Environmental Health ENVIRONMENTAL HEALTH Federally Center for Disease

Environmental Health

ENVIRONMENTAL HEALTH • Federally – Center for Disease Control (CDC) • Internationally – World Health Organization (WHO) • Environmental Health= assesses environmental factors that influence human health and quality of life • Poverty is the largest killer! • The poor have… – – Less adequate health care Lack clean water Lack nutritious food Lack clean air, sanitation, and shelter

11 million children under age of 5 killed by… • diarrhea • acute respiratory illness • malaria • measles • tetanus

ENVIRONMENTAL HAZARDS • Physical – Earthquakes, volcanic eruptions, fires, floods, blizzards, landslides, hurricanes, droughts • Chemical – Synthetic chemicals (disinfectants, pesticides); – Chemicals produced naturally by organisms • Biological – Caused by interaction: infectious disease • Cultural – Smoking, drug use, diet & nutrition, crime, mode of transportation

ENVIRONMENTAL HEALTH – Nontransmissible diseases= cannot spread & are frequently the result of poor choices • Ex. lung cancer or heart disease – Transmissible/communicable/infectious diseases= can be spread from person to person. Caused/passed by: • 1. Air • 2. Food • 3. Water • 4. Person-to-Person contact • 5. Person-to-Animal contact • 6. Invertebrates (bites) pathogens

Infectious diseases are caused by the following… Pathogens= disease causing organisms or viruses • 1. Bacteria • 2. Viruses • 3. Protists • 4. Fungi • 5. Invertebrates Vectors= organisms that carry the pathogen from one host to another

Infectious diseases: account for 23% of deaths worldwide Pathogen Diseases Mosquitos (vector): malaria, yellow fever, dengue, West Nile virus, Zika virus Bacteria tuberculosis, cholera Protozoa malaria, giardia, trypanosomiasis Virus ebola, marburg, HIV, West Nile, dengue fever, yellow fever Worms/flukes schistosomiasis, elephantiasis, guinea worms Waterborne illness diarrheas, hepatitis A, typhoid, cholera, giardiasis, dysentery

Globalization: increasing the spread of infectious diseases • The 2014 Ebola epidemic WAS the largest in history and affected multiple countries in West Africa. – Two imported cases, including one death, and two locally acquired cases in healthcare workers were reported in the United States. • Zika virus outbreak in 2016 replaces this event as the largest in history – All of North and South America except Canada & Chile

Antibiotic Resistance: increasing the spread of infectious diseases • Resurgence of bacterial diseases – Drug-resistant organisms • Due to more traveling & overprescribing/misuse of antibiotics • Antibiotics in many countries are available without prescriptions – Antibiotic soaps may contribute – Widespread use of antibiotics in livestock & diary industry may contribute

Infectious Diseases • Epidemic – When a pathogen causes a rapid increase in disease • Pandemic – When an epidemic occurs over a large geographic region, like a continent

Historical Infectious Diseases • Caused by poor sanitation & unsafe drinking water – Cholera – Hepatitis – Diarrheal Diseases • Plague, Malaria, Tuberculosis

Plague: Bubonic plague/Black death • Caused by infection from a bacterium carried by fleas attached to rodents – Tremendous mobility • Transmitted by flea bites or handling the rodents • Caused swollen glands, black spots on their skin, and extreme pain – – Killed hundreds of millions of people throughout history ¼ of European population in 1300 s Latest pandemic: Asia in early 1900 s Small, occasional outbreaks today • Today we have antibiotics that are highly effective at killing bacterium & preventing human death

Malaria • Caused by several species of protists in the genus Plasmodium • Parasite spends one stage of its life inside a mosquito & another life stage in humans • Causes flulike symptoms – – Has killed millions of people over the centuries Each year 350 -500 million people contract the disease 1 million/year die from it (mostly children) Area most affected: Sub-Saharan Africa, Asia, Middle East, and Central & South America – More than 1, 000 cases/year in U. S. (traveled to regions of world where malarial parasite exists)

Malaria • Hard to eradicate: – Mosquito populations impacted by spraying insecticide quickly bounce back • In Sri Lanka, they reduced the number of malaria cases from 1 million to 18 by spraying insecticide consistently. But when they stopped, within a few years, cases increased to half a million • If one country is spraying to kill mosquitoes but the neighboring country is not, mosquitoes will continue to enter through the neighboring country • Malaria pathogen can evolve resistance to insecticides and antimalarial drugs

