Characteristics of a Safer Chemical

Nowadays, few would challenge Alice Hamilton s position that chemists should intentionally design chemicals to be safe in addition to being efficacious with regard to use. However, until statutory changes are made in the TSCA that authorize the EPA to require that chemical manufacturers provide evidence of safety of new industrial chemical substances before such substances can be marketed, the concept of designing safer chemicals will never fully be adopted, regardless of how many more well-written papers or books are published on the topic. 

Exactly what is a safer chemical Many people naturally think of chemical safety from the context of human health, and automatically interpret safer chemical to mean a chemical that is or is expected to be of reduced toxicity to humans, usually with regard to some other chemical that fulfills the same commercial purpose. This occurs because we tend to prioritize human health over that of other species in our environment. Thus, many of the publications referenced in this chapter that focus on the design of safer chemicals are devoted primarily to the design of chemicals that are expected to have a minimal effect on human health. The same may be said of this book. 

what is a safer chemical A safer chemical is a chemical that causes minimal adverse impacts on human health, other forms of life, and the Earth. It is a relative term, and should not be interpreted to mean that the safer chemical does not cause any adverse impact at any level of exposure, or is in fact totally safe or without risk. A safer chemical is one in which any adverse effects that it may have on humans, other organisms, or the Earth are tolerable, or at least more tolerable than the adverse effects caused by some other chemical under similar conditions of exposure. 

Within the realm of human toxicity, cancer is probably the illness that is most feared by society, since it is a difficult disease to treat and cure, and often culminates in a slow, painful, emaciating death. Hence chemicals that are known to cause, or are even suspected of causing, cancer are generally less tolerated and are regulated more stringently than chemicals that do not cause cancer but may cause other toxicities that are associated with lower morbidity and mortality, and for which better treatment modalities exist (e.g., nephrotoxicity). 

Toxicity to the central nervous system (CNS) is another highly feared illness. Although often not fatal, it is usually long lasting (if not permanent) and debilitating. Fetuses, infants, and even children tend to be more susceptible and sensitive to chemical-induced injury to the CNS. This is because the brain cells and the 

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What do we mean when we speak of an inherently safer chemical process Inherent has been defined as existing in something as a permanent and inseparable element, quality, or attribute (American College Dictionary, 1967). A chemical manufacturing process is inherently safer if it reduces or eliminates the hazards associated with materials and operations used in the process, and this reduction or elimination is permanent and inseparable. To appreciate this definition fully, it is essential to understand the precise meaning of the word hazard. A hazard is defined as a physical or chemical characteristic that has the potential for causing harm to people, the environment, or property (adapted from CCPS, 1992). The key to this definition is that the hazard is intrinsic to the material, or to its conditions of storage or use. Some specific examples of hazards include ... 

In addition, the chemist may infer the structural characteristics that reduce toxic potency, thereby providing a rational basis to design new, less toxic analogs. Typically, in larger data sets the relationship between structure and activity is more apparent, but small data sets can nonetheless be fairly useful. The application of SARs for the design of safer chemicals is demonstrated below using aliphatic carboxylic acids and organonitriles, two classes of important commercial chemical substances. 

Informed substitution enables the move from the use of chemicals of concern to safer chemicals, while minimizing the likelihood of unintended consequences. This technique has been demonstrated to be an effective tool and is recognized [8] for guiding the evaluation of chemicals or products in the context of functional need. The options for meeting a functional need can be arrayed along a spectrum of preference based on environmental and human health characteristics. Decisions based on informed substitution will avoid an inclination to select an alternative that may appear more benign only because it is poorly characterized. 

The word "natural" is used in opposition to the word "synthetic" with the connotation that "natural" products are safer than "synthetics", but there are many toxins made by plants and animals which are very detrimental to man (44-47). Moreover, whether chemicals are made in flasks by man or made by plants and animals, no compounds are made on earth other than those permitted by the laws of nature. Therefore, all molecules on this earth are "natural". This definition is from a chemist s viewpoint, and is in agreement with a dictionary definition of "characteristic of or explainable by the operations of the physical world". 

The environmental benefits are (1) enzymes replace hydrochloric acid in the manufacturing process, (2)eUminate the need for harsh chemical processing, (3) reduce the risk to the environment, and (4) provide a safer workplace due to the elimination of the use of a strong acid. The consumer beuefits are (1) confections and specialty baked goods with excellent mouthfeel and taste characteristics are readily available at reasonable cost due to the use of the enzyme invertase (2) soft centers of fine chocolates remain smooth and creamy and (3) some candies stay chewy and soft cookies are available on the grocer s shelves, rivaling homemade versions because of this special food enzyme. 

Given the above characteristics, why would any chemical engineer be a whistle-blower All three codes of ethics mentioned in Section 23.1.7 require chemical engineers to dedicate their skills to the public welfare, and whistle-blowing has led to inproved automobile safety, safer nuclear and chemical plants, better control of toxic wastes, reduced government waste, safety inprovements in NASA launches, and other laudable results. Whistle-blowers themselves have stated that they could not stand the stress of nondisclosure, which they viewed as an abdication of their ethical responsibilities. In other words, they could be morally autonomous only by whistle-blowing. 

The siliceous and aluminous contents of the effluent from the TSA [6], should be tested for their affinity to the hydraulic lime to form cementitious substances (termed as the special cement). Once experimentations are planned and attempts are made to monitor the physical, chemical, mineralogical and morphological characteristics of such special cement, the inferences would pave some way to a further step ahead towards establishing an innovative fly ash zeolite synthesis technique with zero-emission waste for a safer environment... 

The module provides a search interface as well as directories for chemical classes, characteristics, and use of substances. Particularly interesting is an expert system for designing safer substances based on chemical classes. Selecting, for instance, the chemical class polymers gives access to the designing safer polymers entry, which leads to a series of questions (answers are marked in bold case) ... 

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