Human Health and Environmental Risks

Four categories of human health risks

Physical (floods, blizzards, landslides, radon, UV exposure)

Biological (viruses, bacterial infections)

Chemical (disinfectants, pesticides)

Cultural/Lifestyle (drinking, smoking, bad diet, crime in neighborhood)

Biological Risks

Infectious diseases- those caused by infectious agents, known as pathogens.

Example: pneumonia and Flu

Also referred to as: transmissible, contagious or communicable diseases.

Where you live and your level of poverty may increase the probability of contracting some infectious diseases.

Biological Risks

Epidemic – An outbreak of an infectious disease that is limited to one area or region.

Pandemic – If outbreak of a disease spreads globally.

Biological Risks

Chronic disease- slowly impairs the functioning of a person’s body.

Acute diseases- rapidly impair the functioning of a person’s body.

Historical Diseases

Plague

Malaria

Tuberculosis

Cholera

Dysentery

Emergent Diseases HIV/AIDS

Ebola

Mad Cow Disease

Bird Flu

West Nile Virus

SARS

Antibiotic resistant TB

Agencies

CDC – Center for Disease Control and Prevention (United States)

WHO – World Health Organization (global)

Solutions for Reducing Infectious Disease

Improving drinking water conditions in developing countries

Decreasing malnutrition to improve immune system

Implementing global education programs to prevent HIV/AIDS

Increasing availability to vaccines/antibiotics

Reducing unnecessary use of antibiotics in humans and livestock

Chemical Risks

Toxicology – Study of the detrimental effects of chemicals on both humans and wildlife

Key characteristics that cause a chemical to be toxic include: Persistence – not easily degraded/broken downSolubility – fat soluble chemicals will accumulate in body tissues, water soluble chemicals will be dissolved easily in bodies of waterBiomagnification – Increased concentration of chemical through the food chain.

Bioaccumulation

bioaccumulation- an increased concentration of a chemical within an organism over time

Biomagnification

Biomagnification- the increase in a chemical concentration in animal tissues as the chemical moves up the food chain.

Dose-Response 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 (referred to as sublethal effects)

Because of the short duration of these experiments, referred to as acute studies

Synergistic interactions- when two risks come together and cause more harm that one would. For example, the health impact of a carcinogen such as asbestos can be much higher if an individual also smokes tobacco.

Dose-response curve

LD50 = dose lethal to 50%

of test animals

Threshold = dose at which response begins

Do The MathBased on a LD50 pesticide study on a rat, what amount of the pesticide would be considered safe for a mammal?

LD50 ÷ 10 (mammal) LD 50 = 2mg/kg of mass ÷ 10 = 0.2 mg/kg of mass

LD50 ÷ 1000 (humans)

LD 50 = 2mg/kg of mass ÷1000 = 0.002 mg/kg of mass

Problems with Toxicity TestingThere are many issues in accurately assessing toxicity of chemicals….Genetic Variability – individuals can exhibit different response to a given level or type of chemicalTest only one response to one chemical at a time, difficult to determine synergistic effectsType of exposure may effect response (acute versus chronic) Regulating agencies may rely on Industry sponsored research

Chemical Risks Neurotoxins- chemicals that disrupt the nervous

system

Carcinogens- chemicals that cause cancer

Teratogens- chemicals that interfere with the normal development of embryos or fetuses

Allergens- chemicals that cause allergic reactions

Endocrine disruptors- chemicals that interfere with the normal functioning of hormones in an animal’s body

Routes of Exposure

Many health hazards exist indoors

• Substances in plastics and consumer products

• Lead in paint and pipes

• Radon

• Asbestos

• PBDE fire retardants

Chemical Sources Type Effects

Arsenic Mining, Groundwater, Treated wood products

Carcinogen Cancer

Asbestos Building Insulation Carcinogen Lung Cancer

Radon Soil, Water, Bedrock Carcinogen Lung Cancer

Vinyl Chloride Industry, water from vinyl chloride pipes

Carcinogen Cancer, especially liver cancer

PCBs (Polychlorinated biphenyls)

Industry (electrical insulator, fire retardant, pesticides, adhesives)

Carcinogen Cancer

Phthalates Used in production of plastics and as solvents

Carcinogen Reproductive damage and cancers

Bisphenol A Used in production of plastic bottles and food containers

Carcinogen Reproductive cancers

Benzene Emissions from burning coal , tobacco smoke

Carcinogen Cancer

Dioxins Class of chemical compounds in manufacturing of some herbicides

Carcinogen Bioaccumulates, causes cancer

Chemical Source Type Effects

Thalidomide Morning Sickness Medication prescribed in the early 1960s

Teratogen Birth Defects

Alcohol Alcoholic beverages Teratogen Fetuses with reduced fetal growth, brain damage

Benzene Emissions from burning coal and oil, tobacco smoke

Teratogen Long term exposure can cause birth defects

Vinyl Chloride Precursor to making PVC

Teratogen Birth Defects

The drug thalidomide, used to relieve nausea during pregnancy, turned out to be a potent teratogen, and caused thousands of birth defects before being banned in the 1960s.

