Class Session 16>
I. Chemicals and Hazardous Waste
The U.S.E.P.A. defines a hazardous waste as any solid, liquid, or containerized gas that has one or more of the following properties:
1. ignitability - a waste the easily catches fire such as waste oils, organic solvents and PCB's. These include liquids with a flash point (the temperature at which vapor easily ignites in air) of less than 140 degrees Fahrenheit, materials that burn vigorously and persistently when ignited so that they create a hazard, and ignitable compressed gases.
2. corrosivity - a highly acidic of highly alkaline waste or one that corrodes steel easily. This includes both aqueous waste with a ph of less than or equal to 2.0 or greater than or equal to 12.5 and liquid wastes that corrode steel at a rate equal to or greater than 0.25 inches per year at a test temperature of 130 degrees F.
3. reactivity - a highly unstable waste that can cause explosions or toxic fumes or vapors. This includes materials that react violently with water, those that form potentially explosive mixtures when combined with water, will generate toxic gases, fumes, or vapors in quantities sufficient to endanger human health or the environment and materials that are capable of detonation or explosive reactions if subjected to a strong initiating source or if heated under confinement.
4. toxicity - a waste in which hazardous concentrations of toxic materials can leach out and pose a danger to human health or the environment. Hazardous waste can cause a wide range of harmful effects on human health as well as long term or permanent damage to the environment.
It is very difficult to estimate
how much hazardous waste is produced worldwide, or even in one country. There
is no reliable estimate of global production. Estimates range from 375 million
metric tons to 500 million tons for the 19 most industrialized countries. One
thing is clear, however, the
Ninety percent of the hazardous
Most hazardous wastes are synthetic organic and inorganic chemicals which are used for all kinds of purposes in industrialized countries such as cleaners, solvents, degreasers, insecticides, coatings and paints. The number of synthetic chemicals produced around the world now stands at about 80,000, with between 500 and 1,000 being added every year. Very little data exists on the toxic effects of about 80% of these chemicals and complete data exist for only 2%.
Hazardous wastes are disposed
through various land-based technologies that include containerized burial, open
pit, pond or lagoon, pile, deep well injection, and others. Unfortunately, many
of these disposal techniques are, in actuality, storage techniques rather than
disposal. In the
Only part of the problem is
current disposal of hazardous waste. There are many inactive hazardous waste
sites across the
Several problems can result with hazardous waste disposal. These include:
1. local citizen resistance to the siting of hazardous waste disposal facilities, either incinerators or landfills;
about accidents that occur during the shipment of hazardous materials. In the
dumping, which often occurs. There is lots of incentive to dump hazardous waste
illegally. Waste disposal costs in the
4. shipments of hazardous materials to other countries, many of which are non-urbanized, non-industrialized countries.
The Resource Conservation and Recovery Act, first passed in 1976 and amended in 1984, requires EPA to identify hazardous wastes, set standards for their management, and provide guidelines and financial aid to establish state hazardous waste management programs. All firms that store, treat, or dispose of more than 100 kg (220 pounds) of hazardous wastes per month must have a permit stating how such wastes are to be managed. To reduce illegal dumping, hazardous waste producers granted disposal permits must use a "cradle to grave" manifest system to keep track of waste transferred from point of origin to approved offsite disposal facilities. Keeping track of all this waste, generators and haulers is an enormous task which costs billions of dollars annually.
Inactive, abandoned or old waste sites are handled under EPA's Superfund program. The Superfund program manages a large pot of money used to clean up these old sites. 1n 1989, the EPA estimated that there were over 31,500 sites in the United States containing potentially hazardous waste, with this number increasing at a rate of 2,500 per year. By July 1989, EPA had placed 1,224 sites on a priority cleanup list because of their threat to nearby populations and the priority list is growing at a rate of about 180 per year. By mid 1989, EPA had spent 4.5 billion to start cleanups at 257 priority sites, but only 50 sites had been cleaned and 27 declared clean enough to be removed from the list. EPA estimates that the agency can only clean up about 25 to 30 cleanups a year. At that rate, it would take 41 to 50 years to clean up the 1,224 priority sites listed in 1989. The Office of Technology Assessment estimates that the final list may contain 10,000 sites, with cleanup costs amounting to as much as $300 billion over the next 50 years.
Once the hazardous wastes are deposited in or on the land, engineered control and treatment technologies are the only available option to control the pollution potential. Hazardous wastes can be stabilized, neutralized, or in some other fashion rendered less hazardous. In some cases, the waste are pumped out of the ground and then treated, usually by high temperature incineration.
There are, however, a couple of other options. One is to not use or generate a hazardous chemical to begin with, thereby eliminating the need for disposal. This is referred to as pollution prevention. The concept of a proactive pollution prevention program provides the greatest potential to reduce the impact of society on our limited land and natural resources. Such programs can result in substantial waste stream reduction, health and environmental protection, and cost savings by cutting raw material losses, lowering pollution control costs, and reducing future liability.
Another option is for the generator of hazardous waste or chemicals to transfer their waste or chemical to a facility that uses the material as in input into their processes. This type of approach, which is usually accomplished by a hazardous waste clearinghouse is part of a new movement referred to as industrial ecology. Industrial ecology seeks to have industrial systems mimic natural biological systems in which materials flow between different organisms and no waste is generated or requires disposal.
