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Health Effects of Hazardous Materials

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Presentation on theme: "Health Effects of Hazardous Materials"— Presentation transcript:

1 Health Effects of Hazardous Materials

2 Toxicology The study of poison & substances that cause harmful effects to living things Toxic effects can range from minor irritation to lethal effects Toxins are poisons produced by living organisms (naturally occurring) Toxicants are manufactured by humans

3 Toxicology Dose differentiates a poison and a remedy
Harmful substances are tested on animals How a chemical affects genetic material is determined using microorganisms (i.e. bacteria)

4 Toxicity Relative ability of a substance to
cause harmful effects to living things What quantity does it take to cause damage Determined by the chemical makeup, what elements it contains and how they are combined, how readily it is absorbed and how the body metabolizes it

5 Dose Actual amount of chemical that enters and reacts with body systems to cause harm, measured in mass per unit time (mg/kg/day) [milligram of substance per kilogram of tissue per time of exposure]

6 Exposure The amount of toxic chemical our body comes in contact with
In the air we breathe, the food we eat and our skin is exposed to The higher the concentration of the exposure the larger the dose The longer the exposure the larger the dose Protective clothing, equipment and containment can break the exposure chain

7 Routes of Exposure Dermal absorption Oral (Ingestion) Inhalation
Injection Inhalation and injection are the most rapid

8 Dermal May cause itching, redness, burns, and solvents may dissolve skin oils leaving skin more susceptible to the absorption of chemicals The eyes are especially susceptible to harm

9 Ingestion Not common in the workplace, but issues of facial cleanliness, and eating are concerns Is a serious problem at home with children i.e. lead paint chips

10 Injection Greatest risk in medical facilities, or from microbial exposure from nail puncture Biological sources of toxins as well; insects, scorpions, spiders and snakes! We Will Come Back to Inhalation later

11 Acute toxicity Back to toxicity: Result of short term exposure
Causes effects that are felt at the time of exposure or soon thereafter Most toxic effects don’t cause permanent, irreversible damage (acute & chronic)

12 Chronic toxicity Due to long-term exposure
Effects appear after months or years of exposure Cancer, emphysema, or nervous system damage caused by heavy metals, drugs and alcohol are examples of some chronic health effects

13 Relative toxicity As the dose of a toxic substance increases the harmful effects are generally expected to increase Dose-Response Relationship LOAEL: Lowest Observable Adverse Effect Level - or the lowest dose that causes a lethal effect NOAEL - No Observable Adverse Effect Level

14 Threshold level The lowest concentration that could produce a harmful effect (doesn’t necessarily mean lethal) Varies among people exposed depending upon their sensitivity A safety factor is used to reduce the allowable concentration to assure no ill effects

15 Lethal Dose 50 (LD50) Dose at which 50% of the test population dies
Used with dermal and oral toxicity LC Lethal Concentration used for toxicity from inhalation

16 Effects other than death!
The dose or concentration to produce toxic effects in 50% of the population Toxic Dosage TD50 Toxic Concentration - TC50

17 Toxic Effects Local Effects – damage caused at the site of first contact with toxicant (eyes, nose, throat, lungs, skin) Systemic Effects – Damage done by toxicants carried by the bloodstream to vital organs (liver, kidneys, heart, nervous and reproductive system

18 Additional factors associated w/ Toxic Effects
Local effects provide warning that exposure has occurred Systemic effects may occur without being felt or sensed

19 Accumulation Chronic, or long term exposure is particularly dangerous because some chemicals build up in the body The body does not get a chance to repair itself

20 Latency Period The delay between the exposure and the resultant harmful effects Some effects take a long time to manifest themselves For some chemicals, effects may not appear for 30 or 40 years Example is asbestos

21 Interaction Chemicals can combine with toxicants and alter their behavior

22 Reaction Chemicals can combine and form new harmful substances
i.e. bleach plus drain cleaner = chlorine gas and hydrochloric acid

23 Additive Effect Most health and safety regulations assume that the effects of two chemicals together is equal to the sum of each alone

24 Antagonism A subtractive effect
One substance reduces the effects of another

25 Synergism Two chemicals can interact within the body to produce an effect different from the effect of either chemical alone, and greater than their sum A pack of cigarettes a day or exposure to asbestos increases the chance of lung cancer by six times The two exposures together increases one’s risk by 90 times!

