Overall : Environmental Health Flashcards
Is solid waste disposal a new or old concept?
Solid waste disposal is a relatively new concept.
-Until the 20th century, the individual was responsible for discharging waste.
The major law governing the handling of municipal solid wastes is (MSW) in the U.S. is ______
The Resource Conservation & Recovery Act.
What are the goals of the Resource Conservation & Recovery Act?
1) Ensure that disposal facilities are adequate.
2) Encourage source reduction, recycling, & recovering energy from waste.
Recycling definition
EPA defines recycling as the process of minimizing waste generation by recovering & reprocessing usable products that might otherwise become waste.
What are some advantages of recycling?
(1) Reduces emissions of greenhouse gases
(2) Prevents pollution generated using new materials.
(3) Decreases the number of materials shipped to landfills.
(4) Preserves natural resources.
(5) Opens new manufacturing employment opportunities.
(6) Saves energy
Medical Waste
Medical waste, is any solid waste that is generated in the:
-Diagnosis, treatment, or immunization of human beings or animals.
-In research pertaining to thereto.
-In the production or testing of biologicals.
~The US produces ~3.5 million tons of medical waste annually.
***Before of its disposal into landfills, medical waste is decontaminated.
MSW generated (in 2014), 258 million tons
Paper
Food
Yard trimmings
Plastics
Rubber, leather, & textile
Metals
Wood
Other
Dangers associated with older landfills
-Groundwater contamination & air pollution.
-Leachates may include: toxic heavy metals (lead, cadmium, arsenic, mercury, nickel).
-Solvents & cleaning agents may also contaminate groundwater.
Air pollutants:
-Gaseous emissions from landfills (methane, volatile organic compounds (VOCs), & other gases).
VOC Emissions:
-Potentially carcinogenic
-May cause odors & symptoms of respiratory irritation.
Well-designed landfills
When properly sited, well designed, & efficiently operated, a sanitary landfill can be a perfectly adequate means of urban refuse disposal, free from;
-Offensive odors
-Vermin
-Pollution problems
~Landfills became the overwhelming waste disposal method of choice nationwide, largely because they are the most economical of the legal options.
Modern Landfills:
All items that can not be recycled or composted are deposited into a landfill, which has four major parts;
1) Bottom liner
2) System for collecting leachates
3) Cover
4) Appropriate location that minimizes contamination of groundwater by materials released from the site.
How do modern landfills work?
How a landfill works;
-Begins as a depression dug into the earth’s surface.
The bottom is lined with a dense layer of clay & sealed with thick plastic sheeting to contain leaks of hazardous materials.
The flexible membrane liner holds in toxic chemicals that might contaminate groundwater.
*A leachate sump collects leachates, which is pumped to the surface where it is then subjected to further treatment.
What are the four major categories of Food Hazards?
1) Biological: microorganisms, toxins
3) Physical: stone, glass, metal
4) Chemical: mercury, methanol
5) Nutritional: presence of nutrients & other food constituents in excess or deficient amounts that lead to disease.
What is a food contaminant?
A food contaminant is, any impurity or substance that pollutes food.
-An agent of contamination accidentally or inadvertently introduced into food, water, or soil, that may or may not be harmful or potentially poisonous.
Can you always tell if food is poisoned by the smell, look, or taste?
No, usually you can not tell if food is poisoned by the smell, look, or taste.
Foodborne diseases: biological hazards
1) Mycotoxin
2) Bacterium
3) Virus
4) Parasites
Mycotoxins
Mycotoxins are substances naturally produced by fungi that contaminate crops.
Can occur during cropping season & crop storage.
Crops contaminated with mycotoxin; range from
Corn, rice, peanuts, sorghum, soybeans, millet, rye, wheat, barley, brazil nuts, pecans, pistachios, spices, walnuts, and products from these crops.
Aflatoxicosis
Potent toxin produced by the fungus, Aspergillus flavus.
-Toxin-producing mold growing under high humidity & temperature conditions. (peanuts, pistachios, rice, corn).
Humans become sick when they consume products or food contaminated with aflatoxin.
-Potent carcinogenic & immunosuppressive effects.
-Aflatoxin contamination of foods = global human & animal health problems. (Malnutrition plays a role in this as well).
Aflatoxins: Exposure
Acute: >6,000mg= acute toxicity with lethal effects.
Chronic: small doses for prolonged periods.
*Decreased Vitamin K bioactivity.
(Evidence from China & Africa; aflatoxins & Hep. B virus act synergistically in etiology of liver cancer.)
Aflatoxin: Chronic Exposure
Aflatoxin epidemics in humans:
3rd world countries: large outbreaks due to lack of regulatory measures & high exposure levels.
U.S.: no reports of large human outbreaks.
Most recent severe outbreak:: NW India 1974,
Ergot, Claviceps Purpurea, Ergotism or “St. Anthony’s Fire”
Caused by toxic doses of alkaloid ergotamine.
Produced by purple masses of spores on grains that are infected with ‘Claviceps Purpurea’
*Spores (sclerotia)
Major set of symptoms from Ergot Ergotism, or ‘St. Anthony’s Fire’
*Toxin causes vasoconstriction with severe neurological alterations.
When consumed in bread;
-violent muscle contractions
-vomiting
-deafness
-blindness
-hallucinations
High levels of toxin cause:
Gangrene with burning pain in the body extremities. Convulsions, hallucinations, severe psychosis, & death, or possibly miscarriages.
St. Anthony’s Fire: More Recent Event
Pont-St. Esprit, France
*1851 outbreak
-Small town, one bakery
-strange events
-people developed burning sensation in their limbs.
-began to hallucinate they could fly.
-did strange things to dogs with forks.
Paralytic Shellfish Poisoning
Paralytic Shellfish Poisoning results from eating oysters, clams, or scallops that are contaminated with saxitoxin.
~Nerve poison produced by algae.
Symptoms:
-Numbness in mouth & extremities.
-Gastroenteritis
-Difficulty speaking & walking
-Death (in a small percentage).
Who is at risk?
-All at potential risk with high exposure.
-Greatest risk & health consequences for those with a weakened immune systems.
Ways Bacteria Cause Foodborne Illnesses:
1) Ingestion of bacterial toxin present in food.
2) By ingestion of pathogenic bacteria present in food or water.
Bacterial Toxins in Food: Botulism
Botulism, Clostridium Botulinum
-Anaerobic bacteria
-Life-threatening, systemic paralyses.
-Ingestions of preformed bacterial toxin results in paralysis of the cranial & peripheral nerves.
-Incubation usually 12-36 hours; can be longer.
*****-Shorter incubation= more severe illness
-Low case fatality rate (<15%) during the past decade when treatment adequate.
-High fatality rate w/o treatment: 1/3rd die within 3-7 days.
-Slow recovery: can take months to years.
