Chemical Safety Management(SCU1402)

Universiti Sains Islam Malaysia (USIM)Dr. Mohd Hafez Mohd Isa

1.1: Basic information on chemicals toxicity and hazard

• What are dangerous chemical?• Toxic dose of chemical• Types of chemicals CAS – chemical abstract services system Organic – chemicals based on compounds of carbon

and hydrogen Inorganic – chemicals of any element and their

compounds that do not contain carbon

Toxicology

• Toxicity• Dosage• Bioaccumulation• Biomagnification• Synergism• Response• Acute effect• Chronic affect

Chemical toxicity

• The term “toxicity” is used to describe the nature of adverse effects produced and the conditions necessary for their production.

• Before toxicity can develop, a substance must come into contact with a body surface such as skin, eye or mucosa of the alimentary or respiratory tract.

• The term ‘toxic’ relates to poisonous or deadly effects on the body.

• The term “toxicant” refers to toxic substances that are produced by or are a byproduct of human-made activities.

• A toxic symptom is any feeling or sign indicating the presence of a poison in the system. Toxic effects refers to the health effects that occur due to exposure to a toxic substance.

Classification of toxic agents

• Heavy metals • Solvents and vapours • Radiation and radioactive materials • Dioxin/Furans • Pesticides • Plant toxins • Animal toxins

Factors Affecting Toxicity

• Dose• Age of individual• Immune system (detoxification)• Genetic makeup• Length and frequency of exposure

Principles of Toxicology

Any synthetic or natural chemical can be harmful if ingested in large enough quantity.

THE DOSE MAKES THE POISON Critical questions: what is the lowest level

that will cause harm? Trace amounts of chemicals in the

environment may or may not be harmful.

• How do scientists determine toxicity:• Epidemiologic case studies• Animal Testing (usually with control groups)• Computer modeling

• How good are the estimates of toxicology?

• There are serious limitations to all these types of studies.

• Therefore, most allowable limits are set well below estimated harmful levels.

Spectrum of toxic dose

• Agent Orange is the combination of the code names for Herbicide Orange (HO) and Agent LNX, one of the herbicides and defoliants used by the U.S. military as part of its chemical warfare program, Operation Ranch Hand, during the Vietnam War from 1961 to 1971. Vietnam estimates 400,000 people were killed or maimed, and 500,000 children born with birth defects as a result of its use. The Red Cross of Vietnam estimates that up to 1 million people are disabled or have health problems due to Agent Orange.

• A 50:50 mixture of 2,4,5-T and 2,4-D, it was manufactured for the U.S. Department of Defense primarily by Monsanto Corporation and Dow Chemical. The 2,4,5-T used to produce Agent Orange was later discovered to be contaminated with 2,3,7,8-tetrachlorodibenzodioxin (TCDD), an extremely toxic dioxin compound.

Subcategories for classifications

• Their effect on target organs (liver, kidney, hematopoietic system, etc.)

• Their use (pesticide, solvent, food additive, etc.)• The source of the agent (animal and plant toxins)• Their effects (cancer mutation, liver injury, etc)• Physical state (gas, dust, liquid)• Labeling requirements (explosive, flammable,

oxidizer)• Chemistry

The dangerous properties of chemicals

• Chemicals are the most common and significant health hazards. Chemicals can be hazardous for numerous reasons and can combine with other chemicals to make new hazards. All hazards must be taken into account when using and storing chemicals.

• Different chemical groups• Water soluble/fat-soluble• Chemicals can cause: Physical injury Physiological injury Psychological injury

Physical classification

• Chemicals may be found in solid, liquid, aerosol, or gas and vapor form. The degree of danger varies according to the form of the chemical.

• Not all forms of a chemical pose a health hazard. For example, a lead pipe is not a significant health hazard. However, the lead can become a human health hazard if the pipe is sanded or welded, producing lead dust or fumes. The dust or fumes can become airborne and be inhaled, or it can leach into water and be ingested.

Chemicals that can cause physical injury

• Classification of chemicals: Corrosive Flammable liquid and solidExplosiveIrritantsOxidizers

• A chemical may be hazardous even in solid form. For example, individuals who are sensitized to nickel may develop dermatitis from skin contact with the metal. Fuming solids emit toxic vapours that may be inhaled. Some materials, such as pesticides, can evaporate directly from solid form. Some solids are not a hazard alone but become hazardous when they come into contact with other chemicals (e.g., acid in contact with iron can release hydrogen gas).

