time when exposed to temperature of 400oF to 750oF. Wood must be heated rapidly to 750oF before it ignites; when exposed to temperature of 350oF to 400oF for a period of 30 minutes, however, wood produces gases that are easily ignited when sufficient oxygen is present.

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b. Many Oxidizing agents are employed in industry and agriculture. For example, concentrated nitric acid is used commonly throughout the country and can cause combustion when it contacts with a sawdust or wood shavings. Potassium permanganate, common oxidizer used in the laboratories and in compounding medicine and other formulae is harmless, however, when it comes in contact with glycerin, a reaction occurs that may cause combustion. Potassium nitrate (saltpeter), the oxidizer in black powder, is harmless unless heated; a violent reaction occurs if heat is present. Ordinary gasoline may be solidified by the addition of aluminum stanate.

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Propagation of Burning

A. CONDUCTION – the transmission of heat thru a medium. Heat that is conducted is transferred from molecule to molecule. For example, heat applied to one end of an iron rod spread throughout the entire rod iron. In a similar manner, walls and floors may conduct heat from a burning portion of a building to other portion and help escalate the fire.

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B. CONVECTION – a diffusion of heat through a fluid (gas or liquid) by means of the flow of the hotter parts of the fluid to the colder parts. For example, a fire in a corner of a room will heat the air directly around it. The heated air being lighter than the cooled air, will rise to the ceiling; the displaced cooler air will take the place of the heated air. As this process continues, the heat from the fire will be facilitated.

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C. RADIATION – the process by which heat is transferred in straight lines from a source to a receiving materials without heating the intervening medium. For example, the earth received its heat from the sun by means of radiation from a burning building to a neighboring building, which may set a fire or search by the intensity of the transferred heat. The amount of heat transferred by radiation depends on the intensity of the transferred heat, or intensity of the burning, the distance between the burning and receiving surface, and the angle at which the radiated heat strikes the receiving surface, and the presence or absence of any obstruction to the straight lines of radiation.

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Causes of Fire

A fire may originate intentionally or accidentally. One method of proving arson is to eliminate systematically the possibility of accident. An accidental fire may arise from the working of certain forces of nature or from negligence in the use of equipment and materials. Natural causes of fires are:1.Sun rays focused by bubbles in window panes, shaving mirrors by some other peculiarly shaped glass article which may serve as convex lens.2.Lightning. Lightning usually strikes a high point of the building and may be traced in path to the ground. Traces of lightning are melting of metal parts of the building, streaked paint with burned areas, cracks in the walls, broken bricks and soot driven into rooms from chimney.

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Additional Information to Be Obtained Thru Observation of the Colors of Smokes/Fumes and Odor Evolved:1. White Smoke – indicates burning of humid materials2. Black smoke accompanied by large flame – indicates

petroleum products or rubber3. Reddish Brown Smoke – presence of nitrocellulose

sulfur, sulfuric acid, nitric acid, hydrochloric acid4. Red Flame – presence of petroleum5. Blue Flame – presence of alcohol, aldehyde or ketone6. Biting Smoke – irritating to nose and caused

coughing indicate presence of chlorine.7. Garlic Odor Smoke – presence of phosphorus

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Lab Test Performed on Specimen Submitted

a. Preliminary Test – ashes or debris suspected to contain inflammable substance is placed on a wide mouth test tube/glass with fitted rubber stopper and heated, fumes evolved is tested with SUDAN or RHODOKRIT powder.

b. If positive result is obtained from the above-mentioned test, said sample is subjected to steam distillation. Steam distillate obtained is injected into the GAS CHROMATORGRAPH to identify the accelerant used. Similar instrumental analysis conducted on liquid samples/substances gathered from the crime scene. GAS CHROMATOGRAPH is a highly sophisticated laboratory instrument used in the identification of gases/accelerant.

c. Spectrographic analysis using QUARTZ SPECTROGRAPH – is conducted in cases wherein foreign metals are recovered on the scene of the incident.

