BOS 4201 Unit IV Assessment

Identify the factors that can affect the distribution of a toxicant in the body. Explain how manipulation of these factors can increase toxicity.

Your response should be at least 300 words in length.

Distribution refers to the process of movement of a chemical throughout the fluid compartments of the body after first entering internal body fluid (usually the blood). The factors that can affect the distribution of a toxicant in the body are lipid solubility, ease of crossing cell membranes, blood flow to the tissue or organ, and extent of plasma protein binding. There are a number of concerns regarding the movement and distribution of toxicants throughout the body. These concerns involve: the rate of distribution the role of exposure route on distribution outcome the determinants of equal or unequal distribution to the cells and tissues of the body (Richards & Bourgeois, 2014). Lipid soluble substances are stored in body fat. Biotransformation and degradation occur gradually which allows bioaccumulation and the lengthy retention of these types of toxicants in the body. As small quantities are accumulated over time, the concentration of lipid soluble substance can reach a toxic level. Toxic substances that enter the bloodstream may bind with plasma proteins in an effort to reduce its potential to enter the cells of the body, but there is always some portion that is not bound. As the unbound toxicant passes through the capillaries to the surrounding tissues, the bound toxicant separates form the proteins in order to maintain equilibrium between bound and unbound toxicant in the blood. Toxicants that are not bound to plasma proteins are capable of crossing cell membranes which would increase toxicity. The amount of blood flow to tissues and organs can also be important to the accumulation of a toxicant. Organs and tissues that have high rates of blood flow and are targets for toxicity can experience greater negative effects for a toxicant. Organs, such as the liver and kidneys, have a high perfusion rate which can result in significant exposure to circulating toxic substances.

Reference:

Richards, I. S., & Bourgeois, M. M. (2014). Principles and practice of toxicology in public health (2nd ed.).

Burlington, MA: Jones & Bartlett Learning.

Identify the three systems of the body in which toxicants can enter, give a brief description of how this may occur, and provide an example of a toxicant that can enter the body through each system.

Your response should be at least 300 words in length.

Skin absorption is the first body system that toxicants can enter. The skin can be a significant route of exposure for toxicants, especially at the workplace. The outer layer of the skin (stratum corneum) is the first line of defense between dermal exposure and systemic toxicity. The term percutaneous absorption refers to absorption from the surface of the skin into the blood of the cutaneous vessels, which reside in the dermis. The skin is relatively impermeable to aqueous solutions and ions; however, it can be a significant route of exposure for chemicals that are lipophilic in nature. The skin or integument consists of an outer epidermis, a middle dermis, and a layer of subcutaneous connective tissue (Richards & Bourgeois, 2014). Organic solvents such as benzene can be absorbed through the skin, the toxicant would pass through the epidermis, sweat glands or hair follicles. The solvent must pass through seven layers of skin before entering the small blood and lymph capillaries of the dermis.

Gastrointestinal Absorption is the second body system where toxicants can enter. Chemicals entering the gastrointestinal tract must first cross the mucosa somewhere along the tract before gaining entry into the blood. The degree of absorption is dependent on: Site, pH, time, the physicochemical properties of the chemical (Richards & Bourgeois, 2014). This means if swallowed how long it stays in the throat or if it passes through the liver where the toxic chemicals can be reduced. Another factor that determines the amount of chemicals absorbed is the presence or absences of food. An example for this is the ingestion of Clorox, if swallowed it will not enter the blood until it enters the stomach due to the minimal length of time it takes to pass through the esophagus. Clorox has a high pH level that can eliminate the lining of the liver that can reduce the toxicant.

The third system is the respiratory absorption where toxicants can enter. The respiratory system constitutes a very important route of exposure for airborne contaminants (e.g., toxic gases, particulates, aerosols, volatile organic solvents). Toxicants that are contained within our breathing zone may be absorbed in the nasopharyngeal, tracheobronchial, or pulmonary exchange surfaces of the lungs, depending on the physical and chemical properties of the toxicant (Richards & Bourgeois, 2014). Second hand smoke of nicotine can enter an individual’s blood stream because the smoke is within their breathing zone. It is inhaled through the nasopharyngeal and enters the blood.

Reference:

Richards, I. S., & Bourgeois, M. M. (2014). Principles and practice of toxicology in public health (2nd ed.).

Burlington, MA: Jones & Bartlett Learning.

Explain the processes used by the body to eliminate a toxicant. Provide an example of a situation where one of these processes might be inhibited and how the inability to eliminate the toxicant might impact the individual.

Your response should be at least 300 words in length.

