Maternal Dietary Zinc, and Development and Zinc, Iron, and Copper Content of the Rat Fetus

Abstract

High levels (0.2 and 0.4%) of zinc were fed to adult female rats beginning at either 0-day age of the fetus or 21 days before breeding to study the development and iron, copper, and zinc status of the 15-to 20-day-old fetus. Growth reduction in terms of dry matter or variable degrees• of death and resorption occurred in fetuses from mothers fed 0.4% zinc; 100% resorption occurred in the 15-and 16-day-old fetus of mothers fed 0.4% zinc beginning at 21 days before breeding. Fetal development was normal in the fetus of mothers fed 0.2% zinc beginning at 21 days before breeding. No external anatomical malformations were observed in the fetus from zinc-fed mothers. Total zinc and concentration of zinc were significantly higher in the 15• to 20-day-old fetus of mothers fed 0.4% zinc. No significant elevation of zinc occurred in the fetus from mothers fed 0.2% zinc. Reduced total iron and concentration of iron was the trend found in the fetus from mothers fed excess zinc; the reduction was significant only in the 16-and 18-day-old fetus from mothers fed 0.4% zinc beginning at 0-day age of the fetus. Liver iron was not reduced in the 18-day-old fetus; the decrease in the fetus, therefore, was a reflection of the signiftcant reduction of body iron. Copper was significantly reduced in the fetus from zinc-fed mothers except the 15-and 16-day-old fetus from mothers fed 0.4% zinc beginning at 0-day age of the fetus. No significant change was found in maternal liver, but trends showed liver iron to be increased in mothers fed 0.4% zinc for 15 and 16 days and decreased with the other zinc regimens. With the exception of mothers fed 0.4% zinc for 15 days of fetal age, copper content in the liver was significantly reduced by all zinc regimens.

Toxicological Profile for Zinc

“…Administration of 200 mg zinc/kg/day to dams throughout gestation resulted in decreased growth and tissue levels of copper and iron in fetal rats Schlicker and Cox 1968). In rats, at both 100 and 200 mg/kg/day during gestational days 1-18, maternal zinc levels increased.…”

“…Administration of zinc in rats at 200 mg zinc/kg/day as zinc oxide in the diet for 21 days prior to mating and then throughout gestation resulted in resorption of all fetuses (Schlicker and Cox 1968). Fetal resorptions ranged from 4 to 29% when 200 mg zinc/kg/day was administered only during gestation (controls had no resorptions).…”

“…Information regarding developmental and reproductive effects in animals after oral exposure to zinc is available Ketcheson et al 1969;Kinnamon 1963;Mulhern et al 1986;Pal and Pal 1987;Schlicker and Cox 1968;Sutton and Nelson 1937). Studies regarding genotoxicity in animals after inhalation and oral exposures to zinc are limited (Gupta et al 1991;Kowalska-Wochna et al 1988;Voroshilin et al 1978).…”

“…Increased fetal resorptions were observed in rats after oral exposure to zinc (Schlicker and Cox 1968). No studies were located regarding developmental toxicity in animals after inhalation or dermal exposure to zinc.…”

Preliminary assessment of the ecological risks to wide-ranging wildlife species on the Oak Ridge Reservation. 1996 update

“…The 4000 ppm zinc dose was considered to be a chronic LOAEL. On the basis of the results of Schlicker and Cox (1968), short-tailed shrews foraging on UEFPC OU 2 experiencing exposures greater than or equal to LOAEL may display increased rates of fetal resorption and reduced fetal growth rates.…”