Introduction to Toxicology Environmental Health Institute - July, 2006 University of Rochester Medical Center Introduction to Toxicology

What is Toxicology? Toxicology is the study of how toxins cause adverse effects on living organisms. Toxicology (from the Greek words toxicon and logos) is the study of the adverse effects of chemicals on living organisms. It is the study of symptoms, mechanisms, treatments and detection of poisoning, especially the poisoning of people.

Toxicology Terms to Know toxins (Poison): A chemical capable of producing a harmful reaction in a living organism. Adverse effect: Any change that interferes with an organism’s normal functioning.

What is a Poison? All substances are poisons; there is none that is not a poison. The right dose differentiates a poison and a remedy. Paracelsus (1493-1541) Paracelsus was a scientist and physician who was born in Switzerland in 1493. Paracelsus pioneered the use of chemicals and minerals in medicine. He is sometimes called the "father" of toxicology. A popular short version of this quote is: "The dose makes the poison." In other words, the amount of a substance a person is exposed to is as important as the nature of the substance. For example, small doses of aspirin can be beneficial to a person, but at very high doses, this common medicine can be deadly. In some individuals, even at very low doses, aspirin may be deadly.

Examples of toxins: Chemicals that can Cause Harm Prenatal alcohol abuse → fetal alcohol syndrome www.betterendings.org/FASD/facts/nationalgeo.htm If a woman drinks alcohol during her pregnancy, her baby can be born with fetal alcohol syndrome, a lifelong condition that causes physical and mental disabilities. FAS is characterized by abnormal facial features, growth deficiencies, and central nervous system problems. People with FAS might have problems with learning, memory, attention span, communication, vision, hearing, or a combination of these. Nearly all fish and shellfish contain traces of mercury. For most people, the risk from mercury by eating fish and shellfish is not a health concern. Yet, some fish and shellfish contain higher levels of mercury that may harm an unborn baby or young child's developing nervous system. Women who may become pregnant, pregnant women, nursing mothers, and young children to avoid some types of fish (such as Shark, Swordfish, King Mackerel, or Tilefish) and should only eat fish and shellfish that are lower in mercury. This slide shows a photo of people in Minamata Japan who were severely poisoned in the 1950s by very high levels of mercury in fish that they ate. The mercury was released into the water by improper treatment of industrial waste from factories. Mercury in fish → brain damage

Examples of toxins: Chemicals that can Cause Harm Lead in paint → brain damage Dioxins are byproducts of many chemical manufacturing processes involving chlorine. They acquired notoriety in 1976 following an accidental release from a chemical plant at Seveso in Italy, which caused local residents to develop a severe form of facial scarring called chloracne. Dioxin poisoning made the news more recently with the poisoning of Ukrainian opposition leader Viktor Yushchenko. Yushchenko's face and torso became disfigured after he fell ill during a bitter election campaign in the fall of 2004. He was poisoned, probably by being given food laced with deadly dioxins by his political enemies. Lead-based paint is a major source of lead poisoning for children and can also affect adults. In children, lead poisoning can cause irreversible brain damage. It can retard mental and physical development and reduce attention span. It can also retard fetal development even at extremely low levels of lead. In adults, it can cause irritability, poor muscle coordination, and nerve damage to the sense organs and nerves controlling the body. Eating paint chips is one way young children are exposed to lead. Ingesting and inhaling lead dust that is created as lead-based paint chips or peels from deteriorated surfaces can expose people to lead. Walking on small paint chips found on the floor, or opening and closing a painted frame window, can also create lead dust. As pictured here, lead dust can also be generated by sanding lead-based paint or by scraping or heating lead-based paint. Dioxin poisoning → facial scarring (chloracne) www.seco.noaa.gov

What amount causes harm? Some chemicals are good in small amounts, but toxic in large amounts Example: botulinum toxin Small amount → Large amount →

