Public Health and Public Policy Chapter 8: Environmental Health and Toxicology

 Include physical risks  Exposure to UV radiation  Include chemical risks  Exposure to pesticides  Include biological risks  Pathogens and diseases  Include cultural risks  Smoking, poor diet

 Are caused by pathogens  Can be chronic  Act slowly over a long period of time  Heart disease  Can be acute  Act quickly over a short period of time  Ebola

 Plague  Caused by bacterium Yersinia pestis  Transmitted by fleas  Malaria  Caused by parasitic protist Plasmodium  Transmitted by mosquitoes  Tuberculosis (consumption)  Caused by bacterium Mycobacterium tuberculosis  Transmitted by human breath  Can be treated with antibiotics or other drugs  Can become resistant to drugs

 Are diseases that are new to medicine  Effective treatments do not exist  Are frequently zoonoses  Diseases that reside in animal populations and can infect humans

 Human Immunodeficiency Virus (HIV)  Crossed species from apes to humans  Transmissible in body fluids  Attacks the immune system  Antiviral drugs can reduce viral load  Human AutoImmune Deficiency Syndrome (AIDS)  Significantly weakened immune system  Death results from infection by other pathogens

 Also crossed species from apes to humans  Unlike AIDS it kills its primate hosts  Natural host is unknown  Cause massive bleeding and organ failure  Death rate is 60-90%

 Called Creutzfeldt-Jakob Disease in humans  Caused by mutated proteins called prions  Not destroyed by cooking  Damages the brain and nervous system  Destroys motor coordination  Can be transmitted from infected meat  Spread in cow population from adding ground-up remains from meat processing

 Crossed species from birds to humans  Similar to virus that caused 1918 worldwide pandemic  Could mutate and become far easier to transmit  Could cause another pandemic

 Is transmitted by mosquitoes  Aggressive mosquito control has limited the virus in the US  Causes brain inflammation

 Provides “herd immunity”  Provides protection for those who don’t have immunity by preventing the spread of infectious disease  Due to lack of immunization, measles, whooping cough and other illnesses are on the rise

 Smallpox  Killed more people than any other disease in history  Caused by the Variola virus  Spreads through contact with bodily fluids or items an infected person has touched  The most intense infection causes fever and scarring blisters in the mouth, throat, skin, and corneas  Last case was in 1978  Extensive vaccination prevented transmission of the virus  Last public vaccinations were in 1982

 Polio  Caused by the Poliovirus  Can cause destruction of nerves and paralysis of muscle groups  Transmitted by contamination with feces that contains Poliovirus  Has been eradicated in all developed countries  When it is eradicated in Nigeria, Pakistan, and Afghanistan, it will be the second human disease to be completely controlled

 Is the study of harmful chemicals (toxicants)  Includes  Neurotoxins  Mutagens and carcinogens  Teratogens  Allergens  Endocrine disruptors

 Harm the nervous system  Include lead, mercury, insecticides, and chemical weapons

 Is added to the atmosphere by mining and burning fossil fuels  Can also come from industrial processes and medical waste  Gets into water through leaching or precipitation  Converts to methylmercury  Can bioaccumulate in fish  Can cause nervous system damage in humans (Minamata disease)

 Are chemicals that mutate DNA  Can cause cancer  Include asbestos, radon, benzene, formaldehyde, and polycyclic aromatic compounds (PAHs) from smoke  Can also include radiation

 Are chemicals that interfere with normal embryonic development  Include thalidomide, alcohol, and tetrahydrocannabinol (THC)

 Can cause an extreme reaction from the immune system that can lead to death  Include dust, pollen, nuts, milk, eggs, wheat, soy, penicillin, and codeine

 Are chemicals that interfere with normal hormonal function  Prevent normal hormonal bonding to cell surfaces and disrupt cell signaling  Can interfere with gender and developmental hormone pathways  Found in plastics and health and beauty products

 Is the study of the causes and duration of disease in animals, especially humans  Looks for levels at which toxicants cause disease  Establishes safe levels of exposure in the environment and in tissues

 Expose organisms to toxicants and observe any changes  Can be measured in concentration of chemical exposed  Can also be measured in the dose an organism ingests  Include the LD50 and ED50

 LD50  Are studies that measure the lethal dose that kills 50% of the test subjects  ED50  Are studies that measure the effective dose that causes nonlethal but harmful effects in 50% of test subjects  Results from these studies can be used to set safe levels and exposures  Invertebrates, fish, birds, mammals

 Occurred in Bhopal, India in 1984  Released methyl isocyanate gas  Worst industrial accident ever  2,000 people died in first 24 hours  15,000 more died in the weeks to follow  As many as 500,000 injured

 Acute studies examine the effects of toxicants over short periods of time  LD50, ED50  Occur over hours to days  Chronic studies examine the effects of toxicants over long periods of time  Often follow test subjects for years

 Retrospective studies monitor organisms that have been exposed to a toxicant  Prospective studies monitor organisms that may be exposed to a toxicant  Must compare group that is exposed to a non-exposed group  Need to take into account socioeconomic factors, and exposure to multiple toxicants  Synergistic effects can occur from exposure to multiple toxicants

 Are the same as those for infectious diseases  Can have multiple toxicants from multiple sources  Can be difficult to distinguish which toxicant is causing which symptoms  Are affected by a toxicant’s solubility  Soluble toxicants have a greater likelihood of becoming part of a food chain  Bioaccumulation and biomagnification

 Is how long a toxicant remains in the environment  Depends on temperature, humidity, pH, solubility, radiation, and whether it can be broken down by bacteria  May be different for the same toxicant in water or in soil  Can be measured in half- lives  Pesticide DDT has a half-life in soil of 30 years

 Identifies hazards and determines their potential harm  Can be qualitative  Based on perceptions or personal values  Can be quantitative  Based on data  Risk = proability of being exposed to a hazard X probability of being harmed if exposed  Perceived risk can be different than actual risk

 Is the level of risk that can be tolerated  Some individuals can tolerate more risk than others  EPA risk acceptance is usually set at 1 in 1 million  Case Study: PCBs  PCBs in the Hudson River System were high enough to ban fishing  Fish were thought to be the main vector for humans to acquire PCBs  Swimming and drinking water were discouraged but not banned  EPA recommended dredging river bottom to remove PCBs

 Strikes a balance between possible harm and other interests  Case Study: Arsenic  EPA allowed levels of 50 μg/L in water for many years even though the safe level was 10 μg/l  It was too expensive for some municipalities to remove that much arsenic  Finally reduced levels to 10 μg/L when new research showed that 5 μg/L was the true safe limit

 Innocent-until-proven-guilty principle  Substances must be shown to be harmful before they are treated as toxicants  Precautionary principle  All potentially harmful substances are assumed to be toxicants  Case Study: Asbestos  Use would have been regulated far sooner and more lives would have been saved under the precautionary principle

 Stockholm Convention  Established a list of 12 Persistent Organic Pollutants (POPs) to be banned outright or their use reduced  127 nations signed an agreement to ban these chemicals, phase out their use, or severely restrict their use  Additional meetings have added new chemicals to the list each year since 2001

 REACH  Registration, Evaluation, Authorization and restriction of CHemicals  Puts the precautionary principle into action  Requires risk analysis of all chemicals before they are used industry or consumer products  Is the how the European Union regulates toxicants

 Is often compromised because of  Inadequate funding  Lack of services  environmental regulation  Higher pollution rates  Corporations taking advantage of less punitive laws  Superstition and distrust of medical staff