Tuberculosis (TB) • Highly contagious • Caused by a bacterium Mycobacterium tuberculosis that primarily infects the lungs – Spread when person coughs/expels bacteria into air – Can persist in air for hours – Symptoms: weakness, night sweats, coughing up blood • People can be infected with pathogen but not develop disease • About 9 million are infected each year, with 2 million dying from it

Tuberculosis (TB) • Easily treated by taking antibiotics for a year • Readily available to developed countries, seen a fall in number of deaths from TB • In developing countries, medicine not readily available or affordable. Some don’t take it for the prescribed amount of time

What happens when you don’t finish your antibiotics? • When you stop taking them before the last bacterium are killed…. – The pathogen can quickly rebuild its population – The last few are usually the most drugresistant, so this could lead to a population that are drug-resistant • Newer antibiotics are more expensive

Cholera • Caused by drinking or eating food contaminated with sewage (bacteria Vibrio cholerae) • Causes severe diarrhea, which leads to dehydration & death if left untreated • Prevalent in U. S. in 1800 s before modern water & sewage treatment systems • Today about 10 cases/yr in U. S. (1/2 due to traveling abroad) • Serious problem in developing world where there is poor sanitation, crowding, war, famine – 150, 000 cases/yr according to WHO

Emergent Diseases • Emergent disease – Diseases that were previously unknown or that have recently become prevalent • Many of these diseases have come from pathogens that normally infect animal hosts, but then unexpectedly jump to human hosts – HIV/AIDS, Ebola, Bird flu (H 5 N 1) – Mad Cow Disease, West Nile Virus

Emergent Diseases • Severe Acute Respiratory Disease (SARS) • Severe pneumonia; 2003; started in China • Caught from small animals • No cases reported since 2004 • H 1 N 1; 2009 – Called “swine flu” because the virus was similar to those found in pigs – Currently a seasonal flu virus found in humans – You cannot get it by eating properly handled & cooked pork/pork products

Practice Question Which statement is true regarding the relationship between health risks & income? • A. a major risk in high-income countries is a lack of food • B. a major risk in high-income countries is poor sanitation • C. a major risk in low-income countries is obesity • D. a major risk in low-income countries is a lack of food • E. a major risk in high- & low-income countries are similar

Practice Question Which statement about historical infectious diseases is not true? • A. plague is a disease that is carried by fleas attached to rodents • B. malaria is a disease that is carried by mosquitos • C. tuberculosis is a disease that is transmitted through air • D. the pathogen that causes tuberculosis can become drug-resistant • E. historically important infectious diseases no longer pose a heath risk

Practice Question Which statement about emerging infectious diseases is not true • A. HIV is a virus that most likely came from chimps • B. Ebola hemorrhagic fever causes a high rate of death • C. Mad cow disease is spread by feeding grass to cows • D. Bird flue is a virus that jumps from birds to people • E. West Nile virus is a virus that comes from birds

Practice Question Which statement is true regarding human health risks? • A. More people die from infectious diseases than from noninfectious diseases • B. More people die from accidents than from any other cause • C. more people die from chemical risks than from physical or biological • D. More people die from cancer than from any other cause • E. more people die from heart disease than from any other cause

Pathways of transmitting pathogens

Toxicology

TOXICOLOGY Toxicology= the study of the adverse effects of toxins on living organisms Toxins= chemicals that adversely affect living organisms by disrupting normal metabolic function. Environmental toxicology = toxic substances that come from or are discharged into the environment Includes study of health effects on humans, other animals & ecosystems

Synthetic chemicals = man-made Chemical Risks Pesticides Detergents Drugs Disinfectants Solvents Our society has developed an incredible amount of chemicals to improve human life…pharmaceuticals, insecticides, pesticides, herbicides, fungicides. Improved human health & food production But the large number of chemicals released into the environment naturally raises questions about potential effects these chemicals have on humans & other organisms…

Toxins… May concentrate in water (hydrophilic) Can travel widely through the atmosphere • Can persist for a long time • May accumulate & move up the food chain (lipophilic) • Are not all synthetic • •

