Human Health

APES

LD₅₀

• refers to the dose or concentration of the chemical that kills 50% of the population being studied

LD₅₀ measurement in (units)

• mass (g. mg)/body unit mass (kg)

• ppm - parts per million (in air)

Response Studies

studies that expose an organism to different doses of concentrations of a chemical in order to measure the response (effect) of the organism

Dose Response Curve

• data from a dose response study, graphed with percent mortality or other effect on the y-axis and dose concentration of chemical on x-axis

Threshold or toxicity threshold

• lowest dose where an effect (death, paralysis, cancer) starts to occur

ED₅₀

the dose of concentration of a toxin or chemical that causes a non-lethal effect (infertility, cancer, paralysis, etc) in 50% of the population being tested

What are dose response data done on? 

• data from other mammals (mice, rats)

• used to simulate human toxicity

• to determine maximum allowable levels for humans, divide LD₅₀ or ED₅₀ dose concentration by 1,000 (for extreme caution)

Acute Studies

• only measure effects over a short period of time

• lab isolated 

• don’t measure ecological effects of organisms dying

• most dose response studies are acute

Chronic Studies

• longer-term and follows developmental impacts

Endocrine Distruptors Def.

• chemicals that interfere with the endocrine (hormonal) systems of animals

• bind to cellular receptors ment for hormones, blocking the hormone from being received

What is a common source of endocrine disruptors in the environment?

• human medication flushed down the toilet

Endocrine Disruptors

• Atrazine

• DDT

• Phthalates

• Lead, arsenic, mercury

• Human medications

Mercury

• naturally occurring in coal, released by anthropogenic activities 

  • coal combustion, trash incineration, burning medical waste, heating limestone for cement

  • attaches to PM released by burning & deposits in soil.water wherever PM settles

  • can be released if coal ash stored in ponds overflow & runoff

• endocrine disruptor - inhibits estrogen & insulin

• Teratogen - chemical harmful to developing, can accumulate in fetus brain

Arsenic

• naturally occurring element in rocks underground that can dissolve into drinking water; natural release into groundwater can be worsening by mining 

  • Anthro sources - formerly in pesticides applied to ag fields, lingers in soil, wood treatment, coal combustion

  • Carcinogenic - (lungs, bladder, kidneys) & endocrine disruptor

  • Endocrine disruptor - specifically glucocorticoid system (can be removed with water filters)

Lead

• found in old paint (in homes), old water pipes, and soil contaminated by PM from vehicle exhaust (in 70s)

  • released in fly ash (PM) of coal combustion

  • neurotoxicant (Damages central nervous system, esp. in children)

  • endocrine disruptor

• Can be removed with water filters

Coal Ash

• source of mercury, lead, and arsenic

• attaches to fly ash (PM) from smokestack and be carried by wind, deposited in ecosystems far away

• both fly and bottom coal ash are often stored on site. in ponds, dug into soil & lined with plastic

  • ponds can leach into groundwater, contaminating it with arsenic, lead, mercury

  • ponds can overflow & runoff into nearby surface waters & agricultural fields

  • can be converted to methylmercury by bacteria

Routes of Exposure

ways that a pollutant enters the human body

• lead —> water pipes & paint drops

• mercury —> seafood (tuna)

• CO —> indoor biomass

• PM —> pollen, dust, etc

• Arsenic —> rice, groundwater

Synergism

interaction of two or more substances to cause an effect greater than each of them individually

• ex. asthma caused by PM from coal PPs and COVID-19 damaging lungs

Dysentery

bacterial infection caused by food or water being contaminated with feces (often from sewage release into rivers & streams used for drinking water)

• causes very severe dehydration due to diarrhea

• poor sanitation & unfiltered waters 

Mesothelioma (Asbestos)

a type of cancerous tumor caused by exposure to asbestos, primarily affecting the lining of the respiratory tract, heart or abdominal cavity

• exposure comes primarily from old insulation materials used in attics, ceiling, and flooring boards. when the insulation becomes physically disturbed, asbestos particles are released into the air & inhaled

• must be professional removed 

Tropospheric Ozone (O₃)

worsens respiratory conditions like asthma

• limits overall lung function

• irritates muscles or resp. tract causing constriction of airways & shortness of breath

• worsens the respiratory conditions like asthma, bronchitis, and emphysema

• only harmful in troposphere (beneficial in stratosphere)

Pathogens

living organism (virus, bacteria, fungus, protist, worm) that causes an infectious disease 

