Putting dental mercury pollution into perspective

New insight into the microbiome, resistome, and mobilome on the dental waste water in the context of heavy metal environment

Object

Hospital sewage have been associated with incorporation of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) into microbes, which is considered as a key indicator for the spread of antimicrobial resistance (AMR). The compositions of dental waste water (DWW) contain heavy metals, the evolution of AMR and its effects on the water environment in the context of heavy metal environment have not been seriously investigated. Thus, our major aims were to elucidate the evolution of AMR in DWW.

Methods

DWW samples were collected from a major dental department. The presence of microbial communities, ARGs, and MGEs in untreated and treated (by filter membrane and ozone) samples were analyzed using metagenomics and bioinformatic methods.

Results

DWW-associated resistomes included 1,208 types of ARGs, belonging to 29 antibiotic types/subtypes. The most abundant types/subtypes were ARGs of multidrug resistance and of antibiotics that were frequently used in the clinical practice. Pseudomonas putida, Pseudomonas aeruginosa, Chryseobacterium indologenes, Sphingomonas laterariae were the main bacteria which hosted these ARGs. Mobilomes in DWW consisted of 93 MGE subtypes which belonged to 8 MGE types. Transposases were the most frequently detected MGEs which formed networks of communications. For example, ISCrsp1 and tnpA.5/4/11 were the main transposases located in the central hubs of a network. These significant associations between ARGs and MGEs revealed the strong potential of ARGs transmission towards development of antimicrobial-resistant (AMR) bacteria. On the other hand, treatment of DWW using membranes and ozone was only effective in removing minor species of bacteria and types of ARGs and MGEs.

Conclusion

DWW contained abundant ARGs, and MGEs, which contributed to the occurrence and spread of AMR bacteria. Consequently, DWW would seriously increase environmental health concerns which may be different but have been well-documented from hospital waste waters.

Mercury hygiene and biomedical waste management practices among dental health-care personnel in public hospitals in Lagos State, Nigeria

BACKGROUND

Indiscriminate disposal of hospital wastes including mercury/amalgam wastes pose a serious threat to life and environment. There is a growing concern about biomedical waste (BMW) management among health care workers, however there are limited reports on BMW management by dental personnel in developing countries.

OBJECTIVES

This study investigated the level of knowledge of BMW, observance of proper mercury hygiene and BMW management practice among public dental personnel in Lagos State, Nigeria.

METHODS

A cross-sectional study regarding BMW management across public hospitals in Lagos State, Nigeria was conducted following institutional ethics committee approval. A self-administered questionnaire was utilized to obtain data from different facilities selected by purposive and simple random sampling techniques as applicable. The questionnaires were distributed among 437 respondents by convenience sampling. The resulting data were statistically tested using Chi-square and G-test with p-value < 0.05 indicating significant level.

RESULTS

Amongst 437 respondents, majority were females (62.5%) and the highest proportion fell within the age range of 25-34 years (44.4%). Only 17.2% of the respondents had good knowledge of BMW management/legislation and 4.1% had good BMW practice. Less than half (49.4%) of respondents disposed mercury-contaminated materials inside the trash and majority (92.2%) did not observe proper mercury hygiene. Significantly better mercury hygiene practices were observed in secondary facilities (p=0.040).

CONCLUSION

A minor proportion of public dental personnel had good knowledge and practice of proper mercury hygiene and BMW management. This shows there is an urgent need for training of health personnel on proper BMW handling and disposal in developing countries like Nigeria.

Going green with eco-friendly dentistry

Eco-friendly dentistry is currently transforming the medical and dental field to decrease its affect on our natural environment and reduce the amount of waste being produced. Eco-friendly dentistry uses a sustainable approach to encourage dentists to implement new strategies to try and reduce the energy being consumed and the large amount of waste being produced by the industry. Many reasonable, practical and easy alternatives do exist which would reduce the environmental footprint of a dental office were it to follow the 'green' recommendations. Dentist should take a leading role in the society by implementing 'green' initiatives to lessen their impact on the environment. This article provides a series of 'green' recommendations that dentists around the world can implement to become a leading Stewards of the environment.

Biocompatibility of dental amalgams

Objective. The purpose of this review paper is to review the literature regarding the toxicology of mercury from dental amalgam and evaluate current statements on dental amalgam. Materials and Methods. Two key-words “dental amalgam” and “toxicity” were used to search publications on dental amalgam biocompatibility published in peer-reviewed journals written in English. Manual search was also conducted. The most recent declarations and statements were evaluated using information available on the internet. Case reports were excluded from the study. Results. The literature show that mercury released from dental amalgam restorations does not contribute to systemic disease or systemic toxicological effects. No significant effects on the immune system have been demonstrated with the amounts of mercury released from dental amalgam restorations. Only very rarely have there been reported allergic reactions to mercury from amalgam restorations. No evidence supports a relationship between mercury released from dental amalgam and neurological diseases. Almost all of the declarations accessed by the internet stated by official organizations concluded that current data are not sufficient to relate various complaints and mercury release from dental amalgam. Conclusions. Available scientific data do not justify the discontinuation of amalgam use from dental practice or replacement with alternative restorative dental materials.

Dental office waste - public health and ecological risk

CONFLICT OF INTEREST: NONE DECLARED

Waste management is one of the key ecological challenges of the modern world. As dental practitioners, we must recognize that some of the materials and procedures we use to provide dental health services may present challenges to the environment. Realizing this, we can begin to take measures to minimize the production of these wastes and their potential environmental effects. Dental office waste typically cause toxic chemicals to enter our streams, sewers, and landfills. This paper identifies some common wastes produced by dental offices (dental amalgam, silver, lead, biomedical and general office waste) and provides practical suggestions for reducing the impact of our profession on the environment. To dispose of dental wastes, if recycling is not an option, proper disposal as hazardous waste is necessary. But, problem is that dental waste is in most cases dumped at uncontrolled disposal sites, and that is public health and ecological risk.

A Scandinavian tragedy

This paper briefly reviews the logic surrounding the controversial banning of dental amalgam by the Norwegian government. The very small contribution from dentistry to environmental mercury pollution and the significant advantages of amalgam as a dental restorative are emphasised.