Risk and Toxicology Chapter 18

Smoking in the US Smoking is the number one killer in the US Smoking is the number one killer in the US Worldwide, infectious disease is the number one killer. (This includes TB, HIV, malaria, flu, measles, cholera, and yellow fever.) Worldwide, infectious disease is the number one killer. (This includes TB, HIV, malaria, flu, measles, cholera, and yellow fever.) One study shows that adolescents who smoke more than 1 cigarette have an 85% chance of becoming smokers. One study shows that adolescents who smoke more than 1 cigarette have an 85% chance of becoming smokers.

Risk Risk is the possibility of suffering from a hazard Risk is the possibility of suffering from a hazard A hazard may cause economic loss, environmental loss, injury, disease or death A hazard may cause economic loss, environmental loss, injury, disease or death Risk = exposure X harm Risk = exposure X harm

Hazards Cultural – diet, drugs, drinking, driving, criminal assault, unsafe sex, and poverty Cultural – diet, drugs, drinking, driving, criminal assault, unsafe sex, and poverty Chemical – harmful chemicals in air, water, food and soil. Most people carry around 500 synthetic chemicals in their bodies, whose effects are currently unknown. (buy organic) Chemical – harmful chemicals in air, water, food and soil. Most people carry around 500 synthetic chemicals in their bodies, whose effects are currently unknown. (buy organic) Physical – ionizing radiation, fire, earthquakes, floods, volcanoes, hurricanes, etc. Physical – ionizing radiation, fire, earthquakes, floods, volcanoes, hurricanes, etc. Biological – pathogens, pollens, allergens, animals that bite or sting, parasites Biological – pathogens, pollens, allergens, animals that bite or sting, parasites

Toxicology Toxicity – measure of how harmful a substance is. Toxicity – measure of how harmful a substance is. Dose – the amount substance introduced to the body Dose – the amount substance introduced to the body Vector - agent of disease transmission Vector - agent of disease transmission Not all people are affect the same by the same dose Not all people are affect the same by the same dose

Fig. 16.3, p. 398 Very Sensitive Majority of population Very Sensitive Dose (hypothetical units) Number of individuals affected

Bioaccumulation Some substances are fat or oil soluble (usually organic compounds) and can be stored in body tissues and cells. Some substances are fat or oil soluble (usually organic compounds) and can be stored in body tissues and cells. When a substance is ingested in very small doses, but is stored in the body, it accumulates to a higher dose over time (bioaccumulation) When a substance is ingested in very small doses, but is stored in the body, it accumulates to a higher dose over time (bioaccumulation)

Biomagnification When a substance that bioaccumulates is passed up the food chain, each trophic level receives a higher dose of the substance When a substance that bioaccumulates is passed up the food chain, each trophic level receives a higher dose of the substance This is biomagnification This is biomagnification Animals at the top of the food chain can be exposed to very high doses and hence are usually affected the most (birds and fish) Animals at the top of the food chain can be exposed to very high doses and hence are usually affected the most (birds and fish)

Fig. 16.4, p. 399 DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water ppm, Or 3 ppm

Major Bioaccumulants DDT DDT PCB’s (a class of oily chemicals used in electrical transformers) PCB’s (a class of oily chemicals used in electrical transformers) Radioactive isotopes (strontium-90) Radioactive isotopes (strontium-90) Dioxin Dioxin Other organo-chlorides Other organo-chlorides

Poison A poison is a substance that has an LD 50 of 50 or less. A poison is a substance that has an LD 50 of 50 or less. LD 50 stands for the lethal dose in milligrams of a substance that kills 50 percent of the test organisms (usually rats and mice) per kilogram of body weight. LD 50 stands for the lethal dose in milligrams of a substance that kills 50 percent of the test organisms (usually rats and mice) per kilogram of body weight. So 50 milligrams of “poison” will kill 50 percent of organisms weighing 1 kilogram So 50 milligrams of “poison” will kill 50 percent of organisms weighing 1 kilogram

Fig. 16.5, p Percentage of population killed by a given dose Dose (hypothetical units) LD 50

Dose-response curve Different substance act at different rates and at different concentrations. Different substance act at different rates and at different concentrations. The data of the response tells a lot about the toxicity of a substance The data of the response tells a lot about the toxicity of a substance Substances without threshold levels cause harm even at small doses Substances without threshold levels cause harm even at small doses

Fig. 16.6, p. 401 Effect Dose Nonlinear dose-response Linear dose-response No threshold Effect Nonlinear dose-response Linear dose-response Threshold level Dose