What amount causes harm? Some chemicals are good in small amounts, but toxic in large amounts Example: botulinum toxin Small amount → prevents wrinkles (BOTOX) Large amount → paralysis, death Botulinum toxin (BOTOX) is a purified substance derived from the bacterum, Clostridium botulinum. Is acts to block muscular nerve signals.  Botulinum toxin is the first biological toxin to become licensed for treatment of human disease and it is also considered a biological weapon. Injecting very small amounts of BOTOX into specific facial muscles blocks the muscle’s impulse.  This temporarily weakens the muscle and diminishes the unwanted facial lines.  Botulinum toxin is the most poisonous substance known. A single gram of crystalline toxin, evenly dispersed and inhaled, would kill more than 1 million people. Terrorists have already attempted to use botulinum toxin as a bioweapon. Aerosols were dispersed at multiple sites in downtown Tokyo, Japan, and at US military installations in Japan on at least 3 occasions between 1990 and 1995 by terrorists from a Japanese cult group.

Name the toxins that may be present in each scene

City Scene

Farm Scene

Home Scene

Town Scene                                                                                                                                                                                  

Dose Dose refers to the amount of a toxins entering the body Dose is measured as milligrams of toxins per kilogram of body weight = mg/kg Example: 100 mg caffeine 50 kg adult (110 pounds) dose = 100 mg/50kg = 2 mg/kg 10 kg baby (22 pounds) dose = 100 mg/10 kg = 10 mg/kg Since individual people have different body weights, the amount of a toxins that will effect them will be different. In the science of toxicology, we use the term “dose” to refer to the amount of a toxins (which is a chemical or pother poison) that enters the body. Dose is measured as the amount of toxins (in milligrams) per weight of an individual (in kilograms), or milligrams per killogram. For example, if an adult consumed 100 mg of caffeine (about the amount in a cup of coffee) and if they weighed 50 kg (about 110 pounds), the dose would be 100mf/50 kg of body weight, or 2 mg/kg. If a baby weighing only 10 kg (about 22 pounds) consumed the same 100 mg of caffeine, the dose would be 10 mg./kg, which is 5 time as large, because the body weight is five times smaller. This principal can be extremely important in exposure to lead or pesticides, because the dose that a child received is far greater than the adult dose.

Examples A woman who weighs 80 kg took 3 aspirin pills. Each pill contains 300 mg of aspirin. What is the dose the woman took?

Examples A man who weighs 130 kg took the same number of pills of aspirin. What is the dose the man took?

Example How can each person have taken the same number of pills but each be given the same dose?

Example If a child ingest a poison a parent will call poison control (a government hotline that instructs parents of what to do in these types of situations). What information will poison control need from the parent?

? What factors determine the dose of a toxins that causes harm? Not all toxins are harmful at the same dose. There are a number of factors that determine what the harmful dose is of a specific toxins.

What factors determine the dose of a toxins that causes harm? The concentration of the toxins The chemical properties of the toxins The number of times of exposure (frequency) The length of time of exposure (duration) How it gets into the body (exposure pathway)

Concentration The dose Some doses have a mild affect and some have a severe or even deadly affect

Chemical Properties Some toxins are easily absorbed by the blood stream while others are not Some toxins react with chemicals in our body more easily Example: hemoglobin bonds very quickly to carbon dioxide

Frequency of Exposure Number of times of exposure (Number of glasses of wine) Time in between exposure (Time between each glass of wine) or The response to a toxins can also be effected by the frequency of exposure to that substance. Frequency can be determined by the number of times a person is exposed (for example the number of glasses of wine that are consumed) or by the time between exposure (for example the number of minutes a person waits between drinking each glass of wine). or

Duration of Exposure: How long the exposure lasted Acute < 24hr 1 high dose Subacute 1 month repeated exposures Subchronic 1-3months repeated low dose Chronic > 3months repeated low dose The amount of toxins can build up in body over time and: Can move to different organs (example - lead) Can overwhelm the bodies’ ability to repair damage and remove the toxins (example - radiation) The response to a toxins can also be effected by the duration of the exposure. Duration of exposure can be acute, subchronic, or chronic. Acute exposure is once or twice in a short period of time, such as a week or less. Chronic exposure is long-term or lifetime exposure. Subchronic exposure is somewhere in between acute and chronic Certain toxins can build up in the body over time – for example lead, mercury and fat soluble chemicals such as dioxins and PCBs – and cause damage to the nervous system and other organs.

