Chapter 17 Human 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