“This Addendum was prepared in response to the recommendations of the Dental Products Panel and the Peripheral and Central Nervous System Drugs Advisory Committee (the Panel) concerning a 2006 White Paper presented in draft form to the Panel on September 6 and 7, 2006. FDA prepared this Addendum to address the Panel’s comments on the White Paper.”
“The Medical Device Amendments of 1976 to the Federal Food, Drug, and Cosmetic Act (the act) established three regulatory classes for medical devices. The three classes are based on the degree of control necessary to assure that the various types of devices are safe and effective. The most regulated devices are in Class III. The amendments define a Class III device as one that supports or sustains human life or is of substantial importance in preventing impairment of human health or presents a potential, unreasonable risk of illness or injury . Insufficient information exists on a Class III device so that performance standards (Class II) or general controls (Class I) cannot provide reasonable assurance that the device is safe and effective for its intended use. Under Section 515 of the act, all devices placed into Class III are subject to premarket approval requirements. Premarket approval by FDA is the required process of scientific review to ensure the safety and effectiveness of Class III devices.”
“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.
Dental amalgam is a mixture of metals, consisting of liquid mercury and a powdered alloy composed of silver, tin, and copper. Approximately 50% of dental amalgam is elemental mercury by weight.
Dental amalgam fillings are also known as “silver fillings” because of their silver-like appearance.
When placing dental amalgam, the dentist first drills the tooth to remove the decay and then shapes the tooth cavity for placement of the amalgam filling. Next, under appropriate safety conditions, the dentist mixes the powdered alloy with the liquid mercury to form an amalgam putty. (These components are provided to the dentist in a capsule as shown in the graphic.) This softened amalgam putty is placed in the prepared cavity, where it hardens into a solid filling.”
“Previous investigations have presented evidence for an increased prevalence of late cognitive effects in dental personnel exposed to metallic mercury. We wanted to examine if there was a correlation between mercury exposure and cognitive effects in a Norwegian population of dental workers, and if so, to quantify the occurrence. The study group consisted of 608 female dental assistants from central Norway and 425 female controls from the general population, all under the age of 70. They had responded to a standardized postal questionnaire (Euroquest) inquiring about seven symptoms in regard to neurology, psychosomatics, memory, concentration, mood, sleep disturbances, and fatigue. A score was calculated for each symptom based on 4-15 single questions graded on a scale from 1 (seldom or never) to 4 (very often). Dental assistants and controls had a participation rate of 56.4% and 42.9% respectively. Dental assistants reported more cognitive symptoms than the controls, but on average they reported having each of the symptoms “now and then” or less frequently. There were 4.4% of the dental assistants and 2.8% of the controls who reported having three or more of the seven symptoms “often” or more frequently. The corresponding figures for five or more of the seven symptoms were 1.0% and 0.5% respectively. The occurrence of cognitive malfunction may be moderately increased in dental assistants. For dental assistants there was a relative risk of 1.6 of having three or more symptoms “often” or more frequently, and a relative risk of 2.0 of having five or more symptoms as frequently. It can be assumed from our results that the prevalence of possibly work-related cognitive malfunction in dental assistants is between 0.4% and 2.8%, dependent on the applied severity.”
“A recent report shows a correlation of the historical use of thimerosal in therapeutic immunizations with the subsequent development of autism; however, this association remains controversial. Autism occurs approximately four times more frequently in males compared to females; thus, studies of thimerosal toxicity should take into consideration gender-selective effects. The present study was originally undertaken to determine the maximum tolerated dose (MTD) of thimersosal in male and female CD1 mice. However, during the limited MTD studies, it became apparent that thimerosal has a differential MTD that depends on whether the mouse is male or female. At doses of 38.4-76.8mg/kg using 10% DMSO as diluent, seven of seven male mice compared to zero of seven female mice tested succumbed to thimerosal. Although the thimerosal levels used were very high, as we were originally only trying to determine MTD, it was completely unexpected to observe a difference of the MTD between male and female mice. Thus, our studies, although not directly addressing the controversy surrounding thimerosal and autism, and still preliminary due to small numbers of mice examined, provide, nevertheless, the first report of gender-selective toxicity of thimerosal and indicate that any future studies of thimerosal toxicity should take into consideration gender-specific differences.”
