Chemistry has impacted on society IMMENSELY! The 20th century has seen the birth of three Ages, each with profound social implications. These have been called the Nuclear Age, the Electronic Age and the Chemical Age. The latter is the oldest (beginning ca. 1930), and although its impact has been less dramatic than the other two, its consequences have more thoroughly and deeply permeated our day-to-day lives. Our local grocery, hardware, garden and drug stores carry an impressive array of commonly used chemical "tools", such as detergents, adhesives, lubricants, fabrics, pesticides, pharmaceutical drugs, vitamins and a multitude of fabricated plastic items. Industrial applications of chemical tools include explosives, heat-transfer gases and liquids, specialized coatings, fire retardants and high-performance plastic components.
Despite our widespread use of chemical tools, indeed some might say because of our reliance on them, many people fear exposure to these materials, and have deep concerns regarding the use, storage and disposal of chemicals. Paradoxically, we find our desires for more abundant consumer goods, energy and personal mobility in conflict with maintenance of a healthful environment. To be sure, environmental degradation, with accompanying threats to health and disruption of ecosystems, is not a new phenomenon. From the earliest recorded history, human disturbance of the environment by deforestation, air pollution from cooking and heating fires, and careless sewage and waste disposal has been noted. Today, as global populations grow and per capita energy use and material consumption increases, pollution problems are exacerbated, and previously unnoticed secondary effects manifest themselves.
It must be emphasized that effective strategies for safeguarding our environment require knowledge and understanding. To this end, we must be able to answer the following questions:
What potentially undesirable substances are present in our air, water, soil and food?
Where did these substances come from?
What options, alternative products and processes are available to reduce or eliminate undesireable contaminants?
How does the degree of hazard depend on the extent of exposure to a given substance, and how shall we choose among various corrective options?
The first of these questions requires chemical analysis, and thanks to advances in instrumentation, our ability to detect extremely small amounts of a given substance is unprecedented, and sometimes leads to unwarranted concern. Answers to the second question usually involve collaborative investigations by analytical chemists together with biologists, meteorologists, volcanologists, oceanographers and other scientists. The development of options, as noted in the third question, calls upon our full range of chemical understanding, and often obliges us to make controversial choices. For example, the world mortality rate due to malaria was drastically reduced (over 95%) in the 1950s by widespread application of the insecticide DDT . Because of this chemical's environmental persistence and toxicity to certain birds and crustaceans, use of DDT was effectively terminated ca. 1964. Third world malaria cases immediately spiraled, reaching over 250 million in 1990. Cheap, effective and environmentally friendly alternatives to DDT are needed, but are not necessarily easy to find. The fourth question is addressed by physicians, toxicologists and epidemiologists. A substantial body of knowledge has accumulated on this subject, but there is also considerable public confusion surrounding it.
Our strategies for risk minimization and environmental protection should be based on realistic hazard thresholds, and on our ability to detect specific offending substances well before their presence reaches that threshold. In this sense, detection can be equated to protection. Unfortunately, the public, the media, and government officials all too often equate detection with hazard. This is based on the widely held belief that a substance known to be toxic at a certain concentration will be toxic at any concentration, no matter how low.
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Ok next question...
Which of the following statements is true for all condensation polymers?
a) They are naturally occuring polymers
b) They are formed from monomers, each of which contains double bonds
c) They are formed from the reaction of functional groups on neighbouring monomers
d) They have the same composition as the sum of the atoms in the monomers from which they are formed