The processes of toxicant elimination are critical to the reduction of toxicity or potential toxicity in the body. The term elimination encompasses all of the processes that are used by the body that lead to a decrease in the amount of toxicant, including; Renal elimination, Fecal elimination, Pulmonary elimination, Biotransformation, Elimination via minor routes (sweat, milk, nails, etc.) (Richards & Bourgeois, 2014). The renal form of elimination of toxicants by the body is by using the bladder. The main function of the bladder is to store and release urine. The urinary system filters blood through the kidneys as a means of maintaining homeostasis and physiological pH within the body. The urinary system is the primary system responsible for excreting metabolic waste. Uric acid from nucleic acid metabolism and nitrogen from protein breakdown, are major metabolic bi-products excreted in the urine.

Another elimination process for toxicants in the body is the fecal process through the bowels. As food is ingested, it passes through the digestive tract and is continually broken down and the nutrients absorbed into the body. What isn’t utilized by the body will then be eliminated in the form of stool. Toxins and waste are eliminated in the stool, thus protecting the body from toxic accumulation. In order to adequately eliminate toxins through the bowels an daily bowel movement is needs to occur.

A third elimination process is the pulmonary elimination where the lungs are responsible for eliminating carbon dioxide while breathing. Carbon dioxide is naturally occurring toxin in the body. Breathing is a major way for the body to maintain homeostasis. PH balance in the body is achieved through breathing and optimal kidney function. With these body processes the elimination of toxins allows the body the opportunity to rid itself of waste and unnecessary harmful compounds. If toxins are left in the body they begin to accumulate and over time disrupt the body’s natural physiological functioning and can lead to disease. If the body couldn’t exhale carbon dioxide then there would be an overabundance of this natural toxicant in the body. Carbon dioxide needs to be balanced with adequate oxygenation to maintain homeostasis in the body.

Reference:

Richards, I. S., & Bourgeois, M. M. (2014). Principles and practice of toxicology in public health (2nd ed.).

Burlington, MA: Jones & Bartlett Learning.

A doctor can send hair samples from a newborn infant to be analyzed in the lab to see if the mother drank alcohol during the pregnancy. This is one test that can be performed to assist in diagnosing fetal alcohol syndrome. Recalling what you know about elimination of toxicants, briefly explain why this test can be used to determine exposure to alcohol.

Your response should be at least 300 words in length.

References:

• Toxicant elimination is a vital process to the reduction of toxicity in the body. Elimination refers to all of the process that are used by the body which lead to a reduction in the amount of toxicant. The processes are renal elimination, fecal elimination, pulmonary elimination, and biotransformation (Richards & Bourgeois, 2014). In addition to the previously listed processes toxicants can also be eliminated through minor routs, such as sweat, milk, hair, and nails. Additionally, toxicants can be deposited in inactive tissue such as the nails, hair or outer layer of skin. Although there is negligible elimination of toxicants through the hair and nails, alcohol can be detected in hair by searching for fatty acid ethyl esters. Fatty acid ethyl esters (FAEE) are a becoming a promising biomarker for fetal alcohol exposure. FAEE are products of non-oxidative ethanol metabolism that are formed when ethanol is conjugated to endogenous free fatty acids or fatty acyl-CoA (Zelner et al., 2012). FAEE can be found in the hair of infants that have been exposed to ethanol. FAEE can also be found in meconium, blood, and several organs, but its detection in hair holds the potential for detecting and easing the diagnosis of FASD because of its distinctive benefits. Obtaining hair from the mother or infant is a non-invasive procedure and can be used to measure long-term and past exposure. Additionally, hair provides a larger window for detection because newborn or parental hair can be collected months after birth, while meconium is only obtainable during the first 2 to 3 days of a newborn’s life. FAEEs are also extremely stable in hair and can survive for long lengths of time up to several years, even at room temperature. FAEE’s stability in meconium on the other hand, may only last a few days if not frozen correctly. The flexibility and stability of the FAEE hair test makes it a promising contender for use as a biomarker of alcohol use during pregnancy.

Richards, I. S., & Bourgeois, M. M. (2014). Principles and practice of toxicology in public health (2nd ed.).

Burlington, MA: Jones & Bartlett Learning.

Zelner, I., Shor, S., Lynn, H., Roukema, H., Lum, L., Eisinga, K., Koren, G. (2012). Clinical Use Of Meconium Fatty Acid Ethyl Esters For Identifying Children At Risk For Alcohol- Related Disabilities: The First Reported Case. Journal of Population Therapeutics & Clinical Pharmacology, 19(1). Retrieved from https://www.jptcp.com/index.php/jptcp/issue/view/23