Human Health and Environmental Risks

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Chapter 17

• Human Health and Environmental Risks

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Citizen Scientists

• Norco, Louisiana, Old Diamond District
• Surrounded by Chemical plant and oil refinery
• owned by Shell Oil Company
• Health concerns
• So what happened?
• 1989 Concerned Citizens of Norco
• Fight against Shell took 13 years
• 2002
• 2007 Shell agreed it had violated air pollution
  regulations at several Louisiana plants
• Margie Richard received Goldman Environmental
  Prize

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Three categories of human health risks

• Physical
• Include
• Biological associated with disease
• Disease
• Chemical due to exposure to chemicals

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Leading Causes of Death in World
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Biological Risks

• Infectious diseases- those caused by infectious
  agents, known as pathogens
• Examples
• Pathogens include parasitic worms called
  helminths and
• Diseases fall into two categories
• Chronic disease
• Acute diseases

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Biological Risks

• Risk Factors for Chronic Disease
• Differ significantly between LDC and HDC
• LDC - poverty
• HDC lifestyle choices

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Biological Risks
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Historical Diseases

• Epidemic when a pathogen causes a rapid
  increase in disease
• Pandemic
• Historically important diseases
• Plague caused by Yersinia pestis bacteria
• Malaria caused by protists of genus Plasmodium
• Tuberculosis caused by bacterium Mycobacterium
  tuberculosis

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Emergent Diseases

• Emergent infectious diseases infectious disease
  that were previously not described or have not
  been common for at least the prior 20 years
• 1 emergent disease worldwide each year since
  1970
• Some common emergent diseases
• HIV/AIDS
• Ebola hemorrhagic fever
• Mad Cow Disease
• Bird Flu
• West Nile Virus

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Reasons for Emergence/Reemergence

• Evolution of disease so it can move to human host
• Evolution of antibiotic resistance in disease
• Urbanization and overcrowding
• Increased pop. of elderly- susceptible to disease
• Pollution and environmental degradation
• Growth in international travel and commerce
• Poverty and social inequality

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Transmitting Pathogens

• Various ways to infect humans

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Combating Disease

• LDC

• HDC

• Improve nutrition
• Increase availability of clean drinking water
• Improve sanitation
• Continued education
• Development of rapid response plans to combat
  emerging disease

• Promote healthier lifestyle choices
• Increase physical activity
• Eat balanced diet
• Limit excess food consumption
• Limit tobacco use
• Continued education
• Development of rapid response plans to combat
  emerging disease

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Chemical Risks

• Neurotoxins- chemicals that disrupt the nervous
  system
• Carcinogens- chemicals that cause cancer
• Mutagen
• Teratogens- chemicals that interfere with the
  normal development of embryos or fetuses
• Thalidomide
• Allergens- chemicals that cause allergic
  reactions
• Endocrine disruptors- chemicals that interfere
  with the normal functioning of hormones in an
  animals body

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Dose-Response Studies

• Dose response studies expose animals or plants
  to different amounts of a chemical and then
  observe a variety of possible responses including
  mortality or changes in behavior/reproduction
• Acute studies vs. chronic studies
• LD50- lethal dose that kills 50 of the
  individuals
• ED50- effective dose that causes 50 of the
  animals to display the harmful but nonlethal
  effect

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Testing Standards in US

• Effects of chemicals in US regulated by EPA
• Toxic Substance Control Act of 1976
• Testing done on a few species a birds, mammal,
  fish, and invertebrate that are believed to be
  most sensitive
• Testing not always done on amphibians/reptiles
• Safe concentrations
• For most animals
• For humans scientists use rats and mice and
  extrapolate the results to humans

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Terminology

• Epidemiology field of science that strives to
  understand the causes of illness and disease in
  humans and wildlife populations
• Retrospective studies monitor people who have
  been exposed to a chemical at some time in the
  past
• Prospective studies monitor people who might
  become exposed to harmful chemicals in future
• Synergistic interactions- when two risks come
  together and cause more harm that one would

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Routes of Exposure

• Complex exposure from a variety of sources
• Solubility how well a chemical dissolves in a
  liquid

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Bioaccumulation

• Bioaccumulation- an increased concentration of a
  chemical within an organism over time
• Synthetic chemicals do not metabolize well
• Example mercury

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Biomagnification

• Biomagnification- the increase in a chemical
  concentration in animal tissues as the chemical
  moves up the food chain
• Aka biological magnification

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Persistence

• Persistence- how long a chemical remains in the
  environment
• Synthetic chemicals

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Risk Analysis

• Environmental hazard anything in our
  environment can potentially cause harm
• Follow 3 steps to assess risk of environmental
  hazards

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Risk AssessmentQualitative Risk Assessment

• Making a judgment of the relative risks of
  various decisions based on perception, NOT
  probability
• Probability
• Judgments based on perception ? may not match
  actual risk

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Probability of an individual dying from

• In US

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Risk Assessment Quantitative Risk Assessment

• The approach to conducting a quantitative risk
  assessment is expressed as
• Risk probability of being exposed to a hazard X
  probability of being harmed if exposed

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Risk Acceptance and Risk Management

• Risk acceptance - level of risk that can be
  tolerated
• Very difficult step precise amount of
  acceptable risk is open to heated disagreement
• Risk management seeks to balance possible harm
  against other considerations
• Includes other factors economic, social,
  ethical and political issues

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Worldwide Standards of Risk

• Chemical regulation guided by either

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Stockholm Convention

• 2001 a group of 127 nations gathered in
  Stockholm, Sweden, to reach an agreement on
  restricting the global use of some chemicals
• 12 chemicals were to be banned, phased out, or
  reduced
• Include DDT, PCBs, and certain chemicals that are
  by-products of manufacturing processes
• All known endocrine disruptors
• 2009 9 additional chemicals added, several more
  suggested

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REACH

• 2007 27 nations of EU put into effect agreement
  on how chemicals should be regulated within EU
• Stands for registration, evaluation,
  authorization, and restriction of chemicals
• Embraces precautionary principle