FBI Handbook of Crime Scene Forensics (9 page)

Inhalation is the introduction of a toxic product by the respiratory system. Airborne contaminants may be in the form of a dust, aerosol, smoke, vapor, gas, or fume. Materials may be in a solid or liquid form and still represent an inhalation hazard because they produce vapors, mists, and fumes.

Proper work practices and adequate ventilation can minimize the risk of airborne-contaminant inhalation. When working in areas with airborne contaminants present, personnel must wear respiratory protection. Personnel must be certified to wear respiratory protection and, therefore, to work in areas containing airborne contaminants.

Contamination through the skin can result from direct contact or by absorption. The severity of the injury can depend on the concentration of the contaminant and the amount of exposure time. Systemic effects—such as dizziness, tremors, nausea, blurred vision, liver and kidney damage, shock, or collapse—can occur when the substances are absorbed through the skin and circulated throughout the body. Exposure can be prevented by using personal protective equipment (e.g., gloves, safety glasses, goggles, face shields, and protective clothing).

Ingestion involves introducing contaminants into the body through the mouth. Ingestion can cause severe damage to the mouth, throat, and digestive tract. To prevent entry of contaminants into the mouth, safe work practices—such as washing hands before eating, smoking, or applying cosmetics—must always be used. Personnel should not bring food, drinks, or cigarettes into areas where contamination can occur, regardless of personal protection they may be wearing.

The direct injection of contaminants into the body—either by needle sticks or mechanical injuries from contaminated glass, metal, or other sharp objects—can cause severe complications. Contaminants enter directly into the bloodstream and can spread rapidly. Extreme caution should be exercised when handling objects with sharp or jagged edges. Work gloves must be worn at all times.

On December 6, 1991, OSHA issued Title 29, Section 1910.1030, of the Code of Federal Regulations (CFR),
Bloodborne Pathogens
.
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Occupations at risk for exposure to bloodborne pathogens include law enforcement, emergency response, and forensic laboratory personnel.

Fundamental to the bloodborne pathogens standard is the concept of following universal precautions. This concept is the primary mechanism for infection control. It requires that employees treat all blood, body fluids, or other potentially infectious materials as if infected with bloodborne diseases, such as the hepatitis B virus (HBV), the hepatitis C virus (HCV), and the human immunodeficiency virus (HIV). The following protective measures should be taken to avoid direct contact with potentially infectious materials:

• Use barrier protection—such as disposable gloves, coveralls, and shoe covers—if contact with potentially infectious materials may occur. Change gloves when torn or punctured or when their ability to function as a barrier is compromised. Wear appropriate eye and face protection to protect against splashes, sprays, and spatters of potentially infectious materials.
  
• Wash hands after removing gloves or other personal protective equipment. Remove gloves and other personal protective equipment in a manner that will not result in contaminating unprotected skin or clothing.
  
• Prohibit eating, drinking, smoking, or applying cosmetics where human blood, body fluids, or other potentially infectious materials are present, regardless of personal protection that may be worn.
  
• Place contaminated sharps in appropriate closable, leakproof, puncture-resistant containers when transported or discarded. Label the containers with a BIOHAZARD warning label.
  
• Do not bend, re-cap, remove, or otherwise handle contaminated needles or other sharps.
  
• After use, decontaminate equipment with a daily prepared solution of household bleach diluted 1:10 or with 70 percent isopropyl alcohol or other appropriate disinfectant. Noncorrosive disinfectants are commercially available. It is important to allow sufficient contact time for complete disinfection.
  
• In addition to universal precautions, engineering controls and prudent work practices can reduce or eliminate exposure to potentially infectious materials. Examples of engineering controls include long-handled mirrors used to locate and retrieve evidence in confined or hidden spaces and puncture-resistant containers used to store and dispose of sharps and paint stirrers.
  

Depending on the type of material encountered, a variety of health and safety hazards can exist. Some of these hazards are identified by the following categories:
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• Flammable or combustible materials—such as gasoline, acetone, and ether—ignite easily when exposed to air and an ignition source, such as a spark or flame.
  
