Biomarkers of kidney integrity in children and adolescents with dental amalgam mercury exposure: Findings from the Casa Pia children's amalgam trial

Abstract

Mercury is toxic to the kidney, and dental amalgam is a source of mercury exposure. Few studies have evaluated the effects of dental amalgam on kidney function in a longitudinal context in children. Here, we evaluated urinary concentrations of glutathione S-transferases (GSTs) α and π as biomarkers of renal proximal and distal tubular integrity, respectively, and albumin as a biomarker of glomerular integrity in children and adolescents 8-18 years of age over a 7 year course of dental amalgam treatment. Five hundred seven children, 8-12 years of age at baseline, participated in a clinical trial to evaluate the neurobehavioral and renal effects of dental amalgam in children. Subjects were randomized to either dental amalgam or resin composite treatments. Urinary GSTs α and π, albumin and creatinine concentrations were measured at baseline and annually on all subjects. Results were evaluated using linear regression analysis. GST-α concentrations were similar between treatment groups and in each sex and race (white vs non-white) group in each follow-up year. GST-π levels tended upward over the course of follow-up by 4- to 6-fold. This increase was seen in all groups irrespective of treatment, race or gender. Females had GST-π levels approximately twice those of males at all ages. Albumin concentrations were constant throughout the follow-up period and did not differ by treatment, although females had 39% higher albumin levels than males. Additionally, we found no significant effects of amalgam treatment on the proportion of children with microalbuminuria (>30 mg/g creatinine). These findings are relevant within the context of children’s health risk assessment as relates to the safety of mercury exposure from dental amalgam on kidney function. These data also provide normative values for sensitive indices of renal functional integrity that may serve in the evaluation of children and adolescents with renal disorders.

Randomized Controlled Trial Demonstrates that Exposure to Mercury from Dental Amalgam Does Not Adversely Affect Neurological Development in Children

“…This study adds to the growing body of literature affirming the safety of amalgam as restorative material. [13][14][15][16][17] When the additional factor of the greater longevity of amalgam was compared with composite, 8,18,19 the continued viability of amalgam as a restorative material is confirmed.…”

Environmental exposures and pediatric kidney function and disease: A systematic review

“…These publications were translated by Russian or Chinese speakers before inclusion. Some publications were considered together (Bellinger et al, 2006; Geier et al, 2013; Hawkesworth et al, 2013; Barregard et al, 2008; DeRouen et al, 2006; Skroder et al, 2015; Woods et al, 2008; Kooijman et al, 2015; Taal et al, 2011), as they used the same study population and provided complementary information. Most studies were from non-occupationally-exposed populations, one included children of occupationally exposed parents (Khan et al, 2010).…”

“…manganese (Nascimento et al, 2016), mercury (Barregard et al, 2008; de Burbure et al, 2006; Woods et al, 2008; Geier et al, 2013; Bellinger et al, 2006; DeRouen et al, 2006), selenium (Skroder et al, 2015), thallium (Weaver et al, 2014), or uranium (Weaver et al, 2014) (Table 2). These studies covered Egypt, France, Poland, Czech Republic, Portugal, China, Bangladesh, Mexico, Thailand, Brazil, and the United States.…”

A significant dose-dependent relationship between mercury exposure from dental amalgams and kidney integrity biomarkers

“…10,11 Investigators examined both GST-a and -p in children with and without amalgams (amalgams versus resin composites) over an 8-year-period as a part of the Casa Pia children's amalgam trial (the parent study). 7 The parent study showed no significant difference between the two groups on GST-a and -p levels; however, the dose-dependent relationship between cumulative Hg and GST-a and -p levels was not examined.…”