chapter 17 human health and environmental risks. citizen scientists norco, louisiana, old diamond...
DESCRIPTION
Three categories of human health risks Physical Include – Biological – associated with disease Disease – Chemical – due to exposure to chemicalsTRANSCRIPT
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