There are three major routes in which chemicals enter the body:
- Skin/Eye Contact
- Inhalation (breathing)
- Digestive System (ingestion or eating)
The skin is the largest organ of the body and consists basically of three layers:
(A) Epidermis – outermost layer: Chemicals first make contact with this thin protective layer.
- It consists of five sub-layers of tightly packed cells.
- The visible top sub-layer is coated with keratin – a tough horny protein that contains fat and fat-like substances.
- Keratin cells form the protective barrier against infection, water, injury, harmful ultraviolet rays and damaging pollutants.
(B) Dermis: After a substance passes through all the layers of the epidermis, it contacts this much thicker underlayer called the dermis. The dermis contains most of the skin’s living structures, such as:
- Blood vessels (approximately 19 yards of capillaries per square inch)
- Hair follicles
- Sweat glands
- Elastin protein fibers
Once a chemical seeps into the dermis, it is allowed entry into the veins inevitably circulating throughout the bloodstream.
(C) Hypodermis – deepest layer: This layer connects the skin to muscle fibers. It is rich in fat and provides a network of “shock absorbers” to protect delicate biological structures in the hypodermis, such as:
- Blood vessels
- Hair follicles
- Nerve fibers
Skin Conditions Affect Chemical Penetration
The skin is one of the major routes in which chemicals enter the body and its condition makes them more easily penetrable.
Breaks in the protective layer provide access to the dermis. The protective keratin-rich layer of skin allows chemicals to enter the body when weakened from:
- Skin flaking
Contact with some chemicals, such as detergents or organic solvents can cause acute contact dermatitis, skin dryness, and cracking providing an opportunity for chemicals and bacteria to enter the body. For example, all variations of Dawn®, Ivory® and Joy® Liquid Hand Dishwashing Detergents contain ethanol (ethyl alcohol) to denature proteins and dissolve lipids (fats) on your dishes, but at the same time, this chemical can break down the fatty protective keratin layer on your skin.
The protective layer of a baby’s skin takes about six months to become thick enough to act as an effective barrier against external elements.
Damaged skin of an infant, such as from eczema or diaper rash, is especially vulnerable. Worse yet, chemical exposure has a much greater effect on a child than on an adult because a child’s immune detoxification mechanisms are not fully developed.
More Absorbent Areas of the Skin
The following areas of the skin are more absorbent than others, so use caution when applying products to these areas.
The small duct containing the hair shaft provides an open entryway to chemicals. Areas of the body that are particularly hairy, such as the forearms, legs, head, face, and underarms are most easily penetrable by chemicals.
Sweat pores are contained over the entire area of skin and provide a pathway into the body for chemical compounds. They are more abundant per square inch of skin than the pores of the hair follicle (650 sweat pores to 19 hair follicles) and have a considerably smaller opening. There are higher concentrations of sweat pores on the forehead, under the arm, palms of the hands, and soles of the feet — areas frequently targeted with skin care products.
All Chemicals Are Not Absorbed Alike
Chemicals can vary enormously in the degree that they penetrate the skin.
- Some solvents may soften the keratin cells in the skin and are absorbed with prolonged skin contact.
- In contrast, some chemicals can readily pass through the epidermis (outermost layer) to the dermis and rapidly enter the veins and bloodstream.
- Some chemicals are so corrosive they burn holes in the skin, allowing the entry of bacteria or other chemicals.
Once Chemicals Enter the Skin, Where Do They Go?
Once a substance enters the body and penetrates the deeper layer of the skin (dermis), it is distributed via the bloodstream. As a result, the chemicals can be transported to any site or organ of the body where they may exert their effects far from the original point of entry.
Once the chemicals circulate through the body, they:
- Are broken down as a function of metabolic processing (they lose or gain electrons).
- Are filtered through the liver and kidneys and excreted depending on the individual’s general state of health, chemical exposure level, and detoxification mechanisms (i.e. the ability to disintegrate circulating toxic substances).
- Attack target organs.
But It Only Contains a Little…
If the use of a hazardous substance within a specified concentration is regarded as safe, using it frequently may not. Repeated use could increase the duration and concentration of exposure, especially when it is absorbed through the skin.
The total daily dose of a chemical can be substantial when using it one or more times per day or using several different products in a single day (such as cleanser, shampoo, conditioner, styling gel/spray, sunscreen, makeup, etc.).
Fit Tip: Read product labels and avoid products made with synthetic fragrances and artificial colorants as much as possible. Keep in mind how/where the product will be applied, the condition of the skin, and the age of the person using the skin product.
- Chemical exposure is greatly increased if the product is applied over a large surface area and remains on the skin, such as in body lotion, oil, foundation, or diaper cream.
- If the skin is damaged, exposure is even greater.
- Everyday products, such as shampoos, hair products, and deodorants increase exposure to chemical ingredients.
- Children and young adults are at considerable risk of experiencing the potential effects from long-term exposure.
© 2009 Karen Owoc and The Health Reporter™. All Rights Reserved.