Length of exposure A man works in a lab and is exposed to very low amounts of benzene vapors over a 20 year period

Length of exposure A gardener spills a large quantity of pesticides while working in the shed. She cleans up the mess but is exposed to large amounts of the vapor from the chemicals

Length of exposure A volunteer working at ground zero was exposed to mercury over a 4 week period.

Routes of Exposure Skin (dermal) Oral (gut) Lung (inhalation) Which is the worst? Oral (gut) Lung (inhalation) The job of the lungs is to exchange gases, allowing oxygen to be absorbed into the blood stream from the air we breathe, and get rid of waste carbon dioxide from the body. In the same way, the lungs will readily absorb other chemicals found in air. Some chemicals can penetrate the skin and enter the blood stream. Whether or not a chemical is absorbed through the skin depends on its structure: chemicals need to be able to dissolve in both water and fat (lipids) to get through the skin. Those that are insoluble, or dissolve only in fats or water, and chemicals made up of very large molecules, tend not to penetrate the skin. Chemicals are more easily absorbed where the skin is thin, such as on the forearms, than through the thick skin covering the palms of the hands and soles of the feet. Chemicals are also more easily absorbed if skin is moist or damaged. Chemicals can also enter the body if swallowed. In the workplace, this can occur if areas used to eat, drink or smoke are contaminated with chemicals, or if workers do not wash their hands or remove their gloves before eating or smoking.

Inhalation 1. cause damage to mucous membranes Throat lungs 2. pass through the lungs into the circulatory system to affect other areas of the body* 3. Can be fatal

oral Most toxins are poorly absorbed from the intestines into the blood stream. severe damage lining of the mouth, throat, and gastrointestinal tract Can cause death in some cases

Dermal (skin) If the toxin is extremely hazardous may pass through the skin and cause serious or even fatal poisoning Mostly results inflammation, burning, blistering, and complete destruction of the skin

Measures of Toxicity Toxicity of chemicals is determined in the laboratory The normal procedure is to expose test animals By ingestion, application to the skin, by inhalation, or some other method which introduces the material into the body, or By placing the test material in the water or air of the test animals’ environment

Measures of Toxicity Toxicity is measured as clinical “endpoints” which include Mortality (death) Teratogenicity (ability to cause birth defects) Carcinogenicity (ability to cause cancer), and, Mutagenicity (ability to cause heritible change in the DNA) At this time we will discuss the measure of mortality – the LD50

The dose of toxins which is deadly to 50% of the population LD50 The dose of toxins which is deadly to 50% of the population Toxicologist often measure the toxicity of a substance in terms of the dose (or amount) of the substance that it takes to kill an organism (such as a lab mouse). the term LD50 (or lethal dose 50) refers to the dose of a toxins that will kill 50% of the population – or half of the mice, in the case of this graphic. LD50 is not the lethal dose for all individuals; some may be killed by much less, while others survive doses far higher than the LD50.

Measures of Toxicity: The Median Lethal Dose 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/kg Normally expressed as milligrams of substance per kilogram of animal body weight

Dose-Response Relationship: As the dose increases, the percent of individuals who respond increases 6 100 75 % of Deaths 50 The dose-response relationship is a fundamental and essential concept in toxicology.  Generally, the higher the dose, the more severe the response. A graph can be made with the dose along the bottom (horizontal, X-axis) and response up the side (vertical, Y-axis) to create a dose-response curve. For example, if you wanted to graph the toxic effects of a certain type of chemical that causes liver damage in mice. The dose would be milligrams of chemical per kilogram of body weight (mg/kg) and the response could be the percentage of animals that suffered a certain degree of liver damage. The dose-response curve normally takes the form of a sigmoid curve.  As the dose of the toxins is increased, the percent of individuals who respond (show ill effects) will increase. 25 10 20 30 40 50 60 70 80 90 100 Dose (mg/kg body weight)

