Mars Curiosity rover finds life-supporting chemicals

By Azadeh Ansari and Elizabeth Landau, CNN updated 2:48 PM EST, Tue December 10, 2013 | Filed under: Innovations

An illustration depicts the possible extent of an ancient lake inside Gale Crater, where the Mars rover Curiosity landed on the Red Planet in August 2012. The $2.5 billion NASA mission set out to explore Gale Crater, which was thought to have once hosted flowing water. Curiosity found evidence of clay formations, or "mudstone," in the crater's Yellowknife Bay, scientists said in 2013. This clay may have held the key ingredients for life billions of years ago. It means a lake must have existed in the area.

The rover drilled this hole, in a rock that's part of a flat outcrop researchers named "John Klein," during its first sample drilling on Mars on February 8. The latest self-portrait of the rover combines dozens of images taken by the rover's Mars Hand Lens Imager (MAHLI) on February 3. NASA's Mars rover Curiosity has taken its first set of nighttime photos, including this image of Martian rock illuminated by ultraviolet lights. Curiosity used the camera on its robotic arm, the Mars Hand Lens Imager, to capture the images on January 22. Another nighttime image includes this rock called Sayunei in the Yellowknife Bay area of Mars' Gale Crater. Curiosity's front-left wheel had scraped the rock to inspect for fresh, dust-free materials in an area where drilling for rock soon will begin. An area of windblown sand and dust downhill from a cluster of dark rocks has been selected as the likely location for the first use of the scoop on the arm of NASA's Mars rover Curiosity. Curiosity cut a wheel scuff mark into a wind-formed ripple at the "Rocknest" site on October 3, 2012. This gave researchers a better opportunity to examine the particle-size distribution of the material forming the ripple. NASA's Curiosity rover found evidence for what scientists believe was an ancient, flowing stream on Mars at a few sites, including the rock outcrop pictured here. The key evidence for the ancient stream comes from the size and rounded shape of the gravel in and around the bedrock, according to the Jet Propulsion Laboratory/Caltech science team. The rounded shape leads the science team to conclude they were transported by a vigorous flow of water. The grains are too large to have been moved by wind. This photos shows an up-close look at an outcrop that also shows evidence of flowing water, according to the JPL/Caltech science team. The outcrop's characteristics are consistent with rock that was formed by the deposition of water and is composed of many smaller rounded rocks cemented together. Water transport is the only process capable of producing the rounded shape of conglomerate rock of this size. Curiosity completed its longest drive to date on September 26, 2012. The rover moved about 160 feet east toward the area known as "Glenelg." As of that day the rover had moved about a quarter-mile from its landing site. This image shows the robotic arm of NASA's Mars rover Curiosity with the first rock touched by an instrument on the arm. The photo was taken by the rover's right navigation camera. This image combines photographs taken by the rover's Mars Hand Lens Imager at three distances from the first Martian rock that NASA's Curiosity rover touched with its arm. The images reveal that the target rock has a relatively smooth, gray surface with some glinty facets reflecting sunlight and reddish dust collecting in recesses in the rock. This rock will be the first target for Curiosity's contact instruments. Located on a turret at the end of the rover's arm, the contact instruments include the Alpha Particle X-Ray Spectrometer for reading a target's elemental composition and the Mars Hand Lens Imager for close-up imaging. Researchers used the Curiosity rover's mast camera to take a photo of the Alpha Particle X-Ray Spectrometer. The image was used to see if it had been caked in dust during the landing. Researchers also used the mast camera to examine the Mars Hand Lens Imager (MAHLI) on the rover to inspect its dust cover and check that its LED lights were functional. In this image, taken on September 7, 2012, the MAHLI is in the center of the screen with its LED on. The main purpose of Curiosity's MAHLI camera is to acquire close-up, high-resolution views of rocks and soil from the Martian surface. This is the open inlet where powdered rock and soil samples will be funneled down for analysis. The image is made up of eight photos taken on September 11, 2012, by MAHLI and is used to check that the instrument is operating correctly. This is the calibration target for the MAHLI. This image, taken on September 9, 2012, shows that the surface of the calibration target is covered with a layor of dust as a result of the landing. The calibration target includes color references, a metric bar graphic, a penny for scale comparison, and a stair-step pattern for depth calibration. This view of the three left wheels of NASA's Mars rover Curiosity combines two images that were taken by the rover's Mars Hand Lens Imager on September 9, 2012, the 34th day of Curiosity's work on Mars. In the distance is the lower slope of Mount Sharp. This view of the lower front and underbelly areas of NASA's Mars rover Curiosity was taken by the rover's Mars Hand Lens Imager. Also visible are the hazard avoidance cameras on the front of the rover. The penny in this image is part of a camera calibration target on NASA's Mars rover Curiosity. The image was taken by the Mars Hand Lens Imager camera. The rover captured this mosiac of a rock feature called 'Snake River" on December 20, 2012. The reclosable dust cover on Curiosity's Mars Hand Lens Imager was opened for the first time on September 8, 2012, enabling MAHLI to take this image. The Curiosity rover used a camera located on its arm to obtain this self-portrait on September 7, 2012. The image of the top of Curiosity's Remote Sensing Mast, showing the Mastcam and Chemcam cameras, was taken by the Mars Hand Lens Imager. The angle of the frame reflects the position of the MAHLI camera on the arm when the image was taken. The left eye of the Mast Camera on NASA's Mars rover Curiosity took this image of the rover's arm on Wednesday, September 5, 2012.

Sub-image one of three shows the rover and its tracks after a few short drives. Tracking the tracks will provide information on how the surface changes as dust is deposited and eroded.

Sub-image two shows the parachute and backshell, now in color. The outer band of the parachute has a reddish color. STORY HIGHLIGHTS

• Mars Curiosity rover finds evidence of clay formations, or "mudstone"
• Clay may have held the key ingredients for life billions of years ago
• Scientist calls findings "a game changer"

(CNN) -- Curious about life on Mars? NASA's rover Curiosity has now given scientists the strongest evidence to date that the environment on the Red Planet could have supported life billions of years ago.

Since Curiosity made its rock star landing more than a year ago at Gale Crater, the focal point of its mission, the roving laboratory has collected evidence that gives new insights into Mars' past environment.

MAVEN to study Mars from above

NASA scientists announced in March that Mars could have once hosted life -- at least, in the distant past, based on the chemical analysis of powder collected from Curiosity's drill. An area of the crater known as Yellowknife Bay once hosted "slightly salty liquid water," Michael Meyer, lead scientist for the Mars Exploration Program at NASA headquarters in Washington, said earlier this year.

