SHANGHAI -- Jian Guangzhou was a very nervous man. In September 2008, he’d filed a story to his newspaper’s editors that named a large, state-owned Chinese company as selling milk powder that made infants dangerously ill. It was the sort of moment that ends journalism careers in China, where even if the reporting is solid, ruffling the politically connected can bring excruciating reprisal.

The food safety problem at hand turned out to be epic: Twenty-two dairy businesses were implicated in a scandal over mixing milk with an industrial chemical that can cause kidney failure in babies. At least six infants in China died as a result, and some 300,000 fell ill. The courts convicted more than 20 people linked to the industry, sending two of those off for execution.

The Chinese Communist Party soon moved to quell public outrage and made sure senior leaders weren’t implicated. Still, Jian’s work was seen as a sliver of transparency in a nation often shrouded by censorship.

Then last month Jian announced he was resigning from the newspaper that had published his expose. In an online post, Jian said he planned to no longer “be a journalist in media that fawns over the powerful.”

His resignation was another in a line of high-profile Chinese investigative journalists and their editors who’ve recently either left their jobs or been shoved to the side.

The departures suggest that China’s leadership, about to undergo a once-a-decade transition, is caught in a bind typical of authoritarian regimes. Work such as Jian’s, which in 2008 may have helped save children from dying, provides a pressure valve in a society already laced with pent-up discontent. Allowing it to continue, however, creates the possibility of questions arising about the ruling party – unthinkable for an authority whose power is predicated on its near-infallibility.

Chinese media recently reported that so far, six officials who were fired or punished after the milk powder fallout have been reinstated or promoted.

Wang Keqin, a doyen of Chinese journalists, said in an interview at his Beijing office that this year has been “probably the worst” in a decade or more for investigative journalists, despite one of the biggest political scandals in recent history: the wife of a powerful Communist Party figure convicted of murder, and that official, Bo Xilai, now himself being handed over to the courts. But domestic reporting on the case, viewed by some observers as ruthless political theater during a factional power struggle, has been subject to severe scrutiny by party propaganda apparatchiks.

In discussing the journalism landscape, Wang, 47, said it was typically squeezed by censors during large events such as the 2008 Beijing Olympics or the 2009 anniversary of the party’s founding of the People’s Republic of China.

In tracing a recent downturn starting last year, though, Wang also mentioned other troubles.

“The conflicts among the people of China’s society turned white hot. Mass incidents were in the state of blossoming everywhere,” he said, using a catchall term for public disturbances ranging from street corner demonstrations to citywide riots. “Then the Chinese authorities . . . took ‘maintaining stability’ as the top priority, and in the process of maintaining stability, controlling the media has become one of the most important methods.”