Some chemicals of major concern Chemical Sources Type Lead Paint; gasoline Neurotoxin Mercury Coal burning, fish consumption Neurotoxin Arsenic Mining, groundwater Neurotoxin Carcinogen Asbestos Building material Carcinogen Polychlorinated biphenyls (PCBs) Industry Carcinogen Radon Soil, water Carcinogen Vinyl chloride Industry, water from vinyl chloride pipes Carcinogen Alcoholic beverages Teratogen Atrazine Herbicide Endocrine disruptor DDT Insecticide Endocrine disruptor Phthalates Plastics, cosmetics Endocrine disruptor

Toxins can be grouped into 5 categories Neurotoxins, carcinogens, teratogens, allergens & endocrine disruptors

Allergens Allergen= chemical that causes allergic reaction Cause an abnormally high response from the immune system Given allergens usually cause allergic reactions in a small fraction of people Peanuts, milk, penicillin, codeine, formaldehyde

Allergens Formaldehyde ▪ Commonly used in the manufacture of furniture, carpeting, and particleboard ▪ Because these items are frequently found in buildings, a building may be labeled as inducing sick building syndrome (SBS) Symptoms: headache, sneezing, dry cough, itchy skin, nausea, dizziness, and fatigue

Carcinogens Carcinogen= chemical that causes cancer Carcinogens can either damage DNA or it can interfere with the normal metabolic process of the cell ▪ Mutagen= type of carcinogen that mutates the DNA Asbestos, Radon, Formaldehyde, and chemicals found in tobacco

Teratogens Teratogen= chemical that cause birth defects Thalidomide, a drug prescribed to pregnant women during the late 1950’s/early 1960’s to combat morning sickness ▪ Taken off the market in 1961 Alcohol Excess alcohol consumption reduces growth of the fetus & damages the brain & nervous system ▪ Fetal alcohol syndrome

Endocrine disruptors Endocrine disruptor= chemicals that interfere with the normal functioning of hormones Estrogen & Testosterone are Hormones are normally produced in the endocrine well known system & released into the bloodstream in very hormones low concentrations. As the hormones move through the body, they bind to specific cells Binding stimulates the cell to respond in a way that regulates the functioning of the body

Endocrine disruptors Water pollution in wastewater: hormones from animal-rearing facilities, hormones from birth control pills, and pesticides that mimic animal hormones Male fish, reptiles & amphibians found in this wastewater are becoming feminized ▪ Males having low sperm count ▪ Males that can produce both eggs & sperm Males usually convert estrogen into testosterone- endocrine disruptors interfere with this process

Endocrine disruptors Effect on humans: Low sperm count in males Increased risk of breast cancer in women Atrazine (herbicide), DDT (pesticide), phthalates (plastics, cosmetics), Dioxins & PCBs

Neurotoxins Neurotoxin= chemical that disrupts the nervous system Ex. Insecticide interferes w/nerve transmissions; insect becomes paralyzed, cannot obtain oxygen & quickly die Mercury, Lead & Cadmium Damages a person’s kidneys, brain & nervous system ▪ Kill nerve cells Irreparable Lead in gasoline & paint phased out starting in the 1970 s so lead exposure in US has decreased dramatically, but is still an issue in low-income areas that contain leaded paint

Other common neurotoxins DDT, Dieldren (insecticide), PCBs, industrial solvents, and dioxins ▪ Damage neurons

Mad Hatter Disease “Mad as a hatter”

Minimata Disease “Minimata Disease” Minimata Bay, Japan Birds lost their coordination & fell into ground or flew into buildings Cats running in circles & foaming at the mouth Families of fishermen: fatigue, irritability, headaches, numbness in arms/legs, difficulty swallowing, blurred vision, hearing loss, metallitic taste in mouth

Methyl mercury Vinyl chloride factory used mercury in production process mercury released as waste into Minimata Bay ▪ Mercury forms few organic compounds, so safe, not get into food chains Inorganic mercury converted by bacteria into methyl mercury, an organic compound ▪ Readily passes through cell membranes, transported by red blood cells throughout the body & damages brain cells Fish absorbed methyl mercury from water

Minimata Disease What we can learn from this story: 1. Individuals vary in their response to exposure to the same does, or amount, of a pollutant 2. Pollutants may have a threshold A level below which effects not observable & above which effects are apparent 3. Some effects are reversible 4. The chemical form of a pollutant, its activity, & its potential to cause health problems may be changed markedly by ecological & biological processes

