A government expert contends that copper-plated zinc pennies pose little health hazard despite the death of a dog who had swallowed two such coins. ``The incidence (of zinc poisoning) is exceedingly low,`` said Dr. George E. Hunter, assistant director for technology of the United States Mint. ``We`ve made nearly 50 billion zinc cents since 1982 and have had only two reported (poisoning) cases, neither involving humans. ``Earlier this year, Rep. Eldon Rudd (R., Ariz.) introduced legislation in Congress to revert to the production of copper Lincolns, in part to reduce the threat of zinc poisoning. High concentrations of zinc in the bodies of humans or animals can cause intense vomiting, among other things. In one of the two cases, a small, old dog died after a week of vomiting, unable to discharge two zinc cents from his body, Hunter said. An autopsy revealed high levels of zinc in the animal`s liver. Another dog became violently ill after swallowing 17 zinc cents but recovered completely after throwing them up. Hunter said the dogs may have chewed on the coins before swallowing them, damaging the copper coating and exposing the zinc core. ``One reason we decided to coat the zinc cent with copper is to provide some protection from zinc poisoning,`` Hunter said. In stomach acids, copper dissolves more slowly than zinc, which delays the spread of the zinc into the blood and vital organs. Uncle Sam began making Lincoln cents out of zinc plated with copper during 1982 to reduce production costs. Before then, the U.S. Mint created Lincolns out of an alloy containing 95 percent copper and 5 percent zinc. Last summer, Mint Director Donna Pope said the switch is saving taxpayers more than $20 million a year because zinc is cheaper than copper. Consequently, many hobby pros predict that Rudd`s bill has little chance of passage despite the concern over ingested zinc cents.Rudd`s home state, Arizona, has several copper mines. A return to the copper cent would help the depressed copper industry. -- Members of the Hillside Coin Club will distribute hobby literature and evaluate old coins free of charge as a way of celebrating National Coin Week. The program, which also will include short talks by hobbyists, begins at 7:30 p.m. Tuesday in Richard`s Lilac Lodge, 2135 S. Wolf Rd., Hillside. Admission is free. National Coin Week is an annual observance promoted by the 38,000-member American Numismatic Association. The 1985 week begins today.