Toxicity for humans Supertoxic – less than.01 – nerve gas, dioxin Supertoxic – less than.01 – nerve gas, dioxin Extremely toxic – less than 5 – nicotine, heroin, atropine, potassium cyanide, parathion Extremely toxic – less than 5 – nicotine, heroin, atropine, potassium cyanide, parathion Very toxic – 5-50 – morphine, codeine, mercury salts Very toxic – 5-50 – morphine, codeine, mercury salts Toxic – 50 – 500 – Lead salts, DDT, carbon tetrachloride, caffeine, sulfuric acid Toxic – 50 – 500 – Lead salts, DDT, carbon tetrachloride, caffeine, sulfuric acid Moderately toxic – 500 – 5,000 Moderately toxic – 500 – 5,000 Slightly toxic – 5,000 – 15,000 Slightly toxic – 5,000 – 15,000

Chemical Hazards Toxic chemicals are those that are fatal to 50% of the test population at given concentrations Toxic chemicals are those that are fatal to 50% of the test population at given concentrations Hazardous chemicals cause harm by: Hazardous chemicals cause harm by: Being flammable or explosive Being flammable or explosive Irritating or damaging skin or lungs - acidic/basic Irritating or damaging skin or lungs - acidic/basic Interfering with oxygen uptake - asphyxiants Interfering with oxygen uptake - asphyxiants Inducing allergic reactions Inducing allergic reactions

Neurotoxins Can effect behavioral changes, learning disabilities, ADD, paralysis and death Can effect behavioral changes, learning disabilities, ADD, paralysis and death Examples Examples PCBs - Polychlorinated biphenol PCBs - Polychlorinated biphenol Methyl mercury Methyl mercury Arsenic Arsenic lead lead

Mutagens Agents (chemicals or other (ionizing radiation)) that cause mutations in DNA Agents (chemicals or other (ionizing radiation)) that cause mutations in DNA Most mutations are harmless, but mutations in sperm or egg cells can cause genetic defects like Down’s syndrome, hemophilia, sickle cell anemia, manic depression and thalasseamia Most mutations are harmless, but mutations in sperm or egg cells can cause genetic defects like Down’s syndrome, hemophilia, sickle cell anemia, manic depression and thalasseamia Mutations in other cells are not inherited, but may still cause harm Mutations in other cells are not inherited, but may still cause harm

Teratogens Agents (chemicals, viruses, radiation) that cause birth defects while the human embryo is developing Agents (chemicals, viruses, radiation) that cause birth defects while the human embryo is developing Especially during first trimester Especially during first trimester PCB’s, Thalidomide, Steroid hormones, and metals (arsenic, cadmium, lead, and mercury) PCB’s, Thalidomide, Steroid hormones, and metals (arsenic, cadmium, lead, and mercury)

Carcinogens Agents that promote growth of malignant tumors Agents that promote growth of malignant tumors Cigarette smoke is a major agent in the US Cigarette smoke is a major agent in the US Usually a lag time of 10 – 40 years from initial exposure to development of cancer Usually a lag time of 10 – 40 years from initial exposure to development of cancer Usually due to chronic exposure Usually due to chronic exposure

Synthetic Chemicals Many synthetics can harm the brain and spinal cord and peripheral nerves Many synthetics can harm the brain and spinal cord and peripheral nerves Neurotoxins attack the nerve cells Neurotoxins attack the nerve cells Chlorinated hydrocarbons (DDT, PCBs, dioxin) Chlorinated hydrocarbons (DDT, PCBs, dioxin) Organophosphate pesticide Organophosphate pesticide Formaldehyde Formaldehyde Compounds of arsenic, mercury, lead, cadmium Compounds of arsenic, mercury, lead, cadmium Solvents (trichloroethylene (TCE), toluene and xylene Solvents (trichloroethylene (TCE), toluene and xylene

Chemicals released each year The US releases more than 1,000 new synthetic chemicals into the marketplace each year The US releases more than 1,000 new synthetic chemicals into the marketplace each year 99.5% of these chemicals are not regulated by the federal government 99.5% of these chemicals are not regulated by the federal government Only 2% of 85,000 synthetic chemicals are adequetly tested Only 2% of 85,000 synthetic chemicals are adequetly tested Chemicals can interact within the body or environment to create new chemicals Chemicals can interact within the body or environment to create new chemicals

The Bodies Defenses Immune system - antibodies and cellular defense - fights against disease and harmful substances Immune system - antibodies and cellular defense - fights against disease and harmful substances Endocrine system - regulate hormones/growth and development Endocrine system - regulate hormones/growth and development Hormone mimics disrupt the endocrine sys Hormone mimics disrupt the endocrine sys Dioxins, PCB’s, DDT, lead, other pesticides (especially chloronated hydrocarbons) Dioxins, PCB’s, DDT, lead, other pesticides (especially chloronated hydrocarbons)

Transmissible diseases Transmissible diseases are caused by living organisms Transmissible diseases are caused by living organisms These infectious agents are spread by air, water, food, bodily fluid, insects and other vectors These infectious agents are spread by air, water, food, bodily fluid, insects and other vectors 80% of illness in developing countries is from waterborne infectious diseases (diarrhea, hepatitis, typhoid fever, cholera) mainly from unsafe drinking water and inadequate sanitation 80% of illness in developing countries is from waterborne infectious diseases (diarrhea, hepatitis, typhoid fever, cholera) mainly from unsafe drinking water and inadequate sanitation