Six new studies released Monday by the journal Science add more insights about these formerly habitable conditions and provide other new knowledge that increase our understanding of the Red Planet. The results were also presented at the fall meeting of the American Geophysical Union in San Francisco.

Curiosity found evidence of clay formations, or "mudstone," in Yellowstone Bay, scientists said Monday. Martian mud is a big deal because this clay may have held the key ingredients for life billions of years ago. It means a lake must have existed in this area.

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"This is a game changer since these are the kind of materials that are very 'Earth-like' and conducive for life," said Douglas Ming, lead author of one of the new studies.

This ancient environment, where the clay minerals formed, would have been favorable to microbes, Ming told CNN.

Some bacteria on Earth called chemolithoautotrophs could have lived in that kind of environment. These bacteria derive their energy from breaking down rocks and sediments, Ming said, generally by oxidizing elements in the rock.

Ming and colleagues also found hydrogen, oxygen, carbon, nitrogen, sulfur and phosphorus in the sedimentary rocks at Yellowknife Bay, elements that are all critical for life.

The new findings mean the rover's $2.5 billion mission is "turning the corner," said John Grotzinger, a California Institute of Technology planetary geologist and chief scientist for Curiosity, also known as the Mars Science Laboratory.

Grotzinger and colleagues found the habitable environment existed later in Martian history than previously thought. By studying physical characteristics of rock layers in and near Yellowknife Bay, they determined that Mars was habitable less than 4 billion years ago -- about the same time as the oldest signs we have for life on Earth.

The habitable conditions could have remained for millions to tens of millions of years, with rivers and lakes appearing and disappearing over time.

Curiosity also helped scientists figure out the age of an ancient Martian rock, as described in the new research. The rock is called Cumberland, and it now has the distinction of being the first whose age was measured on another planet through chemical analysis.

The rover used a method for dating Earth rocks that measures the decay of an isotope of potassium as it slowly changes into argon. Scientists determined the rock was between 3.86 billion and 4.56 billion years old. This age range is consistent with earlier estimates for rocks in Gale Crater.

Scientists say roughly 4 billion years ago, the environment on Mars wasn't much different from that of modern-day Earth. But things on Mars then took a drastic turn, and the planet was dramatically transformed from warm and wet to bitterly cold and dry, scientists say. In addition to the cold and dry conditions, scientists say the No. 1 reason life probably wouldn't have thrived on Mars is its extremely high levels of radiation.

Studies: Martian atmosphere was destroyed long ago

"The radiation environment on Mars is unlike anything we have on Earth," said Jennifer Eigenbrode, a biogeochemist and geologist at NASA's Goddard Space Flight Center and an author of one of the studies. "We don't know if life on Mars could have ever adapted to the high levels of radiation the surface is currently experiencing."

Eigenbrode added, "This is a wide-open book, which we have barely started writing the pages of."

New radiation measurements will also be important to planning any human missions to Mars, scientists said.

"Our measurements also tie into Curiosity's investigations about habitability," study co-author Don Hassler of Southwest Research Institute in Boulder, Colorado, said in a statement. "The radiation sources that are concerns for human health also affect microbial survival as well as preservation of organic chemicals."

Organic chemicals come from a variety of sources, including meteorites and comets, but they can also be indicative of life.

What's bad for us is bad for signs of life -- but these organic chemicals could still be hiding on Mars nonetheless.

Follow CNN science news on Twitter at @CNNLightYears

Better Health Care for More People at Less Cost from Bernie Sanders

Tuesday, December 10, 2013

 

Sen. Bernie Sanders on Monday introduced legislation to provide health care for every American through a Medicare-for-all, single-payer system. Rep. Jim McDermott has filed a companion bill in the House.

 

Sanders supported the Affordable Care Act, but in an interview with The Daily Beast he called the health care law passed in 2010 “only a modest step forward toward dealing with the dysfunction of the American health-care system.”  Even under the new law, Sanders added, insurance companies, drug companies and medical equipment suppliers will be able to rake off billions of dollars in profits rather than devoting those resources to providing health care.

 

 

Do you know who doesn’t like American health care? Americans don’t. A recent survey for the Commonwealth Fund of people in 11 countries found Americans were the least satisfied with their own health care system.  The study looked at costs, wait times, barriers to access, quality of care and other measures. In the survey, 75 percent of Americans said our health care system needs fundamental changes or should be completely rebuilt.

 

 

"The United States is the only major nation in the industrialized world that does not guarantee health care as a right to its people," Sanders said. "Meanwhile, we spend about twice as much per capita on health care with worse results than other countries that spend far less. It is time that we bring about a fundamental transformation of the American health care system. It is time for us to end private, for-profit participation in delivering basic coverage. It is time for the United States to provide a Medicare-for-all single-payer health coverage program," Sanders said.

 

While making the case for a single-payer system nationwide, Sanders applauded his home state of Vermont for its progress toward developing its own single-payer system which could become a model for the nation.

Are Genes Really Selfish? -- A Fool's Perspective

Biologist Richard Dawkins coined the phrase "the selfish gene" with his best-selling book of the same name. "Selfish", however, was an unfortunate word choice because genes lack a will and can actually drive altruism. SA editor Eric Olson explains.

David Strumfels' Comments:

Eric Olson -- how many times does it have to be said,  "Next time read a book before you criticize it."  Dawkins has repeatedly explained over the decades exactly what he means by the selfish gene, and he has made it clear over and over and over again -- as if even a high school biology student even needs it explained -- that of course genes don't have wills or are selfish in the human sense. It's pure analogy: genes "act" as though they had selfish wills, and if you use that analogy prudently you will understand a great more about them, as Dawkins has over those decades (and helped me as well) and you clearly haven't.

Shame on Scientific American for printing this ancient rubbish; but then, you haven't been a real science magazine for some years now.  Maybe if you hired some real science journalists and stopped trying to be a combo of real journal and dumbed-down pop sci magazine, you would regain your old respect.

Oh, and the portrait of Dawkins with a rather goofy grin -- that was just coincidence of course.  Hunt around enough photos and of course you will find a few.  Scientific value of a person's photo?  Clearly none whatsoever; it's just there for prejudicial purposes.  I won't even reproduce it.

I know Dawkins and others have posted more serious rebuttals than mine, so I'll stop here and  "go out and dig in the garden, or something."

