Month: June 2021

Hailed as a miracle in the 1950s, the potent bug killer DDT (dichloro-diphenyl-trichloroethane) promised freedom from malaria, typhus and other insect-borne diseases. Manufacturers promoted it as a “benefactor of all humanity” in advertisements that declared, “DDT Is Good for Me!” Americans sprayed more than 1.35 billion tons of the insecticide—nearly 7.5 pounds per person—on crops, lawns and pets and in their homes before biologist Rachel Carson and others sounded the alarm about its impacts on humans and wildlife. The fledgling U.S. Environmental Protection Agency banned DDT in 1972.

Friends and family often ask Barbara Cohn, an epidemiologist at Oakland’s Public Health Institute, why she studies the effects of the long-banned pesticide. Her answer: DDT continues to haunt human bodies. In earlier studies, she found that the daughters of mothers exposed to the highest DDT levels while pregnant had elevated rates of breast cancer, hypertension and obesity.

Cohn’s newest study, on the exposed women’s grandchildren, documents the first evidence that DDT’s health effects can persist for at least three generations. The study linked grandmothers’ higher DDT exposure rates to granddaughters’ higher body mass index (BMI) and earlier first menstruation, both of which can signal future health issues.

“This study changes everything,” says Emory University reproductive epidemiologist Michele Marcus, who was not involved in the new research. “We don’t know if [other human-made, long-lasting] chemicals like PFAS will have multigenerational impacts—but this study makes it imperative that we look.” Only these long-term studies, Marcus says, can illuminate the full consequences of DDT and other biologically disruptive chemicals to help guide regulations.

In the late 1950s Jacob Yerushalmy, a biostatistician at the University of California, Berkeley, proposed an ambitious study to follow tens of thousands of pregnancies and measure how experiences during fetal development could affect health into adolescence and adulthood. The resulting Child Health and Development Study (CHDS) tracked more than 20,000 Bay Area pregnancies from 1959 to 1966. Yerushalmy’s group took blood samples throughout pregnancy, at delivery and from newborns while gathering detailed sociological, demographic and clinical data from mothers and their growing children.

Cohn took the helm of the CHDS in 1997 and began to use data from the children, then approaching middle age, to investigate potential environmental factors behind an increase in breast cancer. One possibility was exposure in the womb to a group of chemicals classified as endocrine disruptors—including DDT.

Human endocrine glands secrete hormones and other chemical messengers that regulate crucial functions, from growth and reproduction to hunger and body temperature. An endocrine-disrupting chemical (EDC) interferes with this finely tuned system. Many pharmaceuticals (such as the antibiotic triclosan and the antimiscarriage drug diethylstilbestrol) act as EDCs, as do industrial chemicals like bisphenol A and polychlorinated biphenyls, and insecticides like DDT. “These chemicals hack our molecular signals,” says Leonardo Trasande, director of the Center for the Investigation of Environmental Hazards at New York University, who was not involved in the study.

Thawing tens of thousands of CHDS samples from decades earlier, Cohn and her colleagues measured the DDT in each mother’s blood to determine the amount of fetal exposure. In a series of studies, they connected this level to the children’s midlife heart health and breast cancer rates.

Fetuses produce all their egg cells before birth, so Cohn suspected these children’s prenatal DDT exposure might also affect their own future children (the CHDS group’s grandchildren). With an average age of 26 this year, these grandchildren are young for breast cancer—but they might have other conditions known to increase risk of it striking later.

Using more than 200 mother-daughter-granddaughter triads, Cohn’s team found that the granddaughters of those in the top third of DDT exposure during pregnancy had 2.6 times the odds of developing an unhealthy BMI. They were also more than twice as likely to have started their periods before age 11. Both factors, Cohn says, are known to raise the risk of later developing breast cancer and cardiovascular disease. These results, published in Cancer Epidemiology, Biomarkers, and Prevention, mark the first human evidence that DDT’s health threats span three generations.

Akilah Shahib, 30, whose grandmother was in the CHDS study and who participated in the current work, says the results provide a stark reminder that current health problems may stem from long-ago exposures. “DDT was a chemical in the environment that my grandparents had no control over,” she says. “And it wasn’t the only one.

To Andrea Gore, a toxicologist at the University of Texas at Austin, the new results are nothing short of groundbreaking. “This is the first really robust study that shows these kinds of multigenerational outcomes,” says Gore, who was not involved in the study.

Laboratory studies, including one by Cohn in 2019, have shown that DDT and other EDCs can lead to effects across generations via epigenetic changes, which alter how genes turn on and off. Cohn is also investigating the multigenerational effects of other endocrine disruptors, including BPA and polyfluorinated compounds.

Such research also highlights the need for long-term testing to determine a chemical’s safety, N.Y.U.’s Trasande says. Gore agrees, arguing that regulators should require more rigorous testing for endocrine-disrupting effects; while scientists learn about the specific mechanisms by which EDCs influence health over multiple generations, she adds, they should routinely look for hallmarks of such influences in lab toxicology studies.

