Chemicals Found in the Skin (Body) and Why pH Is Important in Cosmetics

Chemicals found in the skin and body

When we discuss chemicals and chemical reactions within the body, we are talking about a subject called biochemistry.
Biochemistry is a highly complex subject that we will barely touch.
Many complex chemical reactions take place in the body, and many of these reactions are still not fully understood.
The hormones that tell our cells what to do are chemicals that react with receptor sites.
The pituitary hormones that signal other glands to manufacture other hormones are another example of chemical reactions within the body.

Most of the chemical reactions within the body are called organic reactions.

Organic chemistry does not mean natural chemistry.
Organic chemistry is the chemistry of compounds containing carbon atoms.
Carbon is an element that is a large constituent of almost all the many chemicals in the body.
The chemicals that the body uses most are oxygen, carbon, hydrogen, and nitrogen.
Carbon and hydrogen frequently bond together in chains.
These chains of carbon–carbon, and carbon–hydrogen bonds are known as polymers.
Polymers are found in many of the body’s chemicals.
Proteins, DNA, sugars, and carbohydrates are just a few examples of polymers in the body’s chemistry.

Protein is made of carbon, oxygen, nitrogen, hydrogen, and sulphur.

The basic unit of a protein molecule is called an amino acid.
Think of amino acids as modules or cars of a toy train.
When many different modules are placed together, a protein molecule results.
Simple proteins are groups of amino acids linked together.
Sometimes the amino acids will have another chemical linked to them that is not an amino acid.
These proteins with a non-amino-acid group are called conjugated proteins.
Conjugated proteins make up most of the substances found in intercellular cement.
Glycoproteins are amino acid chains with a carbohydrate group attached to it.
Lipoproteins are amino acid chains with lipids or fats attached to the chain.
Phosphoproteins have a phosphorus or phosphate group attached to the protein chain.
The bond between amino acid groups is called a peptide bond.
When many amino acids are in long chains, there are many bonds.
A chain of amino acids is called a peptide.
A chain of peptides is known as a polypeptide, and polypeptides make up proteins.

Simple proteins make up the basic material for the body’s tissues.

The skin, hair, and connective tissue are made up of a protein called schleroprotein.
The proteins that make up the blood and lymph are called globulins.
Albumin is another type of simple protein used in the blood.
Nucleic acids with protein DNA structures are another type of simple protein product.

The carbohydrate groups include sugars and other compounds.

Carbohydrates are formed by a chain of carbon atoms united with oxygen and hydrogen.
They form units, similar to protein and amino acid units.
A simple unit of a carbohydrate is called a saccharide.
One saccharide by itself is called a monosaccharide.
Two saccharides together are called disaccharide.
Many saccharides bonded together are called polysaccharides.
Monosaccharides are simple sugars like glucose (blood sugar).
Disaccharides include sucrose or table sugar, and maltose, the sugar used to make malted milk.
Polysaccharides are the more complex carbohydrates.
They include the sugars in starch and the carbohydrates that makeup vegetables and cellulose-type substances.

Lipids are fats.

They are a third major chemical group within the body. Lipids are made up of carbon, oxygen, and hydrogen.
Lipids do not form in units like proteins and carbohydrates.
They are more complex.
Triglycerides are the best-known type of lipid.
Other lipids include waxes, fats, and steroids.
Again, lipids are very important chemicals in cosmetology.
They can bind with proteins to form proteolipids, which are a major part of the intercellular cement.
Phospholipids and glycolipids are two examples of lipid–protein compounds found in the intercellular cement.

Why pH Is Important in Cosmetics

The skin has an acid mantle on its surface that is made of a mixture of lipids, sebum, and sweat.
This acid mantle has a pH of about 5.5.
Therefore, it has a slightly acidic pH.
Cosmetics should also have a slightly acidic pH.
Higher pH values tend to swell the skin and make it more permeable.
This can be good or bad, depending on the circumstances.
For example, desincrustation solutions and pre-masks used for treating clogged pores and oily areas need to have a slightly alkaline pH to slightly dilate the pores and work as a solvent to soften fatty plugs of sebum in the follicle for easier extraction.
They also help conduct electricity (galvanic current) better for desincrustation.
Cleansers for oily skin may also have a slightly higher pH than that of the acid mantle.
This enables these cleansers to perform a more efﬁcient job of cutting the sebaceous secretions of oily or problem skin.
Most of these high-pH cleansers are followed by low-pH toners.
A cleanser with a pH of 6.5 or 7.0 is often followed by a toner with a pH of 4.0 or 4.5.
High pH values, however, can be harmful to the skin, particularly if they are not controlled.
High pH increases the permeability of the skin, making it easier for bacteria, microorganisms, and other harmful substances to enter the body.
Harsh, high-pH soaps can be very irritating and can severely over-dry the skin.

Being aware of pH values is very important in chemical exfoliation and peeling procedures.

Alpha hydroxy acid (AHA) and beta hydroxy acid (BHA) professional aesthetic exfoliation treatments have lower pH values.
The lower the pH, the more acidic the product is.
The ideal pH for AHA professional aesthetic treatments is 3.0 with an AHA concentration of not greater than 30 percent.
When the pH is less than 3.0, the irritation potential of these exfoliation treatments increases.
Likewise, concentrations of greater than 30 percent can increase irritation potential.
Exposure to pH values of less than 3.0 increases the chances of barrier function damage and therefore increases the possibility of inﬂammation.
The frequency of application can also increase irritation potential.
Generally, AHA treatments with a pH of 3.0 should not be administered more than once or twice a week to begin treatment, and not more than twice a month after an initial series of 6 to 12 treatments.
Should irritation such as peeling skin or redness develop, exfoliation should be discontinued, at least until the irritation subsides.
Combining chemical exfoliation treatments with mechanical exfoliation such as microdermabrasion further increases irritation chances and is not advisable.
The ideal pH for at-home AHA exfoliation products is 3.5.
Again, repeatedly using products with a pH of less than 3.5 daily can lead to irritation.
Other products, such as certain vitamin serums, can also have very low pHs.
Persons using AHA or BHA products should always use a daily broad-spectrum sunscreen with an SPF of at least 15.