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DRUGS

Drugs Test Used Reactions Noted

Opium and derivatives

Marquis Purple or violet color

Heroin Nitric Acid Yellow or green color

Morphine Nitric Acid Red orange to yellow color

Cocaine Cobalt Thiocyanate Blue precipitate

Barbiturates Dillie-Koppanyi Violet color

Amphetamines a. Marquisb. Mandelin

a. Red orange to darkbrownb. Green to reddish brown color

LSD PABA Purple color

Marijuana Duquenois-LevineKN

Violet colorRed bottom layer

A. Preliminary Test

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B. Confirmatory TestsThere are several methods available to the chemist to confirm the results of the preliminary tests. A technique much more specific than the color tests is microcrystalline examination. A small amount of the drug is dissolved in a few drops of a solvent on a slide. Then a reagent is added, forming crystals characteristic of the drug. This is observed under the microscope.The UV and IR spectrophotometers and the gas chromatograph can also be used for positive identification of the drugs.Another method employed is thin layer chromatography (TLC) which is rapid, sensitive, easy to sue and inexpensive.

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SCIENTIFIC NAME OF CERTAIN DRUGSCocaine – Benzol Methyl EcgonineCoca Plant – Erythroxylon Coca LamarchMarijuana – Cannabis Sativa L.Opium – Papaver SomniferumShabu – Methamphetamine HydrochlorideEcstasy – Methylenedioxymethamphetamine

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TOXICOLOGYToxicology - science of poisons: the scientific study of poisons, especially their effects on the body and their antidotes (Microsoft® Encarta® Reference Library 2004. © 1993-2003 Microsoft Corporation)

Poison – anything other than physical agencies which is capable of destroying life, either by chemical action on the tissues of the living body, or by physiological action by absorption into the living system.

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Site of Action of Poison 1.Local Action – The poison may act on the skin or on the mucous membrane or on any part of body where it is applied.

Example: Sulfuric acid2.Remote Action – The poison may act remotely in any of the following ways:

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a. By production of shock. Ex. Poisoning by strong acid.

b. By absorption into the blood and being carried to the organs they effect. Ex. Morphine is absorbed by the blood and carried to the brain and depresses it.

a. By transmission through the nerves of local parts affected going to the nerve centers and then reflected to the organs on which they act.

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Site of Remote Actions of the Different Poisons are:  

a.On the Brain: Narcotics, alcohols, cerebral stimulants like caffeine.b.On the Cord: Strychnine (Poisonous plant product: a bitter white poisonous alkaloid obtained from nux vomica and related plants, used as a poison for rodents and medicinally as a stimulant for the central nervous system. Formula: C21H22N2O2 )

c.On the Peripheral Nerves: Curare (plant resin causing paralysis: a dark resin obtained from certain South American plants, used by indigenous hunters to poison their arrows and in medicine as a muscle relaxant) d.On the Alimentary Tract: Corrosives

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e. On the Kidneys: Cantharides (INSECTS European beetle: a green European blister beetle, used as a source of the stimulant and irritant cantharides. Latin name: Lytta esicatoriaCantharis vesicatoria Also called cantharis DRUGS toxic preparation used as aphrodisiac: a toxic preparation made from the crushed dried bodies of the Spanish fly, used in the past as an aphrodisiac and to treat skin blisters)

f. On the Salivary Glands: Mercuryg. On the Liver: Phosphorush. On the Mucous Membrane: Arsenic

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i. On the Heart: Digitalisj. On the Blood Vessels: Ergot (fungus attacking

cereals: a disease of cereals caused by a parasitic fungus that grows in dense black masses (sclerotia) in the grains of the ear. Latin name: Claviceps purpurea. Also called black bread mold. Fungal bodies used in medicine: the dried sclerotia of an ergot fungus that yield substances used in drugs to treat migraine and to induce uterine contractions in childbirth), Nitrites

k. On the Blood Cells: Snake venoml. Both Local and Remote: The poison may act at the site

of application and in some distant place. Ex. Carbolic acid is an irritant to the alimentary tract and also toxic when absorbed.

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Circumstances Affecting Action of Poison

1. Method of Administration: Poisons may enter the body in the following ways:

a. Orally – Except irritants and corrosives, poisons must be digested or absorbed in the gastric or intestinal mucosa before producing effect.

b. Hypodermically – Poison reaches the blood stream without passing the digestive organs. This method is only available for such substances that are soluble in the lymph and tissue juices.