“The objective of this study was to determine if proximity to sources of mercury pollution in 1998 were related to autism prevalence in 2002. Autism count data from the Texas Educational Agency and environmental mercury release data from the Environmental Protection Agency were used. We found that for every 1000 pounds of industrial release, there was a corresponding 2.6% increase in autism rates (p<.05) and a 3.7% increase associated with power plant emissions(P<.05). Distances to these sources were independent predictors after adjustment for relevant covariates. For every 10 miles from industrial or power plant sources, there was an associated decreased autism Incident Risk of 2.0% and 1.4%, respectively (p<.05). While design limitations preclude interpretation of individual risk, further investigations of environmental risks to child development issues are warranted.”
“OBJECTIVE:
This study was designed to determine whether prenatal mercury exposure, including potential releases from the World Trade Center (WTC) disaster, adversely affects fetal growth and child development.
METHODS:
We determined maternal and umbilical cord blood total mercury of nonsmoking women who delivered at term in lower Manhattan after 11 September 2001, and measured birth outcomes and child development.
RESULTS:
Levels of total mercury in cord and maternal blood were not significantly higher for women who resided or worked within 1 or 2 miles of the WTC in the month after 11 September, compared with women who lived and worked farther away. Average cord mercury levels were more than twice maternal levels, and both were elevated in women who reported eating fish/seafood during pregnancy. Regression analyses showed no significant association between (ln) cord or maternal blood total mercury and birth outcomes. Log cord mercury was inversely associated with the Bayley Scales of Infant Development psychomotor score [Psychomotor Development Index (PDI)] at 36 months (b = -4.2, p = 0.007) and with Performance (b = -3.4, p = 0.023), Verbal (b = -2.9, p = 0.023), and Full IQ scores (b = -3.8, p = 0.002) on the Wechsler Preschool and Primary Scale of Intelligence, Revised (WPPSI-R), at 48 months, after controlling for fish/seafood consumption and other confounders. Fish/seafood consumption during pregnancy was significantly associated with a 5.6- to 9.9-point increase in 36-month PDI, and 48-month Verbal and Full IQ scores.
CONCLUSIONS:
Blood mercury was not significantly raised in women living or working close to the WTC site in the weeks after 11 September 2001. Higher cord blood mercury was associated with reductions in developmental scores at 36 and 48 months, after adjusting for the positive effects of fish/seafood consumption during pregnancy.”
“As part of a settlement in a lawsuit filed by Moms Against Mercury, the FDA has agreed to classify a controversial mercury-containing cavity filler by July 28, 2009. The agency proposes to classify dental amalgam made of liquid mercury and metal powder as a Class II device. This would enable the agency to impose special controls to ensure the product’s safety and effectiveness.”
“BACKGROUND:
Mercury is nephrotoxic and dental amalgam is a source of mercury exposure.
METHODS:
Children 6-10 years of age (n = 534) with two or more posterior teeth with caries but no prior amalgam restorations, were randomized to one of two treatments–amalgam or resin composite (white fillings)–used for caries treatment during 5 years of follow-up. The primary outcome was change in IQ, but important secondary outcomes were effects on markers of glomerular and tubular kidney function: urinary excretion of albumin, alpha-1-microglobulin (A1M), gamma-glutamyl transpeptidase (gamma-GT), and N-acetyl-beta-d-glucosaminidase (NAG). These markers were measured on several occasions during the trial, together with urinary mercury and covariates. We evaluated the results using repeated-measures analyses.
RESULTS:
There were no significant differences between treatment groups in average levels of renal biomarkers, nor significant effects of number of dental amalgams on these markers. There was, however, a significantly increased prevalence of microalbuminuria (MA) among children in the amalgam group in years 3-5 (adjusted odds ratio 1.8; 95% confidence interval, 1.1-2.9). Most of these cases are likely to be temporary MA, but 10 children in the amalgam group had MA in both years 3 and 5, versus 2 children in the composite group (p = 0.04). There were no differences in the occurrence of high levels of renal tubular markers (A1M, gamma-GT, or NAG).
CONCLUSIONS:
The increase in MA may be a random finding, but should be tested further. The results did not support recent findings in an observational study of an effect of low-level mercury on tubular biomarkers in children.”
“The purpose of this paper is to review the scientific evidence that links environmental mercury exposure and the risk of autism.”