What we know…

Minimata Disease What we can learn from this story: 1. Individuals vary in their response to exposure to the same does, or amount, of a pollutant 2. Pollutants may have a threshold A level below which effects not observable & above which effects are apparent 3. Some effects are reversible 4. The chemical form of a pollutant, its activity, & its potential to cause health problems may be changed markedly by ecological & biological processes

Toxins… May concentrate in water Can travel widely through the atmosphere • Can persist for a long time • May accumulate & move up the food chain • Are not all synthetic • •

How Toxins spread throughout the environment Toxins are either soluble in water or in oil. ► Water-soluble toxins Easily dispersed because water is present virtually everywhere ► Oil-soluble toxins In the body, the oil-soluble toxins are able to enter cells much more readily than the water-soluble toxins Tend to accumulate in fatty tissue: ▪ This is called bioaccumulation

How Toxins spread throughout the environment Toxins that bioaccumulate in the tissues of one organisms may be transferred to other organisms as predators consume prey. Thus with each step up the food chain, concentrations of the toxin can be magnified This is called Biomagnification ▪ Heavy metals ▪ Chlorinated hydrocarbons

POP’s Persistence of the chemical How long it can remain in the environment. Chemicals have half lives Persistent organic pollutants (POPs) are extremely dangerous due to their ability to be biomagnified. For example, phthalates found in polyvinyl chloride plastic & some deodorants & cosmetics have been shown to be toxic to lab animals Nearly everyone in the U. S. has phthalates in their tissues because these chemicals are highly persistent.

Persistence of chemicals Chemical Malathion insecticide Radon Vinyl chloride Phthalates Roundup herbicide Atrazine herbicide PCBs DDT Half-life 1 day 4 days in air 4. 5 days in water 7 to 70 days in water 224 days in wetland soils 8 to 15 years in water 30 years in soil

Stockholm Convention on Persistent Organic Pollutants Seeks to protect human health from the 12 most toxic chemicals (includes 8 chlorinated hydrocarbon pesticides / DDT can be used for malaria control)

Internat’l Regulation: Stockholm Convention; phasing out “DIRTY DOZEN” (table 14. 3) TOXICANT TYPE ALDRIN PESTICIDE CHLORDANE PESTICIDE DDT PESTICIDE DIELDRIN PESTICIDE DIOXINS UNINTENTIONAL BIPRODUCT ENDRIN PESTICIDE FURANS UNINTENTIONAL BIPRODUCT HEPTACHLOR PESTICIDE DESCRIPTION Produced by incomplete combustion; recycling; paper bleaching, automobile exhaust Results from same processes that create dioxins; found in commercial mixtures of PCBs HEXACHLOROBEN FUNGICIDE; unintentional ZENE biproduct MIREX PESTICIDE PCBs INDUSTRIAL CHEMICAL TOXAPHENE PESTICIDE Additive in paint, plastics; used in electrical transformers, etc.

Route of exposure to toxin is important ►Toxins can be inhaled, ingested or absorbed through skin. ●Inhaled toxins are the most dangerous ▪ Breathe constantly & lungs readily absorb toxins due to their structure Other factors which affect exposure to toxins are…age, genetics, & workplace exposure. Some toxins are not toxic in their ingested form, but are converted by the liver into a toxic chemical

Measuring Toxicity To assess the risk a chemical poses to any organism, we need to determine the concentrations that cause harm Bioassay= using the physiology of another species (animal, plant, fungus, or bacteria) to test a foreign substance

Measuring Toxicity Dose-response studies expose animals or plants to different amounts of a chemical and then observe a variety of possible responses Mortality Changes in behavior or reproduction Can be measured in concentrations of a chemical in the air, water, or food (LC 50) Can be measured as the dose of a chemical (LD 50)

LD 50, or median lethal dose The dose that kills one-half of test animals in two weeks. The LC 50 , median lethal concentrations of a chemical in the air, water, or food used for aquatic species: are subject to lethal concentrations of a toxin in the water surrounding their bodies

LD 50 are usually given in mg/kg body weight. The lower the LD 50 value, the greater the toxicity of the chemical. A substance is considered toxic if the LD 50 is 50 mg or less per kg body weight

Dose Response Curve 100 Percent Death 50 -------------------10 1 2 3 4 5 6 7 8 9 10 11 12 Dose The threshold is the first dose in which a response is obvious. There are some natural deaths in the animals at all doses, so the threshold value would be at 5 mg/kg because that is the first dose that the percent death exceeds the natural attrition of the test subjects. the LD 50 would be 10 mg/kg according to the data given.