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c. Intramuscularly – Absorption is faster than in the hypodermic method.

d. Endodermically – The poison may be rubbed into and absorbed through the skin.

e. By Rectum, Vagina or Bladder – Absorption through the rectum is about twice as much as absorption through the mouth.

f. By the Lungs – Poison through this route may be made of a substance which can be transformed to gaseous state.

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2. Idiosyncrasy: Some persons posses sensitivity to certain foods or drugs. The most common drugs are potassium iodide, arsenical preparations, aspirin and the sulfas. As to foods, the most common are fish, shrimps, eggs and oysters.

3. Age: There are substances which are considered poison for babies but wholesome for adults, while the opposite is true for other substances.

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4. Habit: The body may acquire tolerance to some drugs. Habit diminishes the effect of certain poisons. Tobacco, alcohol, opium, barbiturates, arsenic are good examples of this.

5. Dose: The effect of drugs and poisons in the body is usually proportional to the dose taken. Ex. Alcohol, when taken in small dose, stimulates body reflexes and tone, while large amount depressed the whole body.

Fatal Dose: This is the smallest dose known to cause death: not the smallest amount which will certainly cause death.

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Treatment of Patient Suffering from Acute Poisoning

1.Evacuation of the Stomach: a. A long rubber tube is introduced to the mouth and

allowed to reach the stomach. Fluid must first be introduced into the stomach to prevent the tube to come in close contact with its wall. Fluid is withdrawn and introduced until traces of the poison are removed. The procedure is contra-indicated in poisoning by corrosives on account of the danger of tear or laceration of the stomach wall.

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b. Administration of Emetics - causing vomiting: causing a person or animal to vomit (Microsoft® Encarta® Reference Library 2004. © 1993-2003 Microsoft Corporation.)

2. Neutralization of the Poison that Remains in the Stomach

3. Application of Physiological Antidotes - substance that counteracts poison: a substance that counteracts the effect of a poison or toxin. (Microsoft® Encarta® Reference Library 2004. © 1993-2003 Microsoft Corporation)

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4. Keep the Patient Alive by General Measures, While His Organs of Elimination Are Getting Rid of the Poison. Treat Any Urgent and Dangerous Symptoms.

5. Eliminating the Poison: The elimination of the poison is aided by purgatives, sudorifics, and diuretics. Sweating may be encouraged by hot bath, warm packing, and injection with apomorphine.

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SUDORIFICS - causing production of sweat: causing the production of sweat. (Microsoft® Encarta® Reference Library 2004. © 1993-2003 Microsoft Corporation)DIURETICS - causing increased urine output: causing increased flow of urine. (Microsoft® Encarta® Reference Library 2004. © 1993-2003 Microsoft Corporation)

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128

Classification of Poison

Corrosives

Strong Acids Caustic Alkalis Compounds

Sulfuric Acid Potassium Hydroxide

Zinc Chloride

Nitric Acid Sodium Hydroxide

Antimony Trichloride

Hydrochloric Acid

Ammonia

Carbolic Acid

Oxalic Acid

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129

Classification of Poison

Irritants

Non-metals

Salts of Metals

Vegetable Irritants

Animal Irritants

Food Irritants

Castor oil Cantharides

Digitalis

Belladonna

Croton oil, etc.

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130

Classification of Poison

Narcotics

Somniferous Group

Diliriant

Opium Belladonna

Chloral Hyoscyamus

Synthetic Hypnotics

Stamonium

Cocaine

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131

Classification of Poison

Depressants

Neutral Depressan

t: Paralysis

of the spinal cord

Cerebral Depressant

s: Inhibiting the brain functions

Cardiac Depressant

s

Aconite Hydrogen Cyanide

Digitalis

Conium Oil of Bitter Almond

Strophanthus

Laurel Water Camphor

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132

Classification of Poison

Poisons which are Exito-Motor in Action

Strychnine Brucine Thebaine

Poisons and Irrespirable Gases

Poisonous Gases Irrespirable Gases

Carbon Dioxide Chlorine

Carbon Monoxide Benzene

Hydrogen Sulfide Hydrogen Cyanide

Arseniureted Hydrogen

Carbon Disulfide

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133

Classification of Poison

Contact Poisons

Vegetable Irritants

Animal Irritants

Chemical Irritants

Vulnerants

Nails

Broken Glasses

Dust

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The Forensic Chemistry Division of the NBI made the following classification based on the Chemical Standpoint:

