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Risk, Toxicology and Human Health

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1 Risk, Toxicology and Human Health
AP Environmental Science Chapter 8

2 Human Health Health is a state of complete physical, mental, social and spiritual well-being and not merely the absence of disease or infirmity (disability) or The ability to lead a socially and economically productive life

3 Holistic Concept of Health
This concept recognizes the strength of social, economic, personal freedom and environmental influences on health Determinants Heredity Health and family welfare services Environment Life-style Socio-economic conditions

4 Disease Disease results from the complex interaction between man, an agent and the environment Ecological point of view – “maladjustment of the human organism to the environment”

5 Vector (how infected: water, pollution, insect, contact)
Epidemilogical Triad Any Environment  Vector (how infected: water, pollution, insect, contact)  Pathogen: (Virus/bacteria) (Organism) Agent Host

6 Key Concepts Types of Hazards Exposure Assessment
Risk estimation, management, and reduction

7 Types of Hazards Biological Hazards
These are living organisms or their products that are harmful to humans

8 Biological Hazards Water-borne diseases Transmitted in drinking water
Disease organisms shed into water in feces Can produce illness in those who consume untreated, contaminated water

9 Biological Hazards Water-borne diseases
municipal water treatment facilities are usually able to purify water removing these agents by filtration killing them by disinfection

10 Biological Hazards Water-borne diseases Examples Polio virus
Hepatitis A virus Salmonella Shigella Cholera Amoebic dysentery Giardia Cryptosporidium

11 E. coli outbreak in Walkerton
In May 2000 the small community of Walkerton, Ontario was laid waste by a toxic strain of E. coli:0157. The contamination came from the public water supply. Six people died in the first week including a two year old daughter of a local medical doctor. Four new cases surfaced in late July, all very young children. Over a thousand innocent people were infected. The primary cause was manure spread on a farm near a well…but the fault was that the Walkerton PUC workers did not monitor the water quality, in some cases falsifying entries into their logs…. bss.sfsu.edu/ehines/geog600/ Freshwater%20and%20ocean%20Pollution.ppt

12 Waterborne Bacteria Disease symptoms usually are explosive emissions from either end of the digestive tract Escherichia coli Vibrio sp. Barbara E. Moore, Ph.D., Department of Biology, University of Texas at San Antonio

13 Waterborne Protozoans
Disease symptoms are usually explosive emissions from either end of the digestive tract *P. Darben Giardia sp.* Barbara E. Moore, Ph.D., Department of Biology, University of Texas at San Antonio

14 Waterborne Human Viruses
Hepatitis A virus Hepatitis E virus Norwalk virus* Rotavirus* *F. Williams Barbara E. Moore, Ph.D., Department of Biology, University of Texas at San Antonio

15 Indicator Tests Total coliform [Endo agar] Fecal coliform [m-FC agar]
Fecal streptococci [M-enterococcus] Prescott et al., Microbiology Barbara E. Moore, Ph.D., Department of Biology, University of Texas at San Antonio

16 Case Study on Eradicating Dracunculiasis
Water and Sanitation – Critical Elements in Development - Mike Lee Hayward

17 Guinea Worm Disease People have suffered from Guinea Worms for centuries – the “fiery serpent” was mentioned in the bible People are infected by drinking water that contain the larvae in a tiny freshwater crustacean called Cyclops A year later, larvae mature into 3 feet worms that emerge through skin blisters This is such a painful process that men and women can’t work, children can’t attend school Water and Sanitation – Critical Elements in Development - Mike Lee Hayward

18 The Guinea Worm grows down the leg and its sex organs appear at the ankle or on the foot usually, bursting when it senses water, releasing ova. Water and Sanitation – Critical Elements in Development - Mike Lee Hayward

19 No vaccine for Guinea worm is available.
People do not seem to build up any resistance and the disease can be reinfected over and over. No research is being conducted for any vaccine or cure. Worms are removed slowly each day by winding around a stick. Water and Sanitation – Critical Elements in Development - Mike Lee Hayward

20 Biological Hazards Food–borne diseases
To protect against food-borne disease local health departments inspect food service establishments (restaurants) retail food outlets (supermarkets) processing plants verify that food stored handled properly

21 Biological Hazards Food-borne diseases Examples
Salmonella, serotype enteritidis Eggs or undercooked chicken Reptiles Escherichia coli 0157:H7 Spinach Undercooked meat Jack in the Box

22 Biological Hazards Vector-borne diseases
Transmitted by insects, other arthropods and other animals including humans Improper environmental management can cause vector-borne disease outbreaks

23 Biological Hazards Vector-borne diseases Examples Mosquitoes Fleas
Malaria St. Louis encephalitis La Crosse encephalitis West Nile Virus Fleas Bubonic plague Murine typhus

24 3. Mosquito injects Plasmodium sporozoites into human host
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

25 Areas in which malaria has disappeared, been eradicated,
Fig , p. 409 Areas in which malaria has disappeared, been eradicated, or never existed Areas with limited risk Areas where malaria Transmission occurs

26 Biological Hazards Vector-borne diseases Examples Humans SARS
Tuberculosis HIV Gonorrhea Syphilis Chlamydia Etc.

27 Tuberculosis epidemic, kills about 2 million people a year.
Deaths per 100,000 people <2.5 2.5-10 10-35 35-70 70-100 100+ Tuberculosis epidemic, kills about 2 million people a year.