• Over time, some explosive materials, such as nitroglycerine and nitroglycerine-based dynamite, deteriorate to become chemically unstable. In particular, ether will form peroxides around the mouth of the vessel in which it is stored. All explosive materials are sensitive to heat, shock, and friction.
  
• Pyrophoric materials—such as phosphorus, sodium, and barium—can be liquid or solid and can ignite without an external ignition source in air temperatures less than 130 degrees Fahrenheit (540 degrees Celsius).
  
• Oxidizers—such as nitrates, hydrogen peroxide, and concentrated sulfuric acid—are chemical compounds that readily yield oxygen to promote combustion. Avoid storage with flammable and combustible materials or substances that could rapidly accelerate their decomposition.
  
• Corrosive materials can cause destruction to living tissue or objects such as wood and steel. The amount of damage depends on the concentration and duration of contact.
  
• When working with chemicals, be aware of hazardous properties, disposal techniques, personal protection, packaging and shipping procedures, and emergency preparedness. This awareness comes from appropriate training and the information in a Material Safety Data Sheet. The Material Safety Data Sheet provides information on the hazards of a particular material so that personnel can work safely and responsibly with hazardous materials.
  

When using ultraviolet lights, lasers, and other light sources, personnel must protect their eyes from direct and indirect exposure.
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Not all laser beams are visible, and irreversible eye damage can result from exposure to direct or indirect light from reflected beams. Prolonged exposure to the skin also should be avoided.

All personnel in the vicinity of the light source should wear protective eyewear appropriate for the light source. Goggles must have sufficient protective material and fit snugly to prevent light from entering at any angle. The goggles must display the American National Standards Institute’s (ANSI’s) mark denoting eye-protection compliance. Laser-protective eyewear must be of the appropriate optical density to protect against the maximum operating wavelength of the laser source.

A confined space is an enclosed area large enough for personnel to enter and work, but it has limited or restricted means for entry and exit. Confined spaces (e.g., sewers, open pits, tank cars, and vats) are not designed for continuous occupancy. Confined spaces can expose personnel to hazards including toxic gases, explosive or oxygen-deficient atmospheres, electrical dangers, or materials that can engulf personnel entering the space.
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Conditions in a confined space must be considered dangerous, and personnel may not enter the space until a confined-space permit has been issued. The atmosphere must be monitored continuously with a calibrated, direct-reading instrument for oxygen, carbon monoxide, flammable gases and vapors, and toxic air contaminants. Periodic readings from these monitors should be documented. Only certified confined-space personnel may operate in confined spaces. Rescue services must be immediately available to the site.

The following practices must be followed when working in a confined space:

• Never enter before all atmospheric, engulfment, mechanical, and electrical hazards have been identified and documented. Isolating hazards must be performed in accordance with OSHA 29 CFR 1910.147,
  The Control of Hazardous Energy (Lockout/Tagout
  ).
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• Provide ventilation. Ensure that ventilation equipment does not interfere with entry, exit, or rescue procedures.
  
• Provide barriers to warn unauthorized personnel and to keep entrants safe from external hazards.
  
• Provide constant communication between personnel entering the confined space and attendants.
  
• Ensure that back-up communication is in place prior to entry.
  
• Wear appropriate personal protective equipment, such as self-contained breathing apparatus (SCBA), a full-body harness, head protection, and other necessary equipment.
  
• Never attempt a rescue unless part of a designated rescue team.
  
• Ensure that personnel certified in first aid and CPR (cardiopulmonary resuscitation) are on-site.
  
• For additional information, refer to the OSHA standard for
  Permit-Required Confined Spaces
  , 29 CFR 1910.146.
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All excavations must meet the requirements set forth in OSHA’s standards for excavations, 29 CFR 1926.650,
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1926.651,
⁹
and 1926.652.
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Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with 29 CFR 1926.652(b) or 29 CFR 1926.652(c),
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unless excavations are less than five feet in depth and examination of the ground is made by a competent person to prevent cave-ins. A competent person is someone capable of identifying existing and predictable hazards in the surroundings or working conditions that are unsanitary, hazardous, or dangerous to employees and who has the authorization to take prompt corrective action to eliminate those hazards.

