The announcement in December 2010 by NASA researchers that they had discovered bacteria capable of substituting arsenic for phosphorus in their biochemical processes — including, potentially, in the backbone of their DNA — produced one of the more significant controversies in recent science communication history, raising questions simultaneously about the extraordinary claim, the evidence offered for it, and the role of press releases in distorting the process of scientific evaluation.

The bacterium, GFAJ-1, had been found in Mono Lake in California, a highly saline and arsenic-rich environment where unusual biochemistry had been anticipated. The research team, led by Felisa Wolfe-Simon, claimed that when deprived of phosphorus and given arsenic instead, the bacteria not only survived but incorporated arsenic into their molecular structures in ways that had previously been considered biochemically impossible.

The claim, if true, would have been genuinely revolutionary. All known life uses the same six elements — carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur — as the building blocks of its biochemistry. A seventh element, substituting for one of the six, would have expanded the definition of life and had significant implications for the search for life elsewhere in the universe, which is why NASA's press release framed the announcement in those terms.

The subsequent scientific evaluation was less supportive. Multiple research groups attempted to replicate the results and found that the arsenic was not incorporated into the bacteria's DNA in the way the original paper claimed. The most likely explanation, according to the critics, was that the bacteria were simply very good at scavenging trace phosphorus rather than genuinely using arsenic as a substitute.

The episode became a case study in the risks of communicating scientific findings before they have been subject to rigorous independent verification — a problem that the pressure to produce newsworthy results in competitive scientific environments makes difficult to avoid.