A radiologist with an uncanny visual sense, she revolutionized the diagnosis of fetal abnormalities like Down syndrome.Dr. Beryl Benacerraf, a radiologist with an uncanny visual sense who revolutionized the diagnosis of fetal abnormalities like Down syndrome through the use of ultrasound technology, died on Oct. 1 at her home in Cambridge, Mass. She was 73.Her son, Oliver Libby, said the cause was cancer.Dr. Benacerraf — who was a professor of obstetrics, gynecology and reproductive biology and radiology at Harvard Medical School and Brigham and Women’s Hospital in Boston in addition to having a private practice — had struggled academically when she was young because of what she eventually determined was undiagnosed dyslexia.Her later success in using ultrasound images to detect congenital anomalies and gynecological disorders, she said, was tied to “the flip side of that whole problem.”“Pictures just speak to me,” she said in an interview for an oral history project for Barnard College, her alma mater. “I can look at a picture and I can see the pattern. I can see things that nobody else can see.”Perhaps the most notable product of that ability was her discovery that a thickening of a patch of skin at the back of a fetus’s neck, known as the nuchal fold, was associated with Down syndrome and other chromosomal disorders.Before Dr. Benacerraf conducted her research, screening for such defects was generally limited to women 35 and older, those thought to be at greatest risk, and conducted by amniocentesis, an invasive procedure that in a small number of cases can cause miscarriage or other harm.Her first papers suggesting ultrasound’s potential for offering an effective, less invasive form of fetal screening — available to women of any age — were published in 1985. They were not warmly received.“I was almost booed off the stage at several national meetings, and papers emerged discrediting my research and me,” Dr. Benacerraf said in an interview with the American Journal of Obstetrics & Gynecology published last year. “I was devastated, but that much more determined to prevail because I knew I was right.”Her determination was vindicated: As ultrasound became a routine part of prenatal care, so did measuring the thickness of the nuchal fold. The screening, which is now typically augmented by blood tests, was based on her research.An ultrasound showing a thickened nuchal fold — a sign, Dr. Benacerraf discovered, of potential chromosomal disorders like Down syndrome.Brigham and Women’s HospitalBeryl Rica Benacerraf (pronounced buh-NASS-uh-raff) was born in Manhattan on April 29, 1949. Her father, Dr. Baruj Benacerraf, a Venezuelan-born immunologist, later shared the 1980 Nobel Prize in Physiology or Medicine for findings related to genetics.Her mother, Annette (Dreyfus) Benacerraf, a homemaker, belonged to a prominent French Jewish family that included the army captain at the center of the contentious episode known as the Dreyfus affair. Annette Benacerraf’s uncle Jacques Monod also shared a Nobel Prize in Physiology or Medicine, in 1965.The Benacerraf home in Manhattan was a “French oasis,” Dr. Benacerraf said in the 2021 interview. She was often asked to play the flute at dinner parties where the guests included classical music luminaries and scientists like Francis Crick, the British biologist who helped decipher the DNA molecule’s double-helix structure.Beryl, an only child, attended the private all-girls Brearley School in Manhattan but, she said, struggled because of her dyslexia. In an effort to cope with it, she adopted a method of completing assignments as soon as she got them — a practice she would employ throughout her life.“This habit keeps me organized and prevents me from taking on more tasks than what I know I can do,” she said.Despite poor grades, she was accepted at Barnard, her mother’s alma mater. She excelled academically and worked at the Columbia University radio station, WKCR, overseeing classical music programming and anchoring news reports.In an effort to overcome her dyslexia, she took the popular Evelyn Wood speed reading course, twice, to no avail. (She cashed in on the money-back guarantee both times.)After graduating in 1971, she traveled to Italy, unsure of a career path. While living there, she decided to become a doctor and took the Medical College Admission Test. Her predictably poor score became moot when the results were lost.She was accepted at the Columbia University College of Physicians and Surgeons, which at the time did not require the test. Her father’s stature helped ease her entry there, as well as her subsequent transfer to Harvard Medical School, but his admonitions loomed over her.