Chapter 19 - Review Questions

27/10/2010 01:10

1.    How do toxicologists investigate hazardous chemicals? How is this information disseminated to heal practitioners and the public? (pg. 486)

Toxicologists investigate the potential of certain chemicals to cause human health problems by conducting test (on animals) to link the dose (the concentration of the chemical multiplied by the length of time over which exposure occurs) with the response (acute or chronic effects).

 

Data on toxic chemicals are made available to health practitioners and the public via a number of sources, including: the National Toxicology Program (NTP), Chemical Repository and the National Institute of Environment Health Sciences (NIEHS). The EPA also makes available data on toxic chemicals in its Integrated Risk Information System (IRIS). All of these sources are available on the Internet.

 

2.    What four categories are used to define hazardous chemicals? (pg. 486 -at the end of the page-)

Ignitability: Substances that catch fire readily (e.g. gasoline and alcohol)

 

Corrosivity: Substances that corrode storage tanks and equipment (e.g. acids)

 

Reactivity: Substances that are chemically unstable and that may explode or create toxic fumes when mixed with water (e.g. explosives, elemental phosphorus and concentrated sulfuric acid)

 

Toxicity: Substances that are injurious to health when they are ingested or inhaled (e.g. chlorine, ammonia, pesticides, and formaldehyde).

 

3.    Define what is meant by “total product life cycle”, and describe the many stages at which pollutant may enter the environment. (pg. 487-488)

Total product life cycle is a term that encompasses all steps, from obtaining raw materials to final disposal of the product (see example below):

1.    Mining & refining raw materials → generate:

1.   by-products: large piles of soil removed from mines

2.   pollution: inorganic chemical residues, heavy metals in water, etc.

 

2.    Transportation → generate

1.   waste: Disposal of lubricants, solvents, cleaning fluids, cooling fluids, etc.

2.   pollution:

i.      accidental spills generates pollution

ii.    Burning of gasoline

 

3.    Production of consumer goods (industries) → generate:

1.   pollution:

i.      accidental leaks

ii.    elements directly introduced to the environment (e.g. pesticides, fertilizers, road salts, etc.)

iii.  Burning of gasoline / coal

 

4.    End user

1.   waste: disposal of packaging

2.   pollution: accidental leaks (e.g. harmful gases in refrigeration systems or spray cans)

 

5.    Waste disposal (landfill pollution)

 

4.    What are the two classes of chemicals that pose the most serious long/term toxic risk, and how do they affect food chains? (pg.489)

1.    Heavy metals (HM) & their compounds:

Most dangerous heavy metals are: lead, mercury, arsenic, cadmium, tin, chromium, zinc and copper.

 

HM are extremely toxic; as ions or in certain compounds, they are soluble in water and many be readily absorbed into the body (bioaccumulation and biomagnification), where they tend to combine with and inhibit the functioning of particular vital enzymes.

 

2.    Synthetic organic:

Petroleum derived and synthetic compounds are the chemical basis for all plastics, synthetic fibers, synthetic rubber, modern paint-like coatings, solvents, pesticides, wood preservatives, etc.

 

These compounds are toxic because they are often readily absorbed into the body (bioaccumulation and biomagnification) where they interact with particular enzymes, but their nonbiodegradability prevents them from being broken down or processed further. When ingested in large amounts the effect may be acute poisoning or death. In small amounts over large periods of time they can cause mutations, cancer or birth defects.

 

5.    What are the “dirty dozen” POPs (persistent organic pollutants)? Why are they on a list? (pg. 489)

They are halogenated hydrocarbons (organic compounds in which one or more of the hydrogen atoms have been replaced by atoms of chlorine, bromine, fluorine or iodine -these elements are classed as halogens, hence the name-). Examples of their use include: plastics (polyvinyl chloride), pesticides (DDT, Kepone, and mirex), solvents (carbon tetrachlorophenol and tetrachloroethylene), electrical insulation (polycholrinated biphenyls), etc.

 

They are on a list because all are toxic to some extents, and most are known animal carcinogens (cancer causing) and suspected of being endocrine disruptors at very low levels.

 

6.    How were chemical wastes generally disposed of before 1970? (pg. 491)

It was common practice to exhaust all combustion fumes up smoke-stacks, vent all evaporating materials and solvents into the air, and flush all waste liquids and contaminated wash water into sewer systems or directly into natural waterways.

 

7.    What two laws pertaining to the disposal of hazardous wastes were passed in the early 1970s? Describe how the passage of the laws shifted pollution form one part of the environment to another. (pg. 491)

The Clean Water Act of 1970 and Clean Water Act of 1972 were passed to reduce the worsening pollution problem of air and waterways. These acts set standard for allowable emissions into air and water and timetables for reaching those standards.

 

Their passage in the early 1970s left an enormous loophole. If you can't vent waste into the atmosphere or flush them into waterways, what do you do with them? Industry turned to land disposal, which was essentially unregulated at the time. In retrospective, the Clean Air and Clean Water acts, improved air and water quality, but succeeded in transferring pollutants from one part of the environment to another.

 

8.    Describe three methods of land disposal that were used in the 1970s. How has their use changed over time? (pg. 492 - 494)

Deep well injection:

·       Involve drilling a bore hole thousands of feet below groundwater into a porous geological formation of brine. A well consists of concentric pipes and casing that isolate the wastes as they are injected and the well is sealed at the bottom to prevent wastes from backing up.

·       Used mainly for disposing of volatile compounds like: pesticides, fuels and explosives.

·       The EPA requires this wells to be made in geological stable regions to avoid leakages.