Dose-Response Relationship: As the dose increases, the percent of individuals who respond increases All individuals respond at a dose of 100 mg/kg 100 75 % of Deaths 50 Half of deaths were at a dose of 43 mg/kg For this example of the response to a hypothetical toxins, half (50%) of the individuals in a population will respond to the toxins at a dose of 43 milligrams per kilogram. All of the individuals (100%) will respond to a dose of 100 mg per kilogram. 25 10 20 30 40 50 60 70 80 90 100 Dose (mg/kg body weight)

Glasses of Wine: Dose-Response 100 75 % of people who have difficulty walking 50 Half of people have difficulty walking after 4.5 glasses of wine This graph shows an example of the dose-response curve of the effects of wine on the ability to walk. The “dose” (X-axis) is the number of glasses of wine. The “response” (Y-axis) is difficulty in walking. As seen in this graph, half (50%) of people will have difficulty walking if they drink about 4 ½ glasses of wine. 25 1 2 3 4 5 6 7 8 Glasses of Wine

Glasses of Wine: Dose-Response 100 75 % of people who have difficulty walking 50 Half of people have difficulty walking after 4.5 glasses of wine Why don’t all people have difficulty walking after drinking 4 ½ glasses of wine? 25 Why don’t all people respond the same? 1 2 3 4 5 6 7 8 Glasses of Wine

Different individuals can show a greater or lesser response to the same toxins What factors can cause a difference in response? ? Different individuals have more or less response to the same amount of toxins.

Different individuals can show a greater or lesser response to the same toxins What factors can cause a difference in response? Age - young or old Gender - male or female Genetic differences – different genes Nutrition Health – previous or current diseases Exposure to other toxins – previous or current Different people can respond very differently to the same dose of a chemical. This variation is due to many factors, such as age, gender, and genetics. People can also be more at risk from toxic chemicals if they are taking certain drugs, if they have certain diseases, and if they are exposed to mixtures of chemicals. Very young and very old people are usually more susceptible to toxic chemicals than the rest of the population. Young children can absorb relatively large doses of chemicals, and the systems break down and get rid of chemicals have not yet matured, and parts of their body, such as their brains, are more easily damaged. Older people are more susceptible because their bodies may stored up larger amounts of certain chemicals. Also older people may have other diseases which could put them at greater risk from toxic chemicals. Men and women may differ in their response to chemicals in other ways. Women usually have lower body weight than men, and they will be more strongly affected by the same dose of chemical. Different genetic make-up and different proportions of body fat may also have an influence. For example, as women have a higher proportion of body fat than men, they are more prone than men to retain fat soluble chemicals such as pesticides.

Which has the highest LD50? Which has the lowest LD50? toxins LD50 (mg/kg) Ethyl alcohol 10,000 Salt (sodium chloride) 4,000 Iron (Ferrous sulfate) 1,500 Morphine 900 Mothballs (paradichlorobenzene) 500 Aspirin 250 DDT 250 Cyanide 10 Nicotine 1 Black Widow Spider venom 0.55 Rattle Snake venom 0.24 Tetrodotoxin (from fish) 0.01 Dioxin (TCDD) 0.001 Botulinum Toxin 0.00001 Notice that Botulinum Toxin (BOTOX) has the lowest LD50 – it is the most toxic of these substances.

Remember – The less you need to cause a toxic effect – the more toxic the substance is Thus an LD50 of 25 mg/kg is more toxic than is one of 7,000 mg/kg

Which is more toxic? Alcohol Morphine Nicotine Why?

A 75 kg person consumes 25 mg of tetradotoxin while eating puffer fish A 75 kg person consumes 25 mg of tetradotoxin while eating puffer fish. Is this dose dangerous? Explain why or why not?

