Dermal Absorption

One organ that we often forget that has the ability to absorb chemicals and toxins is through our skin. The skin in the largest organ in the body and when we think of routes of exposure and absorption, it is through either ingestion or inhalation. Through dermal absorption, chemicals can travel through the different layers of skin which can cause irreversible damage. Principles and Practices of Toxicology in Public Health written by Ira S. Richards discusses the properties of skin, including its purpose, structure, absorption, and toxicity.

The Purpose and Structure of the Heaviest Organ in the Body: Skin

Ira S. Richards describes the properties of the skin, including its purpose, structure, absorption, and toxicity. Skin is defined as a physical protection from environmental agents and has hydroregulation ability through both passive and active mechanisms. Thermoregulation is utilized in place to maintain core body temperature, chemical synthesis of vitamin D, and the sensory reception of pain, temperature, touch, and pressure are recognized with this organ. This is not a passive structural barrier, meaning that it participates actively in a variety of defense strategies designed to prevent widespread internal or cutaneous damage. From a toxilogical viewpoint, the skin is a major concern because of its route of exposure for systemic toxicants, direct exposure or toxicity, Xenobiotic metabolizing organ, and a minor pathway for the elimination of certain toxicants. The skin can be divided into three basic regions known as the epidermis, dermis, and hydrodermis.

Skin Absorption of Chemicals

Absorption through the skin occurs when the chemical moves fro the epidermis layer into the dermis of the skin. This movement occurs by passive diffusion and is called percutaneous absorption. The major barrier of the method of absorption is the stratum corneum. Conditions that alter the structural integrity of the skin such as lacerations or abrasions can enhance the absorption of xenobiotics. The rate of penetration is largely related to the lipophilicity of the chemical; the more lipophillic a chemical is, the greater its rate of penetration. Factors affecting skin absorption according to Nursing 411 include the permeability of the skin, degree of skin hydration, contact time, degree of friction, skin temperature, and epidermal damage. 

Skin Toxicity

Ira S. Richards discusses that there are a number of effects certain chemicals can have on the skin. Hands wrists, and forearms are the most common sites of occupational contact dermatitis. Factors that affect the development of skin reactions to chemical exposures include: preexisting skin conditions, allergies, age, work experience, temperature, humidity, and the seasons. The Extension Toxicology Network states, that during mixing, loading and application of pesticides, the skin is the most likely body surface to come into contact with the product. Many pesticides can be absorbed through the skin into the blood, and can cause toxic effects. The amount of pesticide absorbed through the skin (percutaneous absorption) may be enough to produce severe toxic reactions including death. In addition, pesticides can also injure the skin directly, a process known as cutaneous toxicity. Skin irritation and skin rashes produced by irritating chemical substances are a very noticeable type of chemical toxicity. Skin infections by fungi (ringworm, athlete's foot, etc.), bacteria, or parasites are also very common medical problems and often have the same symptoms as skin irritation caused by chemical exposure.