Snapshot of cobalt, chromium and nickel exposure in dental technicians

It is not fully understood where and how people are exposed to sensitizing metals. Much can be learnt from studying occupational settings where metals are handled.

To quantify cobalt (Co), chromium (Cr) and nickel (Ni) exposure on the skin and in the air, and urine levels, in dental technicians working with tools and alloys that may result in skin and respiratory exposure.

The metal skin dose was quantified with acid wipe sampling in dental technicians (n = 13). Air exposure was monitored by personal air sampling. Spot urine samples were collected for 24 h. Metals were analysed with inductively coupled plasma mass spectrometry.

Before work, Co was detected on the skin of 10 participants (0.00025-0.0039 µg/cm² ), and Cr (0.00051-0.011 µg/cm² ) and Ni (0.0062-0.15 µg/cm² ) on the skin of all participants. After a 2-h period without hand washing, CoCr-exposed participants had more Co on the skin (p = 0.004) than non-CoCr-exposed participants. Co was found in 10 air samples (0.22-155 µg/m³ ), Cr in nine (0.43-71 µg/m³ ), and Ni in four (0.48-3.7 µg/m³ ). Metal urine concentrations were considered to be normal.

Dental technicians were exposed to Co, Cr and Ni on the skin and through the air, which was not reflected in the urine concentrations in this study. Cobalt skin doses may potentially elicit allergic contact dermatitis and cause sensitization.