7 Deadly Diseases According to WHO the seven deadliest infectious diseases are: According to WHO the seven deadliest infectious diseases are: Acute respiratory infection (pneumonia, flu) Acute respiratory infection (pneumonia, flu) HIV/ AIDS HIV/ AIDS Diarrheal diseases Diarrheal diseases TB tuberculosis TB tuberculosis Malaria Malaria Measles Measles Hepatitis B Hepatitis B

Virus vs. Bacteria Viral disease Viral disease AIDS AIDS Ebola Ebola Influenza Influenza Rabies Rabies Avian or bird flu Avian or bird flu West Nile virus West Nile virus SARS SARS Hepatitus B Hepatitus B Bacterial disease Bacterial disease Tuberculosis (TB) Lyme disease Pneumonia

Tuberculosis A highly infectious bacterial disease A highly infectious bacterial disease It is estimated that between 2006 and million people will die of tuberculosis, most of which live in developing countries It is estimated that between 2006 and million people will die of tuberculosis, most of which live in developing countries Half of the people infected with TB do not know they have it and can infect another people on average Half of the people infected with TB do not know they have it and can infect another people on average

Tuberculosis Population growth, urbanization, and air travel have increased contact with TB Population growth, urbanization, and air travel have increased contact with TB Luckily four inexpensive drugs in combination can cure 90% of cases, but the drugs must be taken every day for 6-8 months Luckily four inexpensive drugs in combination can cure 90% of cases, but the drugs must be taken every day for 6-8 months Because symptoms disappear after a few weeks, many patients stop taking the medication Because symptoms disappear after a few weeks, many patients stop taking the medication

Tuberculosis The incidence of TB has increased due to The incidence of TB has increased due to Increased size in population Increased size in population Increased number of elderly in the population Increased number of elderly in the population Poverty Poverty World travel World travel TB bacterium have developed resistance to antiobiotics TB bacterium have developed resistance to antiobiotics Weakened immune systems (from AIDS and other diseases) Weakened immune systems (from AIDS and other diseases)

Malaria Symptoms come and go and include: fever, anemia, enlarged spleen, severe abdominal pain, headaches, extreme weakness to other diseases Symptoms come and go and include: fever, anemia, enlarged spleen, severe abdominal pain, headaches, extreme weakness to other diseases Kills about 1.5 million each year, most under 5 Kills about 1.5 million each year, most under 5 Caused by parasitic protozoa (Plasmodium) passed on typically by Anopheles mosquitoes Caused by parasitic protozoa (Plasmodium) passed on typically by Anopheles mosquitoes

Reduction in Malaria Incidences of malaria were temporarily decreased during the mid 1900’s Incidences of malaria were temporarily decreased during the mid 1900’s Draining wetlands/swamps Draining wetlands/swamps Spraying DDT to kill mosquitos Spraying DDT to kill mosquitos Use of drugs to kill parasite in patients Use of drugs to kill parasite in patients Increased awareness of symptoms for early treatment Increased awareness of symptoms for early treatment Unfortunately, since 1970 malaria has risen due to genetic resistance and deforestation

West Nile Virus Transferred to humans by mosquitos Transferred to humans by mosquitos It arrived in the US in 1999 (estimated) It arrived in the US in 1999 (estimated) Since then has spread coast to coast and infected more than 1.2 million people Since then has spread coast to coast and infected more than 1.2 million people

SARS Severe acute respiratory syndrome Severe acute respiratory syndrome First appeared in 2002 in China First appeared in 2002 in China Flu-like symptoms that can quickly turn to pneumonia (and death) Flu-like symptoms that can quickly turn to pneumonia (and death) Spread quickly in 2003, but was contained by WHO and other local agencies Spread quickly in 2003, but was contained by WHO and other local agencies

Lyme Disease Spread by deer ticks Spread by deer ticks Bacteria that attacks the nervous system Bacteria that attacks the nervous system The bite from the tick leaves a red bulls-eye target on the skin The bite from the tick leaves a red bulls-eye target on the skin With immediate antiobiotics the effects are minimal With immediate antiobiotics the effects are minimal

Poverty This is the greatest risk humans face This is the greatest risk humans face Other than poverty, most people face the greatest risk from their lifestyle choices Other than poverty, most people face the greatest risk from their lifestyle choices Avoid risk – no smoking, avoid excess sun, low to zero alcohol consumption, reduce cholesterol and saturated fats, eat a variety of fruits and vegetables, exercise, lose excess weight, and use safety equipment (seatbelts, helmets, life jackets, etc) Avoid risk – no smoking, avoid excess sun, low to zero alcohol consumption, reduce cholesterol and saturated fats, eat a variety of fruits and vegetables, exercise, lose excess weight, and use safety equipment (seatbelts, helmets, life jackets, etc)

The End Stay healthy Stay healthy Live long Live long Enjoy life! Enjoy life!