"People said, 'You shouldn't be shocked because you knew people were doing this.' But when you see it in print, it's a shock," Nichols said.
When the journal Nature subsequently approached him about writing an essay on the topic, Nichols obliged.
"I have never considered my research to be dangerous, and in fact hoped one day to develop medicines to help people," he wrote in the essay published Jan. 5, 2011. "I have worked for nearly four decades synthesizing and studying drugs that might improve the human condition. I strive to find positive things, and when my research is used for negative ends it upsets me."
As research becomes more accessible through online, open-access journals, researchers increasingly are aware that their audience no longer is restricted to scientific inner circles.
"It gets tricky when every drug dealer, home meth lab and drug cartel gets immediate access to the same information," said Arthur Caplan, chairman of medical ethics at the University of Pennsylvania.
Studies relating to biological warfare and nuclear weapons are restricted to the public for reasons of national security. But there is no way to keep research like Nichols' -- and the materials necessary to replicate it -- out of malicious hands.
"You publish and I think you just have to hope people use it responsibly," Nichols said, adding that a sophomore organic chemistry student could make MTA with a few hundred dollars of glassware and chemicals. "Before, you would order laboratory equipment from a standard supplier and the DEA could be alerted. But with the Internet, you can order things without much scrutiny."
Caplan thinks measures should be taken to limit the potential for science to do harm. Journals could restrict access to complete formulas and recipes, drug enforcers could be on the lookout for compounds with high potential for misuse, and scientists could think hard about who they share their research with.
"None of these things are perfect." Caplan said. "I'm not saying you can prevent the misuse of scientific knowledge. But at least you could make it tougher for the bad guys."
Although the knowledge that his discovery has killed people -- and may have had yet unknown long-term effects in many more -- haunts Nichols, he plans to continue his research. Understanding the function of receptors in the brain, called G protein-coupled receptors, is the "holy grail of pharmacology," he said. He currently is developing a rat model of schizophrenia that can be used to discover drug targets and develop therapies.
And while Nichols can't help but feel in some way responsible for the harm caused by MTA, the notion that people have a personal responsibility for what they do to themselves has carried some of the weight, he said.
"Young people often feel invincible," Nichols said. "They think, 'Oh, it's legal. I can't get in trouble.' They don't think about whether it will hurt them. One of the messages that I'd like to get out is that a legal high does not equal a safe high -- it just means it's not illegal yet."