26 Sensitivity Individuals vary in how they react
Age, sex, inherited traits, diet, state of health, use of medication, drugs, alcohol and pregnancy Includes Allergies Some people are affected by a very low dose of a substance (i.e. bee stings) Substances that initiate allergic responses are called sensitizers

27 Respiratory System Exchange of gases, oxygen in, carbon dioxide out
The air we breathe contains 78% nitrogen, 21% oxygen, and 1% trace gases Evaporation of liquids such as gasoline or formaldehyde allows them to enter the body

28 Inhalation (Back to Routes of Exposure)
Most critical route of entry for most workers handling toxic chemicals Quick entry and absorption into the bloodstream Ability of some toxic agents to accumulate in the respiratory system itself

29 The nose and mouth warm and humidify the air we breathe
The bronchial tubes lead to alveoli, 300 million tiny air sacs where air is exchanged Oxygen is transferred to hemoglobin within the red blood cells of the bloodstream and carbon dioxide is released

30 Fibrosis Some particles cause a build up of fibrous connective tissue
Emphysema is an example of this type of effect Hampers the transfer of oxygen to the bloodstream Silica from mining, quarrying and pottery glazing, coal dust and asbestos

31 Inhaling dusts or mists
Harmful particles may be deposited in the bronchi or the alveoli Larger particles may be coughed up but smaller ones remain to cause lung damage Particles less than 10 microns penetrate deeper into the lungs causing bronchitis Low level long term exposure to smoke, vehicle exhaust can trigger chronic bronchitis and emphysema

32 Sulfur dioxide and nitrogen oxides combine with water vapor in the alveoli forming acids
Ammonia and chlorine gas can dissolve in the mucus of the lungs creating caustic solutions Injured lung tissue allows liquids to move from the capillaries into the alveoli causing pulmonary edema A person can literally drown in their own fluids

33 Smell Our sense of smell does not always warn of exposure
Carbon monoxide is odorless We can become desensitized to some smells after exposure “olfactory fatique” Example is H2S (page 81)

34 Cardiovascular system
The heart and blood vessels transport oxygen and nutrients to all parts of the body The heart and brain are especially sensitive to a lack of oxygen Waste products are picked up and carried to the lungs and kidneys

35 Hemoglobin An iron containing protein in red blood cells which carry oxygen to the rest of the body Some chemicals (i.e.CO) interfere with this process causing chemical asphyxiation Hemoglobin has a much greater affinity for CO than oxygen (300 times greater)

36 Digestive and Filtration Systems
Food and water supply the body with materials for maintenance and repair and a source of energy The digestive system breaks down large molecules like proteins, complex carbohydrates and fats

37 Liver Processes chemicals found in the blood traveling from the intestine Converts foods into other chemicals, destroys toxins, manufactures protein and stores glucose

38 Liver Disease Severe liver disease prevents the organ from rendering toxic chemicals harmless, some which may be normal body chemicals When they reach the brain they may cause tremors, confusion or coma

39 Some chemicals are stored in the liver
The liver can destroy toxic substances like alcohol and nicotine If exposure is chronic and long term, cells may be damaged and replaced by fibrous tissue, a condition called cirrhosis

40 Bloodstream and Kidneys
Our body fluids must maintain a balanced amount of potassium, sodium, chloride and calcium ions and blood acids The kidneys maintain this balance and filter out waste materials

41 The body must remain hydrated for the kidneys to perform their function
If the body loses more that 10% of it’s weight in water cells will no longer function and the result is coma & death Kidney malfunction causes toxic chemicals to build up in the bloodstream which can result in coma and death

