 In 2007, Domingo's search of the PubMed database using 12 search terms indicated that the "number of references" on the safety of GM or transgenic crops was "surprisingly limited", and he questioned whether the safety of GM food had been demonstrated.The review also stated that its conclusions were in agreement with three earlier reviews.However, Vain found 692 research studies in 2007 that focused on GM crop and food safety and found increasing publication rates of such articles in recent years.