28 Biological Hazards Vector-borne diseases
Greatest viral health threat to human life are virulent flu strain 1918 Swine Flu Killed 20 – 30 million Today flu kills 1 million per year worldwide 20,000 in the U.S.

29 Spread of Diseases Increases international travel
Migration to urban areas Migration to uninhabited areas and deforestation Hunger and malnutrition Increased rice cultivation Global warming Hurricanes and high winds Accidental introduction of insect vectors Flooding

30 Reducing Spread of Diseases
Increase research on tropical diseases and vaccines Reduce poverty and malnutrition Improve drinking water Reduce unnecessary use of antibiotics Educate people on taking antibiotics Reduce antibiotic use in livestock Careful hand washing by medical staff Slow global warming Increase preventative health care

31 Types of Hazards Chemical Hazards Biological Hazards
Harmful chemicals in the air, water, soil, and food Most human have small amounts of about 500 synthetic chemicals

32 Hazardous Chemicals Methods to determine threat Case Studies
MD with actual patient record

33 In-depth, longitudinal examination of a single instance or event
Case Studies In-depth, longitudinal examination of a single instance or event 18 year- old, 5-8, 145 pound healthy male Circumstances Collapsed on 2/4/07 at 4:30 PM while in the kitchen Ambulance rushed him to VHH where he died of cardiac arrest a little after 5 PM Toxicology results – negative Brain Aneurysm History Broken neck at age 7 Hit by car June of 2005

34 Pesticide Effects The effect of atrazine on amphibians and eventually humans.

35 Hazardous Chemicals Methods to determine threat Epidemiology
Case Studies MD with actual patient record Epidemiology Health officials investigating case studies

36 Epidemiology Study of the distribution and causes of disease in populations how many people or animals have a disease the outcome of the disease (recovery, death, disability, etc.) the factors that influence the distribution and outcome of the disease

37 Epidemiology of Rabies
In 2001, 49 states, the District of Columbia, and Puerto Rico reported 7,437 cases of rabies in animals and no cases in humans to CDC The total number of reported cases increased by 0.92% from those reported in 2000 (7,369 cases)

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39 Epidemiology of Rabies
Wild animals accounted for 93% of reported cases of rabies in 2001 Outbreaks of rabies infections in terrestrial mammals like raccoons, skunks, foxes, and coyotes are found in broad geographic regions across the United States

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45 Epidemiology of Rabies
Geographic boundaries of currently recognized reservoirs for rabies in terrestrial mammals

46 Epidemiology of Rabies
Domestic species accounted for 6.8% of all rabid animals reported in the United States in 2001 The number of reported rabid domestic animals decreased 2.4% from the 509 cases reported in 2000 to 497 in 2001

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48 Epidemiology of Rabies
Successful vaccination programs that began in the 1940s caused a decline in dog rabies in this country But, as the number of cases of rabies in dogs decreased, rabies in wild animals increased

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50 Epidemiology of Rabies
Human rabies Declined from 100 or more each year to an average of 1 or 2 each year Programs Animal control and vaccination programs begun in the 1940's have practically eliminated domestic dogs as reservoirs of rabies in the United States Effective human rabies vaccines and immunolglobins have been developed

51 Hazardous Chemicals Methods to determine threat
Case Studies MD with actual patient record Epidemiology Health officials investigating case studies Laboratory Investigations Substances that are fatal to more than 50% of the test animals (LD50) at a given concentration

52 Laboratory Investigations
Animal Studies Populations of lab animals usually rodents Measured doses under controlled conditions Takes two to five years Costs $200,000 to $2,000,000 per substance Newer methods

53 Laboratory Investigations
Newer methods Bacteria Cell and tissue culture Appropriate tissue Stem cells Chicken egg membrane

54 Percentage of population killed by a given dose
100 75 50 25 2 4 6 8 10 12 14 16 Percentage of population killed by a given dose Dose (hypothetical units) LD Fig. 16.5, p. 400

55 Why?

56 Number of individuals affected Dose (hypothetical units)
Very Sensitive Majority of population low Sensitivity 20 40 60 80 Dose (hypothetical units) Fig. 16.3, p. 398