New long-lived greenhouse gas discovered by University of Toronto chemistry team

Chemical appears to have highest global-warming impact of any compound to date

Posted on December 9, 2013

Strumfels comment:  the structure of this molecule is easily worked out as N(C₄F₉)₃, which would make it a highly potent greenhouse gas in two different ways, like combining methane with CFCs. And it would be very stable chemically. Have we been able to measure it in the atmosphere though? It would be a very heavy gas (MW > 700), perhaps mostly liquid at STP(?), so I doubt there is much of it in the vapor phase; I suggest no more than a few ppt (parts per trillion) and possibly less.  More research needs to be done here -- I doubt it will be easy to even detect, even by modern chromatography, if its level is that low.  So it very well might not be a serious concern.

 

TORONTO, ON - Scientists from U of T’s Department of Chemistry have discovered a novel chemical lurking in the atmosphere that appears to be a long-lived greenhouse gas (LLGHG).  The chemical – perfluorotributylamine (PFTBA) – is the most radiatively efficient chemical found to date, breaking all other chemical records for its potential to impact climate.

Radiative efficiency describes how effectively a molecule can affect climate. This value is then multiplied by its atmospheric concentration to determine the total climate impact.

 

PFTBA has been in use since the mid-20^th century for various applications in electrical equipment and is currently used in thermally and chemically stable liquids marketed for use in electronic testing and as heat transfer agents.  It does not occur naturally, that is, it is produced by humans. There are no known processes that would destroy or remove PFTBA in the lower atmosphere so it has a very long lifetime, possibly hundreds of years, and is destroyed in the upper atmosphere.

“Global warming potential is a metric used to compare the cumulative effects of different greenhouse gases on climate over a specified time period,” said Cora Young who was part of the U of T team, along with Angela Hong and their supervisor, Scott Mabury.  Time is incorporated in the global warming potential metric as different compounds stay in the atmosphere for different lengths of time, which determines how long-lasting the climate impacts are.

 

Carbon dioxide (CO₂) is used as the baseline for comparison since it is the most important greenhouse gas responsible for human-induced climate change.  “PFTBA is extremely long-lived in the atmosphere and it has a very high radiative efficiency; the result of this is a very high global warming potential. Calculated over a 100-year timeframe, a single molecule of PFTBA has the equivalent climate impact as 7100 molecules of CO₂,” said Hong.

 

The research was funded by the Natural Sciences and Engineering Research Council of Canada and was published online at Geophysical Research Letters on November 27, 2013.

 -30-

MEDIA CONTACTS:

Angela C. Hong
Department of Chemistry, University of Toronto
ahong@chem.utoronto.ca
416-946-3011

Meet the Senate Candidate Who Might be Too Crazy for Texas -- or not.

By Tim Murphy

Tue Dec. 10, 2013 7:31 AM GMT

 

David Strumfels -- well, he is rather off-center, even for a conservative Republican politician from Texas, but he is right about at least one thing.  E.g., his quote,  "The best thing about the Earth is if you poke holes in it oil and gas come out,"  is NOT nuts as Mother Jones and I imagine most left-leaning.  Let e respond with my quote:

 

"Stockman is right -- though I'm sure he meant it in jocularly. Why (so many) liberals don't perceive the near miracle of fracking and natural gas (and even oil to a lesser extent) is beyond me; to the extent gas replaces coal (and oil) the air is cleaner, greenhouse emissions are at least halved, and the environment is improved. These are not my opinions but scientific truths demonstrated over and over again over many years. Again I implore you Mother Jones: be as leftwing as you want, but don't apply it to science because science has no biases, politically or ideologically or economically."  You know, out of all the vast legitimate material below, the one sensible thing is isolated out and made to look like the craziest.  Being left-wing doesn't make you right about everything, anymore than being right-wing.  Please learn this simple truth.

 

Rep. Steve Stockman (R-Texas). Steve Stockman/Facebook

 

Rep. Steve Stockman (R-Texas), the weirdest member of a Congress that also includes a Santa-impersonating reindeer herder and this guy, is challenging Sen. Cornyn (R-Texas) in next year's U.S. Senate primary. In an interview with WorldNetDaily, a birther website that once reported that President Obama had perhaps hidden his gay life in order to run for president, Stockman explained that he was entering the race—just before the filing deadline—because Cornyn had "undermined (Sen.) Ted Cruz's fight against Obamacare" and was guilty of "stabbing fellow Republicans in the back."

If his very short career in Washington is any indication, Stockman will at least give us a reason to tune in. Some highlights from his second term in Congress:

undermined (Sen.) Ted Cruz’s fight to stop Obamacare
Read more at http://www.wnd.com/2013/12/tea-party-favorite-takes-on-gop-big-name/#EWwys4WrHXRiUYdf.99

• His campaign bumper sticker: "If babies had guns, they wouldn't be aborted."
• This tweet: "The best thing about the Earth is if you poke holes in it oil and gas come out."
• And this one: "Democrats are playing the knockout game with your health insurance."
• The time he raffled off an AR-15 as a campaign fundraiser.
• The second time he raffled off an AR-15 as a campaign fundraiser.
• His interview with Ted Nugent, in which he wondered whether victims of gun violence who advocated for gun control were "useful idiots"?
• His decision to bring Nugent as his plus one to last year's state of the union.
• His (empty) threat to impeach President Obama over gun control.
• The time he compared Obama to Saddam Hussein.
• The time he explained he would vote against the Violence Against Women Act because it helps "men dressed up as women."
• The $350,000 in income that's unexplained in his personal financial disclosures.

And that was just his second act. As I reported last January, Stockman has mellowed some since the days when he was caught smuggling 30 mg of valium into jail by hiding it in his underwear. Or the time he showed up at the airport to go to his sister's wedding wearing nothing but a speedo. Or the time he publicly fretted that his interest in ceramics would cause voters to "think I'm a fag." But if Stockman can't beat Cornyn, he'll have to wait a while to get back to Washington; by Texas law, he can't run for re-election and seek a Senate seat at the same time.

Brain Connectivity Study Reveals Striking Differences Between Men and Women

Penn Medicine Brain Imaging Study Helps Explain Different Cognitive Strengths in Men and Women

PHILADELPHIA — A new brain connectivity study from Penn Medicine published today in the Proceedings of the National Academy of Sciences found striking differences in the neural wiring of men and women that’s lending credence to some commonly-held beliefs about their behavior.

Brain networks show increased connectivity from front to back and within one hemisphere in males (upper) and left to right in females (lower).