Each black widow spider releases 2. 0 mg of venom with each bite Each black widow spider releases 2.0 mg of venom with each bite. How many bites would each person below need in order to have a 50% chance of death? 75 kg male 50 kg female 10 kg baby

How toxic is it? Safe Low Risk

The three possible signal words are The relative acute toxicity of a chemical is reflected on the label in the form of a “signal word” The (toxicologically) appropriate signal word MUST appear on every chemcial label The three possible signal words are CAUTION WARNING DANGER

Signal Words: CAUTION “Caution” reflects the lowest degree of relative toxicity All chemicals with an LD50 of greater than 500- ~5000 mg/kg must display this word on their package

Signal Words: WARNING “Warning” reflects an intermediate degree of relative toxicity All chemicals with an LD50 of greater than 50 and less than 500 mg/kg must display this word on their label Chemicals in this category are classed as “moderately toxic”

Signal Words: DANGER “Danger” reflects the highest degree of relative toxicity All chemicals with an LD50 of less than 50 mg/kg must display this word on their label chemicals here are classed as “highly toxic”

POISON!!! Legally defined term – not just anything you don’t like Any chemcial with an LD50 of 50 mg/kg or less Labels must reflect this classification Label must have the signal word “DANGER” plus the word “POISON” Label also must display the skull and crossbones icon

Distribution: Where the toxins accumulates in the body Fat soluble Water soluble Bone Muscle Once absorbed into the blood, the chemical is carried around the body in the blood stream, and where it ends up is influenced by its structure and properties. However, some barriers exist in the body which can keep out some (but not other) chemicals, such as the blood-brain barrier which helps protect the brain, and the placenta which helps protect a fetus. Inside the body, some chemicals are stored in certain tissues, such as fat or bone, and while they remain bound up there, they may do little damage. However, under certain conditions such as rapid weight loss, large amounts of the chemical are released into the blood. How long such chemicals remain in the body varies, but some, like the pesticide DDT, remain for years. One of the reasons why DDT stopped being used in the developed world was because of this persistence in the environment, and even though it has not been used for years in the developed world, most of us have DDT in our bodies.

Metabolism of toxins How the body breaks down a toxins Using enzymes in the body Where the toxin builds up Water-soluble toxins are easier to excrete How fast does the breakdown of the toxin take Can take hours, days, weeks or years If chemicals are not stored, the body deals with them by metabolizing (changing their structure) and excreting them. This occurs mainly in the liver, but also the skin, lungs, gut and kidneys, by similar processes used by our bodies to metabolize the chemicals which make up our food. The products of metabolism are known as metabolites, and these can be more or less toxic than the original chemical. In fact, many of the adverse effects of chemical exposure are due to the effects of metabolites. The pathways involved in metabolizing chemicals vary greatly between species, and also between individuals, which explains why some people are harmed by very low levels of chemicals that others seem able to tolerate. Chemicals and their metabolites are excreted from the body, mainly through urine produced by the kidneys. Small amounts are also excreted by the lungs, and in sweat, semen, milk, saliva and bile. The amount of a chemical a person has been exposed to can sometimes be estimated by measuring how much of the chemical, or certain metabolites, is found in urine. This is known as biological monitoring.

Half-life: How long it takes for ½ to go away 14 12 10 8 Concentration of toxins in blood (microgram/ml) 6 Chemicals can be degraded and eliminated by the body or may be stored in tissues, depending on the biochemical properties of the chemical. The 'Half-life' of a toxins refers to the amount of time it takes for the body to eliminate half of the amount of the toxins. Half-life is used as a measure of the lifespan of a chemical or toxic compound. The half-life of a chemical measures how much of the chemical is still available in the body. Some chemicals are eliminated quickly, and have short half-lives. Other chemicals accumulate in the body, and are eliminated very slowly. These chemicals have long half-lives (they are often called “persistent chemicals”). Chemicals that have long half-lives and that accumulate in the body can cause more disease than chemicals which are rapidly degraded and eliminated before producing disease. 4 2 1 2 3 4 5 6 7 8 9 10 11 Time (hours)

Half-life: How long it takes for ½ to go away 14 12 10 8 Concentration of toxins in blood (microgram/ml) Half life is 4 hours 6 4 2 1 2 3 4 5 6 7 8 9 10 11 Time (hours)

Which type of toxin most likely has the shortest half life? Water soluble toxin Fat soluble toxin Toxin that accumulates in the bones Toxin that accumulates in the muscles Why?

