Environment in the News

profilenayo0f033
chapter_4.ppt
Home>Environmental science homework help>Environment in the News

Risk Analysis and Environmental Health Hazards

Chapter 4

Pesticides and Children

  • More harmful to children than adults
  • Greater exposure
  • Playing in contaminated fields
  • Putting fingers/things in mouth
  • Greater response
  • Developing bodies, more sensitive
  • Range of Effects
  • Cancer, mental and/or physical disabilities
  • Intelligence
  • Motor skills

*

Pesticides and Children

*

  • Learning Objectives:

Define risk and risk assessment

Explain how risk assessment helps is manage potential health threats

A Perspective on Risks

*

A Perspective on Risks

  • Risk
  • The probability of harm (injury, disease, death, environmental damage) occurring under certain circumstances
  • Inherent in our actions and our environment
  • Walking on stairs, using household appliances, driving/riding cars, flying, etc.
  • Few of us think twice about it, even though it’s risky
  • In order to manage risks, we need to have a sense of their causes, likelihoods, and effects

*

A Perspective on Risks

*

A Perspective on Risks

  • Risk Management
  • The process of identifying, assessing, and reducing risks.
  • Qualitative and quantitative method
  • Estimates the probability that an even will occur, so we can determine behavior/actions

*

A Perspective on Risks

*

A Perspective on Risks

  • Curious dilemma:
  • People accept big risks
  • 1/3 of smokers die of diseases caused by smoking
  • Average life expectancy is 8 yrs less for smokers)
  • Get upset over very small risks
  • 1 in 1 million chance of getting cancer from pesticide residues on food)
  • Perhaps due to perception of risks as things we can control
  • smoking, diet, exercise, etc.
  • vs. things we “can’t” control
  • Plane crashes, pesticides, nuclear waste

*

A Perspective on Risks

*

Global Climate Change

What are risk and risk assessment?

What are the four steps of risk assessment?

Environmental Health Hazards

  • Learning Objectives:

Define toxicology and epidemiology

Explain why public water supplies are monitored for fecal coliform bacteria despite the fact that most strains of E. coli do not cause disease

Describe the link between environmental changes and emerging diseases, such as swine flu

*

Environmental Health Hazards

  • Toxicants
  • Chemicals with adverse effects on health
  • All chemicals are toxic if exposure is high enough
  • Toxicology
  • studies the effects of toxicants on living organisms
  • studies the mechanisms that cause toxicity
  • develops ways to prevent or minimize adverse effects

*

Environmental Health Hazards

  • Epidemiology
  • The study of the effects of chemical (toxicants), biological (disease), and physical agents (accidents, radiation) on the health of human populations
  • Studies large groups of people and investigate range of causes and types of disease and injuries

*

Environmental Health Hazards

  • Toxicity
  • Acute
  • Immediate (short-term) effects after a single exposure; dizziness, nausea, death
  • Chronic
  • Prolonged effects, to long-term exposure to toxicant

*

Environmental Health Hazards

  • Disease-Causing Agents in the Environment
  • Pathogens: disease-causing organisms
  • Usually microorganisms: viruses, bacteria, protozoa
  • Transmissible in the environment (contaminated water, food, etc.)
  • Non-transmissible in the environment (e.g., AIDS)
  • Sewage-contaminated water
  • Environmental threat to public health
  • Fecal Coliform Test
  • Tests water for coliform bacteria (like E. coli)

*

Environmental Health Hazards

*

Environmental Health Hazards

*

Environmental Health Hazards

  • Environmental Changes and Emerging Diseases
  • Environmental factors remain a significant cause of disease in the world, despite medical advances
  • 25% of injury and disease is related to human-caused environmental changes
  • Some effects are direct and obvious:
  • Drinking contaminate water and contract dysentery
  • Causes diarrhea, which causes 4 million deaths/yr
  • Some effects are indirect and complex:
  • Disruption of natural environments may give disease-causing agents an opportunity to thrive and reach human populations
  • Cutting down forests, building dams, etc., increases contact with, and distribution of, disease-causing agents

*

Environmental Health Hazards

*

Environmental Health Hazards

  • Social factors may affect spreading of disease:
  • Concentrated urban populations
  • Global travel
  • Population Growth (which requires opening of new land for agriculture and dwellings)
  • Malaria
  • Mosquito transmitted disease
  • 200-500 million infections annually, 1 million deaths
  • 60 different species of mosquitoes transmit parasite
  • Each species has unique combination of optimal environment: elevation, precipitation, temperature, humidity, surface water.