Credit: Ragini Verma, PhD, Proceedings of the National Academy of Sciences

Related Links

Perelman School of Medicine at the University of Pennsylvania
University of Pennsylvania Health System

In one of the largest studies looking at the “connectomes” of the sexes, Ragini Verma, PhD, an associate professor in the department of Radiology at the Perelman School of Medicine at the University of Pennsylvania, and colleagues found greater neural connectivity from front to back and within one hemisphere in males, suggesting their brains are structured to facilitate connectivity between perception and coordinated action. In contrast, in females, the wiring goes between the left and right hemispheres, suggesting that they facilitate communication between the analytical and intuition.
“These maps show us a stark difference--and complementarity--in the architecture of the human brain that helps provide a potential neural basis as to why men excel at certain tasks, and women at others,” said Verma.
For instance, on average, men are more likely better at learning and performing a single task at hand, like cycling or navigating directions, whereas women have superior memory and social cognition skills, making them more equipped for multitasking and creating solutions that work for a group. They have a mentalistic approach, so to speak.
Past studies have shown sex differences in the brain, but the neural wiring connecting regions across the whole brain that have been tied to such cognitive skills has never been fully shown in a large population.
In the study, Verma and colleagues, including co-authors Ruben C. Gur, PhD, a professor of psychology in the department of Psychiatry, and Raquel E. Gur, MD, PhD, professor of Psychiatry, Neurology and Radiology, investigated the gender-specific differences in brain connectivity during the course of development in 949 individuals (521 females and 428 males) aged 8 to 22 years using diffusion tensor imaging (DTI).  DTI is water-based imaging technique that can trace and highlight the fiber  pathways connecting the different regions of the brain, laying the foundation for a structural connectome or network of the whole brain.
This sample of youths was studied as part of the Philadelphia Neurodevelopmental Cohort, a National Institute of Mental Health-funded collaboration between the University of Pennsylvania Brain Behavior Laboratory and the Center for Applied Genomics at the Children’s Hospital of Philadelphia. 
The brain is a roadmap of neural pathways linking many networks that help us process information and react accordingly, with behavior controlled by several of these sub-networks working in conjunction. 
In the study, the researchers found that females displayed greater connectivity in the supratentorial region, which contains the cerebrum, the largest part of the brain, between the left and right hemispheres. Males, on the other hand, displayed greater connectivity within each hemisphere. 
By contrast, the opposite prevailed in the cerebellum, the part of the brain that plays a major role in motor control, where males displayed greater inter-hemispheric connectivity and females displayed greater intra-hemispheric connectivity. 
These connections likely give men an efficient system for coordinated action, where the cerebellum and cortex participate in bridging between perceptual experiences in the back of the brain, and action, in the front of the brain, according to the authors. The female connections likely facilitate integration of the analytic and sequential processing modes of the left hemisphere with the spatial, intuitive information processing modes of the right side.
The authors observed only a few gender differences in the connectivity in children younger than 13 years, but the differences were more pronounced in adolescents aged 14 to 17 years and young adults older than 17.
The findings were also consistent with a Penn behavior study, of which this imaging study was a subset of, that demonstrated pronounced sexual differences.  Females outperformed males on attention, word and face memory, and social cognition tests. Males performed better on spatial processing and sensorimotor speed. Those differences were most pronounced in the 12 to 14 age range.
“It’s quite striking how complementary the brains of women and men really are,” said Dr. Ruben Gur.  “Detailed connectome maps of the brain will not only help us better understand the differences between how men and women think, but it will also give us more insight into the roots of neuropsychiatric disorders, which are often sex related.”
Next steps are to quantify how an individual’s neural connections are different from the population; identify which neural connections are gender specific and common in both; and to see if findings from functional magnetic resonance imaging (fMRI) studies fall in line with the connectome data.
Co-authors of the study include Madhura Ingalhalikar, Alex Smith, Drew Parker, Theodore D. Satterthwaite, Mark A. Elliott, Kosha Ruparel, and Hakon Hakonarson of the Section of Biomedical Image Analysis and the Center for Biomedical Image Computing and Analytics.
This study was funded by in part by the National Institutes of Mental Health: MH089983, MH089924, MH079938, and MH092862.

Quantum steps towards the Big Bang#inlRlv

Quantum steps towards the Big Bang#inlRlv

Moons of Jupiter and Saturn could have been seeded with life

Moons of Jupiter and Saturn could have been seeded with life

How We're Destroying Our Kids' Brains

As many as one in six children has a neurodevelopmental disability, and scientists are finding links to pollution.  Although I am often as skeptical of environmental claims from the left as denials from the right, this one has a strong ring of truth to it, and is, chemically and biologically, plausible; indeed, there is a lot of good factual material (and historical material) in here.  It should be borne in mind, however, that things have been getting generally/steadily better over the decades and centuries.

 

By Florence Williams in Mother Jones magazine

 

Sandrinka/Shutterstock

This story originally appeared on the OnEarth website.

Carlos Jusino grew up a typical kid in Harlem, rollerblading near the Hudson River, eating at the McDonald's on 145th Street and Broadway, hanging out with friends in his building. Also typical was the fact that many of Jusino's neighbors and family members, including his mother, had asthma. "When I was growing up, she went to the hospital about once a month for asthma," he says. Although he didn't know it at the time, more than 30 percent of the kids in Harlem have asthma, one of the highest rates in the country.

Jusino's family was worried about the air quality around Harlem, but most of its attention was directed to a sewage treatment facility built in 1985 along the West Side Highway next to the Hudson, where a foul-smelling settling tank lay exposed. The plant galvanized the community, including a group of environmental justice activists known as the Sewage Seven. They sued the city and won a settlement in 1994 that helped establish air-monitoring stations around the plant.

 

Harlem is plagued by health conditions not uncommon among the urban poor. In addition to suffering from asthma, children here have high rates of obesity and, perhaps most alarming, significant learning disabilities. Increasingly, medical researchers are discovering that all of these syndromes are linked at least in part to environmental factors, from nutrition to tobacco smoke to industrial chemicals. Jusino, like many, was stunned to learn that pollution's biggest target may be not our lungs but our brains.

Researchers are finding the Harlem population to be a valuable source of data, and what they're learning is both illuminating and worrisome. And if you think poor air quality is limited to disadvantaged urban neighborhoods, think again. Harlem's problems are shared by the rest of the country. If clues can be found here, the lessons can apply elsewhere.

 

If you think poor air quality is limited to disadvantaged urban neighborhoods, think again.