Chemical Source Type Effect

Lead Paint, gasoline Neurotoxin NS disorders, Death

Mercury Coal burning, fish consumption, batteries, fluorescent lights, smelting, incineration of municipal waste

Neurotoxin Brain damage

Heavy Metals (lead, mercury, Arsenic, Cadmium)

Neurotoxin/Teratogen

Biomagnify through food chain and cause neuological damage especially in fetuses

PCB’s Industry, electrical insulators, fire retardants, adhesives, pesticides

Neurotoxin/Teratogen

Brain damage, especially in fetuses

Vinyl Chloride Precursor to PVC Neurotoxin Brain damage

Bisphenol A Plastic bottles and containers

Neurotoxin Neurological damage

http://www.youtube.com/watch?v=ihFkyPv1jtU

Link – Minamata Disease

Chemical Source Type Effect

Atrazine Herbicides Endocrine Disruptor Feminization of males, low sperm count, damage to sexual development , reduced penis size, having both male and female sex organs

DDT Pesticide Endocrine Disruptor Biomagnifies, reproductive damage, thin egg shells, cancers in birds

Phthalates Production of plastics, solvent in some cosmetic products

Endocrine Disruptor Feminization of males, low sperm count, damage to sexual development , reduced penis size, having both male and female sex organs

Frogs show reproductive abnormalities in response to small doses of the herbicide atrazine, researcher Tyrone Hayes has found.

Others suggest that atrazine may have effects on humans as well, lowered sperm count, may also be linked to increasing incidence of breast and testicular cancers.

Endocrine Disruptor

Well Known Case Studies

• Love Canal Housing Development in Niagara Falls, New York – Hazardous waste chemicals buried in old canal leaked into homes, school yard, soil, and ground water. Led to the passage of Comprehensive Environment Response Compensation and Liability Act (CERCLA) aka “Superfund Act”

Well Known Case Studies

Minamata, Japan – mental impairments, birth defects, and deaths caused by mercury dumped in Minamata Bay by a factory. The mercury was converted to methylmercury, bioaccumulated in fish, and biomagnified through food chains. Mercury entered humans who ate a traditional fish based diet.

http://www.youtube.com/watch?v=ihFkyPv1jtU

Know Well Known Case Studies

Bhopal, India – On December 2, 1984, poisonous methyl isocyanate gas was released accidentally by a Union Carbide pesticide plant killing about 5,000 people and causing serious health effects for 50,000 - 60,000.

http://www.youtube.com/watch?v=ELllSxnDS0g

Risk• Risk = the mathematical probability that some

harmful outcome will result from a given action, event, or substance

• Probability = a quantitative description of the likelihood of a certain outcome

• Harmful outcome could be defined as injury, death, environmental damage, economic loss, etc.

Perception different from realityOur perception of risks tends not to match statistical reality.

smoking

plane

crash

Risk assessment•Analyzes risks quantitatively

•Measures and compares risks involved in different activities or substances

•Helps identify and prioritize serious risks

•Helps determine threats posed to humans, wildlife, ecosystems

Risk assessmentInvolves:• Dose-response

analysis or other tests of toxicity

• Assessing likely exposure to the hazard (concentration, time, frequency)

Risk management• Consider risk

assessments in light of social, economic, and political needs and values.

• Weigh costs and benefits, given both scientific and nonscientific concerns.

• Decide whether or not to reduce or eliminate risk.

Risk assessment and risk management inform policy

Following risk management, policy decisions are made.

Philosophical approaches

•“Innocent until proven guilty”:Assume harmless until shown to be harmful

•Precautionary principle:Assume harmful until shown to be harmless

Implications for product testing

•“Innocent until proven guilty”:• Industry can introduce any products it

wants.

• Government bears the burden of proof to show if products are dangerous.

•Precautionary principle:• Industry cannot introduce a product until it

is very thoroughly tested and shown convincingly to be harmless.

Implications for product testing

• Industry has pressured government to take an “innocent-until-proven-guilty” approach.

• Environmental advocates have pressured government to follow the precautionary principle.

Stockholm Convention

In 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 (aka “dirty dozen”)

These include DDT, PCBs, and certain chemicals that are by-products of manufacturing processes.

International Treaty – Persistent Organic Pollutants Treaty (POPs)

Signed but not ratified by United States