As Trasande puts it: “This study reinforces the need to make sure that this doesn’t happen again.”

Major phone companies and other voice providers have only a matter of days to implement a new caller ID verification system designed to rid Americans of that dreaded auditory plague, the robocall.

The Telephone Robocall Abuse Criminal Enforcement and Deterrence Act (TRACED Act), which was passed in 2019, requires that voice providers adopt a new suite of protocols and procedures, dubbed STIR and SHAKEN, designed to authenticate caller ID and weed out fraudsters who illegally spoof calls to target mobile users. Last week, the Federal Communications Commission sent out a reminder, notifying relevant companies—including the likes of Verizon, T-Mobile, and AT&T—that they have until June 30th to implement STIR/SHAKEN or risk failing to comply with the new federal regulation.

Obviously, this is good news. Automated calls and texts, often designed to sell you garbage, steal your identity, or rip you off, are so bad that today most Americans have just stopped answering their phones unless they recognize the person calling. While not all robocalls are illegal (political campaigns use them legally and local governments often employ them for PSAs), most of them are unequivocally annoying—the digital equivalent of a shady salesman showing up on your doorstep. Since their emergence in the 1990s, robocalls have only continued to grow as a trend: in 2019, Americans received some 58.5 billion of them, which represented an increase of 22 percent from the previous year. That number dipped slightly last year, but it’s still in the same ballpark. On the whole, consumers lose billions of dollars a year to robo-related scams.

The TRACE Act will hopefully help mitigate this trend. In essence, the framework of protocols it introduces will help to further verify whether a caller is who they say they are. This is important because, in most illegal robocalls, bad actors will spoof their connection—meaning they use obfuscation techniques to falsify their caller ID information. The fake number they employ is often designed to encourage the victim to pick up the phone, with fraudsters often spoofing a nearby area code or pretending to be an official from a government agency.

The specific protocols and framework that TRACE introduces essentially force carriers to take part in a multi-stage verification process. STIR, which stands for Secure Telephony Identity Revisited, and SHAKEN—the Signature-based Handling of Asserted information using tokens—are designed so that calls traveling through a phone network must be “signed” and validated by carriers in order to establish their legitimacy. This process is designed to take place before a call ever reaches a person’s phone.

Critics have noted, however, that this program may not be the robocall purge we’ve all been hoping for. Indeed, a lot of companies have already been implementing STIR/SHAKEN for a while (Verizon, for example, recently announced its rollout), so it’s unclear whether what happens on Wednesday will truly be a huge sea-change when it comes to bad actors, or whether it’ll merely be a more imperceptible, statistical sort of shift. Still, we can dream, right?

Confirming once more that it cannot be trusted, the metal known as fool’s gold, aka pyrite, can contain bits of the real thing, according to an Australian-Chinese research team. Getting at the trapped gold, however, is likely to be more trouble than it’s worth.

To the trained eye, the differences between the two minerals are somewhat obvious. Pyrite is magnetic; gold is not. Pyrite can manifest in bizarrely perfect geometries, while soft gold looks more like lustrous pebbles, smoothed by harder outside forces. Plenty of folks entranced by pyrite’s sparkle have bought and sold the stuff around the world. Pyrite even turned up during the California gold rush, deluding the fortune-seekers sifting through the state’s waterways.

This research team examined pyrite and found gold inclusions—exceptionally small ones that could only be seen using an atom probe, an instrument that can visualize the cross-sections of objects on an atomic scale. In other words, they’re invisible. The scientists used the atom probe to detect a new sort of way that gold hides inside fool’s gold. Their research was published in Geology last week.

“Previously gold extractors have been able to find gold in pyrite either as nanoparticles or as a pyrite-gold alloy, but what we have discovered is that gold can also be hosted in nanoscale crystal defects, representing a new kind of ‘invisible’ gold,” said Denis Fougerouse, a geologist at Curtin University in Australia and lead author of the new paper, in a university press release.

The block of pyrite the team inspected was collected from Jiangnan, China and formed where the Yangtze and Cathaysia tectonic plates collided about one billion years ago. Deep in the ground, and at the mercy of geologic processes, the pyrite developed imperfections that warped its crystalline structure. These defects, called dislocations, are extraordinarily small and trap the gold within the less precious mineral, which is composed of iron and sulfur.

In a Conversation article accompanying the paper’s release, Fougerouse wrote that it was previously suspected that bits of gold in pyrite crystals came about at different times, and the two minerals glommed together later on. The pyrite specimen the team inspected suggested that the two minerals can crystallize simultaneously, in a single process. Fougerouse also noted that different methods could be used to release the gold particles from their pyrite prison, which could be more energy efficient than the typical means of gold extraction, reactor-based oxidation, or smaller-scale methods like separating the gold from slag by smelting the ore.

We’ve yet to dislodge all of pyrite’s secrets. Some of them, it seems, were tucked away on the atomic level. But here’s hoping we won’t be fooled again.

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