Risk, Toxicology and Human HeathPresentation Transcript
G. Tyler Miller’s Living in the Environment 14th Edition Chapter 19 Risk, Toxicology, and Human Health Shohail Motahir Choudhury
Types of hazards people face
Methods of toxicology
Types and measurement of chemical hazards
Types and effects of biological hazards
Risk estimation, management, and reduction
Hazard and Risk A risk is a measure of your likelihood of suffering harm from a hazard. Risks and hazards—some avoidable, some not—compromise everyday life. 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.
Hazard identification What is the hazard? Probability of risk How likely is the event? Consequences of risk What is the likely damage? Risk Assessment Risk Management 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?
4 major 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.
3. Physical hazards : radioactivity, fire, earthquake, floods, etc.
4. Biological hazards: pathogens, pollen, other allergens, and animals such as bees and poisonous snakes.
Toxicology: Assessing Chemical Hazards
Toxicity measures how harmful a substance is in causing injury, illness, or death to a living organism.
Harm depends on factors:
Dose: amount of a substance.
Frequency of exposure
Age and size of the individual exposed,
Body’s detoxification system , and
Genetic makeup of the individual,
Five major factors can affect the harm caused by a substance.
Solubility: 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.
Bioaccumulation: absorbed and stored in the body at higher than normal levels.
Biomagnification: moved up from one trophic level to the next higher one.
Chemical interactions: can decrease or multiply the harmful effects.
Antagonistic interaction reduces. Synergistic interaction multiplies the harmful effects.
Effects can be chronic or acute. 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 Very Sensitive Majority of population Very Sensitive 0 20 40 60 80 Dose (hypothetical units) Number of individuals affected
Poisons 25 Fig. 16.5, p. 400 See Table 16-1 p. 400 Five top toxic named by the EPA: arsenic, lead, mercury, vinyl chloride, and polychlorinated biphenyls. 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. 100 75 50 0 2 4 6 8 10 12 14 16 Percentage of population killed by a given dose Dose (hypothetical units) LD 50
Chemical Hazards Toxic chemicals can kill, and hazardous chemicals can cause various types of harm. 3 major types of toxic agents: Mutagens are chemicals or ionizing radiation that cause or increase random mutations in the DNA molecules. No safe threshold for exposure. Teratogens are 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.
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.
3. Mosquito injects Plasmodium sporozoites into human host 2. Plasmodium develops in mosquito 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 Anopheles mosquito (vector) in aquatic breeding area eggs larva pupa adult
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
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 Pneumonia and flu Air pollution HIV/AIDS Diarrhea TB Auto accidents Work-related injury and disease Malaria Hepatitis B Measles 5 million (34) 3.2 million (22) 3 million (21) 3 million (21) 1.9 million (13) 1.7 million (12) 1.2 million (8) 1.1 million (8) 1 million (7) 1 million (7) 800,000 (75)
7-10 years Poverty Born male Smoking Overweight (35%) Unmarried Overweight (15%) Spouse smoking Driving Air pollution Alcohol Drug abuse AIDS Drowning Pesticides Fire Natural radiation Medical X rays Oral contraceptives Toxic waste Flying Hurricanes, tornadoes Living lifetime near nuclear plant 6-10 years 5 years 2 years 1 year 7 months 5 months 4 months 4 months 3 months 2 months 1 month 1 month 8 days 5 days 5 days 4 days 1 day 1 day 10 hours Flu Air Pollution 6 years 5 months 1 month 7.5 years Hazard Shortens average life span in the United States by
Risk management means answering the following questions.
How reliable is the risk analysis for each risk?
Which risks have the highest priority?
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?
Comparative risk analysis
Fig. 16.14, p. 412 Risk probability Risk assessment Risk severity Is the risk acceptable? Acceptable if benefits outweigh costs Cost–benefit Expressed preferences Acceptable if people agree to accept the risks Natural standards Acceptable if risk is not greater than those created by natural hazard Revealed preferences Acceptable if risk is not greater than those currently tolerated