Unit 5 Food, Pesticides, and Human Health

1. Lethal Dose-50% (LD50)

the amount of a chemical that kills 50% of the organisms in test population

2. Effective Dose-50% (ED50)

the dose that affects 50 % of the pop. (with a response other than death)

3. Threshold Level

level below which there are no noticeable toxic effects observed

4. Mutagen

causes changes to DNA that result in hereditary changes

Examples of common mutagens

ethidium bromide, formaldehyde, dioxane, and nicotine

5. Teratogen

causes birth defects

Examples of common teratogens 

ethanol, mercury compounds, lead compounds, phenol, carbon disulfide, toluene and xylene

6. Carcinogen

substance that causes cancer

Examples of common carcinogens

benzene, vinyl chloride, formaldehyde, dioxane, and acrylamide

Does EVERYTHING cause cancer?

No

7. Endocrine disruptor

chemicals which mimic human hormones such as estrogen, thereby interfering with their normal functions

Examples of common endocrine disruptors 

BPA, Phthalates, PBDE's (flame retardants)

8. Bioaccumulation

chemical build-up of toxins in fatty tissue in a single organism

9. Biomagnification

build-up in toxins as you move up the food chain; they must consume more to survive.

Think magnification = MULTIPLE organisms!

Example of biomagnification 

DDT caused problems in large predatory birds (Osprey)

10. How Does Mercury get into the Environment and Fish?

• burning of coal

• atmospheric deposition

11. Perfluorooctanoic Acids (PFOA, PFOS)

chemical used in nonstick coating have been recently found in the water on Long Island. Linked to kidney and testicular cancer, thyroid disease, lower sperm count and smaller penis size.

13. BPA or Bisphenol A

chemical that has been used since the 1960s to make lightweight, hard plastics; Possible health effects of BPA on the brain, behavior and prostate gland of fetuses, infants and children

12. Polybrominated diphenyl ethers (PBDEs)

group of highly toxic chemicals that are persistent in the environment; flame-retardants that are used in many consumer products to make them difficult to burn like couches, mattresses, pillows, etc.

14. Phthalates

group of chemicals used to soften and increase the flexibility of plastic and vinyl.

Used in cosmetics and personal care products, like hair spray, soap, shampoo, nail polish, plastic and vinyl toys

Implicated as a cause of breast cancer, increased obesity, insulin disruption, testicular disease

15. Synergism

when the sum of the effects of multiple chemicals is more dangerous than each chemical individually.

16. Persistent Organic Pollutants (POPs)

man-made (aka "forever") chemicals that are not biodegraded, therefore transported by wind and water all around the Earth (grasshopper effect). Since they last for a long period, they biomagnify/bioaccumulate; adversely affecting human health and the environment.

Examples of Persistent Organic Pollutants

DDT, dioxins, PBDEs, and PFAS

17. World's Main Food Source

Wheat, rice, and corn provide more than ½ of the calories in the food consumed by the world's people

18. Slash-and-burn

agriculture method that involves burning a forest or field of vegetation and using the resulting ash as fertilizer—ancient technique that pre-dates modern fertilizers.

Which method do the natives use to clear the forests of the Amazon to farm and raise cattle?

slash and burn

19. Green Revolution

began in the 1940's, greater increase in food production due to genetically altered crops, improved synthetic fertilizers, man-made pesticides and using fossil fuels to power machines

20. Monoculture

farm focuses on just one organism; all resources are focused on producing it efficiently, highly susceptible to disease/pests, needs high amounts of synthetic fertilizers and pesticides

21. Monarchs and the Milkweed Case Study

milkweed is the only plant on which monarch butterflies will lay their eggs, and it is the primary food source for monarch caterpillars.

Extensive monoculture and herbicide use the milkweed population has declined dramatically.

22. Economic Advantages of CAFO (Concentrated Animal Feeding Operations)

a large percentage is produced on factory farms, maximizing profit by increasing the yield and decreasing cost by cramming animals into small spaces. This provides humanity with high quality protein at reasonable prices for millions

23. Environmental Disadvantages of Factory Farming (CAFO)

· Contamination of surface and groundwater due to the high volume of animal waste from runoff. This contributes to cultural eutrophication when the runoff enters lakes and streams, eventual dead zones

· Using antibiotics and hormones poses unknown risk to human health, possible antibiotic resistance

· Takes a tremendous amount of energy, land, and water to produce a small amount of meat (beef is the most energy intensive) which is a major contributor to climate change and habitat destruction

· Methane, a GHG 25x more potent than CO2, is released from flatulent animals, especially beef

24. Genetically Modified Organisms (GMO's) aka Bioengineered

involves taking beneficial genes from an organism and inserting them into the genome of the crop or livestock species.