Risk Assessment Risk: The probability or likelihood that exposure to a particular toxins at a specific concentration or dose may cause an adverse effect. Risk Assessment: The process used to estimate the likelihood that humans will be adversely affected by a chemical or physical agent under a specific set of conditions. Risk assessment is the characterization of the potential adverse health effects of human exposures to a toxins. The toxicity of a substance is difficult to determine. In general, the toxicity of a chemical is determined through animal studies which are extrapolated to humans. The extrapolated values are calculated for the most sensitive humans (for example, children) because their immune systems are much weaker than the average healthy middle-aged person. Children are more susceptible to have an adverse effect through exposure to a hazardous chemical. oxicology data helps estimate the risk of exposure to certain chemicals.

An estimate of the likelihood that exposure to a toxins may cause harm Risk Assessment An estimate of the likelihood that exposure to a toxins may cause harm Toxicity Assessment Exposure Assessment Chemicals are tested for toxicity and the results of these tests are used to decide how chemicals are used, controlled, labeled, and regulated in the workplace. Toxicity studies can be divided into laboratory studies using live animals (in vivo studies) or groups of cells (in vitro studies), and studies of human populations (epidemiological studies). Animal studies are used to test chemicals for their acute and chronic toxicity by various routes of exposure. The standard way of measuring a chemical's acute toxicity is to feed it at a range of single doses to groups of laboratory animals, such as rats. The dose that kills 50% of the group (the LD50), is then recorded as well as the effects noticed in the animals. The effects of chronic exposure are also tested in animals. In these tests, the animals are fed, inhale, or have the chemical painted on their skins throughout their lives. The type and amount of disease they develop are then compared with the effects in a control group. The controls should be the same as the exposed group in every respect except the chemical exposure. They should, for example, be the same strain of the same species, and be fed the same diet. The differences in rates of various diseases are then tested by various statistical means to see if they are significant. If a study is badly designed, its results will not be reliable. For example, when testing chemicals for their cancer-causing effect on animals, the US National Cancer Institute required that the chemical should be tested at two doses in both sexes of two species of rodent, and each group should contain at least 50 animals. Trying to predict what will happen in humans is one of the major problems of animal testing. Risk Assessment

Toxicity Assessment Toxicity testing: Determines the hazard which a substance may present to humans Exposure limits are established If exposure to the substance is kept below the exposure limit, the risk from the substance is considered to be acceptable. Risk assessment is the characterization of the potential adverse health effects of human exposures to a toxins. The toxicity of a substance is difficult to determine. In general, the toxicity of a chemical is determined through animal studies which are extrapolated to humans. The extrapolated values are calculated for the most sensitive humans (for example, children) because their immune systems are much weaker than the average healthy middle-aged person. Children are more susceptible to have an adverse effect through exposure to a hazardous chemical. oxicology data helps estimate the risk of exposure to certain chemicals.

Exposure Assessment Must evaluate potential for exposure to a substance: What is the chemical properties? How often will you encounter it? How might it enter the body? How long does it remain in the body? Risk assessment is the characterization of the potential adverse health effects of human exposures to a toxins. The toxicity of a substance is difficult to determine. In general, the toxicity of a chemical is determined through animal studies which are extrapolated to humans. The extrapolated values are calculated for the most sensitive humans (for example, children) because their immune systems are much weaker than the average healthy middle-aged person. Children are more susceptible to have an adverse effect through exposure to a hazardous chemical. oxicology data helps estimate the risk of exposure to certain chemicals.