Mammals are typically used for these studies because they are most similar to humans ▪ Rats & mice Unfortunately results may not easily be extrapolated to humans ▪ Different in body size, metabolic activity & physiology Ethical concerns ▪ Most reliable data done this way

ED 50, sublethal effect Experiments are conducted to determine the effective dose that causes 50% of the individuals to display the harmful, nonlethal, effect Allows scientists to identify harmful teratogens, carcinogens & neurotoxins.

Type of exposure can affect the response Acute exposure High exposure for short periods of time Easier to detect LD 50 values generally reflect this type of exposure Chronic exposure Lower exposure over long periods of time More common

Chemical Interactions 1. Additive response The effect is the sum of individual responses ▪ Ex) Rats exposed to lead & arsenic show twice the toxicity of an exposure to just one of the toxins 2. Synergistic response One substance increases the response to another substance. ▪ Ex) Exposure to asbestos by someone who smokes cigarettes results in a 400 -fold increase in cancer rates, not just double the rates as expected. 3. Antagonistic effects When chemicals negate the effects of another chemical

Effects of chemicals on humans & wildlife are regulated by EPA

Toxic Substances Control Act of 1976 & Federal Insecticide, Fungicide & Rodenticide Act of 1996 Toxic Substances Control Act of 1976 gives the EPA the authority to regulate many chemicals, excluding food, cosmetics & pesticides. Pesticides are regulated under the Federal Insecticide, Fungicide & Rodenticide Act of 1996 (FIFRA) A manufacturer must demonstrate that a pesticide “will not generally cause unreasonable adverse effects on the environment”

The United States Federal Food, Drug, and Cosmetic Act, FFDCA U. S. Food and Drug Administration (FDA) to oversee the safety of food, drugs, and cosmetics. Delaney Clause of 1958 Forbade addition of any amount of carcinogen to foods or drugs. Amended in 1996 to state that a substance could be added to food if less than one cancer for every 1 million people exposed over their lifetime resulted in exposure to the chemical

Regulations in US (EPA) FIFRA Regulates manufacture & use of pesticides (register usage) FFDCA EPA sets tolerance levels for amount of toxic residues in food, drugs and cosmetics (Delaney Amendment) CERCLA Established Superfund for emergency response and remediation of toxic sites Federal Hazardous Substances Act (1960) Requires cautionary labels in household products Hazardous Materials Transportation Act (1975) Regulates transport of hazardous material Toxic Substances Control Act (TOSCA, 1975) EPA must track toxic substances coming into the US and can ban manufacture and import of toxic substances that pose unacceptable risk. Resource Conservation and Recovery Act (RCRA, 1976) Regulates hazardous waste storage and disposal

Risk analysis helps us assess, accept, and manage risk Risk= possibility of suffering harm

Risk Assessment Government Agencies that Assess Risk Food and Drug Administration (FDA) ▪ Assesses risks of food additives, & medicines before released to market Consumer Product Safety Division ▪ Identifies risks to consumers from nonfood, nonmedical products Environmental Protection Agency (EPA) ▪ Determines risk by determining acceptable standards of pollutants in the air and water Centers for Disease Control (CDC) ▪ Assesses risk due to disease and social factors Occupational Safety and Health Administration (OSHA) ▪ Assesses risk in the workplace.

The process of risk analysis Risk assessment 1. Identify the hazard 2. Characterize toxicity (dose/response) 3. Determine extent of exposure Risk acceptance Determine acceptable level of risk Risk management Determine policy input from private citizens, industry, interest groups

Risk management example Arsenic in drinking water 50 ug/L of arsenic in drinking water could cause cancer ▪ 1942 -1999 federal govt. set acceptable concentrations at 50 ug/L ▪ 1999, EPA wanted to lower it to 10 ug/L The problem? New economic burden on mining companies that produced arsenic as a by- product Several Western State municipalities had high concentrations of arsenic in their drinking water In 2001, before the change was to occur, the EPA announced that 50 ug/L would stay Later in 2001, a study proved that the acceptable amount of arsenic was actually 5 ug/L EPA revised its ruling, setting safe arsenic concentrations at 10 ug/L.

Misconception: If it’s on the shelf it’s safe