Kansas City, Mo. ? When Amy Crump took over as director of the Marshall Public Library in central Missouri two years ago, she decided to build up the library’s offerings for young adults by buying the literary world’s hot new thing – graphic novels.

The novels, using the pictures and dialogue balloons of comic books to tell sometimes sophisticated stories in book form, are one of the fastest-growing sectors of the publishing industry, selling $250 million last year, according to market research firm ICV2 Publishing. But they’re also leading to challenges of libraries from some parents, who complain that the books with adult content could be read by children attracted to the comic book-like drawings.

Among Crump’s new acquisitions was “Blankets” by Craig Thompson and “Fun Home: A Family Tragicomic” by Alison Bechdel, two semi-autobiographical accounts of the respective authors’ turbulent childhoods that include ruminations on a strict religious upbringing and homosexuality.

Those two novels touch off what Crump said was the first challenge of library materials in the library’s 16-year history. Parents complained that the books, which include pictures of a naked couple, could be read by children, attracted by the comic book-like drawings.

“My concern does not lie with the content of the novels, rather my concern is with the illustrations and their availability to children and the community,” said Marshall resident Louise Mills during a recent public hearing. “Does this community want our public library to continue to use tax dollars to purchase pornography?”

The library board has since removed the two books from circulation while it develops a policy governing how it collects materials in the future, a policy that would determine the novels’ eventual fates.

Library board president Anita Wright, left, and Amy Crump, director of the Marshall Public Library, look at a graphic novel at the library in Marshall, Mo. Two graphic novels have been taken out of circulation while the library reviews its policies.

Sales of graphic novels have more than tripled from $75 million in 2001. Milton Griepp, chief executive of ICV2, which tracks pop culture retail, estimated libraries add 5 percent to 10 percent to those retail sales.

“The last two or three years’ growth has been pretty rapid in libraries, and that’s because graphic novels have started to be respected as legitimate literature,” Griepp said.

“Maus,” a Holocaust memoir by Art Spiegelman, won a Pulitzer Prize in 1992, while Gene Luen Yang’s “American Born Chinese” this year became the first graphic novel to be nominated for the National Book Award.

But some people who may have never heard of graphic novels are alarmed to see cartoon characters doing and saying very adult things.

The Chicago-based American Library Assn said it knows of at least 14 graphic novel challenges in U.S. libraries over the past two to three years. Among the titles were “The Watchmen” by Alan Moore, which was challenged in Florida and Virginia as unsuitable for younger readers; “Akira, Volume 2” by Katsuhiro Otomo, challenged in Texas for offensive language; and “New X-Men Imperial” by Grant Morrison, challenged in Maryland for nudity, offensive language and violence.

Sometimes the challenges are successful. In April, county officials in Victorville, Calif., removed from their library “Manga: 60 Years of Japanese Comics,” because the book included nudity and sexuality.