Silica, sometimes referred to as silicon dioxide or quartz, is a naturally occurring mineral and a major constituent of soils, sand, surface materials above the bedrock, as well as the three rock types, i.e. sedimentary, igneous, and metamorphic rocks. It’s the second most abundant mineral in the earth’s crust, occurring in two polymorphs - crystalline and amorphous. Crystalline silica is ubiquitous in nature constituting about 15% of the earth’s crust but, unlike amorphous silica, it’s toxic. Crystalline silica comes in nine main forms, the prevalent ones being tridymite, cristobalite, and quartz, which is the most common of the three.
Different silica compounds that may be used in the formulation of personal care products are hydrated silica, silica, aluminum calcium sodium silicate, alumina magnesium metasilicate, sodium potassium aluminum silicate, and aluminum iron silicate. They perform various roles in natural and mainstream personal care products by acting as bulking, opacifying, viscosity-increasing, moisture-absorbing, suspending, and anti-caking agents. They’re essentially added to antiperspirants and many ‘natural’ deodorants to absorb sweat. It’s important to understand that it’s not unusual for these products to be contaminated by crystalline silica.
In spite of the likely contamination, manufacturers of personal care products that contain silica do argue that it’s natural and, therefore, safe. Nonetheless, it’s been documented that exposure to (crystalline) silica can lead to skin abrasion and skin irritation as well as kidney damage, heart problems and respiratory diseases such as bronchitis, tuberculosis, lung cancer, and silicosis. The latter is an incurable condition that results from inflammation and scarring of the lung tissue that can lead to shortness of breath, chest pains, fatigue, persistent cough, respiratory failure and even death. According to international organizations such as the International Agency for Research on Cancer, there’s sufficient evidence to suggest crystalline silica is carcinogenic and have classified it as such.
Silica exposure can also lead to systemic autoimmune diseases such as rheumatoid arthritis and lupus. People with reduced lung capacity, e.g. asthmatics, the elderly, children, and those with pre-existing allergies, can succumb to the hazardous effects of silica in a shorter amount of time.