*

Environmental Health Hazards

*

Environmental Health Hazards

  • Pandemic
  • Disease reaches nearly all parts of the world
  • Influenza (flu)
  • Avian influenza affects birds and then infects humans
  • Hard to transmit to humans, but once infected, human mortality is high
  • H1N1(Swine) Flu
  • Late Spring 2009, Mexico
  • Pandemic by early Summer
  • Understanding and controlling pandemics requires:
  • understanding of the environment and conditions that allow the virus to survive and travel
  • Cooperation among many governments and individuals

*

Environmental Health Hazards

*

Global Climate Change

What is the difference between acute and chronic toxicity?

Why is the fecal coliform test performed on public drinking water supplies?

How is the incidence of malaria related to human activities that alter the environment?

Movement and Fate of Toxicants

  • Learning Objectives:

Distinguish among persistence, bioaccumulation, and biological magnification of toxicants

Discuss the mobility of persistent toxicants in the environment

Describe the purpose of the Stockholm Convention on Persistent Organic Pollutants

*

Movement and Fate of Toxicants

  • Some toxicants are particularly dangerous
  • Resist degradation
  • Travel quickly in the environment
  • Radioactive isotopes, some pesticides, PBDEs, PCBs.
  • DDT
  • Pesticide banned in the US in 1972
  • Causes birds to lay eggs with thin shells
  • Chicks die, species face extinction

*

Movement and Fate of Toxicants

  • Impact of DDT on Birds:
  • Persistence
  • Substance is very stable, takes years to break down into less toxic form
  • Bioaccumulation
  • When an organism can’t break down (metabolize) a toxicant, it stores it in its tissues. The buildup of a persistent toxicant in an organism over time is bioaccumulation

*

Movement and Fate of Toxicants

  • Impact of DDT on Birds:
  • Biological magnification
  • the increase in toxicant concentrations as it passes through successive levels of a food chain
  • Top carnivores are at most risk
  • DDT sprayed for mosquitoes: shrimp  eel  needlesfish  gull

*

Environmental InSight

*

Environmental InSight

*

Movement and Fate of Toxicants

  • Mobility in the Environment
  • Persistent toxicants move through soil, water, and air
  • E.g., agricultural pesticides get washed by rain into a stream, hurts aquatic life
  • At high concentrations, life will die
  • At lower concentrations, will have chronic toxicity symptoms, e.g., bone degeneration, decreased competitive ability

*

Movement and Fate of Toxicants

*

Movement and Fate of Toxicants

  • Mobility in the Environment
  • Environmental Working Group, 1994
  • Analyzed 5 common herbicides found in drinking water
  • 3.5 million people in the Midwest have elevated cancer risk due to exposure to herbicides
  • EPA has mandated a reduction in the use of those herbicides

*

  • Global Ban of Persistent Organic Pollutants
  • Stockholm Convention on Persistent Organic Pollutants, 2001
  • UN treaty to protect human health form the 12 most toxic persistent organic pollutants (POPs)
  • Requires countries to develop plans to eliminate the production and use of intentionally produced POPs
  • Exception: DDT used to control malaria mosquitoes. No affordable alternatives

Movement and Fate of Toxicants

*

Movement and Fate of Toxicants

*

Movement and Fate of Toxicants

*

Global Climate Change

What is a persistent toxicant?

How does DDT become magnified through a food chain?

What problems are associated with bioaccumulation and biological magnification?

What is the Stockholm Convention on Persistent Organic Pollutants?

How We Determine the Health Effects of Pollutants

  • Learning Objectives:

Describe how a dose-response curve is used to determine the health effects of environmental pollutants

Describe the most common method of determining whether a chemical causes cancer

Distinguish among addictive, synergistic, and antagonistic interactions in chemical mixtures

Explain why children are particularly susceptible to toxicants

*

  • Toxicity Measures
  • Dose - the amount that enters the body
  • Response - type and amount of damage to a particular dose
  • Lethal dose- causes death
  • Expressed in mg/kg of body weight
  • Sub-lethal dose- causes harm, but not death

How We Determine the Health Effects of Pollutants

*

  • Toxicity Measures
  • Finding the Lethal Dose
  • Administer different doses to lab animals
  • Amount that kills 50% of test animals is called LD50
  • The smaller the LD50, the more toxic the chemical

