Dr. Marvin C. Ziskin, an emeritus professor of medical physics at Temple University School of Medicine, agreed. For decades, Dr. Ziskin explored whether such high frequencies could sow illness. Many experiments, he said, support the safety of high-frequency waves.

Despite the benign assessment of the medical establishment, Dr. Curry’s flawed reports were amplified by alarmist websites, prompted articles linking cellphones to brain cancer and served as evidence in lawsuits urging the removal of wireless classroom technology. In time, echoes of his reports fed Russian news sites noted for stoking misinformation about 5G technology. What began as a simple graph became a case study in how bad science can take root and flourish.

“I still think there are health effects,” Dr. Curry said in an interview. “The federal government needs to look at it more closely.”

An authoritative mistake

Dr. Curry was not the first to endorse the idea that advances in wireless technology could harbor unforeseen risks. In 1978, Paul Brodeur, an investigative journalist, published “The Zapping of America,” which drew on suggestive but often ambiguous evidence to argue that the growing use of high frequencies could endanger human health.

In contrast, Dr. Curry’s voice was authoritative. He became a private consultant in the 1990s after federal budget cuts brought his research career to an end. He had degrees in physics (1959 and 1965) and electrical engineering (1990). His credentials and decades of experience at federal and industrial laboratories, including the Lawrence Livermore National Laboratory, seemed to make him a very strong candidate to conduct the Broward study.

“He was a very bright guy,” recalled Gary Brown, an expert in the district’s technology unit who worked with Dr. Curry to prepare the reports. But Dr. Curry lacked biological expertise. He could solve atomic and electromagnetic puzzles with ease, but he had little or no formal training in the intricacies of biomedical research.

In 2000, Dr. Curry, writing on letterhead from his home office in the Chicago suburbs, sent the Broward district two reports, the first in February 2000 and the second in September of that year. The latter study went to the superintendent, the school board and the district’s head of safety and risk management.