Amalgam Generation from Dental Offices

Objective: The main objective of this study was to estimate the total amount of amalgam used in dental offices in the Chicago region. Methods: The collection system consisted of containers, placed in eight dental offices to collect the material from the in line trap (contact amalgam) and the excess dental amalgam not placed into the oral cavity (non-contact amalgam). A second objective was to estimate the non-contact, contact, and tooth retained amalgam. In order to have comparable results, the data was adjusted by the number of dental chairs being used for treatment and the number of working days. Results: The range for the non-contact amalgam was from 0–385 g, and for the contact amalgam, from 2-30 g. The median amount of non-contact amalgam generated from the 8 dental offices was 420.6 mg/day/chair, whereas the median amount of contact amalgam was 38.0 mg/day/chair. For 40 one and two surface amalgams (bicuspids and molars), amalgam was distributed as follows, 47±19% in the tooth, 42±18% non-contact amalgam, and 11±4% contact amalgam. Conclusions: Based on survey data from the ADA for the number of working days per year (225), the number of practicing dentists, a 50% by weight of mercury content in amalgam, and the estimates from this project, it was found that the practicing dentists in the State of Illinois (6,455) have the potential to generate 947 kg of non-contact mercury per year, which is recyclable, and 86 kg of contact mercury which may enter the sanitary sewer system. If this approach is applied to the total population of practicing dentist in the United States (123,641), then 18,159 kg of recyclable, non-contact mercury may be generated per year, whereas 1,641 kg of mercury may enter the sanitary sewer system. Supported in part by EPA grant GL-97537001.