How We Determine the Health Effects of Pollutants

*

How We Determine the Health Effects of Pollutants

*

How We Determine the Health Effects of Pollutants

*

  • Toxicity Measures
  • Effective dose - 50 percent (ED50)
  • Causes 50% of the population to exhibit a variety of responses, such as,
  • Effects on fetus of a pregnant animal, reduced enzyme activity, hair loss
  • Threshold level
  • The maximum dose at which the toxicant has no measurable effect. Found by producing a
  • Dose-Response Curve
  • Test the effects of a high dose and work the way down to the threshold level
  • Many chemicals have NO safe level

How We Determine the Health Effects of Pollutants

*

How We Determine the Health Effects of Pollutants

*

  • Carcinogens: Cancer-Causing Substances
  • Methods to detect
  • Expose rats to levels of substance and count how many animals develop cancer.
  • Humans are not rats
  • Lab rats are exposed to massive doses not relative to their body weight
  • Bodies respond to small and large doses of the same chemical in different ways
  • Risk Assessment assumes that we can extrapolate from these experiments- there are problems, BUT we can tell when a chemical is ‘safe’
  • Another method is to collect data from accidental exposures of humans to various chemicals (industrial accidents)

How We Determine the Health Effects of Pollutants

*

How We Determine the Health Effects of Pollutants

*

  • Risk Assessment of Chemical Mixtures
  • Most studies are done on single chemicals
  • Most exposures in the environment are to mixtures of chemicals
  • Chemicals can interact in various ways:
  • Additivity
  • Combined effects of 2 substances add up
  • Synergy
  • Combined effect of substances is greater than expected
  • Antagonism
  • Combined effect of substances is smaller than expected

How We Determine the Health Effects of Pollutants

*

  • Children and Chemical Exposure
  • Children are more susceptible than adults
  • Children weigh less than adults
  • Rapid growth and development
  • Rapid metabolism
  • Children and Air Pollution
  • Greater threat to children than adults
  • Pollution restricts lung development in childhood
  • Rapid metabolism needs more oxygen
  • Children breathe about twice the amount of air per pound of body weight than adults
  • Los Angeles found that 80% of children who died for reasons other than respiratory disease, had lung damage

How We Determine the Health Effects of Pollutants

*

How We Determine the Health Effects of Pollutants

*

The Precautionary Principle

*

EnviroDiscovery

  • Smoking: A Significant Risk
  • Largest cause of preventable death
  • Causes serious diseases
  • Responsible for premature death of 500,000 people in the US per year (5 million worldwide)
  • Passive smoking also increases risk of cancer
  • Good News:
  • Tobacco use in the US is going down
  • Anti-tobacco campaigns are working
  • Bad News:
  • Tobacco companies are promoting their products abroad
  • Smoking is increasing in developing nations
  • US refuses to sign 2005 international treaty to ban tobacco advertising worldwide

*

Global Climate Change

What is a dose-response curve?

What is one way that scientists determine whether a chemical causes cancer? What are two problems with this method?

What are three ways that chemical mixtures interact?

The Precautionary Principle

  • Learning Objectives:

Discuss the precautionary principle as it relates to the introduction of new technologies or products

*

The Precautionary Principle

  • States that we should not introduce a new technology, practice, or material until it is demonstrated that:

The risks are small

The benefits outweigh the risks

  • Puts the burden of proof onto the developers
  • Need to demonstrate that a product is safe before we use it, instead of finding out that it is harmful after the fact
  • “An ounce of prevention is worth a pound of cure”

*

The Precautionary Principle

  • To many people it’s common sense
  • There is also much controversy:
  • Scientists worry that it endorses the making of decisions without the input of science
  • European nations have banned beef from US and Canada because of the use of hormones to make cattle grow faster
  • Fear that humans may be harmed by those hormones
  • Another example: genetically modified foods

*

The Precautionary Principle

*

Global Climate Change

What is the precautionary principle?

What are two criticisms of the precautionary principle?

Case Study

  • Endocrine Disrupters
  • Evidence that industrial and agricultural chemicals are endocrine disrupters of humans and animals
  • Hormones:
  • Some disrupters mimic estrogens and androgens
  • Female and male sex hormones
  • Affect reproductive development of animals, including humans
  • Congress dictated that EPA develop a plan to test potential endocrine disrupters as part of the Food Quality Protection Act, and the Safe Drinking Water Act of 1996

*

Case Study