As many as one in six children nationwide has a neurodevelopmental disability, including autism, speech and language delays, and attention deficit hyperactivity disorder. The Centers for Disease Control and Prevention estimates that ADHD alone affects 14 percent of children, although experts debate whether it may be overdiagnosed. In any case, the number of children needing special education services has increased 200 percent in the past 25 years. In a 2000 report, the National Research Council of the National Academy of Sciences estimated that 3 percent of brain disorders are caused outright by environmental toxicity and an additional 25 percent by environmental exposures interacting with genetic susceptibilities.

Every day, America's pregnant women and young children are exposed to a trifecta of suspected neurotoxicants in the form of pesticides (mostly via food and water but also home, lawn, and farm applications), polycyclic aromatic hydrocarbons, or PAH (mostly via exposure to vehicle exhaust), and polybrominated diphenyl ethers, or PBDEs (flame retardants, mostly in upholstered furniture and electronics). The CDC routinely samples Americans for these and other industrial by-products in our bodies, so we know their reach is pervasive. But we are not all equally exposed, and some of us appear to be more vulnerable to them for reasons that may include genetic susceptibility, poor nutrition, stress, and age.

Andrei Zveaghintev/Shutterstock

Jusino joined a youth group through his high school in Washington Heights in 1994 and started mapping, block by block, local sources of pollution, including dry cleaners and diesel-spewing bus depots. In 1997 he joined the staff of West Harlem Environmental Action (We Act), a group co-founded by Peggy Shepard, one of the Sewage Seven. Today, as a GIS mapping specialist and technician, he is the proud chief caretaker of Aethan, a retro-looking black box that records real-time black carbon pollution. The size of a microwave oven, the Aethalometer (from the Greek word meaning "blacken with soot") sends out several feet of PVC pipe through a window overlooking the corner of 152nd Street and Amsterdam Avenue, where the We Act offices occupy a light-filled, redbrick former police precinct house.

Aethan looks retro, but he has a Twitter account, where he says things like "Holy pollution, Batman! Look, the WE ACT Aethalometer reading is at 2,780 nanograms per cubic meter." (For perspective, during low-traffic weekends, the readings hover around 1,200.)

"The readings get really high around 3:00 p.m.," said Jusino, who, at age 35, sports silver-rimmed glasses and a trim goatee. Outside, it was early evening, and the machine was reading in the mid-700s. I couldn't help imagining dark whorls of goblin-faced spirits wafting up to choke us at the windows. It's a misconception, though, that the worst air pollution is visible. We tend to equate it with smog. Smog exists, of course, but it was largely knocked back under the air-quality controls of the 1970s. Over its 40-year life, the Clean Air Act has radically cut many ingredients of smog: carbon monoxide emissions are down 82 percent, sulfur dioxide 76 percent, and ozone concentrations 28 percent.

 

The monitor's pollution readings "get really high around 3:00 p.m."

However, there are virtually no regulations governing the black carbon component of fine particulate matter smaller than 2.5 microns, known as PM 2.5. Black carbon is responsible for two million premature deaths globally each year. It also contributes substantially to climate change. A recent study by a team of 31 geophysicists found that black carbon is "the second most important human emission in terms of its climate forcing in the present-day atmosphere."

Black carbon is a component of particulate matter left over from the incomplete combustion of fuels in vehicle engines, apartment-building boilers, cooking stoves, and other sources. Aethan's 3:00 p.m. peak is the product of diesel-powered vehicles, including school buses. Harlem has one of the highest levels of black carbon in New York. In part, this is because of the high density of older buildings, which tend to have older, less efficient, and poorly maintained heating systems. But diesel fuel is also a major source of black carbon, and Harlem is home to six of Manhattan's seven transit bus depots as well as commercial trucking routes. By 2006, after a big public campaign spearheaded by the Natural Resources Defense Council (NRDC), city transit buses that had previously used dirty diesel switched to a combination of filters and cleaner fuel. But plenty of other fleet vehicles, older school buses, and ships passing close by still burn the bad stuff.

A host of ills has been attributed to fine particulate pollution, including heart and lung disease, sometimes causing premature death. Black carbon is considered a reliable co-conspirator of PAH, a class of compounds that are also by-products of combustion. (Black carbon is easier to measure than PAH and, depending on location and source, tends to be highly correlated with them.) When inhaled, fine particulates go deep into the lungs, but they also travel to the brain, where they can alter DNA expression, cause inflammation, and possibly gum up neuronal circuitry. Jusino and others wondered: Could these and other common contaminants be contributing to the high incidence of neurodevelopmental delays in the children of Harlem?

* * *

Northern Manhattan is home to not only some of the best music, soul food, and dance troupes in the city but also one of its most venerated medical research institutions, Columbia University Medical Center. Frederica Perera was a young cancer researcher there in the 1980s when she decided to collect tissue samples from human placentas, expecting that they would be "pristine," or untouched by environmental exposures. "But we found there were fingerprints on these samples of DNA damaged by pollution, even in women who weren't smokers," she recalled from her office at the Columbia Center for Children's Environmental Health on West 168th Street. "It made me concerned about fetal exposures. I really wanted to look more closely at this window." Although she started out looking for cancer markers, she was soon curious about other pressing health conditions in the Harlem community.

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That Perera was even looking at environmental causes of illness was both unusual and unfashionable. For the past two decades, cancer researchers and other molecular biologists have spent much of their time riveted by the genome, believing it would unlock the secrets of disease. But cellular life isn't determined simply by the blueprints of DNA. It's now understood that cells are designed to interact nimbly with the outside world and that genes get turned on or off—and are sometimes mutated altogether—by environmental exposures from diet, inhalation, even transmission through the skin. To truly understand human health and disease, scientists need to look at both the genome and—to use a term coined in 2005 by Christopher Wild, a cancer epidemiologist—the "exposome."

Perera decided to do just that.

Today, as director of the Columbia center, she oversees what has become one of the most respected epidemiological data troves in the country. (She is also a trustee of NRDC.) Starting in late 1998, Perera and her colleagues recruited more than 700 pregnant women from hospitals in Harlem, Washington Heights, and the South Bronx for what's known as the Mothers and Children Study. Now, 15 years later, the team has retained three-quarters of its original participants, and the first babies are entering their teenage years. Such "prospective" studies, which follow a group over time and measure their health outcomes, are considered the gold standard in scientific research because they don't rely on retrospective memory or old, imperfect medical records. Blood and urine samples have been banked since the mothers' pregnancies and deliveries, as have samples from the children, and researchers can go back to these as they ponder new questions.

