Risk, Toxicology, and Human Health. G. Tyler Miller’s Living in the Environment Chapter 11. Key Concepts. Types of hazards people face Methods and methods of toxicology Types and measurement of chemical hazards Types and effects of biological hazards
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Risk, Toxicology, and Human Health G. Tyler Miller’s Living in the Environment Chapter 11
Key Concepts • Types of hazards people face • Methods and methods of toxicology • Types and measurement of chemical hazards • Types and effects of biological hazards • Risk estimation, management, and reduction
Hazard and Risk Risks and hazards—some avoidable, some not—compromise everyday life. Arisk is a measure of your likelihood of suffering harm from a hazard. The probability of exposure x probability of harm. (R=Exposure x Harm) Hazard may cause injury, disease, economic loss, or environmental damage. Risk assessment is projected as a probability: It gives the estimate of an event’s actually happening. Risk management involves deciding whether or how to reduce a particular risk to a certain level and at what cost.
Risk Assessment Risk Management Hazard identification What is the hazard? Probability of risk How likely is the event? Consequences of risk What is the likely damage? Comparative risk analysis How does it compare with other risks? Risk reduction How much should it be reduced? Risk reduction strategy How will the risk be reduced? Financial commitment How much money should be spent? Components of Risk
5major types of hazards. • Cultural hazard: unsafe working conditions, smoking, poor diet, drugs, unsafe sex, poverty, criminal assault, etc. • 2. Chemical hazards are harmful chemicals in the air, water, soil, and food. Over 500 synthetic organic chemicals are present in our bodies…none of which were in existence 90 years ago. • 3. Physical hazards : radioactivity, fire, earthquake, floods, etc. • 4. Biological hazards: pathogens, pollen, other allergens, and animals such as bees and poisonous snakes. • 5. Environmental: malnutrition, smoking, cooking fires, skin cancer, exposure to pesticides and hazardous chemicals, air and water pollution = 40%of world’s annual deaths
Toxicology: Assessing Chemical Hazards Toxicity measures how harmful a substance is in causing injury, illness, or death to a living organism. Harm depends on 6 factors: Dose: amount of a substance. Size of dose over a period of time Frequency of exposure Age and sizeof the individual exposed, Body’s detoxification system, and Genetic makeupof the individual,
Five major factorscan affect the harm caused by a substance. A substance harm is measured by its resistance to breakdown factors Solubility:Inorganic and organic water-soluble toxins can move throughout the environment. Oil- or fat-soluble toxins can in the body. Persistence:resist breakdown and have long-lasting harmful effects. CFC’s Bioaccumulation:absorbed and stored in the body at higher than normal levels. Biomagnification:moved up from one trophic level to the next higher one. (DDT, PCB, radioactivity Chemical interactions:can decrease or multiply the harmful effects. Antagonistic interaction reduces. (vitamins).Synergisticinteraction multiplies the harmful effects.
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 0.000003 ppm, Or 3 ppm Number of individuals affected Very Sensitive Majority of population Very Sensitive 0 20 40 60 80 Dose (hypothetical units) .The type and amount of health damage due to exposure(response) a. Acute effect: immediate and rapid reaction(dizziness, rash) b. Chronic effect: permanent or long-term consequences (kidney / liver damage)
Toxins in the Environment Should we be concerned? Depends on chemical and it’s concentration. Toxicology: any synthetic or natural chemical can be harmful if ingested in large enough amt. • “The dose makes the poison”(water, coffee) • Concentration is the key • Synthetic v natural chemical
100 75 Percentage of population killed by a given dose 50 LD 50 0 2 4 6 8 10 12 14 16 Dose (hypothetical units) Poisons A poison or toxin is a chemical that adversely affects the health of a living human or animal by causing injury, illness, or death. Lethal Dose:estimating toxicity A median lethal dose (LD50)for a chemical is the amount in one dose that kills 50% of the test animals within a 14-day period. Threshold: a minimum dosage that must be reached before detectable harm occurs Non-threshold dose response: any dose of toxin that causes harm & increases with dosage (usually causing birth defects) 25
Use of Dose-Response Relationship Toxicity Rating LD50 mg/kg body weight Average LD Examples Supertoxic Less than .01 Less than 1 drop Nerve gas, botulism, mushroom toxin, dioxin Extremely toxic Less than 5 Less than 7 drops K cyanide, heroin, nicotine, parathion Very toxic 5-50 7 drops – 1 tsp Hg salts, morphine, codeine Toxic 50-500 1 tsp - 1 ounce Pb salts, DDT, H2SO4, NaOH Mod. Toxic 500-5,000 1 oz – 1 pint Methyl alcohol, ether, kerosene Slightly toxic 5000-15,000 1 pt – 1 quart Ethyl alcohol, Lysol, soaps Non toxic 15,000 or greater More than 1 qt Water, glycerin, sugar
How do we determine harmful effects? • Case Reports: usually through primary care physicians; accidental poisoning, drug OD suicide stats..quantitative • Epidemiological studies: exposed group v control group; statistics, levels, if problem exists..statistical, limited(small group, new drug • Lab experiments: decrease in animal tests • Toxicity levels and dose response curves : no threshold vs. threshold
Chemical Hazards Toxic chemicals can kill, and hazardous chemicals can cause various types of harm. Toxic chemicals: fatal to more than 50% of lab animals at a given concentration Hazardous: flammable or explosive; irritant to lungs/skin; interfering with O2 uptake (CO and H2S); inducing allergic reaction 3 major types of toxic agents: Mutagensare chemicals or ionizing radiation that cause or increase random mutations in the DNA molecules. No safe threshold for exposure. Teratogensare chemicals that cause harm or birth defects to a fetus or embryo. Ex: Alcohol Carcinogens are chemicals or ionizing radiation that cause or promote cancer. ) 80% are due to lifestyle and environmental factors…smoking, diet, job exposure, pollution.