• capable of being spread of transmitted

• noninfectious diseases are not transmissible

• pathogens adapt and evolve to take advantage of humans as hosts for their reproduction and spread 

Vectors

a living organism (rats, mosquitos) that carry and transmit infection pathogens to other organisms

• climate change is shifting equatorial climate zoners north and south away from the equator, this brings warmer temps to subtropical and temp regions —> allows pathogens and their vectors to spread north & south to parts of the world previously too close

Infectious Disease & Development

less developed, poor countries typically have higher rates of infectious disease

• less sanitation

• less access to healthcare

• lack of treatment/filtration

• tropical climates & more open air living can expose to vectors

Plague

bacterial (pathogen) infection transmitted by fleas (vector) that attach to mice & rats

• transmitted by bite, rodent contact or contaminated human fluids

Tuberculosis (TB)

bacterial (pathogen) infection that targets the lungs

• transmitted by breathing bacteria from body fluids of an infected person (can linger in air for hours)

• causes night sweats, fever, coughing blood ; treatable in developed nations with access to powerful antibiotics

Malaria

parasotic protist (pathogen) infection caused by bite from infected mosquitos

• most comm in in sub-Saharan Africa and other tropical regions

West Nile

virus (pathogen) infection caused by bite from infected mosquitos 

• birds are main host, but the virus can be transmitted to humans by mosquitoes that bite infected bird and then bite humans

Zika Virus

virus (pathogen) infection caused by bite from infected mosquitos & sexual contact

• causes babies to be born with abnormally small heads and damaged brains (can be passed down)

SARS (Severe Acute Respiratory Syndrome)

coronavirus (pathogen) infection caused by respiratory droplets from infected person

• primarily transmitted by touching or inhaling fluids from an infected person

• causes form of pneumonia

MERS (Middle East Respiratory System)

Virus (pathogen) respiratory infection transmitted from animals to humans

Cholera

bacterial(pathogen) infection caused by drinking infected water

• vomiting, muscle cramps and diarrhea

• severe dehydration

Developing Countries

use more subsistence fuels such as wood, manure, charcoal (biomass)

• biomass fuels release CO, PM, NO, VOCs

Developed Countries

use more commercial fuels (coal, oil, natural gas) supplied by utilities

• typically burned in closed, well ventilated furnaces, stoves

• major indoor air pollutants in developed nations come from chemicals in products: adhesive in furniture, cleaning supplies, insulation lead paint

Particulate Matter (PM) Asbestos

PM are a common indoor air pollutant 

• ex. smoke from indoor biomass and dust and asbestos

• absestos is a long, silicate particle previously used in insulation

CO (Carbon Monoxide)

CO is produced by incomplete combustion of basically any fuel

• CO is an asphyxiant: causes suffocation due to CO binding to hemoglobin in blood, displacing O₂

• developed nations: CO released into home by malfunctioning natural gas furnace ventilation

• developing nations: CO emitted from indoor biomass combustion for heating/cooking

VOCS (volatile organic compounds)

chemicals used in variety of home products that easily vaporize, enter air, and irritate eyes, lungs, bronchioles

• ex. adhesives/sealants, cleaners, plastics and fabrics

  • (formaldehyde - common adhesive in boards carpets, manufactured things)

Radon Gas

radioactive gas released by decay of uranium naturally found in rocks underground (granite)

• usually enters homes through cracks in the foundation & then disperses up from basement/foundation through home

  • also seeps into groundwater sources

• causes lung cancer

Dust & Mold

natural indoor air pollutants that can worsen asthma, bronchitis, COPD, emphysema

• Dust: settles in homes naturally, entering air and then respiratory tract

• Mold: develops in areas that are dark and damp and not well ventilated

Lead

• Found in paint in old homes

• lead water pipes also release lead into drinking water sources (as in flint)

• damages central nervous system of children due to smaller size and still developing brain

Urban noise pollution

any noise at great enough volume to cause physiological stress (difficulty communicating, headaches, confusion) or hearing loss

• ex. construction (jack hammers) transportation (cars), industrial activity (manufacturing plants) , domestic activity (lawn mowing)

Wildlife effects (land)

noise pollution can disrupt animal communication, migration, and damage hearing

• physiological stress 

• hearing: prevent predators from hearing prey and vice versa ; prevent mates from locating each other, decreasing survival chances

Wildlife effects (aquatic)

Aquatic noise pollution comes from the noise of ship engines, military sonar, and seismic air blasts from oil & gas surveying ships

• physiological stress: hearing loss, disruption communication

• seismic surveying: ships send huge air blasts into water