 

It's now known that many chemicals can cross the placenta, once believed to be a sacrosanct barrier.

It's now known that many chemicals can cross the placenta, once believed to be a sacrosanct barrier. This is disquieting, because the vast majority of these chemicals have never been tested for human health effects. Furthermore, the medical community agrees that many diseases and conditions, including obesity, cancer, and autism, are modulated by both genes and fetal exposures. In September, the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine issued a joint statement saying, "The scientific evidence over the last 15 years shows that exposure to toxic environmental agents before conception and during pregnancy can have significant and long-lasting effects on reproductive health." (The chemical industry, however, is seeding doubt. The American Chemistry Council's chief medical officer responded that ACOG's evidence was based on "a limited number of flawed studies.") It makes sense to developmental biologists that fetal exposures matter; this is when the cells in the body and brain are on the biggest adventure of their lives, differentiating and replicating like a one-way train. Once it's left the station, it doesn't go back.

Children, of course, are harder to study than lab animals, because they are exposed to so many different conditions that can confound the results. That's why large, prospective epidemiological studies are so critical. Perera knows both what's in these babies' bloodstreams and what happens to them as they age. The larger the study, the stronger the statistical power. Even so, epidemiological findings are necessarily couched in terms of "associations" rather than causal links. So epidemiologists often look to better-controlled animal studies as a guide, as well as to molecular lab investigations of human blood and tissue samples.

With enough replication and diverse strategies, a picture begins to emerge. The center's early studies found significant associations between pollutants measured in the mothers and difficult birth outcomes, including low birth weight and small head circumference. The main culprits were PAH and chlorpyrifos, a then-common organophosphate pesticide used indoors to kill roaches and bedbugs. (Later the team would look at flame retardants.) Perera also documented that these chemicals damaged cellular DNA. Chlorpyrifos was found in the umbilical cords of virtually every mother in the early samples. Since 2001 it has been phased out of residential use, but exterminators are still caught using it. It also remains a common agricultural pesticide and so ends up as a residue in food. Perera and her colleagues knew that reduced head circumference had been linked to lower IQ scores, and animal experiments had shown that chlorpyrifos killed developing brain cells and induced behavioral changes in rats. In some well-known experiments, for example, rats given low doses of the pesticide while in the womb or shortly after birth later had trouble learning their way around a maze.
Although Perera and her team didn't know how these chemicals might be changing the brain, they were determined to find out all they could about the children's growth and development. The children (now teenagers), who are mostly Dominican and African American, would be regularly tested on everything from reading ability and motor skills to psychological yardsticks like aggression, risk-taking, and depression.

By the time they were 3 years old, the children with the highest exposures to the pesticide tested as much as six points lower on motor skills and three points lower on mental development and were significantly more likely than those with lower exposures to suffer from attention and hyperactivity problems. These findings were published in 2006 in Pediatrics. Other studies showed that children most exposed to PAH were nearly three times as likely to show cognitive developmental delays. By the time they were 7, the children most exposed to chlorpyrifos were showing deficits in working memory, a key component of IQ. Their working memory declined by 2.8 percent and their full-scale IQ by 1.4 percent, after adjusting for variables like tobacco smoke and maternal intelligence.
The center's findings on the cognitive impacts of PAH and pesticides bolster what other researchers have found in Boston, Cincinnati, and California. Perera led a similar cohort study with researchers in Poland and found that higher prenatal exposure corresponded to an average 3.8-point drop in IQ in 5-year-olds. This drop is comparable to the effects of lead, the discovery of which, in the 1970s, eventually triggered a massive public health response in the form of laws removing lead from automobile gasoline, restricting it in household paint, and, to this day, requiring lead tests in children in many parts of the country.

 

Now that the Harlem children are older, the team is examining whether the ill effects of fetal and cumulative exposures play out in other ways—poor academic performance, impaired social skills, anxiety and depression, and self-destructive behavior.

Now that the Harlem children are older, the team is examining whether the ill effects of fetal and cumulative exposures play out in other ways—poor academic performance, impaired social skills, anxiety and depression, and self-destructive behavior.

On the day I visited the center this fall, a mom—let's call her Michelle—and her 14-year-old son came in for a couple of hours of assessments. They were both greeted by a tremendous hug from Diurka Maria Diaz, a researcher and counselor who has followed the families from the beginning.

"You're taller than I am now!" she teased the boy. Hefty, dressed in black pants and a black sweatshirt, he towered over his toddler sister. She is also in the study, which continues to recruit new participants who likely have different exposomes. While Michelle's placenta absorbed chlorpyrifos during her son's gestation, it probably absorbed replacement pesticides during her daughter's. The replacements come from a class of chemicals known as pyrethroids, whose neurodevelopmental effects remain largely unstudied.

Diaz, who is known to the families as Didi, exudes warmth and charisma as well as concern for the challenges faced by kids in the study. "It's hard to be a 14-year-old," she says. "Many of these kids are overweight, many are depressed. We've referred about 40 percent for counseling." Furthermore, a remarkable 24 percent of the cohort children at age 2 had a potentially diagnosable developmental delay. About 70 percent of these children qualified for New York City’s early intervention services.
Such delays are typically attributed to growing up in impoverished environments with relatively low parental involvement, low mental stimulation, and pervasive psychological stress. Perera's team, though, is convinced that fetal environmental exposures play a role and that their effects may be aggravated when combined with maternal stress, as well as when combined with one another.
"In the past, we took a reductionist approach," Perera says, "a single exposure, a single effect. But now we think that pollution interacts with nutritional and social susceptibility factors. We're making heroic attempts to measure these. We're building the exposome."

The environmental trail of brain damage extends far back in history. Accounts of lead toxicity date to the Greek physician Nicander of Colophon in 200 B.C. In more recent times, a French physician in 1848 described ill-tempered infants who'd been sucking on lead soldiers. More examples of damaged childhoods came to light after twentieth-century commercial and industrial exposures. A cheap, arsenic-laced stabilizer was added to powdered milk in Japan during the spring of 1955, causing sickness, epilepsy, or lowered IQ in more than 12,000 victims, most of them infants. (Studies of nerve cells in a Petri dish suggest that arsenic inhibits cell growth and, in the developing brain, reduces the branching of dendrites—the structures of neurons that send and receive signals.) Also in the 1950s, a factory in Minamata, Japan, began releasing mercury into the local bay, ultimately causing severe physical and cognitive problems in children whose mothers ate contaminated fish while pregnant.

