2l: Safe and reliable handling of mercury in science & technology

Mercury (Hg) is known to be widely distributed in nature, and the average amount of it in the Earth’s crust ranges between 15 and 500 ng g-1. Mercury determination in rocks poses major problems, because its abundances are generally extremely low.

The aim of this work was to develop a new method to determine the Hg concentrations in phosphate rock using a dedicated analytical instrument (the DMA80 Tricell by Milestone) that employs an integrated sequence of thermal decomposition followed by catalyst conversion, amalgamation and atomic absorption spectrophotometry. However, releasing the mercury totally from this material is a challenge because hot temperatures are required. When phosphorite and apatite rocks are investigated with a classic thermal decomposition treatment that complies with US EPA method 7473. Therefore, to improve the recovery of total Hg, we performed alkaline fusion digestion (AFD) directly inside the furnace of the instrument, using BCR(32) as a certified reference material (Moroccan phosphate rock – phosphorite). The salts used for the AFD were a mixture of Na2CO3, K2CO3 and Li2CO3, which melt at about 400 °C, due to their ability to form a ternary eutectic and to decompose the phosphorite matrices at 700 °C. By adopting this analytical approach, the Hg recovery in BCR(32) was about 100%, compared to 40% when the reference material was analysed without using the alkaline fusion salt. We suggest that the AFD allowed the decomposition of the sample matrix and that some Hg compounds linked with other functional groups may be transformed in carbonates that sublimate at lower temperatures than other Hg compounds.

This original method was tested on a number of different geological samples to compare the differences between the AFD method and the thermal treatment in order to verify the working range and to check the robustness of the new approach. This method would be an important step ahead in the Hg speciation studies in phosphate rock samples.

The Treaty vs. the Reality - Mercury Free Dentistry the time is now

Dental mercury amalgam is one of the top mercury containing products used in the world and is listed as a phase down product in the Minamata Convention [1]. Mercury from the dental sector has many pathways into the environment, through respiration, cremation, burial, and human waste; however, the largest contributor of mercury into the wastewater comes from the dental offices. New regulations have been passed by the Environmental Protection Agency (EPA) to mandate mercury amalgam separators throughout the United States to capture the mercury waste at its source [2].

In 2004, the estimate of practicing dentists worldwide was approximately 1.8 million [3]. Research shows that dental workers are exposed to mercury through removing and placing fillings, polishing restorations, and handling the mercury waste [4]. We have developed a comprehensive technique and protocol for the safe removal of dental mercury and replacement with non-mercury alternatives. These methods can be utilized in developing countries, countries with emerging economies, as well as developed countries.

According to Sahani et al. (2016) exposure to the high levels of mercury from dental amalgam can lead to serious health effects among the dental health care workers [5].

Mercury has been found to be a causative agent of various sorts of disorders, including neurological, nephrological, immunological, cardiac, motor, reproductive and even genetic. Recently heavy metal mediated toxicity has been linked to diseases like Alzheimers, Parkinsons, Autism, Lupus, Amyotrophic lateral sclerosis, etc. [6].

Multiple studies have shown that occupational exposure to dental mercury is negatively impacting the health of dentists and dental workers. Dental assistants with high exposures to mercury were less fertile than the controls according to Rowland et al. (1994) [7].

In early December 2016, the three major regulatory institutions in Europe, specifically, the European Council, Commission, and Parliament have recommended a ban on mercury dental fillings in children under the age of 15 and pregnant and breast-feeding women as of 2018 [8].

The treaty has created guidelines and recommendations for the Partys actions for the safety and protection of dental personnel, patients and the safe handling of environmental waste created from this source. Our protocol will be able to assist all countries in the early implementation and the elimination of mercury dental amalgam in a safe, environmentally sustainable way.