Prior to the late 1980's there was a booming international trade in hazardous waste. Poor countries were accepting hazardous materials and waste from industrialized countries for hard currency. Rather than deal with existing environmental regulation in their own country, many companies were only too happy to export their hazardous waste. This practice has been curtailed thanks to an international treaty, signed in 1989, to control export of hazardous waste. This treaty specified that the government in the recipient country must give permission for the waste to be imported into their country. Further, in 1994, the countries that make up the OECD agreed to stop dumping their wastes in poor countries. The ban on exports for burial and incineration of hazardous waste was made effective immediately and hazardous waste exports for recycling became illegal as of 12/31/97.
II. Chemicals – Case Study – Chloroflourocarbons
From the week seven notes, we learned that the homosphere, or lower atmosphere, is divided into three layers. The troposphere, closest to the earth, is where daily weather phenomenon occurs and where air pollution and acid rain is distributed. The second layer out is the stratosphere. The stratosphere sits some 11 to 30 miles from the earth’s surface. As 90% of the gas molecules in the atmosphere are within the first ten miles, the air in the stratosphere is very thin.
Despite the thinness of the stratosphere, however, there is one gas located there which performs a critical function to life on earth. The gas is ozone, or O3. Ozone filters ultraviolet radiation from the sun. Various forms of energy have different wavelengths. The wavelength of light energy, for example, is shorter than that of heat energy. Ultraviolet, or UV, energy has a wavelength that is shorter than light energy. Even UV energy itself is divided into three types, based on wavelength with UVC being the shortest, UVA the longest and UVB in the middle.
Humans need a small amount of ultraviolet radiation to maintain health. Ultraviolet radiation activates vitamin D in the human body, which assists the intestines in absorbing minerals. Humans, as well as other life forms, can tolerate radiation through the UVA range, but radiation with shorter wavelengths, such as UVB and UVC is harmful. Oxygen molecules absorb the shortest and most harmful UVC radiation and ozone absorbs most of the remainder before it reaches the earth’s surface. Ozone, a molecule containing three oxygen atoms, is made when the shortest wavelengths of UVC are absorbed by oxygen and break apart into two oxygen atoms. These atoms then combine with 02 molecules to form stratospheric ozone and it is these O3 molecules that shield the surface from too much ultraviolet radiation.
Stratospheric ozone depletion occurs when O3 molecules interact with chlorine-based compounds such as chlorofluorocarbons, also known as CFCs, and halons. Chlorofluorocarbons are synthetic compounds containing chlorine, fluorine and carbon. CFCs have been used in a wide variety of consumer and commercial applications such as refrigeration, air conditioning, foam production, aerosol propellants, and circuit board cleaning. Halons are another class of synthetic chemicals which are used to extinguish fires.
Both CFCs and halons are extremely long-lived and stable chemicals that can remain chemically active in the atmosphere for decades. Not only do CFCs and halons destroy the molecular bonds of the O3 molecule, but also a single chlorine molecule can eliminate as many as 100,000 ozone molecules. Halons contain bromine and are even more potent ozone destroyers than CFCs.
The result of ozone destruction is a gradual thinning of the stratospheric ozone layer. Over the past 20 years, ozone levels above the Antarctic have dropped by almost 50%, resulting in an “ozone hole”. Every year, beginning in September, ozone levels in the stratosphere above the Antarctic begin to decline. As they decline, more and more ultraviolet radiation reaches the earth’s surface. Scientists believe that a 1% drop in ozone accounts for a 2% increase in ultraviolet radiation at the earth's surface.
Over time the Antarctic ozone
hole has gotten larger. In September 2003, the World Meteorological Association
reported that the 2003 hole equaled the all time record set in September 2000.
Over the past decade, stratospheric ozone levels have begun to decrease in the
Artic as well, though scientists believe that a “hole” like that at the South
Pole is not likely to develop. Nonetheless, there have been short period with
significant ozone loss in the
Increasing ultraviolet radiation at the surface results in effects on human health, natural ecosystems, and crops. The human effects of increasing ultraviolet radiation include increase in skin cancer cases, development of cataracts, and suppression of human immune systems. Effects on natural ecosystems include decrease in photosynthetic productivity and adaptive strategies. Phytoplankton in the oceans, for example, are thought to stay further away from the ocean surface in response to changing ultraviolet light concentrations. The crop productivity of certain crops can be adversely affected by changes in UV concentrations at the surface .
The Montreal Protocol, adopted in 1987, required nations to freeze production levels of CFCs. Additional agreements enacted since 1987 accelerated the CFC phase out timetable to December 31, 1995. Atmospheric concentrations of chlorofluorocarbons peaked in 1994 and began to decrease in 1995, marking the first time that a atmospheric concentrations of chlorine began to decrease. Chlorine concentrations in July 2002, were about 5% less than the 1994 peak. However, the amount of atmospheric bromine continues to increase, albeit at a slower rate.
Many scientists believe that the stratospheric ozone layer will be somewhat “mended” by the year 2050, though uncertainty remains. In the mean time, it is difficult to predict, with any reasonable accuracy, the amount of ozone depletion that might continue to take place, how much additional UVB will reach the earth’s surface in the next fifty years, and the potential impacts of this increased radiation on terrestrial and aquatic ecosystems as well as on human health.