Among archaeologists who report rampant thefts of antiquities from their dig sites worldwide, U.S. archaeologists are unique in reporting run-ins with methamphetamine addicts bent on looting dig sites.

From Italy's Etruscan tombs to Egypt's ancient pyramids to Cambodia's Angkor Wat temples, thieves have pillaged ancient heritage sites for centuries, and a new survey finds looting widespread in both wealthy and poor nations.

Hobbyist "pot hunters" have long disturbed U.S. archaeological sites looking for early Native American artifacts to steal or sell, but anecdotal reports of "meth heads" invading sites adds a new worry for scholars.

"Archaeological fieldwork has become an increasingly dangerous occupation around the world," finds the survey of 2,358 archaeologists (initially it was mailed to about 15,000 researchers, for a 16% response rate) reported in the current Journal of Contemporary Criminal Justice, noting looters -- sometimes armed -- at archaeological sites worldwide. "From a global perspective, looting is not an isolated problem," says survey author Blythe Bowman Proulx of Virginia Commonwealth University in Richmond, Va.

Archaeologists commonly visit sites during "field seasons," digging and retrieving artifacts for later study and cataloging. About 79% reported looting of their sites, in locales ranging from Italy to Peru. And 24% reported finding it "in progress" at their digs, in the survey.

Alone among survey respondents, U.S. archaeologists described methamphetamine addicts as often responsible for looting, in 18 states. A 2005 Bureau of Land Management report has noted "many" suspects arrested for thefts from federal archaeological sites also ran meth "labs". And Archaeology Magazine in 2009 noted more reports of meth lab operators stealing Anasazi relics. In the survey, Proulx collected comments such as "Meth nuts are the relic collectors," from one Arkansas researcher, as well as similar ones in California, Oregon and Southeastern states.

"The survey started to get these comments from U.S. archaeologists, just popping out of the responses," Proulx said. She suggests that since meth labs are often found in isolated areas, just like archaeological sites, geographical coincidence may explain the complaints. Meth addicts are known for repetitive behavior and may find digging at sites soothing, she adds in the study.

Drug crime experts such as UCLA's David Farabee, however, voiced some skepticism about the "meth heads" reports, citing the survey's low response rate. Only 14 archaeologists who received the survey gave detailed descriptions of looting. "The provocative conclusions linking drugs and looting come from anecdotes," Farabee says. "That's not a solid foundation."

Although methamphetamine arrests or convictions figure weekly in FBI news releases, federal drug survey data suggest that methamphetamine users dropped by more than half from 2006 to 2008, the last year surveyed in a nationwide federal survey. And claims about methamphetamine abuse leading to brain damage have been questioned by some recent findings. About 1.17 million people nationwide reported illicit methamphetamine use last year, according to the federal Drug Enforcement Agency.