Mercury from maternal "silver" tooth fillings in sheep and human breast milk. A source of neonatal exposure.

Neonatal uptake of mercury (Hg) from milk was examined in a pregnant sheep model, where radioactive mercury (Hg203)/silver tooth fillings (amalgam) were newly placed. A crossover experimental design was used in which lactating ewes nursed foster lambs. In a parallel study, the relationship between dental history and breast milk concentration of Hg was also examined in 33 lactating women. Results from the animal studies showed that, during pregnancy, a primary fetal site of amalgam Hg concentration is the liver, and, after delivery, the neonatal lamb kidney receives additional amalgam Hg from mother's milk. In lactating women with aged amalgam fillings, increased Hg excretion in breast milk and urine correlated with the number of fillings or Hg vapor concentration levels in mouth air. It was concluded that Hg originating from maternal amalgam tooth fillings transfers across the placenta to the fetus, across the mammary gland into milk ingested by the newborn, and ultimately into neonatal body tissues. Comparisons are made to the U. S. minimal risk level recently established for adult Hg exposure. These findings suggest that placement and removal of "silver" tooth fillings in pregnant and lactating humans will subject the fetus and neonate to unnecessary risk of Hg exposure.

Detecting GD and preeclampsia. Effectiveness of routine urine screening for glucose and protein.

OBJECTIVE: To assess why urine collection and analysis for proteinuria and glycosuria is routinely performed during each antepartum visit at prenatal clinics. STUDY DESIGN: Six hundred ten antepartum medical records were reviewed. RESULTS: One hundred nine (18%) patients had proteinuria, while 17 patients (2.8%) developed preeclampsia. Fifteen patients (2.5%) had at least one episode of glycosuria (100 mg/dL), while 11 had gestational diabetes. Of those with gestational diabetes, four (36%) had glycosuria. Of those with preeclampsia, three (17.7%) had proteinuria that preceded the finding of hypertension. CONCLUSION: These results support our observation that routine oral 50-g glucose diabetes screening and careful monitoring of blood pressure are better screens for gestational diabetes and preeclampsia. The increased patient inconvenience and clinic staffing necessary for routine urinalysis may be avoided by eliminating that ritual.

Mercury from dental "silver" tooth fillings impairs sheep kidney function.

In humans Hg vapor is released from "silver" amalgam fillings that contain 50% Hg by weight. Previous studies show that when 12 such fillings are placed in sheep teeth, the kidneys will concentrate amalgam Hg at levels ranging from 5 to 10 micrograms Hg/g renal tissue 4-20 wk after placement. In the present study 12 occlusal fillings were placed in each of six adult female sheep under general anesthesia, using standard dental procedures. Glass ionomer occlusal fillings (12) were inserted in two control sheep. At several days before dental surgery, and at 30 and 60 days after placement of fillings, renal function was evaluated by plasma clearance of inulin and by plasma and urine electrolytes, urea, and proteins. An average plasma inulin clearance rate of 69.5 +/- 7.2 ml/min before amalgam placement was reduced to 32.3 +/- 8.1 ml/min by 30 days and remained low at 27.9 +/- 8.7 ml/min after 60 days. Inulin clearance did not change in controls. After amalgam placement urine concentration of albumin decreased from 93.0 +/- 20.5 to 30.1 +/- 15.3 mg/l and urine Na+ concentration increased steadily from 24.8 +/- 7.7 to 82.2 +/- 20.3 mmol/l at 60 days. Concentrations of K+, urea, gamma-glutamyl transpeptidase, alkaline phosphatase, and total protein did not change significantly from 0 to 60 days in urine. Plasma levels of Na+, K+, urea, and albumin remained unchanged from 0 to 60 days after amalgam. Renal histology remained normal in amalgam-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)