57 Laboratory Investigations
Validity Challenged Human physiology is different Different species react different to same toxins Mice die with aspirin Species can be selected depending on physiological area Pigs circulatory very similar to humans

58 (LD50 measured in mg/kg of body weight)
Toxicity Toxicity LD50 Lethal Dose Examples Super < 0.01 less than 1 drop dioxin, botulism mushrooms Extreme <5 less than 7 drops heroin, nicotine Very drops to 1 tsp morphine, codeine Toxic tsp DDT, H2SO4, Caffeine Moderate K 1 oz.-1 pt aspirin, wood alcohol Slightly 5K-15K 1 pt ethyl alcohol, soaps Non-Toxic >15K >1qt water, table sugar (LD50 measured in mg/kg of body weight)

59 ~2% determined to be carcinogen, teratogen or mutagen
Hazardous Chemicals Why so little is known of toxicity Only 10% of at least 75,000 commercial chemicals have been screened ~2% determined to be carcinogen, teratogen or mutagen >1000 new synthetic chemicals added per year >99.5% of US commercial chemicals are NOT regulated

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

61 Chemical Hazards Mutagens Hazardous Chemicals
Chemicals (and ionizing radiation) that changes DNA or RNA in cells

62 Chemical Hazards Hazardous Chemicals Mutagens Teratogens
Chemicals, radiation, or viruses that cause birth defects while the human embryo is gestating, especially in the first three months

63 Teratogens Examples: Rubella Mercury in water Fetal alcohol syndrome
Crack babies Methamphetamine

64 Ocean Pollution: Mercury and Minamata Disease
Mercury has many industrial uses but is extremely toxic A chemical plant released large quantities of mercury into Minamata Bay, Japan Residents who ate highly contaminated fish suffered neurological disease and birth disorders Minamata is a farming and fishing area on the west coast of the southern Island of Kyushu. The town is located on Minimata Bay on the Shiranui Sea. Minimata is also a factory town and the largest factory is run by the Chisso chemical company. Construction of the factory began in In 1932 Chisso began producing acetaldehyde, which is used in making plastics, drugs, perfumes and photographic chemicals. Mercury was used in the process as a catalyst. In 1956 a strange disease became an epidemic in Minimata. The sickness came to be known as Minimata disease. The mercury was discharged into the bay, where bacteria degraded it into a form where it was ingested by ocean organisms…. Mercury poisoning showed up in 1953, known there as Minimata disease, which degenerates the nervous system…this was the first major human disaster resulting from ocean pollution. The Japanese government did not announce mercury as the cause of the disease until 1968… By 1970, 47 fishing families had the disease, over 100 people, ½ died… The government officially recognizes 2,265 victims - 1,435 already dead - of the dumpings in the bay in southern Japan, Some victims died after eating mercury-tainted fish, while others suffered spasms and blurred vision. Babies of poisoned mothers were born with gnarled limbs. Reports of victims began appearing in the 1950s. Another 15,000 people have registered with the government as victims of mercury poisoning - but that number could more than double under new research that suggests weaker concentrations of the chemical than previously thought can cause brain damage and birth defects. ``Twenty-thousand more could very easily be damaged, that we can clearly say,'' said Shigeo Ekino, a professor at the Kumamoto University medical school who is spearheading new attempts to identify what concentrations pose a danger level to humans. bss.sfsu.edu/ehines/geog600/ Freshwater%20and%20ocean%20Pollution.ppt

65 Chemical Hazards Hazardous Chemicals Mutagens Teratogens Carcinogens

66 Carcinogens Causative agents Promote growth of malignant tumors
Chemicals – Tobacco smoke Radiation – Pilots and cosmic radiation Viruses – HPV and cervical cancer Texas Governor mandated vaccination of all School females with Merck’s HPV vaccine Promote growth of malignant tumors

67 Carcinogens Latent Period Long time lapse between exposure Symptoms
Smoking Eating Lifestyle choices – laying in sun Symptoms Lung cancer AIDS Melanoma

68 Chemical Hazards Hormonally Active Agents Hazardous Chemicals Mutagens
Teratogens Carcinogens Hormonally Active Agents

69 Hormonally Active Agents
Estrogen-like chemicals Alter development Early pubescence Low sperm count Runts in wildlife Examples of hormone mimics PCB Organophosphates pesticides Industrial solvents

70 Normal Hormone Process
Receptor Cell Normal Hormone Process Normal Mimic Hormone Blocker Estrogen- like chemical Antiandrogen chemical

71 Normal Hormone Process
Receptor Cell Normal Hormone Process Normal Mimic Hormone Blocker Estrogen- like chemical Antiandrogen chemical