• Aerosol is a term used to describe fine particles (solid or liquid) suspended in air. Examples of aerosols include dust, fumes, mist, fog, smoke, and smog. Knowing how various aerosols are generated will help you anticipate where aerosol hazards may exist in the field. Aerosols may be a hazard to the eyes, skin, and the respiratory system.

• Many liquids are hazardous in contact with the skin. They either damage the skin or they are easily absorbed through the skin. It is important to remember that chemicals that can damage or be absorbed through the skin will have this effect on all skin, not just the hands. The degree of hazard associated with a liquid depends on its characteristics and how it is handled.

• For example, inhalation is the primary route for a chemical to enter the body. Its vapour pressure is important in determining the liquid degree of hazard. Liquids with a low vapor pressure may create a low airborne concentration. Liquids with a high vapor pressure may produce high airborne concentrations. The hazard level of an airborne concentration depends on the chemical's toxicity.

Chemicals that can cause physiological injury

• Chemicals reaction with body’s chemical• LD50 and LC50 • Asphyxiation • Immediate (acute) or delay/late (chronic)

effects

• Acute Toxicity - Toxicity which exerts a stimulus severe enough to rapidly induce an effect. The duration of exposure applicable to acute toxicity is typically 96 hours or less. Tests of total toxicity normally use lethality as the measure of acute impacts.

• Chronic Toxicity - Toxicity which continues for a long-term period after exposure to toxic substances. Chronic exposure produces sub-lethal effects, such as growth impairment and reduced reproductive success, but it may also produce lethality. The duration of exposure applicable to the most common chronic toxicity test is seven days or more.

The Median Lethal Dose

LD50

The amount (dose) of a chemical which produces death in 50% of a population of test animals to which it is

administered by any of a variety of methods

mg/kgNormally expressed as milligrams of substance per kilogram of animal body weight

The Median Lethal Concentration

LC50

The concentration of a chemical in an environment (generally air or water) which produces death in 50% of an exposed population of test animals in

a specified time frame

mg/LNormally expressed as milligrams of substance

per liter of air or water (or as ppm)

Chemicals that can cause psychological injury

• May be divided into:Analgesic effects:DepressantStimulantHallucinogen

Depressants

• Depressants depress the central nervous system and reduce pain, relieving stress, anxiety and fear putting the person at ease.

• However, depressants are very addictive and the end result is usually a lessening of ones ability to deal with any stress, fear or anxiety.

• Heroin is the most frequently used illegal depressant.

• Other depressants include morphine, codeine methadone, barbiturates and tranquilizers.

Stimulant

• Stimulates elevate the mood, producing feelings of excitement, feeling good and euphoria.

• Heavy use of stimulants result in paranoia, restlessness, fidgetiness (constant body movements), apathy, irritability and depression.

• The most frequently used stimulant is coffee and caffeine. The most common illegal stimulant is cocaine and amphetamines.

Hallucinogen

• Hallucinogens alter perceptual functions or better known as mind-altering drugs.

• There are no legalized hallucinogens as this type of drug is extremely dangerous and unpredictable.

• The most frequently used hallucinogens are LSD. • Users of hallucinogens, experience a complete

fantasy or hallucination including; out of body experiences or misperceptions of reality, distortion, the mixes of senses – hearing colours and seeing sounds and experience a combination of emotions or go from one emotion to the next rapidly.

Local and systemic effects

• Local effect is associated to physical injury by chemicals due to (e.g. corrosivity, irritability)

• Persistent irritation of respiratory system• May lead to systemic effect (e.g.

endangering other organs – liver and kidney)

• Central nervous system

Tragedies That Have Changed theTragedies That Have Changed theSafety MovementSafety Movement

• Bhopal Tragedy - On Dec. 3, 1984, over 40 tonsof methyl isocyanate (MIC) & other gases, including hydrogen cyanide, leaked into north Bhopal, India.– Killing more than 3,000 people in its aftermath.

• It was discovered the protective equipment that could have halted impending disaster was notin full working order.

• The International Medical Commission found thatas many as 50,000 people were exposed, andmay still suffer disability as a result.– This disaster shocked the world.

• Union Carbide Corporation, owner of the plant, was accused of many things, including: – Criminal negligence.– Corporate prejudice - choosing poverty-stricken

Bhopal, on the assumption few would care if anything went wrong.

– Avoidance - putting its plant in Bhopal to avoid stricter US safety & health standards.

• In February 1989, India’s Supreme Court ordered Union Carbide India Ltd., to pay $470 million in compensatory damages.– Funds were paid to the Indian government to be

used to compensate the victims.