·       The use of deep well injections has declined over the years.

 

Surface impoundments:

·       Are simple excavated depressions (ponds) into which liquid wastes are drained and held.

·       Least expensive and hence most widely used way to dispose of large amounts of water carrying relatively small amounts of chemical wastes.

·       Inadequate sealing of the bottom of the pond may allow waste to percolate into groundwater, storms may cause overflow and volatile materials can evaporate to the atmosphere.

 

Landfills:

·       [External definition: method of hazardous and non-hazardous waste disposal. Non-hazardous materials are spread in layers, compacted to the smallest practical volume, and buried. Hazardous material have to be treated in accordance with their chemical and physical characteristics (regulated by EPA), before disposal in specific (licensed) landfills.]

·       Changed from being unregulated to heavily regulated by the EPA through waste treatment standards.

 

9.    What law was passed to cope with the problem of abandoned hazardous-waste sites? What are the main features of the legislation? (pg. 496)

The Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA) was passed, also known as Superfund.

Through tax on chemical raw material, this legislation provides a trust fund for:

·       the identification of abandoned chemical waste sites,

·       protection of groundwater near the site

·       remediation of groundwater (if contaminated)

·       cleanup of the site

Congress has refused to renew the tax on industry, leaving US taxpayers with the continuing cleanup bill.

 

10.                    What is being done about leaking underground storage tanks and brownfields? (pg. 499 - 500)

Brownfields:

·       EPA definition: “abandoned, idled, or underused industrial and commercial facilities where expansion or redevelopment is complicated by real or perceived environmental contamination”.

·       The Brownfield Act was passed in 2002 which provides grants for the assessment of sites and remediation work.

·       The legislation limit liability for owners and prospective purchasers of contaminated land.

 

Leaking Underground Storage Tanks (LUST):

·       Referring mainly to underground fuel-storage tanks.

·       Underground Storage Tanks regulation (part of the Resource Conservation and Recovery Act -RCRA-) require strict monitoring of fuel supplies, tanks and pipping to ensure early leak detection.

·       When leaks are detected, remediation must begin within 72 hours

·       Tanks have to be upgraded or replaced if the they are only made of steel.

·       LUST is financed by the 0.1-cent-per-gallon tax.

 

11.                    What law was passed to ensure the safe land disposal of hazardous wastes? What are the main features of the legislation? (pg. 501)

The Resource Conservation and Recovery Act (RCRA) was passed. It has three main features:

1.    It requires all disposal facilities be sanction by permit. The permitting process requires that the facilities have all the required safety features.

2.    Toxic wastes destined for landfills have to be pretreated to convert them to form that will not leach (e.g. biodegradation or incineration).

3.    Cradle to grave tracking of all hazardous wastes. The [waste] generator must fill out a form detailing the exact kinds and amounts of waste. Persons transporting the waste and those operating the disposal facility must each sign the form, vouching that the amounts of waste transferred are accurate.

 

12.                    What laws exists to protect the public against exposures resulting from hazardous chemical accidents? What are the main features of the legislation? (pg. 520 - 503)

Department of Transportation Regulations (DOT): Specify the kinds of containers and methods of packaging to be used in the transport of various hazardous materials. They also require that every individual container and the outside of a truck or railcar to carry a standard placard identifying the hazard of the material inside.

 

Worker Protection – OSHA ACT and the “Worker's Right to Know”: Basically the law requires businesses, industries and laboratories to make available both information regarding hazardous materials and suitable protective equipment.

 

Community Protection and Emergency Preparedness – SARA, Title III: Superfund Amendments and Reauthorization Act of 1986 (SARA), Title III is better known as Emergency Planning and Community Right-to-know Act (EPCRA).

It requires companies that handle in excess of 5 tons of any hazardous material to provide a “complete accounting” of storage sites, feed hoppers, and so on. The information goes to a local emergency planning committee, which has the task of drawing up scenarios for accidents involving the chemicals on-site and to have a contingency plan for every case. The committee is mad up representatives of local fire and police departments, hospitals and other groups that may be involved in case of emergency.

 

13.                    What role does the Toxic Substances Control Act play in the hazardous waste arena? (pg. 503)

It requires that, before manufacturing a new chemical in bulk, manufacturers submit a “pre-manufacturing notice” to the EPA in which the potential environmental and human health impacts of the substance are assessed (including those which may derive from the ultimate disposal of the chemical). Depending of the results of the assessment, the EPA may authorize further testing and will determine the final restrictions on the products use or keep it of the market all together.

 

14.                    Why does the EPA have an environmental justice program? (pg. 504)

EPA definition: “[environmental justice is] the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. Fair treatment means that no group of people, including racial, ethnic, or socioeconomic group[s], should bear a disproportionate share of the negative environmental consequences resulting from industrial, municipal and commercial operations or the execution of federal, state, local and tribal programs or policies”

 

The program was started amongst other things, because several recent studies have shown that, all across the US, waste sites and other hazardous facilities are more likely to be located in towns and neighborhoods where most of the residents where non-Caucasian.

 

15.                    Describe the advantages of pollution prevention efforts? (pg. 505)

It involves changing the production process, the materials used, or both so that harmful pollutants won't be produced in the first place.

 

Pollution prevention often results in better product or materials management – that is, less wastage, thus creating cost savings.

 

Pollution prevention can be achieved by:

·       Minimization or elimination of pollution

·       Substitution (finding non-hazardous substitutes for hazardous materials)

·       Reuse (recycle)

·       Consumer reduction or avoidance of products containing harmful chemicals