72 Normal Hormone Process
Receptor Cell Normal Hormone Process Normal Mimic Hormone Blocker Estrogen- like chemical Antiandrogen chemical

73 Chemical Hazards Precautionary Principles Hazardous Chemicals Mutagens
Teratogens Carcinogens Hormonally Active Agents Precautionary Principles

74 Precautionary Principle
Better safe than sorry Two scenarios Assume new chemicals guilty – Humans are not guinea pigs Most Chemicals not toxic and too expensive to test

75 Precautionary Principle
Better safe than sorry Two scenarios Assume new chemicals guilty – Humans are not guinea pigs Most Chemicals not toxic and too expensive to test

76 Precautionary Principle
Bioaccumulation An increase in concentration of a chemicals in specific organs or tissues in organisms

77 Precautionary Principle
Biomagnification Increase in concentration in organisms DDT PCB Slowly degradable, fat-soluble chemicals At successively higher trophic levels of food chains or in fatty tissue

78 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

79 Types of Hazards Physical Hazards Biological Hazards Chemical Hazards
Ionizing radiation, airborne particles, equipment design, fire, earthquake, volcanic eruptions, flood, tornadoes, and hurricanes

80 Physical Hazards Example: Radon Source: Can cause lung cancer
Arises naturally from decomposition of uranium in the earth Occurs at dangerous levels in some buildings and homes Can cause lung cancer Test kits available for under $20

81 Types of Hazards Cultural Hazards Biological Hazards Chemical Hazards
Physical Hazards Cultural Hazards Sociological Psychological

82 Cultural Hazards Sociological
result from living in a society where one experiences noise, lack of privacy and overcrowding Population growth Beyond carrying capacity when environmental resources can support no further growth

83 Cultural Hazards Psychological
Environmental factors that produce psychological changes expressed as stress, depression, hysteria

84 Key Concepts Exposure Assessment Types of Hazards
Methods of toxicology Risk estimation, management, and reduction

85 Exposure Assessment 4 important considerations 1. Route 2. Magnitude
3. Duration of exposure 4. Frequency

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87 Key Concepts Risk estimation, management, and reduction
Types of Hazards Exposure Assessment Risk estimation, management, and reduction

88 Risk Analysis How can risks be estimated, managed and reduced?

89 Risk Analysis involves…
Identifying hazards Evaluate risks Ranking risks Determining options and deciding course of action Informing policy makers and public about risks

90 Risk Analysis Risk Risk=Exposure X Harm
The possibility of suffering harm from a hazard that can cause injury, disease, economic loss, or environmental damage. Risk is Expressed in terms of probability, a mathematical statement about How likely it is that some event or effect will occur. Risk=Exposure X Harm Fig. 16.2, p. 297

91 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 Fig , p. 412

92 Risk Analysis Usefulness
Organize and analyze available scientific information Identify significant hazards Focus on areas that warrant more research

93 Risk Analysis Usefulness
Help regulators decide how money for reducing risks should be allocated, Stimulate people to make more informed decisions about health and environmental goals and priorities.

94 Risk Perception If chance of death is 1 in 100,000 people are not likely to be worried or change behavior. Most of us do a poor job of assessing relative risks from hazards around us.

95 Risk Perception Most people deny the high-risk activities they voluntarily enjoy Motorcycles (1 in 50) Smoking (1 in 300 pack a day smokers, by 65) Hang-gliding (1 in 2,500)

96 What do you think are the highest risk hazards in the U.S.?

97 Cause of Death Deaths Tobacco use 431,000 Alcohol use 150,000
Accidents 95,600 (42,000 auto) Pneumonia and Influenza 84,400 Suicides 30,500 Homicides 19,000 Hard drug use 15,000 AIDS 14,000 Fig. 16.1, p. 396

98 Shortens average life span
Hazard Shortens average life span in the United States by 7-10 years Poverty Born male 7.5 years Smoking 6 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 AIDS 3 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 Fig , p. 414 Living lifetime near nuclear plant 10 hours

99 Yet some of these people are terrified of dying from…
Commercial plane crash 1 in 4.6 million Train crash 1 in 20 million Snakebite 1 in 36 million Shark attack 1 in 300 million

100 Each year 99.1% of the people on Earth do not die.
Average life expectancy continues to increase.

101 Bibliography Humayun, Ayesha, “Introductory Lecture on Environment and Bent Flyvbjerg, “Five Misunderstandings About Case-Study Research,” Qualitative Inquiry, Volume 12, Number 2, April 2006 Centers for Disease Control: National Center for Infectious Disease, “Epidemiology of Barbara E. Moore, Ph.D., Department of Biology, University of Texas at San Issues I final.ppt Water and Sanitation – Critical Elements in Development - Mike Lee Hayward


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