The secret of Perera's success, I concluded, was adaptability, both personal and professional. When air pollution declined in American cities in the 1980s, Perera found new urban sites abroad, first in Finland and then in Poland, where she could pursue hydrocarbons and their biological signatures. The opportunity to work in Poland came after the collapse of Soviet Communism. U.S. health officials offered to help their counterparts who were struggling with rampant, unrestricted coal burning by factories and homes.
The pollution in Poland jolted Perera into thinking about children as study subjects. "The air stung my eyes," she said. "I was alarmed—well, not alarmed, but I was concerned. I thought about the children. Let's go into the womb, I thought."
In the 1990s health officials and researchers converged on the view that children were more sensitive than adults to pollutants and so merited additional protection. Exhibit A was lead, which set back children's mental development without appearing to harm adults. Pesticides in foods and contaminants in air and water posed extra hazards, if only because children absorb relatively more of these substances. Perera and her associate Robin Whyatt pointed out in a 1995 paper that children have "higher breathing rates, ingest more drinking water, and consume more calories of food per unit body weight than do adults." So the researcher adjusted her sights for cancer risk from adults to children and added markers for cognitive development and asthma to her molecular toolbox.
"The value of a susceptible subpopulation like children," says Gwen Collman of the National Institute of Environmental Health Sciences, "is that it helps you get away from the mean, which may cloud the truth. Why waste your efforts on protecting everybody when not everybody is affected?" When the institute and the EPA awarded funding in 1998 to create children's health research centers around the country, Perera set up shop as director of the Columbia Center for Children's Environmental Health.
Her assumption was that if air pollution is bad for mothers and infants, it's worse in communities where mothers and infants are poor. Perera's team analyzes housing conditions and psychosocial stressors as well as polycyclic aromatic hydrocarbons, cigarette smoke, insecticides, toxic metals, and indoor allergens. The Columbia center not only collects health data from its subjects but also offers health instruction.
Counting staff and scientists, about 50 people are employed full- or part-time on projects. Perera has teamed economists and psychologists with toxicologists and analytical chemists. "I'm an interdisciplinary figure," she said, smiling at the grand description. "I like bringing together juxtapositions. As one of my advisers said, to be 'interdisciplinary' is to have several skills in one skull."
Perera has people skills in spades. Christopher Dickey, one of her graduate students and later a research assistant, recalled going to scientific meetings with Perera in the early 1990s, when molecular epidemiology was new. Dickey would watch in admiration as his boss picked the brains of potential partners. It wasn't just advice on biological markers she sought, it was also help in paying for the analyses. "She is a master of those collaborations," he said. "She's phenomenal at it. She gets people with different agendas to work together."
Dickey gave two reasons for her persuasiveness: "Sensitivity—I haven't seen it honed in other people as finely as it is in Ricky. Also, she's physically striking and extremely polished. It's a little intimidating even. There aren't that many with that charisma."
When I visited, Perera was confident enough to open all her staff meetings to me. She ran the agenda and dealt with problems and interruptions with an unfailing calm, her voice relying on a softly rising tremolo for its effect rather than a boost in volume. She penned a note to herself on a fingernail—"Wed at 9"—for the next meeting.
No edges were evident, nor any abrasions from the harder climb a woman has to make in the largely male world of science. The closest she came to a feminist statement was when I referred to the DNA adduct, in use for more than 20 years, as the granddaddy of biological markers.
"It's the grandmother, don't you think?" she says, arching an eyebrow.
On the last day of my visit we went to see her latest collaborator, Benjamin Tycko, a cancer geneticist at the Columbia-Presbyterian Medical Center with much fancier digs than her own. Perera had sent him cord-blood samples for a trial run of their project.
Tycko studies a phenomenon called gene silencing, in which one of a person's two copies of a gene is shut off. Normally a person's gene-silencing patterns are inherited from one parent or the other. But chemicals, including those in cigarette smoke, can shut genes off, too, or turn inactivated genes back on. Sometimes, when genes regulating growth are switched on or off, a cell turns cancerous.
Tycko is examining gene silencing in PEG-1, a growth-factor gene that's active in the placenta and in the development of the fetus. Perera would like to know if the gene's activity can be switched on and off by environmental toxins. If so, Tycko's PEG-1 marker might be paired with one of her own. Ideally, the markers would lie on the same path in the maze connecting the mother's environment, the placenta, and the newborn.
Perera turned the full beam of her attention on Tycko as he explained how the cord-blood samples showed that the gene's activity varied and that it varied in ways that suggested the differences were not random but environmentally influenced. In other words, the project that she had in mind, to test PEG-1 as a marker, was feasible.
"What's this gene's relation to cancer?" Perera asked.
"It's not clear-cut," Tycko said cautiously. "It's related to growth."
They began to discuss a joint venture. "You're the one who knows how to measure the exposures," Tycko said. Perera left the meeting encouraged, saying, as she strode briskly back toward the Hudson River: "We're very poor compared with the 'hard' sciences. On the other hand, the hard sciences are saying they need the environmental side."
The sky was a high, hard blue, clean as a whistle. If there is a single cloud hanging in the way of molecular epidemiology, it's called "validation." A validated marker can be used precisely, accommodating whatever question is asked of it, so that scientists and policymakers can take it off the shelf, plug it into their risk calculations, and have confidence in the results. Blood levels of lead predict neurological deficits far better than any DNA adduct or aberrations can predict a cancer. The day for cancer markers will come, but it will take more spending, and it will take a much deeper understanding of carcinogenesis.
"It's slow," Perera said, "but I'm patient." She read from notes she had written, so as to be clear. "The picture has become more complex. It won't be solved in my lifetime. I won't solve these problems, but I hope to establish methods for others to follow."