pH   
Okay
The pH tells you how acidic or alkaline a given product or ingredient is. The range is from 1-14, with 1 being the most acidic, and 14 being the most alkaline. Sulfuric acid is a 1, lemon juice about a 2. Water is neutral at 7. Lye (sodium hydroxide) is a 14. Depilatories, oven cleaners and drain cleaners are about a 14. Pg 166. Most hair care products are made around 4.5-6.0, a bit acidic, so they can get the cuticles to lie flat. It isn't that important, because hair will soon return to its regular pH in time. An alkaline product (pH of 8-14) can cause the hair shaft to swell, and damages the cuticle and cortex, permanently altering the hair. Perms and relaxers are in the 13-14 range (the same range as depilatories, oven cleaners and drain cleaners). Begoun pg 77.
Source(s): Begoun

Phellodendron amurense bark extract    (aka Amur corktree)
Okay
This is made from the powdered bark of the phellodendron, also known as a Amur corktree. There is no reported function of this ingredient for skin or hair [Gottschalck pg 1362]. A native tree to China, Manchuria, and Japan, it has leaves with a turpentine aroma when they are crushed. It looks like it may have some antimicrobial action. I'm thinking that since there is no reported function for this ingredient for hair, it is added mainly to sound exotic, or because there is some "buzz" about it perhaps helping with cancer, but in a hair care product, it has no real purpose. —T
Source(s): Gottschalck http://plants.usda.gov/java/profile?symbol=PHAM2 http://www.hort.uconn.edu/Plants/p/pheamu/pheamu1.html http://www.raysahelian.com/phellodendron.html

Phenethyl Benzoate   
Okay
A synthetic flavoring ingredient that adds a fruit or honey taste to food, or a rose/honey/floral scent to products.
Source(s): http://food.oregonstate.edu/glossary/p/phenethylbenzoate.html http://www.thegoodscentscompany.com/data/rw1012671.html

Phenoxyethanol   
Okay
Preservative believed to be less irritating than others. Can also be used as a fragrance [Winter pg 399].

Phenoxyethanol is mild to the skin but can be hugely irritating to eyes—though it isn't found to be irritating in the tiny amounts normally used in products. Surprisingly, it also has some conditioning and emollient properties.

This is an oily, white to off-white liquid that smells a bit like roses. It doesn't dissolve easily in water, but will in ethanol or alkaline environments. Though Phenoxyethanol kills bacteria, it doesn't kill all types of them, so it's often combined with other anti-bacterial ingredients to kill all bacteria that may form in a product. Because it is conditioning, Phenoxyethanol may be found more often in conditioners or cosmetics, or shampoos meant to be moisturizing. The problem with Phenoxyethanol is that you do have to use higher amounts to do the job, and since it smells like roses, it may be hard to cover up the scent (if you aren't wanting your product to smell rosy) [Hunting (Shampoo) pg 317-318]. This is in one of my favorite, go to conditioners that I've been using for well over ten years. It has not caused any problems as far as conditioning and defining my hair. That's why I'm calling it a

* * * Tried and true ingredient * * *
See also: Preservative
Source(s): Winter Hunting

Phenylalanine   
Okay
Amino acid found in hair. This can be a humectant, but it can't repair hair, since hair is dead. Pg 84.
See also: Amino acid
Source(s): Begoun

Phenyl functional siloxane    (aka Polydimethylcyclosiloxane; Silicone)
Good
A group of modified Silicones (this means that other molecules have been added to the silicone that changes its function or characteristics). Used as a hair and skin conditioner and increases slip in products. This type of silicone gives greater sheen to hair than other silicones. They also tend to cut down on the white foam that may occur when a product is rubbed in, as well as decreasing any residue a product might leave behind [Schueller pg 179].
See also: Silicone Phenyl functional siloxane
Source(s): Schueller

Phenyl trimethicone    (aka Polydimethylcyclosiloxane; Phenyl functional siloxane)
Good
A type of Silicone. Used as a hair and skin conditioner and increases slip in products. This type of silicone gives greater sheen to hair than other silicones [Schueller pg 179].

This is in one of my favorite, go to conditioners that I've been using for well over ten years. It has not caused any problems as far as conditioning and defining my hair. That's why I'm calling it a

* * * Tried and true ingredient * * *
See also: Silicone Phenyl functional siloxane
Source(s): Schueller

Phosphoric acid   
Caution
Used to protect the appearance of products, as well as used as an antioxident. An acid that's colorless and odorless, made from phosphate rock that's water soluble. It's often found ini hair products, nail polish, and skin care products. In high concentrations it can be irritating to the skin [Winter (7th ed., pg 409].
Source(s): Winter

Phthalates   
Caution
Phthalates such as Dibutyl phthalate (DBP), Dimethyl phthalate (DMP), Diethylhexyl phthalate (DEHP) and Diethyl phthalate (DEP) are mainly used to make products more flexible, like rubber, plastic, cosmetics, toys, or even nail polishes. Each one is a bit different, but these have been studied for years about their safety. There are concerns that these may be cancer-causing, and effect human reproduction, among other issues. Phthalates are hardly being used any longer, though the FDA found them to be generally safe for use in small doses. They are now found mostly in fragrances, most surprisingly fragrances that are in baby products (such as baby lotion, shampoo, and baby powder).

There is still ongoing disagreement and testing of Phthalates throughout the world. One reason for the confusion is that different Phthalates seem to be made differently, so a Phthalate that's found chemically safe in one country might be found to have risks in other countries because they are chemically different. The FDA has said they are safe, but there are still ongoing studies by other groups and in other countries to discover it's health risks [Winter 7th ed., pgs 410-411].
Source(s): Winter

Phytantiol   
Okay
An emollient conditioning ingredient, made from chlorophyll [Hunting (Conditioning) pg 330].
Source(s): Hunting