Recently it has come to our attention that a paper was published in this journal entitled "recycling greenhouse gas fossil fuel emissions into low radiocarbon food products to reduce human genetic damage" (Williams in Environ Chem Lett 5:197-202, 2007). In this article, it is argued that food grown in a greenhouse is healthier for people, when the greenhouse is fertilised with CO(2) prepared from fossil fuels. In this comment, however, we argue that the effect on human health is completely negligible.