Environmental Toxicity, week 9

* hazmats and sources, love canal and CERCLA, hazardous waste, toxic chemicals

ecotoxicology

• study of contaminants in biosphere and their effects on ecosystems

• Is dilution the solution to pollution (dilution paradigm)? or does what you throw away come back to bite you (boomerang paradigm)?

the nature of hazardous materials (HAZMATs)

any solid, liquid, or gas…

• toxic

• flammable

• corrosive/reactive

accounts for 1% of the US waste stream, but has an oversize impact on the US.

examples of HAZMATs

• CFCs- component of Greenhouse gases (chloroform carbons, from the cooling component of air conditioners and refrigerators)

• arsenic

• lead

• pesticides

• mercury

• acids

total product life cycle

• concept

• sum of all the steps in the manufacturing of a product that extends exposure to HAZMATs

→ extracting raw material

→ production

→ use

→ disposal- never fully prevents material from leeching its way into the groundwater

• following passage of the clean water act and the clean air act, industries turned to land disposal methods

Toxicity

• Effects can be immediate or prolonged

• Acute toxicity- occurs immediately or within several days following a single exposure

• Chronic toxicity- long-term, low-level exposure

persistence

• a characteristic of certain chemicals that are extremely stable and may take years to break down into simpler forms.

leads to 2 problems, which happen together

1. bioaccumulation- the buildup of persistent toxic substance in an organism’s body (most prominent in fatty tissue)

2. biomagnification- increased concentration of toxic chemicals in an organism’s body at higher levels in the food web (as they consume the organisms below them, and therefore consume the total of the DDT in the organisms they eat, and the organisms their food has eaten, etc)

Love Canal, NY

• 1942-1953: Hooker Chemical Co. disposed of 22,000 tons of toxic chemical waste in a makeshift landfill and covered it with soil

• Then, a small neighborhood with a school was later built in this area.

→ Hooker Chemical donated the landfill to the Board of Education & inform them that it was a landfill.

→ The Board of Education still built a building on top of the landfill

→ The landfill started to ooze waste

→ A mother named Lois addressed this issue and brought it to the attention of higher ups

• In 1978, President Carter declared this area a national emergency disaster area, and the residents got help

• 1980, led to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)

• If a company created a landfill, citizens could file for compensation

surface impoundments

• Temporary storage or treatment of liquid hazardous waste

key features:

1. dig shallow depression with an underlying impermeable layer, but it can crack and leak waste

2. higher possibility of contamination of nearby areas

3. residue is transported elsewhere

natural evaporation can clear freshwater, and waste that’s bonded to water molecules gets left behind and can be discarded

cons:

• high possibility that contamination can occur

• leeching can occur

• overflow

Hazardous landfill

• long term storage of solid hazardous waste

key features:

1. put them in barrels

2. far from aquifers, streams, wetlands, and residences

3. several layers of impermeable layers at the bottom

4. must be treated at detoxified as much as possible

5. eventually buried 

6. ventilation checks for leaks

7. gas vents are implemented

deep-well injection

• long term storage of hazardous waste

key features:

1. well must be isolated from groundwater and human contact

2. several layers of impermeable layers at the bottom

3. must be treated and detoxified as much as possible

4. must ensure that nothing will come back up to the surface

phytoremediation

• Rhizofiltration- roots in water absorb pollutants, radioactive isotopes, and organic chemicals

→ ex= sunflowers. They are placed in a radioactive environment and uptake radioactive material in the water 

• Phytostabilization- block chemicals and prevent them from reaching ground or surface water 

→ ex= willow tree

• Phytodegradation- breakdown chemicals into less toxic compounds that are released into atmosphere

• Phytoextraction- roots absorb and store toxic metals, requires proper power plant disposal

Threats from toxic chemicals

• persistence is exacerbated by chemicals that do not degrade in the environment

→ Carcinogenic: cancer causing

→ Mutagenic: mutation causing 

→ Teratogenic: birth defect causing

• the severity of these effects depends on intensity and duration of exposure

heavy metals

• naturally occurring in earth’s crust

• ex= lead, mercury, cadmium, arsenic, tin, chromium, zinc, and copper

• uses= batteries, electronics, metal working, paint pigments, glazes, inks, dyes

• effects= harm to the brain, heart, kidney, lungs

reducing heavy metal exposure 

• heavy metal poisoning is rare in the US, but can happen to those who have consistent exposure

• knowledge: test your home if there is a risk of lead exposure

• limit the amount of fish that contain heavy metals in your diet

Bisphenol-A (BPA)

• industrial chemical used to make certain plastics and resins

• uses: polycarbonate plastics (food and beverage containers)

Endocrine disrupting chemicals (EDCs)

1. MIMIC a natural hormone

2. BLOCK the effects of a hormone

3. STIMULATE OR INHIBIT the endocrine system

• alter reproductive development

• causes sterilization

• has been linked to diabetes, obesity, cardiovascular problems, etc

who is vulnerable

children

• physical- bodies are small, still developing, and are not as effective in dealing with toxicants

• other characteristics- play on floors and lawns, put items in their mouth

• consequences- developmental effects, death