Time was when all you needed for Halloween was a mask, a shopping bag and a good pair of tennis shoes, and if you were fast and didn't eat yourself sick the first night, you had enough jawbreakers, Hershey bars, Baby Ruths and Mary Janes to last till Easter.

No more.

Now you need a proclamation from the county council telling you when to do your trick-or-treating, and maybe some advice from your doctor about what you can eat when you get back.

In the Washington area, exactly when Halloween falls this year is anybody's guess. Counties in Northern Virginia have decreed Sunday, Oct. 31, officially Halloween -- precisely the day it used to be. In Prince George's County, police are recommending Saturday for celebrating Halloween: that's when they will be out in additional force.

Officials in Montgomery County are expecting people to celebrate both Saturday and Sunday, but have chosen Saturday to put out extra police patrols. In the District of Columbia, officials have taken no position at all.

"Everybody's getting so serious about Halloween, I can't believe it," said Annette Samuels, spokeswoman for Mayor Marion Barry. "My understanding of Halloween is that it's the day before the 1st of November."

The deaths in Chicago caused by cyanide in Extra-Strength Tylenol capsules have put a genuine scare into this Halloween.

"All this Tylenol stuff is what's stirred people up the most," said Alexandria Hospital spokeswoman Jody Wilson, explaining why the hospital is offering free X-rays of children's bags of treats this Sunday. "There just seems to be so much concern this year because of all the tampering."

Two dozen hospital staffers have been assigned to X-ray Halloween treats between 3 p.m. and 8 p.m. Sunday to make sure the goodies don't contain any lethal metal objects. Children get to keep the picture, and compare it with another prepared by the hospital staff of treats containing pins and scalpel blades.

Wilson cautioned that the X-rays will detect only metal objects. "I almost hate to say this stuff, because I don't want to give people ideas," she added. "But you also have to protect yourself."

"We talked about doing something like that, but we had a real problem giving people a false sense of security," said Holy Cross Hospital spokesman Tom Burke. "It's so sad. The Chicago thing has developed in all of us a fear of tricks rather than treats."

U.S. Assistant Secretary of Health Edward N. Brandt last week issued a Halloween warning to parents across the country. Youngsters, Brandt said, should not be permitted to eat trick-or-treat candy "until an adult family member has a chance to examine each treat individually."

Candy packages or fruit that appear to have been tampered with, he said, should be detroyed.

The U.S. Consumer Product Safety Commission this week issued its annual list of Halloween safety tips, advising parents to buy flame-resistant or flame-proof costumes for their children, keep lighted jack-o-lanterns away from doorways, have children carry flashlights at dark and wear reflecting tape on clothing.

Several safety agencies advise that children stick to their own neighborhoods and that parents accompany their children on trick-or-treat rounds after dark.

Said D.C. police spokeswoman Lania Bryant: "If parents are that concerned about trick-or-treating, then they shouldn't let their kids go."

Yet, go they will, some of them in disguises more realistically gruesome than ever.

Toy store shelves this year are stocked with kits to turn the prettiest baby face into a war victim. One such line of make-up promises punched noses, chewed thumbs, open wounds, vampire bites and bullet holes, all oozing blood.

"You've got so much in the way of makeup and special effects, people want to imitate some of the stuff they see in the movies," said Barry Taylor of Barry's Magic Shop in Wheaton, where eight E.T. costumes were rented long ago. "They've seen how realistic things can be and they want to recreate that with their own costumes."

"I'm thoroughly disgusted with this," said 10-year-old Susan Lee of Reston, perusing stacks of Rubik's Cube, E.T., Smurfs, Strawberry Shortcake and Pac-Man costumes at the Tysons Corner Toys R Us. "All they have is dumb baby stuff."

"I'd say Halloween is now an adult holiday," Taylor said.

Several hundred costumed adults are expected in Georgetown over the weekend, where last year crowds blocked traffic for nearly three hours.

"We were lucky it didn't get nasty," said Greg Doherty, manager of Nathan's restaurant at Wisconsin Avenue and M Street. "The police were real good about it. They just made sure nobody got hurt."

On Sunday, the best costume at Nathan's wins a bottle of champagne. "We expect people to celebrate Friday, Saturday and Sunday," Doherty said. "If the weather holds out, it could be like Mardi Gras."