“My father once told me that ‘whatever you end up doing, if you’re not the best in the world there’s no point in doing it,’” she said in the Barnard interview. “So I grew up with that kind of background.”Her dyslexia, she found, did not hamper her medical studies.“You can get through medical school by going to all the classes, by listening, by watching,” she said. “The books have a lot of graphs and images and charts.”In 1975, she met Peter Libby, a fellow Harvard medical student. They were married that year. When she graduated in 1976, she planned to become a surgeon and was accepted for an internship at Brigham and Women’s. But she found the field unwelcoming to women and decide to change course.Considering her options, she recalled what a senior radiologist had told her during a medical school rotation: that even from the back of a room, she could spot an abnormality in an image. “You have a gift that I’ve never seen before,” he told her.She completed a radiology residency at Massachusetts General Hospital, followed by a fellowship at Brigham and Women’s in ultrasound, which was then still a rudimentary discipline. She chose that field because she wanted to have children and did not want to be exposed to radiation.After completing her fellowship and giving birth to a son and a daughter precisely a year apart, Dr. Benacerraf was unable to get a hospital job in Boston and opened her own practice there, Diagnostic Ultrasound Associates, in 1982.In addition to her son and her husband, a cardiologist and a professor of cardiovascular medicine at Harvard Medical School, Dr. Benacerraf is survived by her daughter, Brigitte Benacerraf Libby, and three grandchildren.For 10 years after opening her practice, Dr. Benacerraf said in the oral history interview, she was effectively the only doctor in the Boston area who specialized in prenatal ultrasound. As a result, her practice grew quickly, as patients from around New England and beyond sought her out.During this period she arrived at her finding relating to the nuchal fold, as well as discoveries about, among other things, the development of fetal hearing. In recent years she shifted her focus to gynecological imaging and conditions like endometriosis, pelvic pain and ovarian cancer.In the course of her four-decade career, Dr. Benacerraf saw tens of thousands of patients while publishing hundreds of journal articles and several books. She also trained legions of doctors. One of them, Dr. Laura E. Riley, the chair of obstetrics and gynecology at Weill Cornell Medicine in New York, described Dr. Benacerraf in an interview as “incredibly brilliant” and “a great teacher.”She also called Dr. Benacerraf a “trailblazer” in using ultrasound in the service of women’s reproductive health — in most instances to reassure expectant mothers.“Her diagnostic ability,” Dr. Riley added, “was second to none.”

A dentist with a parallel career as a political scientist, he drew attention to a program that made millions of Americans unwitting guinea pigs.Leonard Cole, a dentist who became an expert on biological weapons and chronicled in troubling detail a secret U.S. Army program that turned millions of Americans into unwitting germ-warfare guinea pigs in the 1950s and ’60s, died on Sept. 18 in Ridgewood, N.J., He was 89.His death, at a hospital, was confirmed by his daughter, Wendy Cole.Dr. Cole’s dental practice was firmly established when he began a second career as a political scientist. He had written two other books — one on New Jersey’s emerging class of Black elected officials, the other on the intersection of politics and science — when he began to look into the clandestine military tests.The program, which ran from 1949 until President Richard M. Nixon halted it in 1969, involved releasing ostensibly harmless bacterial and chemical agents in the New York City subway, over the skies of San Francisco and in dozens of other places to test the country’s vulnerability to biological and chemical attacks.The experiments first came to light after Army reports about them were leaked to reporters in the 1970s. A 1977 Senate hearing brought the program to wider public attention.Dr. Cole augmented testimony from the hearing and declassified files with court documents, other government records and his own interviews to write “Clouds of Secrecy: The Army’s Germ Warfare Tests Over Populated Areas,” published in 1988.The book offers an in-depth examination of the Army program, which encompassed 239 open-air tests over 20 years. Using inert chemicals and bacteria that researchers believed were harmless, the tests were meant to measure how actual biological and chemical weapons might spread under real-world circumstances.When the experiments were disclosed in the 1970s, the Army insisted that no one had been sickened. But Dr. Cole was skeptical.He devoted a substantial portion of “Clouds of Secrecy” to a September 1950 test