Chemicals journeys

Chemistry is the science of change. It is ironic then that, although we have become so knowledgeable about the properties of reactants and products—about the beginnings and ends of chemical journeys—we remain more often than not unsure of just how those journeys are made. Our modern armory of sophisticated spectroscopic and diffraction methods provides every expectation of a direct hit on the fixed objects represented by reactants and products, but is seldom... 

Ships and their cargoes are subjected to stresses in ah directions during handling, transfer, and the journey. Adequate stowage is crucial. In line with the transportation of chemicals on land systems to address include ... 

Kazarians, Boykin, and Kaplan investigated tlie risk of transporting an acutely toxic and flanunable chemical 400 miles in a specially equipped railroad tank car. During its journey, the tank car clianges trains in three major rail yards. Each change of trains is teclmically described as a classification . The chemical is generally shipped one tank at a time. There are approximately 150 shipments a year. 

Although thermodynamics can be used to predict the direction and extent of chemical change, it does not tell us how the reaction takes place or how fast. We have seen that some spontaneous reactions—such as the decomposition of benzene into carbon and hydrogen—do not seem to proceed at all, whereas other reactions—such as proton transfer reactions—reach equilibrium very rapidly. In this chapter, we examine the intimate details of how reactions proceed, what determines their rates, and how to control those rates. The study of the rates of chemical reactions is called chemical kinetics. When studying thermodynamics, we consider only the initial and final states of a chemical process (its origin and destination) and ignore what happens between them (the journey itself, with all its obstacles). In chemical kinetics, we are interested only in the journey—the changes that take place in the course of reactions. 

These stories describe some of the roads taken to solve the puzzle of illness caused by exposure to chemicals. For many the journey is long and involves a parade of doctors and misdiagnoses. Often MCS is discounted by health care professionals and others who doubt the validity of the illness. When the validity of an illness is discounted, the ill suffer profound discord within their world, according to Kathy Charmaz in her book Good Days, Bad Days The Self in Chronic Illness and Time. This discord can be heard in the collection of narratives in this volume. 

There are nine households of chemically ill people in this area, so far. Some of the people have had horrible losses, and it s hard not to take that out on each other sometimes. At least we know where it s coming from. Some of the people don t like each other, but we re stuck with each other, just like if we had gone on some really long wagon train journey and got trapped together in this remote place. Even if we get absolutely sick to death of each other, we look out for each other. We have to. Bruce and I talk every day, and the neighbors all touch base often to try to keep each others morale up, or we would get too lonely and too homesick. 

I am also grateful to The growing circle of physicians, researchers, policymakers, activists and others who are responding to environmental health issues with right action. My family members and friends who honor my need for chemical- and fragrance-free encounters. And Bart Paff, Ph.D., for an incredible journey to joy and self. 

But these sources of health harm have a characteristic that is not associated with chemicals - they are living organisms that can reproduce. So, in their journey from farm to table, organism counts can increase and, if conditions for growth are unfavorable, they can decrease. Some chemicals may undergo a degree of destruction as they move from source to target, but this phenomenon is far more problematic and unpredictable in the case of microbes. 

The nature-nurture problem revisited in most vertebrates, early experience of certain odors, interwoven with genetically anchored developmental processes, produces lasting, often irreversible odor recognition, preferences, or avoidance. Such behavioral development often occurs during more or less defined critical windows in time. The development of responses to odors often precedes that of odor production. Neonates already orient towards odors, while many pheromones are not produced until adulthood. Even before hatching or birth, the journey of chemical communication starts in the egg or the uterus. Knowing how chemical communication and chemosensoiy responses to food or danger develop is essential in areas such as animal husbandry or human behavior. 

This paper traces in some detail the path which led to the discovery of a new class of herbicides, the 2-(5-oxo-2-imidazolin-2-yl)arylcarboxylates. The journey started when it was found that a phthalimide, a-isopropyl-a-methyl-l,3-dioxo-2-isoindoline-acetamide, had sufficient herbicidal activity to warrant further synthesis effort. This work led to a series of analogs essentially devoid of herbicidal activity yet possessing interesting plant growth regulating effects. Further chemical modifications resulted in the synthesis of two new groups of compounds, imidazoisoindolediones and dihydro-imidazoisoindolediones, and the return of herbicidal activity. The imidazoisoindolediones were in turn transformed into o-(5-oxo-imidazo-lin-2-yl)benzoates, the first members of a very interesting new class of herbicides. 

There are numerous parameters to characterize the environmental effects of a chemical, once it is released either by accident and leakage or by disposal after the end of the usefulness of a product. We need to follow the journey of the chemicals released. 

As reactions proceed, reactants are chemically combined into compounds, which then perform their functions. These compoimds are eventually consumed in other reactions, and their fragments are used to generate new molecules or are excreted. The life cycle of chemicals in the body is a critical aspect of biochemistry, though neurochemistry researchers are hampered by a limited access to the brain. The following sidebar on pages 82-83 describes a neurotransmitter s metabolic journey. 

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