A Utah Health Department official says unified political pressure from Western states may be the only way to convince Amtrak officials to stop dumping untreated human waste along railroad rights of way in the region.

Dale E. Marx, with the department's Bureau of Drinking Water and Sanitation, said an exemption granted by Congress in 1978 to allow Amtrak to dump the waste from trains makes a court challenge by the state or regulation by federal agencies almost impossible.Amtrak sprays waste, which receives no chemical treatment, from specially designed tanks on Superliner trains that run on routes west of Chicago, Amtrak spokesman Art Lloyd says.

Health officials are concerned the sewage may be getting into rivers supplying drinking water and poses a health risk to railroad workers. Human excrement carries hepatitis, typhoid and strep viruses.

Marx's response follows a letter sent by Amtrak officials last week to Rep. Howard Nielson, R-Utah, that Nielson said was merely a "justification" for dumping raw sewage and does not offer a satisfactory response to the problem.

The Amtrak letter was written by T.J. Gillespie Jr., Amtrak assistant vice president of government and public affairs, following a meeting with Nielson in May. Nielson called the meeting after raw sewage was found dumped in train yards in several Utah cities and it was sprayed on railroad workers.

Nielson, Marx and railroad unions want Amtrak to change its practice of spraying ground-up waste on rights of way. They want Amtrak instead to store waste in tanks and dump it in city sewer systems along their routes.

"We are operating today essentially with only enough federal support to operate the existing system, with practically no extra funds available for capital projects," Gillespie wrote. "It accordingly would simply not be feasible for Amtrak to engage in a retrofitting program."

Marx said that Amtrak intransigence requires a unified political attack from Western congressman. Marx has written to health officials in 17 states asking them to make their representatives aware of the problem and join with Nielson in fighting Amtrak.

Officials in Oregon and Washington already have begun their own investigations into the problem.

"We are requesting they get hold of legislators, otherwise this thing could be tied up for years. Legally we can't do a thing about it," Marx said.

While Gillespie offered little hope for changing the Amtrak system, he wrote Nielson that officials will reinforce instructions to employees to stop dumping wastes in stations and points were people are working.

Lloyd confirmed Friday that a strongly worded memo had been issued to employees instructing them to not dump waste in stations or use employee toilets that flush directly onto tracks.

Nielson said, however, the Amtrak actions don't go far enough.