Chapter 17Human Health and Environmental Risks

Citizen Scientists Norco, Louisiana, Old Diamond District

Surrounded by Chemical plant and oil refinery – both owned by Shell Oil Company

Health concerns: So what happened?

1989 –Margie Richard organized Concerned Citizens of Norco Fight against Shell took 13 years

2002 – Shell purchased the homes and pay additional $5 million for community development

2007 – Shell agreed it had violated air pollution regulations at several Louisiana plants

Maggie Richard – received Goldman Environmental Prize

Three categories of human health risks Physical

Include –

Biological – associated with disease Disease –

Chemical – due to exposure to chemicals

Leading Causes of Death in World

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

Biological Risks Risk Factors for Chronic Disease

Differ significantly between LDC and HDC LDC - poverty HDC – lifestyle choices

Biological Risks

Historical Diseases Epidemic – when a pathogen causes a rapid increase in disease

Pandemic Historically important diseases

Plague – caused by Yersinia pestis bacteria Symptoms – swollen glands, black spots on skin, extreme pain

Malaria – caused by protists of genus Plasmodium Symptoms – flu-like

Tuberculosis –caused by bacterium Mycobacterium tuberculosis Symptoms – weakness, night sweats, coughing Easily treated with antibiotics for ~1 year

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

Transmitting Pathogens Various ways to infect

humans

Combating Disease

LDC Improve nutrition Increase availability of clean

drinking water Improve sanitation Continued education Development of rapid

response plans to combat emerging disease

HDC 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

Chemical Risks Neurotoxins- chemicals that disrupt the nervous system Carcinogens- chemicals that cause cancer

Mutagen – carcinogens that cause damage to the genetic material of cell

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 animal’s body

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

Testing Standards in US Effects of chemicals in US regulated by EPA

Toxic Substance Control Act of 1976 – gives EPA authority to regulate many chemicals, but excludes food, cosmetics, and pesticides

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 - determine by dividing the LD50 value by 10

For humans –scientists use rats and mice and extrapolate the results to humans

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

Routes of Exposure Complex – exposure from a

variety of sources

Solubility – how well a chemical dissolves in a liquid

Bioaccumulation Bioaccumulation- an increased concentration of a chemical within

an organism over time Synthetic chemical do not metabolize well Example – mercury accumulation in fish

Biomagnification Biomagnification- the increase in a

chemical concentration in animal tissues as the chemical moves up the food chain Aka – biological magnification Image – biomagnifcation of DDT

Persistence Persistence- how long a chemical remains in the environment

Synthetic chemicals Natural decomposers

(bacteria) have not evolved a way to break it down

Risk Analysis Environmental hazard – anything in our environment can

potentially cause harm Follow 3 steps to assess risk of environmental hazards:

Risk Assessment:Qualitative Risk Assessment Making a judgment of the relative risks of various decisions based

on perception, NOT probability Probability - the statistical likelihood of an event occurring and the

probability of that event causing harm Judgments based on perception may not match actual risk

Probability of an individual dying from…

In US

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

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

Worldwide Standards of Risk Chemical regulation guided by either:

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

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