There's a story about a scientist forced to conduct research into creating genetically modified food grains that will kill off the people of poor nations who import these food grains. The scientist tailors the sandwiches they have for lunch to his own DNA, so he will die first, but so will many of those around the table who are plotting this genocide.
This is "The Winnowing", a short story by Asimov first published in Analog in 1976. The plot is essentially as you described it. In the future world of 2005, with the world's population at 6 billion, the World Food Organization was looking to triage the world's population by using a scientist's discovery of lipoprotein to make a selective poison, and kill off about 70% of the world.
"The winnowing out will be done precisely where overpopulation and hopelessness is worst and enough will be left to preserve each nation, each ethnic group, each culture."
He puts a lipoprotein in the sandwiches served at the meeting, so that a random proportion of the bureaucrats will die, to give them a taste of the fate they could so casually deal out to the world.
"It's quite a painless death, and it will be the finger of God, as one of you told me. It's a good lesson as another of you said. For those of you who survive, there may be new views on triage."
As you recalled, he arranged to die first by matching the lipoprotein to his own biochemistry.
"You'll have to carry on without me - those of you who survive."
The full story is available in the Luminist Archives, in the February 1976 issue of Analog.