Health Effects of Hazardous MaterialsToxicologySlide 3ToxicityDoseExposureRoutes of ExposureDermalIngestionInjectionAcute toxicityChronic toxicityRelative toxicityThreshold levelLethal Dose 50 (LD50)Effects other than death!Toxic EffectsAdditional factors associated w/ Toxic EffectsAccumulationLatency PeriodInteractionReactionAdditive EffectAntagonismSynergismSensitivityRespiratory SystemInhalation (Back to Routes of Exposure)Slide 29FibrosisInhaling dusts or mistsSlide 32SmellCardiovascular systemHemoglobinDigestive and Filtration SystemsLiverLiver DiseaseSlide 39Bloodstream and KidneysSlide 41Slide 42Nervous System and Sensory OrgansSlide 44BrainEyesSkinSlide 48CarcinogenicitySlide 50Slide 51MutagenicityTeratogenicityDetermining CarcinogenicitySlide 55Animal testingRisk ManagementRisk/Benefit AnalysisPerception of RiskRisk AssessmentNational Research Council Guidelines 1983Risk Assessment IIHealth Effects of Hazardous MaterialsToxicology•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 humansToxicology•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)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 itDose•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]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 chainRoutes of Exposure•Dermal absorption•Oral (Ingestion)•Inhalation•Injection•Inhalation and injection are the most rapidDermal•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 harmIngestion•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 chipsInjection•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 laterAcute 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)Back to toxicity: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 effectsRelative 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 LevelThreshold 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 effectsLethal Dose 50 (LD50)•Dose at which 50% of the test population dies•Used with dermal and oral toxicity•LC50 - Lethal Concentration used for toxicity from inhalationEffects other than death!•The dose or concentration to produce toxic effects in 50% of the population•Toxic Dosage 50 - TD50•Toxic Concentration - TC50Toxic 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 systemAdditional factors associated w/ Toxic Effects•Local effects provide warning that exposure has occurred•Systemic effects may occur without being felt or sensedAccumulation•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 itselfLatency 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 asbestosInteraction•Chemicals can combine with toxicants and alter their behaviorReaction•Chemicals can combine and form new harmful substances•i.e. bleach plus drain cleaner = chlorine gas and hydrochloric acidAdditive Effect•Most health and safety regulations assume that the effects of two chemicals together is equal to the sum of each aloneAntagonism•A subtractive effect•One substance reduces the effects of anotherSynergism•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!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 sensitizersRespiratory 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 bodyInhalation (Back to Routes of Exposure)•Most critical route of entry for most workers handling toxic chemicals•Quick entry and absorption into