Industrial Toxicology

Industrial Toxicology

Introduction

Toxicology is both the scientific study and direct application of principles regarding xenobiotics (foreign chemicals). Earth is a chemical environment exposing humans to various harmful substances through ingestion ?(Bingham 2001) inhalation ? and contact. Toxins are naturally occurring substances ? whereas toxicants are human-produced substances. Both have the potential to cause death or disease.

Discussion

Chemicals may be classified according to target organ (central nervous system ? liver ? etc) ? use (solvent ? herbicide ? etc.) ? source (animal ? metal ? etc) ? or effects (cancer ? birth defects ? etc). Chemicals might be classified by their physical state (gas ? particulate ? etc) ? (American Conference of Governmental Industrial Hygienists 2004) their chemical makeup ? labeling requirements ? potential for poisoning ? or the biochemistry within life-forms.

In addition to defining and identifying possible poisons or the exposure point of drugs ? pesticides ? chemical weapons ? synthetic fibers ? and industrial chemicals ? toxicologists study toxic effects at the cellular ? biochemical ? and molecular levels and determine the probability of the toxic effect as well as safe versus toxic levels in animals ? plants ? and the environment. (Lewis 2000)

Exposure To Harmful Substances

The potential for toxicity and adverse effects from chemicals introduced into a human or living organism depends on the route and site of exposure ? the duration and frequency of exposure ? and other chemical interactions (intentional or unintentional) introduced by other chemicals or the breakdown of the chemical into metabolites. (Winder 2004) Considerations of exposure include:

Route and Site—chemicals enter the body by ingestion ? inhalation ? and direct contact. Direct injection into the bloodstream causes the highest and most immediate toxic effect. Localized or systemic effects depend on the chemical and biochemical transformation to more toxic products or reaching target organs. (Richards 2008)

Duration and Frequency—the chemical stays in a poisonous state or is transformed to a toxin within a living system. Acute exposure is a single occurrence ? exposure ? or multiple exposures within 24 to 48 hours often occur within a work setting. Chronic exposures occur over a longer period of time and are often environmental. Delayed toxicity might not be noticed at the time of exposure and the effects occur in the future. (Nelson 2006)

Chemical interactions—a single chemical may not cause a toxic reaction ? but when combined with other chemicals ? it produces toxicity. When two or more chemicals combine ? the additive effect means individual toxicities create a sum of all effects and the synergistic effect means the chemicals create a greater effect than either one individually or added together. (Richards 2008)

Body fluid compartments

Just less than sixty percent of the adult human body weight is water ? the major constituent of body fluids. Thus in a 70 kg man there will be 42 kg ? or about 42 liters ? of water distributed in three main compartments: about two-thirds is contained within the cells (the intracellular fluid) and one-third is in the spaces between the cells (the extracellular fluid). ...