By the mid-1970s researchers around the world had documented cases of lowered IQ in children exposed to lead from air pollution, mercury-based preservatives in grain, and polychlorinated biphenyls (PCBs) in fish, as well as in those exposed to alcohol in utero. The effects were much greater in children than in exposed adults. These were, as the neurotoxicologist Pam Lein of the University of California, Davis, puts it, "the blunt ones"—exposures whose effects became apparent after some concerted research. But no one really understood how the toxins worked, and they didn't know if other, more subtle, discoveries awaited.

In 1972, a Danish medical student named Philippe Grandjean saw a young woman on television who was suffering from so-called Minamata disease. Exposed to mercury in the womb, she could hardly talk and was afflicted by a severe spastic limb condition. Grandjean wondered why he wasn't being taught about environmental exposures if they could cause so much damage. He decided to spend his life researching neurotoxicants, which he terms "brain drainers." Since then he has written more than 100 papers on mercury, taught a couple of generations of scientists, and as both a physician and a researcher has an understanding of the micro and macro scope of the problem. What he told me wasn't comforting.

 

"Because the human brain is so complex, it's incredibly vulnerable," says Grandjean, now an adjunct professor at the Harvard School of Public Health and the author of the 2013 book Only One Chance: How Environmental Pollution Impairs Brain Development and How to Protect the Brains of the Next Generation. "Even if something goes a little bit wrong, you don't get a second chance," he says. "You're stuck with it, and even small deficiencies can be quite significant."

As Grandjean explains it, shortly after conception, the brain begins to form from a tiny strip of cells. At its fetal growth peak, 12,000 cells are generated every minute, or 200 per second. These cells start sending and receiving messages and migrating to specific locations. By the time the brain is fully baked, it has close to 100 billion nerve cells and roughly as many caretaking glia cells, which provide nutrients, sweep out dead cells, and insulate nerve fibers. "If cells are in the wrong place or they don't form the right connections," Grandjean says, "that's what you've got for your whole life."

In a groundbreaking review published in the Lancet in 2006, Grandjean and his co-author, Philip Landrigan, of Mount Sinai Hospital in New York City, identified 201 heavy metals, solvents, pesticides, and endocrine disruptors known to have toxic effects in the human brain (at least 1,000 other substances are neurotoxic in animals but haven't been tested in humans). Of those 201, about half are "high production volume" chemicals, made in or imported to the United States in excess of one million pounds per year. At the time, the authors could point to only half a dozen as showing evidence of developmental toxicity in the fetal brain, but the count is now up to 10 and growing. All of these neurotoxicants are relatively common, routinely found in the blood of pregnant women.
They include the usual suspects—lead, methylmercury, and PCBs—but also organochlorine pesticides like DDT (which was banned in the 1970s but still persists in soil and water), organophosphate chemicals like the roach-killer chlorpyrifos, PAH, PBDEs (this pervasive class of flame retardants is now being phased out), arsenic, ethanol, and the solvent toluene.

We are beginning to learn more about how these substances may alter brain development. Their strategies are complex and varied. Under the influence of methylmercury, for example, the brain's nerve cells "are lying helter-skelter, not in their usual logical locations," says Grandjean. Pesticides are designed to be neurotoxicants—that's the whole point—and some, like chlorpyrifos, work by inhibiting cholinesterase, an enzyme critical to brain-cell communication. Different neurotoxicants affect children differently. At high levels, methylmercury appears to cause memory deficits, while lead primarily decreases attention span and pesticides tend to impair spatial perception. Black carbon apparently affects attention and processing speed.

Not all kids are equally vulnerable. Other factors matter, like genes, psychosocial stress, and, interestingly, gender. Boys tend to be more vulnerable than girls to the deficits associated with PAH. Studies of prenatal exposures to phthalates and bisphenyl-A (BPA), both endocrine disruptors, also show gender differences. Phthalates are considered anti-androgens, while BPA acts like an estrogen, and the developing brain takes important cues from both hormones. With chlorpyrifos exposure, for example, boys have greater difficulty than girls with working memory.

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Many of these substances disproportionately affect the poor, but not all. Poor kids are exposed to more lead and first- and secondhand tobacco smoke. More affluent populations accumulate more mercury from their diet. Urban kids may be exposed to more PAH and black carbon, farm kids to more pesticides and arsenic from well water.

Of all the suspects, brominated flame retardants may be the most democratic. Although levels of PBDEs are now dropping in pregnant women, Americans still have the highest levels tested anywhere in the world. Flammability standards enacted in California in the 1970s resulted in the addition of PBDEs to everything from electronics to home furnishings nationwide. Unfortunately, the molecules easily migrate, accumulating in blood and breast milk and persisting for years. Structurally similar to PCBs in some cases, they appear to interfere with thyroid hormone signaling, either by directly altering the amounts of hormone or by blocking the hormone transporters. As researchers learned from studying cretinism, thyroid hormones are critical to brain development, among other functions.

A University of California, Berkeley, study of children in the state's Salinas Valley reported that those born to mothers with the highest levels of PBDEs during pregnancy averaged six points lower in verbal IQ and had lower scores for fine motor skills and a higher risk of hyperactivity. And PBDEs probably don't act in isolation. Per Eriksson, a Swedish toxicologist, has found that when lab animals are exposed to both PBDEs and mercury, the neurological effects are significantly stronger than those of mercury alone.

Philip Landrigan directs the children's environmental Health Center at Mount Sinai Hospital. Like Grandjean, he is a pillar in the field; in the 1970s, he linked childhood IQ deficits to low levels of lead. More recently he's been integral to health studies of rescue workers who were exposed to toxic particles during 9/11. Caps from the New York City police and fire departments and the US Navy decorate his office on East 102nd Street.

 

But do a few IQ points matter? Should society care if a boy behaves a few shades more or less aggressively?

What worries Landrigan is how easily many neurological effects can fly under the radar. These are not the kinds of acute poisonings that land kids in emergency rooms. Most doctors are not trained to look for prenatal or childhood environmental exposures. If parents ask them about it, he says, "they tend to offer bland reassurance." But for the individuals and families involved, learning, psychological, and behavioral impairments can have dramatic, lifelong impacts on meaningful measures from happiness to income.