Risk Assessment Must take into account the possible harmful effects of the toxins on many individual people Risk assessment is the characterization of the potential adverse health effects of human exposures to a toxins. The toxicity of a substance is difficult to determine. In general, the toxicity of a chemical is determined through animal studies which are extrapolated to humans. The extrapolated values are calculated for the most sensitive humans (for example, children) because their immune systems are much weaker than the average healthy middle-aged person. Children are more susceptible to have an adverse effect through exposure to a hazardous chemical. oxicology data helps estimate the risk of exposure to certain chemicals.

Risk is only part of the picture Risks are only half of the story.

Choices As part of our society, you must make decisions which assess risks, benefits, and potential trade-offs. Thalidomide: Leprosy treatment vs. birth defects Pesticides: Mosquito abatement vs. toxicity Sunlight: Vitamin D and skin cancer Each of us makes decisions at the voting booth, in what we purchase, in everything we do.

Tradeoffs Plan to reduce risks to take advantage of the benefits offered by use of a particular ‘product.’ Sunlight: Vitamin D and skin cancer

Precautionary Principle If the consequences of an action are unknown, but judged to have some potential for negative consequences, then it is better to avoid that action. “Better safe than sorry.”

Identifying Risks To identify possible risks from exposure to a particular toxins, scientists use simple plants or animals, rather than humans, as test subjects. Canary in a coal mine

Bioassay A procedure that uses living organisms to determine the toxicity of a chemical. 1. Expose living organisms to different concentrations of a potential toxins 2. Observe the effects on the organisms’ behavior and survival 3. Determine if, or at what concentration, a chemical has harmful effects A method used to determine the toxicity of specific chemical contaminants. A number of individuals of a sensitive species are placed in water containing specific concentrations of the contaminant for a specified period of time. www.nsc.org/ehc/glossary.htm Alternative use as an indirect measure of concentration: A method for quantitatively determining the concentration of a substance by its effect on the survival, development, growth, behavior, or measurable physiological response of a suitable animal, plant, or microorganism under controlled conditions. www.seagrant.sunysb.edu/BTRI/btriterms.htm

Model Organisms What type of model organism would you use to determine effects to humans? What other kinds of organisms might be used for bioassays?

Units Used to Measure Chemicals in the Environment PPM – Parts per million PPB – Parts per billion PPT – Parts per trillion

One part per million is 1 inch in 16 miles 1 minute in two years 1 cent in $10,000 1 ounce of salt in 31 tons of potato chips 1 bad apple in 2,000 barrels of apples

One part per billion is 1 inch in 16,000 miles 1 second in 32 years 1 cent in $10,000,000 1 pinch of salt in 10 tons of potato chips 1 lob in 1,200,000 tennis matches 1 bad apple in 2,000,000 barrels of apples

One part per trillion is 1 postage stamp in the area of the city of Dallas 1 inch in 16 million miles (more than 600 times around the earth) 1 second in 320 centuries 1 flea on 360 million elephants 1 grain of sugar in an Olympic sized pool 1 bad apple in 2 billion barrels

ppm to % ppm X 100 = % 1,000,000

Example: What is the percent concentration of a 5000 ppm solution?

% to ppm % concentration X 10,000 = ppm

Example: What is the part per million of a 4. 5 % solution. 4 Example: What is the part per million of a 4.5 % solution? 4.5 X 10,000 = 45,000 ppm

Grams of solute to ppm Gram of solute X 1,000,000 = ppm Grams of solvent

Example: 50 grams of sodium chloride was dissolved in 500 grams of water. What is the ppm of sodium chloride in solution?

Example: 90 grams of sucrose was placed in 750 mL of water Example: 90 grams of sucrose was placed in 750 mL of water. What is the ppm of sucrose in solution?

A student wanted to make up a 5. 0 % solution of nicotine A student wanted to make up a 5.0 % solution of nicotine. How should he/she do this?

1st step: change percent to ppm

2nd step: Determine the grams of solute * You determine the volume of solvent ppm X grams of solvent = grams of solute 1,000,000