We have a dispiriting shortage of high-quality health research for many reasons, including the fact that it’s expensive, difficult and time-intensive. But one reason is more insidious: Sometimes groups seek to intimidate and threaten scientists, scaring them off promising work.

By the time I wrote about the health effects of lead almost two years ago, few were questioning the science on this issue. But that has not always been the case. In the 1980s, various interests tried to suppress the work of Dr. Herbert Needleman and his colleagues on the effects of lead exposure. Not happy with Dr. Needleman’s findings, the lead industry got both the federal Office for Scientific Integrity and the University of Pittsburgh to conduct intrusive investigations into his work and character. He was eventually vindicated — and his discoveries would go on to improve the lives of children all over the country — but it was a terrible experience for him.

I often complain about a lack of solid evidence on guns’ relationship to public health. There’s a reason for that deficiency. In the 1990s, when health services researchers produced work on the dangers posed by firearms, those who disagreed with the results tried to have the National Center for Injury Prevention and Control shut down. They failed, but getting such work funded became nearly impossible after that.

I have also discussed the too-slowly changing approach to back pain. There’s a reason for that, too. When research was published, also in the early 1990s, arguing that the proper treatment of back pain was nonsurgical, some with a financial interest in surgical intervention tried to have the Agency for Health Care Policy and Research (now known as A.H.R.Q.) defunded. They failed, too, but left researchers skittish about focusing on this topic.