in which a military vessel cruising the San Francisco coast blanketed the city with an aerosol cocktail that contained the bacterium Serratia marcescens.Before long, about a dozen people with similar symptoms had checked in to a hospital in the city. The diagnosis was a rare pneumonia caused by bacteria believed by doctors there to be Serratia marcescens. One patient, Edward J. Nevin, a 75-year-old retired pipe fitter, died.The Army denied that Mr. Nevin’s death and the other hospitalizations were linked to its spraying, and a lawsuit brought by Mr. Nevin’s family was unsuccessful.But military officials acknowledged separately that contemporaneous monitoring of people who had been exposed to its tests was not part of the program, which Dr. Cole found alarming.Writing about open-air tests in Minneapolis in 1953 that used fluorescent particles of zinc cadmium sulfide to simulate bacterial agents, Dr. Cole wrote, “Who was breathing the material, and how much, seems to have been of no concern.”The Department of Health and Human Services classifies cadmium compounds as carcinogens, but a 1997 National Research Council report said that the tests in Minneapolis and other cities — including St. Louis, Winnipeg and Fort Wayne, Ind. — had not exposed residents to harmful levels of the chemical.Some critics said that Dr. Cole’s book “Clouds of Secrecy” exaggerated the risks of the Army’s tests. Others deemed it a vital public service.Some critics said that “Clouds of Secrecy” exaggerated the risks of the testing program, and that Dr. Cole had not adequately accounted for the military’s need to conduct such experiments in the Cold War era.Others deemed the book a vital public service.Hugh L’Etang, a British doctor and editor, said in the journal Politics and the Life Sciences that Dr. Cole, “through painstaking investigation,” had “written not only a real horror story, but even more important, shown how conscientious individuals were led to risk the health and even the lives of fellow Americans.” Reviewing the book in The New York Times, David Weir called it “a penetrating study” of the clandestine operation.Dr. Cole was born Leonard Aaron Cohen on Sept. 1, 1933, in Paterson, N.J. An only child, he changed his surname as a young man because of concerns about antisemitism. (He later held prominent positions in several Jewish community organizations.) His father, Morris Cohen, owned delis in New Jersey and New York City. His mother, Rebecca (Harelick) Cohen, was a homemaker.Leonard graduated from high school in Paterson and began his college studies at Indiana University before enrolling at the University of Pennsylvania’s dental school. In 1957 he earned his dental degree, married Ruth Gerber and joined the Air Force. He was stationed in Japan for two years.He and his wife then moved to Berkeley, Calif., where Dr. Cole worked at a dental office and earned a bachelor’s degree in political science at the University of California.In 1961, the couple moved to northern New Jersey, where Dr. Cole started a family dental practice in Hawthorne. He subsequently began graduate studies in political science at Columbia University, earning a doctorate in 1970.Dr. Cole first explored the issue of government-sponsored scientific research on unsuspecting human subjects in his second book, “Politics and the Restraint of Science” (1983).A later book about biological and chemical weapons, “The Eleventh Plague” (1996), solidified his credentials as an authority on the subject. When anthrax-laced letters began showing up in the U.S. mail in the wake of the Sept. 11 terrorist attacks, he became a sought-after commentator. He published “The Anthrax Letters: A Medical Detective Story” in 2003.Dr. Cole, a longtime adjunct professor of political science at Rutgers University-Newark, testified before Congress a number of times on topics related to biological weapons. He was the founding director of Rutgers New Jersey Medical School’s terrorism medicine program.In addition to his daughter, he is survived by his wife, a retired public-school teacher; two sons, William and Philip Cole; and six grandchildren. He lived in Ridgewood.Dr. Cole retired from dentistry in 2000 but continued to write books. His 10th, published last year, told the story of Dr. Frederick Reines, who won a Nobel Prize in Physics for codiscovering the neutrino, a subatomic particle. Dr. Reines was Dr. Cole’s cousin.As for how he balanced his various endeavors, Dr. Cole said in an interview with the online publication Authority Magazine last year that he gave his “undivided attention” to whatever he was doing at the moment.A friend once told him, he added, “that I surely was the best dentist among political scientists, and the best political scientist among dentists.”Kirsten Noyes contributed research.