Why would GMOS be beneficial?

create traits such as drought resistance, pesticide resistance, need for less fertilizer, or even more nutritional value

25. Problems with GMO's

Native diversity may be decreased by the spread of GMO genes to nonengineered organisms, beneficial insects may be harmed or killed unintentionally (ex. pollen toxic to monarch butterflies)

ECONOMIC ISSUE: Companies have patented, sterile seeds which commit the farmer to annual purchase of seeds that are often too expensive for poor farmers

26. First Generation Pesticides

made from natural substances

• Examples are sulfur, arsenic, lead, mercury

• Abandoned due to human poisoning and contamination of soil

• Also botanically derived pesticides like nicotine sulfate from tobacco leaves

27. How are Heavy Metals Getting into our Food?

· Remnants of past pesticide use remain in soils like inorganic arsenic (especially in the US South)

Ex. High levels of inorganic (toxic) arsenic in some rice and juices (more in brown vs. white rice)

· Use of leaded gasoline put lead into the air and then it contaminated soils

Ex. High levels of lead in some chocolate (more in dark vs. milk), juices, and sunflower products

· Emissions from the metal industry, mining, and contaminates of fertilizer use

Ex. How metals like cadmium gets into chocolate

28. Chlorinated Hydrocarbons

second generation pesticide Examples are DDT, Aldrin, Methoxycholor

• Contain chlorine

• Broad Spectrum which kill many species

• Slow to degrade aka persistence (2 - 15 years)

• Biomagnifies and bioaccumulates; Suspected carcinogen & endocrine disruptor

29. Rachel Carson

wrote a book called Silent Spring detailing use of DDT and its effects on birds. DDT biomagnified and in larger predatory birds weaken the shells of their offspring so much so that when they sat on them to keep them warm, they cracked, killing the developing baby bird.

30. Organophosphates

second generation pesticide; examples are Malathion, Parathion, Diazonon

• Contain phosphorus; derived from nerve gas (German research during WWII)

• More poisonous than others, high level of toxicity to mammals

• Degrades more easily because it is water soluble (several weeks)

31. Neonicotinoids

relatively new class of pesticide similar in chemistry to nicotine

• Highly toxic to most insects by attacking their nervous system, but less toxic to birds and mammals

• Most widely used insecticide, persists for years (about 4)

• Linked to colony collapse disorder (CDC) which are killing pollinators. (Bees are dying!!!!)

32. Roundup (Glyphosate)

is an extensively used herbicide made by the Monsanto Corporation

• World Health Organization (WHO) listed it as "probably" causing cancer in humans

• Similar in structure to a natural growth hormone (endocrine disruptor)

• Broad spectrum; used to kill dandelions and many other "weeds"

• Very small amounts (parts per billion) have found in common foods like cereal and grain products

33. Pesticide Pros

saves lives from insect-transmitted disease; increases food supply and lowers food costs therefore increasing profits for farmers; works faster than alternatives

34. Pesticide Cons

genetic resistance, ecosystem imbalance, pesticide treadmill, persistence, bioaccumulation and biomagnification, can runoff, can kill unintended species

35. Pesticide Resistance

when a pesticide is applied it kills most organism except for organisms that are naturally resistant to the chemical. These "pesticide resistant" organisms reproduce and overtime the entire population is now evolves a resistance the pesticide.

36. Pesticide Treadmill

as the development of pesticide resistance increases the farmer requires increased applications, which then leads to more resistance! (like a drug addict needs more/stronger drugs to get same high)

37. Circle of Poison

• US pesticide companies can make and export pesticides that have been banned or never approved in the US

• Foreign farmers assume they are safe because the US is making them

• Residues of these chemicals return to US consumers on imported produce (25% of all produce consumed in the US is produced overseas)

38. Pesticides Effects on Humans

• Short Term Exposure i. Farm workers poisoned

• Long Term Exposure i. Cancers, leukemia, birth defects

ii. Disruption of human hormone systems (endocrine disruptor) ex. breast cancer, decrease in sperm counts

39. Delaney Clause of Food, Drug, and Cosmetic Act (FDCA) 1958

1 shall not approve any food additive that has not been test or found to induce cancer in man, or after tests, found to induce cancer in animals

40. Problems with Delaney Clause

technology for detecting pesticide residues was in its infancy. New tech makes it impossible for any processed food to meet the standard of no pesticides causing cancer at some level

41. Integrated Pest Management (IPM)

involves multiple strategies such as introduction of pest predators (lady bugs/praying mantis), pheromones traps, hormones to disrupt the pest's life cycle, sterile males, and/or crop rotation to reduce the use of pesticides. GOAL: to learn more about pests, only use pesticides as a last resort and while still making a profit

42. IPM Examples

know a few examples for the test (this is what we use in our courtyard garden)

• Agricultural Methods

i. Crop rotation or intercropping (monoculture invites pests)

ii. Pick off insects or pick out weeds like dandelions (by hand or drill)

iii. Adjust planting times (squash vine borer example)

iv. Mosquitoes (drain standing water, wear long sleeves)

• Natural Enemies 129 beneficial insects are sold in the US

i. Parasitic wasps control the boll weevil

ii. Lady bugs and praying mantis control aphids

• Biological Agents

i. Milly spore fungus controls white grubs/Japanese beetles

ii. Repellents: Fox/Coyote Urine or marigolds to keep pests like rabbit/deer away

iii. Pheromones: chemical sex attractants to lure pests

• Miscellaneous

i. Sterilize the males: fruit flies

ii. Physical barriers like small fences, sticky materials or netting

iii. Motion activated sprinklers

iv. Diatomaceous earth: harm only insects with exoskeletons

v. Natural oil spray

43. Pros and cons of becoming vegetarian or vegan

Pros: Healthier for you, less cancers and heart disease, Animal rights/poor treatment, Feeds more people by eating lower on the food chain (10% rule), Reduces greenhouse gases (climate change) like methane from livestock and fossil fuel use (about 15% of all greenhouse gas emissions)

Cons: Could be protein deficient and must need to take B12 supplements due to scarcity in non-animal products

44. Organic Food

food produced without antibiotics; growth hormones; and most conventional pesticides; petroleum - based fertilizers; bioengineering (GMO's); or ionizing radiation