Gaseous Poisons (Poisons Present in the Gaseous State):1.Carbon dioxide2.Carbon monoxide3.Hydrocarbons4.Hydrogen sulfide5.Sulfur dioxide6.Oxides of nitrogen (Nitrous oxide, Nitric acid and Nitrogen dioxide)7.War gases

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Inorganic Poisons

Corrosives (Poisons characterized

principally by an intense and destructive action – a few organic

corrosives are included in this group for the

sake of completeness)

Metallic Poisons and Salts: (These chemicals

are protoplasmic irritants, but their chief

action is the deleterious effect

produced after absorption into the

system.)

Acid; Mineral and Organic: Sulfuric acid; Hydrochloric acid; Nitric acid; Oxalic acid; Acetic acid.

Heavy Metals: Phosphorus; Antimony; Arsenic; Bismuth; Mercury; Lead; Radioactive substances; Thallium; Gold; Osmium; Platinum; Nickel; Chromium; Tin; Vanadium.

Alkaline Corrosives: Potassium hydroxide; Sodium hydroxide; Calcium oxide; Ammonium hydroxide

Inorganic Salts: Alum; Alkaline earths; Magnesium sulfate; Lithium salts; Potassium salts; Boric acid and borax; Tellurium; Sodium silicate.

Halogens: Chlorine; Bromine; Iodine; Fluorine.

Corrosive Metallic Salts: Silver; Zinc.

Organic Corrosives: Phenol; Pyrogallol; Formaldehyde

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Organic Poisons:1. Volatile Poisons (Volatile liquids or easily

sublimated solids many of which are irritants; their chief action occurs after absorption):

a. Alepathic Compounds: Methyl alcohol; Ehtyl alcohol; Fuel oil; Amyl alcohol; Tertiary or Dimethyl carbinol; acetaldehyde; Paraldehyde; Methyl chloride; Methyl bromide; Tribromoethanol; Ethyl chloride; Ethyl bromide; Ether; Chloroform; Bromoform; Chloral hydrate; Carbon tetrachloride; Tetrachlorethane; Amyl nitrite; Nitroglycerin; Carbon bisulfide; Hydrocyanic acid and the cyanides; Paraffin hydrocarbons.

b. Atomic compounds: Benzene series; Essential oil

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Non-Alkaloidal Poisons (A conglomerate collection of other organic toxic substances, non-volatile and non-alkaloidal):a.Hypnotics: Alepathic series; aromatic series.b.Aromatic Compounds: Naphthol; Salicylic acid; Picric acid; Dinitrophenol; Trinitrotoluene; Acetanilid; Antipyrine; Atophan; and the Cinchopen group.c.Glucosides: Digitalis, Strophanthus; Olenader; Hellebore; Gossypium; Locust; Scilla; Cannabis indica.

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d. Organic Purgatives: Purgative oils; anthracene group; Jalap; purgatives.

e. Essentials Oils: Aspidium; Abortifacients; Oil of Chenopodium; Apiol; Affion; Turpentine.

f. Picrotoxin Group: Picrotoxin; Water of hemlock.

g. Miscellaneous Group: Taxus; Sparteine; Abrus; Laburum; Larkspur; Health family; Sntonin; Cantharides.

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Miscellaneous Poisons: (Associated with botulism; food poisoning; mushroom poisoning; snake venom poisoning).

1. Food Poisoning: Toxic substances in the food; abnormal hypersensitivity to normal constituents of food.

2. Poisonous Plants.3. Poisonous Animals and Their Poisons: Arachnids;

Centipedes; Insects; Caterpillars; Vertebrates.4. Biological Products.5. Ground Glass.