Are there any health risks from wearing a watch made of anodized aluminum? Will aluminum get into the body through the skin?
What is anodized aluminum?
Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. - Wikipedia
So, it's a layer of aluminum oxide. But since pure aluminum is soft, your watch would most likely be made of an alloy. Some of the most common metal added to aluminum alloys are Si, Fe, Cu, Mn, Mg, Cr, Zn, V, Ti, Bi, Ga, Pb, and Zr. But since the concentrations of these metals are minuscule, we won't account for their presence in the alloy.
Aluminum oral intake from dietary sources is usually greater than aluminum absorbed in the skin
...about 2.5% of the aluminum typically absorbed by the gut from food over the same time period. - A preliminary study of the dermal absorption of aluminum from antiperspirants using aluminium-26.
Used as a component of paints and varnishes and in the manufacture of alloys, ceramics, glass, electrical insulators and resistors. **Toxicity** Significant toxicity has been reported only following **chronic occupational inhalation**. Topical - Aluminium contact sensitivity has been described but is extremely rare
Inhalational and Oral Toxicity?
Aluminium bioavailability from occupational inhalation exposure is ~ 2% whereas oral aluminium bioavailability from water has been reported to be 0.1 to 0.4%
Increased oral aluminium absorption has been suggested in Alzheimer’s disease (AD) and Down’s subjects. Oral aluminium bioavailability from the diet has been estimated to be ~ 0.1 to 0.3%, based on daily aluminium intake and urinary elimination.
Your anodized aluminum watch is safe to wear. Not unless you have a rare allergy to aluminum.
Read the HUMAN HEALTH RISK ASSESSMENT FOR ALUMINIUM, ALUMINIUM OXIDE, AND ALUMINIUM HYDROXIDE. It's all there.