The U.S. Environmental Protection Agency issued last week its pretreatment standards to reduce discharges of mercury from dental offices into publicly owned treatment works (POTWs).
Dental offices discharge mercury present in amalgam used for fillings. According to the Agency, "amalgam separators are a practical, affordable and readily available technology for capturing mercury and other metals before they are discharged into sewers that drain to POTWs." EPA anticipates that once captured by a separator, mercury may be recycled.
Approximately fifty percent of dental amalgam is elemental mercury by weight. Dental amalgam is a dental filling material used to fill cavities caused by tooth decay. It has been used for more than 150 years in hundreds of millions of patients. EPA expects compliance with this final rule will annually reduce the discharge of mercury by 5.1 tons as well as 5.3 tons of other metals found in waste dental amalgam to POTWs.
EPA indicated that the rule will apply to offices, including large institutions such as dental schools and clinics, where dentistry is practiced that discharge to a POTW. "It does not apply to mobile units or offices where the practice of dentistry consists only of the following dental specialties: oral pathology, oral and maxillofacial radiology, oral and maxillofacial surgery, orthodontics, periodontics, or prosthodontics."
The final rule purports to ease administrative burdens from those initially proposed. "Administrative burden was a concern of many of the commenters on the 2014 proposed rule and EPA has greatly reduced that burden through streamlining the administrative requirements in this final rule." The Agency claims that to simplify implementation and compliance for the dental offices and the regulating authorities, the final rule establishes that dental dischargers are not Significant Industrial Users (SIUs) as defined in 40 CFR part 403, and are not Categorical Industrial Users (CIUs) or "industrial users subject to categorical pretreatment standards" as those terms and variations are used in the General Pretreatment Regulations, unless designated such by the Control Authority.
"While this rule establishes pretreatment standards that require dental offices to reduce dental amalgam discharges, the rule does not require Control Authorities to implement the traditional suite of oversight requirements in the General Pretreatment Regulations that become applicable upon the promulgation of categorical pretreatment standards for an industrial category." This, the EPA asserts, will significantly reduce the reporting requirements for dental dischargers that would otherwise apply by instead requiring them to demonstrate compliance with the performance standard and BMPs through a one-time compliance report to their Control Authority.
The approach will also eliminate additional oversight requirements for Control Authorities that are typically associated with SIUs, such as permitting and annual inspections of individual dental offices. "It also eliminates additional reporting requirements for the Control Authorities typically associated with CIUs, such as identification of CIUs in their annual pretreatment reports."
In its proposal EPA estimated that there approximately 160,000 dentists working in over 120,000 dental offices who use or remove amalgam in the United States – "almost all of whom discharge their wastewater exclusively to POTWs." According to the EPA news release at that time, "this is a common sense rule that calls for capturing mercury at a relatively low cost before it is dispersed into the POTW."
Specifically the rule requires dentists to cut their dental amalgam discharges to a level achievable through the use of the "best available technology," known as amalgam separators, and the use of other Best Management Practices. Amalgam separators are devices designed to remove amalgam waste particles from dental office wastewater.
In response to the proposed rule the American Dental Association said that it believes the "new federal regulation represents a fair and reasonable approach to the management of dental amalgam waste.... The rule includes reasonable exemptions, a phase-in period and considerations for dental practices that have already installed the devices."
The compliance date for existing facilities is three years from the rule publication in the Feedral Register.
The international research team assessed a dozen measures of physical health, including lung function, systemic inflammation and several measures of metabolic syndrome, including waist circumference, HDL cholesterol, triglycerides, blood pressure, glucose control and body mass index.
Tobacco users in the study, which appears online the week of June 1 in JAMA Psychiatry, were found to have gum disease as well as reduced lung function, systemic inflammation and indicators of poorer metabolic health.
“We can see the physical health effects of tobacco smoking in this study, but we don’t see similar effects for cannabis smoking,” said Madeline Meier, an assistant professor of psychology at Arizona State University who conducted the study with colleagues at Duke University, King’s College in the UK and the University of Otago in New Zealand.
While study participants who had used marijuana to some degree over the last 20 years showed an increase in periodontal disease from age 26 to 38, they did not differ from non-users on any of the other physical health measures. To measure cannabis use, they asked study subjects to self-report their use at ages 18, 21, 26, 32 and 38.
The study’s statistical analysis found that the decline in periodontal health in pot smokers was not explained by tobacco smoking, alcohol abuse or less tooth brushing and flossing. The lack of physical health problems among cannabis users also was not attributable to their having had better health to begin with or to living healthier lifestyles.
“We don’t want people to think, ‘Hey, marijuana can’t hurt me,’ because other studies on this same sample of New Zealanders have shown that marijuana use is associated with increased risk of psychotic illness, IQ decline and downward socioeconomic mobility,” Meier said.
“What we’re seeing is that cannabis may be harmful in some respects, but possibly not in every way,” said study co-author Avshalom Caspi, the Edward M. Arnett Professor of psychology and neuroscience at Duke. “We need to recognize that heavy recreational cannabis use does have some adverse consequences, but overall damage to physical health is not apparent in this study.”
“Physicians should certainly explain to their patients that long-term marijuana use can put them at risk for losing some teeth,” said Terrie Moffitt, the Nannerl O. Keohane University Professor of psychology and neuroscience at Duke and co-director of the Dunedin Multidisciplinary Health and Development Study, from which these data were gathered.