APES UNIT 8 - Part 2

Municipal Solid Waste (MSW)

Everyday household and commercial trash such as food scraps, paper, and packaging; disposed of in landfills, incinerators, or recycling

Agricultural Waste

Waste produced by farming and livestock operations including manure, pesticide containers, and crop residue

Industrial Waste

Waste generated by manufacturing and factories including chemicals, scrap metal, and sludge; regulated by federal law

Hazardous Waste

Waste that is toxic, flammable, reactive, or corrosive; examples include batteries, paint, and solvents; must be disposed of in secure facilities

E-Waste

Discarded electronic devices such as phones, computers, and TVs; should be recycled at certified e-recycling centers to prevent toxic leaching

Waste Incineration

Burning waste at high temperatures; reduces volume by ~90% and can generate energy, but releases air pollutants like dioxins and CO₂

Sanitary Landfill

An engineered waste burial site with liners, leachate collection, and methane capture systems; most common MSW disposal method in the US

Open Dump

An unregulated waste pile; illegal in the US; causes disease, contamination, and pollution

Integrated Waste Management

A comprehensive system combining recycling, composting, incineration, and landfilling; considered most sustainable

Leachate

Toxic liquid produced when water filters through landfill waste; collected and treated to prevent groundwater contamination

Landfill Liner

Layer of clay and HDPE plastic beneath a sanitary landfill that prevents leachate from contaminating groundwater

Landfill Methane

CH₄ produced by anaerobic decomposition of organic waste in landfills; can be captured and burned for energy

Rebuy

Purchasing products made from recycled materials; the most energy-efficient step in waste reduction

Reduce

Consuming less material overall; second most energy-efficient waste reduction strategy

Reuse

Using products multiple times before disposal; reduces need for new material production

Recycle

Processing used materials into new products; least energy-efficient of the 4 R's but still reduces mining demand

Why recycle metals over mining?

Recycling aluminum uses 95% less energy than virgin mining and avoids habitat destruction, erosion, and pollution

Composting

Converting organic waste into nutrient-rich soil amendment; reduces landfill volume but can attract pests and produce methane if done improperly

Basel Convention Treaty

International treaty that controls the movement of hazardous waste across national borders; prevents rich countries from dumping in poorer nations

RCRA (Resource Conservation and Recovery Act)

1976 US law that regulates hazardous waste from cradle to grave — covering generation, transport, storage, treatment, and disposal

CERCLA (Superfund Act)

1980 US law that funds cleanup of abandoned hazardous waste sites; enforces the polluter pays principle; established the Superfund National Priority List

Primary Sewage Treatment

Physical process using screens and settling tanks to remove large solids and sludge from wastewater; removes ~35% of BOD

Secondary Sewage Treatment

Biological process using aerobic bacteria to digest organic matter in wastewater; removes ~85-90% of BOD

Tertiary Sewage Treatment

Chemical and physical treatment that removes remaining nutrients (N, P) and pathogens using chlorination, UV, or reverse osmosis

BOD (Biological Oxygen Demand)

Amount of oxygen needed by bacteria to decompose organic matter in water; high BOD indicates heavy pollution

What cannot be removed from wastewater?

Pharmaceuticals, microplastics, some heavy metals, and endocrine disruptors are not fully removed by standard sewage treatment

Dose

The amount of a substance administered to a test organism

Toxicity

The ability of a substance to cause harm to a living organism

LD50 (Lethal Dose 50%)

The dose of a substance that kills 50% of a test population; lower LD50 = more toxic; measured in mg/kg body weight

LC50 (Lethal Concentration 50%)

The concentration of a substance in air or water that kills 50% of test organisms; used for inhaled or aquatic toxins

Threshold (toxicology)

The dose below which no harmful effect is observed in a population

LD50 vs LC50

LD50 measures dose of an ingested substance; LC50 measures concentration of a substance in air or water

Dysentery

Disease caused by contaminated water/food (Shigella bacteria or amoeba); symptoms: bloody diarrhea, severe cramps, fever, dehydration

Mesothelioma

Cancer of the lung lining caused by asbestos inhalation; symptoms: chest pain, shortness of breath, pleural effusion, persistent cough

Respiratory Disorders from Tropospheric Ozone

Caused by ground-level ozone and PM2.5; symptoms: wheezing, reduced lung function, asthma attacks, chest tightness

Pathogen

An organism or agent (bacteria, virus, fungus, parasite) that causes disease; examples: Salmonella, Influenza virus

Vector

An organism that transmits a pathogen to a host without being sick itself; examples: mosquito (malaria), tick (Lyme disease)

Intermediate Host

An organism that temporarily harbors a pathogen during part of its life cycle; examples: pig (flu), snail (schistosomiasis)

Infectious Disease

A disease caused by a pathogen that can spread from host to host; examples: cholera, tuberculosis

Cholera Life Cycle

Vibrio cholerae contaminates water via fecal matter → ingested by human → colonizes intestine → causes severe diarrhea → feces re-contaminates water; spread via fecal-oral route

Zika Life Cycle

Aedes aegypti mosquito bites infected person → virus replicates in mosquito → mosquito bites new host → infection spreads; also spread sexually; causes microcephaly in fetuses

Plague

Disease caused by Yersinia pestis; vector: flea on rodents; symptoms: fever, swollen lymph nodes (buboes), chills, skin blackening

Tuberculosis (TB)

Airborne bacterial disease (Mycobacterium tuberculosis); spread by inhaling droplets; symptoms: chronic cough, coughing blood, night sweats, weight loss

Malaria

Caused by Plasmodium parasite; vector: Anopheles mosquito; symptoms: cyclic fever/chills, anemia, headache, vomiting

West Nile Virus

Caused by flavivirus; vector: Culex mosquito; symptoms: fever, headache, body aches, rash

SARS

Severe Acute Respiratory Syndrome; airborne virus; spread by respiratory droplets; symptoms: fever, cough, breathing difficulty, pneumonia

MERS

Middle East Respiratory Syndrome; spread from camels to humans and via droplets; symptoms: fever, cough, shortness of breath, kidney failure

Zika Virus

Caused by flavivirus; vector: Aedes mosquito; also sexually transmitted; symptoms: rash, joint pain, red eyes, mild fever; causes microcephaly in newborns

Cholera

Waterborne bacterial disease (Vibrio cholerae); spread via contaminated water; symptoms: severe watery diarrhea, dehydration, vomiting, muscle cramps

Why are low-income areas more vulnerable to infectious disease?

Lack of clean water/sanitation, overcrowded housing, limited healthcare, poor nutrition weakening immunity, and inadequate vector control

Infectious disease and global travel

Air travel allows pathogens to cross continents in hours before symptoms appear, enabling rapid spread of pandemics like SARS and COVID-19

First step of an epidemiologist

Establish a case definition — identify who is sick, where, and when — then trace the source/index case to determine the outbreak's origin