Interaction of chemicals: How can they harm systems? • Long term, low level exposure can disrupt and weaken the body’s immune, nervous, endocrine systems. -Immune system: can be weakened by ionizing radiation, viruses, some synthetic chemicals (pesticides),malnutrition -Nervous system: neurotoxins…chlorinated hydrocarbons, pesticides, formaldehyde, cadmium, TCE, toluene, xylene -Endocrine system: hormonally active agents, hormone mimics (estrogen), hormone blockers (androgens) Page 235 connections
Biological Hazards: Diseases Non-transmissible disease:Caused by living organisms, and do not spread from one person to another. Examples: cancer, diabetes, asthma, malnutrition, and blood vessel disorders. Transmissible disease: Caused by living organism and spread. Infectious agents/pathogens are spread in air, water, food, and body fluids and by some insects and vectors. Deaths/year : WHO 30% by non-transmissible cardiovascular disease, 26% by transmissible infectious disease, and 12% by non-transmissible cancers. As a country industrializes infectious disease-caused deaths decreases and chronic diseases of adulthood increase. NEWS:Death from infectious diseases has decreased, but many bacteria have developed immunity to widely used antibiotics.
Anopheles mosquito (vector) in aquatic breeding area eggs adult larva pupa 1. Female mosquito bites infected human, ingesting blood that contains Plasmodium gametocytes 4. Parasite invades blood cells, causing malaria and making infected person a new reservoir 2. Plasmodium develops in mosquito 3. Mosquito injects Plasmodium sporozoites into human host Transmittable disease - Malaria
World’s Deadliest Infectious Agents. • Acute respiratory infection: pneumonia/flu • HIV/AIDs – kills 4 million/yr • Diarrheal disease • TB • Malaria • Hepatitis B • measles
How rapid are viral diseases spreading? • STD’s: 23% Americans; 15.3 million people/year affected; can cause infertility, warts, genital CA, death • AIDS: Acquired Immune Deficiency Syndrome, Caused by HIV ( Human Immunodeficient Virus) by 2001 40 million world- wide affected. In 2001 5.4 million are newly infected; (80% in sub-Saharan Africa/Asia; by 2001 25 million have died of AIDS related diseases • TB and HIV/AIDS are synergistic interactions
Solutions Infectious Diseases Increase research on tropical diseases and vaccines Reduce poverty Decrease malnutrition Improve drinking water quality Reduce unnecessary use of antibiotics Educate people to take all of an antibiotic prescription Reduce antibiotic use to promote livestock growth Careful hand washing by all medical personnel Immunize children against major viral diseases Oral rehydration for diarrhea victims Global campain to reduce HIV/AIDS
Risk Analysis There are scientific ways to evaluate and compare risk, to decide how much risk is acceptable, and find affordable ways to reduce risk. Risk assessment involves identifying hazards and evaluating their associated risks. Poverty: the greatest risk. Premature deaths per year and reduced life span. Reducing poverty would improve human rights, provide more people with income to stimulate economic development, and reduce environmental degradation and the threat of terrorism. Avoidance of cultural hazards also improves longevity of life.
Cause of Death Annual Deaths 11 million (75) Poverty/malnutrition/ disease cycle Tobacco 5 million (34) Pneumonia and flu 3.2 million (22) Air pollution 3 million (21) HIV/AIDS 3 million (21) 1.9 million (13) Diarrhea TB 1.7 million (12) Auto accidents 1.2 million (8) 1.1 million (8) Work-related injury and disease 1 million (7) Malaria 1 million (7) Hepatitis B 800,000 (75) Measles
Risk Management and what are the limitations Risk management means answering the following questions. How reliable is the risk analysis for each risk? Who profits from these numbers? Which risks have the highest priority? Short or long term How much risk is acceptable? How much is a life worth? How much will it cost to reduce each risk to an acceptable level? How should funds be spent to provide the greatest benefit? How will the risk management plan be monitored, enforced, and communicated to the public?
Risk probability Risk assessment Risk severity Is the risk acceptable? Cost–benefit Expressed preferences Acceptable if benefits outweigh costs Acceptable if people agree to accept the risks Natural standards Revealed preferences Acceptable if risk is not greater than those created by natural hazard Acceptable if risk is not greater than those currently tolerated Risk Analysis • Risk analysis • Comparative riskanalysis • Cost-benefitanalysis • Risk management • Risk perception Fig. 16.14, p. 412
Hazard Shortens average life span in the United States by Poverty 7-10 years Born male 7.5 years Smoking 6-10 years Overweight (35%) 6 years Unmarried 5 years Overweight (15%) 2 years Spouse smoking 1 year Driving 7 months Air pollution 5 months Alcohol 5 months Drug abuse 4 months Flu 4 months AIDS 3 months Air Pollution 2 months Drowning 1 month Pesticides 1 month Fire 1 month Natural radiation 8 days Medical X rays 5 days Oral contraceptives 5 days Toxic waste 4 days Flying 1 day Hurricanes, tornadoes 1 day Living lifetime near nuclear plant 10 hours