Library copies of the bestselling sadomasochistic romance were found to carry traces of herpes and cocaine

Library copies of Fifty Shades of Grey have reported positive for traces of herpes virus and cocaine, according to two Belgian professors.

A second novel, Tango – a romance by Pieter Aspe – also tested positive for herpes, after tests were run on the most popular books on the shelves of Antwerp library.

The study was carried out by researchers at the Catholic University of Leuven in Belgium, who ran chemical tests on the 10 most-borrowed books at the library. All 10 tested positive for traces of cocaine.

Jan Tytgat, a professor of toxicology at the Catholic University of Leuven, told website the Flanders News that the traces both of herpes and of cocaine were too small to be harmful to future readers of the book.

"The levels found won't have a pharmacological effect. Your consciousness or behaviour won't change as a result of reading the tomes," Tytfat said.

It is isn't the first time academics have tested the hygiene of books. Students at Brigram Young University, Utah, found that books categorised by their university library as in high demand averaged 25-40% more microbial life than neglected volumes .

The research team team counted the number of colony-forming units – little spots of bacterial growth – that developed in agar dishes containing samples from the library books. "We just counted them all up … 'one, two, three, OK, there are 16 spots … ew, gross,'" said team member Joshua Nicholson.

The research stopped short of identifying what type of microbes were present, and whether they were harmful to humans. But it did reveal that books harboured far less bacteria than the library doorknobs.

An earlier study, Are public library books contaminated by bacteria? published in the Journal of Clinical Epidemiology, concluded that library books posed no risks. Authors Itzhak Brook and Sara J Brook concluded: "The microbial flora on the surfaces of 15 books obtained from a public library and from 15 books obtained from a family household were studied. Staphylococcus epidermidis was recovered from four of the library books and three of the family household books. The number of organisms per page was between one to four. This data illustrates the safety of using library books, as they do not serve as a potential source of transmission of virulent bacteria."

Hygeine-conscious libraries in Japan are taking no chances, however, installing Bacteria Elimination Boxes to kill off any harmful microbes.

The box uses UV rays to kill off bacteria, and is said by its manufacturers, the Kiraha Corporation, to be effective against Yellow Staphylococcus and E Coli, and also against the influenza virus. However, according to a report in the Tokyo Times, it only cleans book covers and not the individual pages.