But do a few IQ points matter? Should society care if a boy behaves a few shades more or less aggressively? These are questions that currently interest epidemiologists more than family physicians. One of Landrigan's associates at Mount Sinai, research scientist Megan Horton, who worked previously with Perera, told me that an average drop of five IQ points in the United States translates into 2.4 million gifted kids instead of 6 million, and 9.4 million mentally retarded children instead of 6 million, or a 57 percent increase. Leonardo Trasande, a pediatrician formerly at Mount Sinai and now at the New York University School of Medicine, has estimated that mercury exposures alone have led to losses of 0.59 to 3.2 IQ points in several hundred thousand children born every year in the United States, resulting in decreased lifetime economic productivity valued at $8.7 billion annually. Thanks in large part to the laws spurred by Landrigan's epidemiological sleuthing, airborne lead pollution has declined 90 percent since 1980. With the decline has come a concomitant improvement in IQ scores and an intriguing drop in youth aggression and urban crime.

Landrigan argues that the field of environmental health must become a centerpiece of public health. Mount Sinai has one of just 11 children's environmental health centers nationwide. He's disappointed that Congress last year pulled substantial funding from the once-promising National Children's Study, which aimed to follow the exposures and health of thousands of children. At the same time, federal legislation that would strengthen the way chemicals are tested and regulated gets repeatedly stalled.
"Clearly there's a need for a new regulatory apparatus for testing chemicals, and the backlog is huge," says Miriam Rotkin-Ellman, a senior scientist specializing in public health at NRDC. "There are also a lot of gaps in the science, both in terms of characterizing the health end points, such as autism, and in terms of understanding the mechanisms by which chemicals can interact with neurodevelopment. What's the timing and what are the pathways of exposure?"

Recognizing the need for more data, Landrigan's program is about to launch its own $20 million prospective study following children from the womb through childhood. It will complement the work being done at Columbia and also at the University of Utah. "We will in some instances combine and pool our data in order to increase our ability to discover links between environmental exposures and disease," says Landrigan.

Meanwhile, Perera's group has embarked on the next frontier in environmental health: brain imaging. Now that Columbia has data on exposures and cognitive problems, it makes sense to look at the brain structures themselves. Have the chemicals altered the brain in physically obvious ways?
In a nutshell, "yes," says Virginia Rauh, a perinatal epidemiologist at Columbia. Brain images of 5- to 11-year-olds with the highest exposures to chlorpyrifos show subtle deformations in parts of the brain associated with receptive language and social cognition and a thinning of areas of the parietal and frontal cortices, which are involved in executive functions like attention and problem solving.
Using brain imaging to complement large-scale epidemiology is brand new. It's also very expensive, and the technology is still being validated. Although Rauh admits that her team is "far from being able to say these changes are linked to impairment," it's time to focus on that question. "Public health has not really looked at the brain, other than with metals like lead and mercury," she says. "Our challenge is to link particular deficits we're seeing to meaningful impairment so that we can intervene and prevent them."

I took the train back home to Washington, DC, passing through the northeast corridor's confused, tight mix of commercial promise and marginalized decay. Over it all hung the molecular by-products of progress. To get a sense of just how far black carbon reaches into my own family's life, I decided to take a cue from Jusino and his pet Aethan and order up my own air-monitoring companion for a few days. I called Steven Chillrud, co-director of the Exposure Assessment Facility Core at Columbia's Lamont-Doherty Earth Observatory. An environmental geochemist, he tries to figure out how much black carbon people are exposed to by strapping carbon-measuring machines to buildings and sometimes car commuters, pedestrians, and bicyclists. He FedExed me a loaner micro-Aeth patched into a twill vest. I decided to call it Aethchyluth, honoring the urban Greek tragedian with a lisp. Aside from a few lumps, the device was fairly unobtrusive. No one seemed to notice the small sensor stretching upward toward my chin like a playful pet monkey. I wore it for most of three days while walking and driving around Washington in my daily routine.

 

"Schools and day-cares are typically built on the cheapest land, often next to highways."

After I shipped Aethchyluth back, Chillrud sent me the data graph, which looks like an EKG reading, drawn in thin blue spikes. Then we matched the graph to the record from a GPS app, which had tracked my travels. High spikes occurred on I-495, the Capital Beltway, which wasn't a surprise. Although I avoid it like the plague at peak rush hour, I'd driven it a couple of times at off-hours to visit relatives in southern Maryland. Even in my car with the windows rolled up, my levels hovered around the 6,000 nanograms per cubic meter mark, or more than twice the average reading Jusino was getting on his Harlem corner on a typical weekday.

I pitied the people who drive this twice a day in slow-moving traffic, but they don't get the most sympathy from Chillrud. "Schools and day-cares are typically built on the cheapest land, often next to highways," he says. "That's where developing lungs are, and susceptible kids."

But as my readings made clear, schoolchildren don't need a major freeway to breathe in black carbon and PAH. Aethchyluth got readings equal to the beltway in the parking lots at my kids' schools. That's because idling cars and school buses sit there just as kids are leaving. I was reminded of what a neuroscientist who studies brain inflammation told me: "I hold my breath when I'm behind a diesel bus."

Nineteen percent of Americans live near high-volume roads, and most areas don't monitor the air. So just how bad were my readings? We don't really know, says Chillrud, because the EPA hasn't issued guidelines for black carbon pollution the way it has for other pollutants. Black carbon is complicated because it's a proxy for many pollutants, he explains, and there are no consistent ways to measure it. In the meantime, city and federal officials recommend we reduce it through the use of cleaner fuels, newer engines, and, in New York City's case, mandated higher-quality fuel oil. "It will gradually get better," he says. "But there's still a lot to do."

When I was in Harlem, Frederica Perera had laid out a busy future of continued studies of childhood exposures to everything from PAH to phthalates to BPA to the newer pyrethroid pesticides. Her windows looked out over the Hudson River, a reminder of our collective interdependence on the air and water that both nourish us and transport pollution into our cells. The river glinted as it flowed out to sea. Once ragingly filthy, it is now cleaner than it has been in two generations.

Policy changes work, and some of those changes are quickly mirrored in our bodies. After the residential phaseout of chlorpyrifos, levels in pregnant women fell significantly. A small study published in September in the journal Environmental Science and Technology found that levels of some brominated flame retardants in pregnant Californians were 65 percent lower than in a similar group tested three years earlier (a phaseout began in 2004). By 2006, after converting to cleaner fuel and using filters, New York City's transit buses reduced their emissions of particulate matter by 97 percent.

"If the science is utilized well, policy makers can act. That's why it is enormously helpful," said Perera. "The good news is that by nature these exposures are preventable." She stood up to go to a meeting, passing framed photos of four of her grandchildren. On her way out she sent a warm greeting to Michelle. More families would be arriving soon.