42 Kidney cancers are known to be associated with exposure to some industrial chemicals
Mercury in waterways is converted to methyl mercury, which is ingested by fish If the fish are eaten the chemical inhibits the kidney’s ability to balance the body’s chemicals which blocks nerve transmissions, Minimata Disease

43 Nervous System and Sensory Organs
Brain, spinal cord are considered the central nervous system and process signals from the peripheral nervous system The two types of nerves are motor and sensory The autonomic nervous system takes care of all the bodily functions which are in the background

44 Pesticides and metals, such as lead and mercury, can interfere with the chemical transfer of information This may cause tremors, paralysis, loss of reflexes and/or feeling Mercury caused “Mad Hatter’s Disease”

45 Brain Must receive a continuous supply of oxygen
See chart on page 86 for symptoms of oxygen deficiency

46 Eyes Inflammation and infection of the mucus-membrane lining of the eyelids and eyeballs can be caused by irritation from chemical pollutants Acids and bases are corrosive and can penetrate to the interior of the eye very quickly i.e. lime in wall plaster Methyl or wood alcohol can cause total blindness from damage to the optic nerve

47 Skin Made up of three layers, the epidermis, the dermis and subcutaneous tissue The dermis, or live skin, contains blood vessels, nerves, nerve receptors, hair follicles and sweat and oil glands The skin protects against the invasion of bacteria, the sun’s rays and the loss of moisture

48 It senses pressure, pain and temperature and regulates the body’s temperature through blood flow and sweat glands Corrosive chemicals can dissolve naturally protective coatings and/or react with the skin Some chemicals, like solvents that` dissolve fats, are absorbed directly into the bloodstream

49 Carcinogenicity The tendency for cancer to occur
Cancer is the uncontrolled growth and spread of abnormal cells It is first indicated by malignant tumors which tend to invade the surrounding tissue and then spread to distant sites within the body

50 During the 1970’s the public became aware of the potential for chemicals to cause cancer
Studies of chemicals indicate that only a small number in commercial use cause cancer

51 One in three people will develop cancer during their lifetime
Yet only 10 – 15% of these are from occupational exposure to chemicals There are 30 chemicals considered to be human carcinogens and 200 that are suspect based on animal studies

52 Mutagenicity The ability of a substance to cause damage to genetic material A substance that is a carciogen is usually a mutagen But not all mutagens cause cancer

53 Teratogenicity A substances tendency to interfere with the development of an unborn child A teratogen causes birth defects

54 Determining Carcinogenicity
Epidemiological studies are retrospective and look at past exposures to a sample group and compare this with their health history Lifestyle risk contributors like smoking, alcohol consumption and obesity are considered

55 A prospective study maintains environmental data as well as exposure and medical records on workers as they are exposed These studies are difficult in companies where there is a large turnover of employees because the latency period of many cancers is over 20 years

56 Animal testing Usually performed on rodents using procedures endorsed by regulatory agencies like the EPA Animals are given doses likely to yield maximum incidence of tumor formation then statistical analysis is used to estimate the cancer risk of low doses in humans

57 Risk Management Government policy is determined by the public’s opinion of acceptable risk and is based on political considerations Definition of risk What defines acceptable risk Risk assessment uses scientific methods to determine the actual level of risk

58 Risk/Benefit Analysis
Used by regulatory agencies in the decision making process Subjective concerns such as politics, lifestyles, freedoms, economics and progress are considered

59 Perception of Risk We tend to perceive voluntary risks as less perilous than those we are forced to take i.e. smoking

60 Risk Assessment Evaluating the toxic properties of a substance and the conditions of human exposure to determine The likelihood that exposed humans will be adversely affected And describe the nature of the effects they may experience

61 National Research Council Guidelines 1983
Hazard evaluation - determining the toxic properties of the substance Dose-response relationships - how much it takes to cause negative effects Exposure assessment - how much the public is exposed to and for how long Risk characterization – determining a numerical risk factor

62 Risk Assessment II Risk assessments are required by regulatory agencies when contaminants have been released into the environment Aids in determining acceptable cleanup levels


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