As with all excavations, personnel should be aware of buried utilities and control standing water, hazardous environments, confined spaces, and oxygen-deficient atmospheres.

Portable, handheld X-ray machines, often used to identify the contents of unknown packages, pose a risk for exposure to X-ray radiation at crime scenes.

Keep X-ray exposure as low as reasonably achievable by adhering to the following:

• Shield the X-ray device, the questionable object, and the operator.
  
• Remove all nonessential personnel from the X-ray field.
  
• Limit the time that personnel must be in the area of operation.
  
• Always wear assigned monitoring devices appropriate for X-ray radiation.
  
• Ensure that standard X-ray operating procedures are in place and followed and that adequate training has been provided in accordance with federal and state regulations.
  

Hand protection should be selected on the basis of the type of material being handled and the hazard(s) associated with the material.
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Detailed information can be obtained from the manufacturer. The following list provides information about glove material types and functions:

• Nitrile provides protection from acids, alkaline solutions, hydraulic fluid, photographic solutions, fuels, lubricants, aromatics, petroleum, and chlorinated solvents. It also offers some resistance to cuts and snags.
  
• Neoprene offers resistance to oil, grease, acids, solvents, alkalies, bases, and most refrigerants.
  
• Polyvinyl chloride (PVC) is resistant to alkalies, oils, and limited concentrations of nitric and chromic acids.
  
• Latex (natural rubber) resists mild acids, caustics, detergents, germicides, and ketonic solutions. Latex will swell and degrade if exposed to gasoline or kerosene. When exposed to prolonged, excessive heat or direct sunlight, latex gloves can degrade, causing the glove material to lose its integrity.
  
• Using powder-free gloves with reduced protein content reduces the risk of developing latex allergies. Personnel allergic to latex usually can wear nitrile or neoprene.
  

Guidelines for glove use include the following:

• Prior to donning gloves, inspect them for holes, punctures, and tears. Remove rings or other sharp objects that can cause punctures.
  
• When working with heavily contaminated materials, wear a double layer of gloves.
  
• Change gloves when they become torn or punctured or when their ability to function as a barrier is compromised.
  
• To avoid contaminating unprotected skin or clothing, remove disposable gloves by grasping the cuffs and pulling them off inside out. Discard disposable gloves in designated containers. Do not reuse.
  

Personnel handling chemical, biological, and radioactive materials should wear appropriate eye protection, such as safety glasses and goggles.
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Face shields offer better protection when there is a potential for splashing or flying debris. Face shields must be worn in combination with safety glasses or goggles because face shields alone are not considered appropriate eye protection.

Contact lens users must wear safety glasses or goggles to protect the eyes. In the event of a chemical splash into the eye, it can be difficult to remove the contact lens to irrigate the eye, and contaminants can be trapped behind the contact lens.

Protective eyewear also should be worn over prescription glasses. Alternately, safety glasses may be made to the wearer’s eyeglass prescription.

Shoes that completely cover and protect the foot are essential.
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Protective footwear should be worn at crime scenes when there is a danger of foot injuries from falling or rolling objects, from objects piercing the sole, or from exposure to electrical hazards. The standard recognized by OSHA for protective footwear is the
American National Standard for Personal Protection—Protective Footwear
, ANSI Z41-1991.
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In some situations, nonpermeable shoe covers can provide barrier protection to shoes and prevent the transfer of contamination outside the crime scene.

Certain crime scenes, such as bombings and clandestine laboratories, can produce noxious fumes and other airborne contaminants in which responders must use respiratory protection.
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Compliance with 29 CFR 1910.134,
Respiratory Protection
,
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is mandatory whenever respirators are used. Critical elements for the safe use of respirators include a written program, training, medical evaluation, fit testing, and a respirator maintenance program. Without these elements, the wearer is not guaranteed protection.

At certain crime scenes where structural damage has occurred or may occur, protective helmets should be worn. The standard recognized by OSHA for protective helmets is ANSI’s requirements for industrial head protection, Z89.1-2003.
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