Recently, there has been a rumor circulating online that 90% of shampoos contain an ingredient called "polydimethylsiloxane", also known as silicone oil smoothing agent. After washing the hair, it is very smooth, but silicone oil can block pores, making the scalp itchy and even causing hair loss and shedding!
When washing hair, silicone oil has viscosity and extensibility, which has a moisturizing effect on the hair. The silicone oil in shampoo adheres to the gaps in the hair scales, filling the surface of the hair and making it feel very smooth to the touch.
Does silicone oil really cause hair loss?
There are many reasons for hair loss, including endocrine seborrheic dermatitis hair loss, alopecia areata caused by mental stress, hair loss caused by internal diseases, postpartum hair loss, insomnia hair loss, etc. However, hair follicle blockage is not the cause of hair loss, and hair loss caused by shampoo is relatively rare.
Silicone oil is a large molecular substance that is not absorbed by hair follicles, and there is not much silicone oil in shampoo. With the action of surfactants that have a cleaning effect and a large amount of water washing, there is almost no residue left, so consumers do not need to worry too much.
Can clear water distinguish silicone oil?
There is also a method online to identify the "silicone oil" component in shampoo: add shampoo to water and stir. If the water becomes turbid after standing, then the shampoo has added silicone oil component; If it remains clear, then there is no silicone oil. It is said that the principle of this identification is that silicone oil is insoluble in water and appears turbid in water.
The silicone oil component in shampoo is usually treated with emulsifiers and does not remain cloudy, presenting a colorless and odorless state. Moreover, the dosage is not large, so using water alone cannot make a judgment.
The function of silicone oil is to make hair smooth and has a certain moisturizing effect. Because after thorough cleaning, the hair scales open, and if there are damaged scales, it will increase the friction between the hair, making it more difficult to comb later and exacerbating the damage to the scales. That's also why shampoos without silicone oil can make hair very dry and difficult to comb after washing.
These lubricating "silicone oils" have a low content, so there is no need to worry about their impact on the body. It is a large molecular component that the human body cannot absorb, and normal use does not harm the body.
Does dioxane in shampoo cause cancer?
There is no need to panic about the carcinogenicity of shampoo dioxane, as trace amounts of dioxane are not harmful to health.
Dioxane is a colorless and transparent liquid, belonging to a relatively active nitro carcinogen. It is easily soluble in ethanol, ether, and water, volatile, and flammable. Widely present in nature, 1 liter of water contains 1 microgram of dioxane, while 1 cubic meter of air contains 100-400 micrograms of dioxane. Marine fish, meat products, tomatoes, pepper, coffee and other foods may contain dioxane, and trace amounts of dioxane do not pose a threat to human health.
Dioxane can act as a gas bubble and dissolve in water. When exposed to air, it quickly evaporates, so the chance of entering the body through the skin is relatively rare. Unless inhaled in large quantities, it can cause dizziness, drowsiness, eye, nose, and throat irritation.