Environmental t News Plastics chemical alters female brains
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generation of mice. In a section of the brain that controls the sexual cycle, female mice have 2–3× as many neurons as males. But female mice who had been exposed to BPA while still in the womb were found to have fewer neurons than usual in this area of the brain. Female mice are typically more energetic than males, but the activity level of females who had been exposed to BPA dropped and mirrored that of their brothers.
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chemical that leaches out of plastics has been discovered to modify the developing brains of female mice, who later behave much more like their brethren. This latest study builds on a growing body of literature about the toxicity of bisphenol A (BPA) and raises questions about its effects in humans. In 1936, researchers found that BPA acts much like the hormone estrogen. Scientists now estimate that >6 billion lb of the chemical are manufactured for use in products such as polycarbonate plastic, the resin lining food cans, and dental sealants. Beverly Rubin, an associate professor of cellular biology at Tufts University, and colleagues placed tiny pumps into female mice. From the 8th day of pregnancy until the 16th day of nursing, these pumps released doses of BPA into the mothers. This time period is critical because on the eighth day of development, embryonic mice begin growing neurons in a region of the brain that is critical for sexual behavior. Most importantly, says Rubin, the concentrations administered were very tiny. One set of mothers was exposed to doses of 250 ng/kg/d of BPA, while the other set was dosed at only 25 ng/kg/d. “The levels of bisphenol A that were used are within the range that is estimated to be found in humans,” she says. Last year, the Centers for Disease Control and Prevention reported that 95% of Americans excrete ≥100 ppt of BPA in their urine (Environ. Health Perspect. 2006, 113, 391–395). The scientists then examined the brains and behavior of the new
From the 8th day of pregnancy until the 16th day of nursing, tiny pumps in female mice released doses of BPA into the mothers’ bloodstreams.
“We found that the differences between males and females, at least for these two markers, were obliterated,” adds Rubin. But Steve Hentges, executive director of the American Plastics Council, says he finds little that is compelling in the research. “This study is of limited relevance to human health. A more robust study should be done,” he says. “We are within the human exposure range,” counters Ana Soto, a Tufts professor of cellular biology and coauthor of the paper. She points out that other studies have found that BPA can lead to problems of the reproductive tract in both male and female rodents. Few studies have reported on how BPA might harm humans. One
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study found that exposure to BPA is associated with recurrent miscarriage (Hum. Reprod. 2005, 20, 2325– 2329). For almost two decades, Fred vom Saal, a professor of biology at the University of Missouri, has been investigating chemicals that alter the hormone system. “The findings reported in this study show permanent changes to the brain at doses that are 2000–20,000× lower than what is estimated to be safe,” he says. In January, vom Saal published an article that examined 120 papers on BPA (Environ. Res. 2006, 100, 50 – 76). Of these studies, 109 found effects on experimental animals from low doses—40 of them at concentrations below the U.S. EPA’s recommended safe level of 50 μg/kg/d. However, he reported that 11 studies funded by industry found no effect from BPA. And in a paper published in Cancer Research (2006, 11, doi 10.1158/0008-5472.CAN-06-0516), researchers exposed fetal rats to BPA at similar levels to those found in humans. When later tested, the male rats had DNA with an altered methylation pattern. Rats with this pattern showed an increased incidence of precancerous prostate lesions. Commenting on Rubin’s research, Scott Belcher, an associate professor of pharmacology at the University of Cincinnati, says that the work does an excellent job of measuring low-dose responses. Last December, Belcher reported in Endocrinology that rat brains were affected by BPA at doses 20× as much nitrogen on April 21, 2002 (left), when it was flooding, as on July 2, 2002 (right). july 1, 2006 / Environmental Science & Technology n 4047
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Bass says. As a result, green-roof advocates successfully lobbied the City of Toronto for a bylaw that mandates that every city-owned building will get a green roof unless physical reasons preclude it. “When you look at the big-picture impact of green roofs, when you find out that they can reduce the urban heat island by 1–2 °C, and you further find out that a 1 °C reduction in the temperature of the city in Toronto reduces peak [electrical] demand by 5% — we’re starting to talk about hundreds of millions of dollars,” Peck points out.
Environmentalt News dumped in the Gulf in May feed the growth of excess algae that die, sink to the bottom, and ultimately absorb oxygen in late summer, he explains. Most of these nutrients originate in upper Midwestern farms, particularly those with underground tile drainage systems, Royer says. “Roughly 20 million hectares of farmland in the Mississippi River basin are drained by tile systems,” he says. Practices such as fertilizing bare fields in the fall, before the next summer’s plants have a chance to absorb the nutrients, leave nitrogen and phosphorus free to be washed off fields during winter and spring rains and floods, he adds.
Currently, the nutrient-laden floods that take place outside the growing season receive little regulatory scrutiny, Royer says. The federal Total Maximum Daily Load (TMDL) program, which determines the amount of pollution that can be tolerated by healthy water bodies, tends to focus on summers, when excess algae can foul local streams, he says. Because Midwest summers tend to be relatively dry, that is the time of year when nutrient runoff into the Mississippi is the lowest. In fact, a TMDL for the Stillwater River in western Ohio allows nitrogen loads to more than double, from 3122 kg-N/d in October to 6700 kg-N/d for December
Nanoparticles remove arsenic from water Researchers at the U.S. Department of Energy’s Idaho National Laboratory (INL) have developed a new material that uses nanosized particles to remove arsenic from drinking water and that promises to be easy to use and cheaper than the current alternatives. At least three technologies— activated alumina, ion exchange, and coagulation—are capable of enabling utilities to meet the U.S. EPA’s drinking-water standard of 10 μg/L for arsenic, which went into effect this past January. But all of the alternatives come with caveats. For example, activated alumina technology, which is broadly considered to be the best available technology and is also the one most commonly used, works best in the pH range of 5.5– 6. It therefore requires utilities to install a pH adjustment unit that can cost a few thousand dollars. INL’s new technology is made of nanosized polymer beads infused with hydrous iron oxide, according to its developer, Troy Tranter. He refused to be more specific about the particle size, claiming that the information is proprietary. Laboratory testing of Idaho ground-
water—which contains 20 μg/L of arsenic, a concentration typical for waters in the western U.S.—shows that the technology can remove 100% of the arsenic. Both INL’s new technology and activated alumina work because they are able to sequester arsenic by attaching themselves, or adsorbing, the toxic metal. Such adsorbent technologies are sensitive to the pH of water, and the amount of arsenic they can adsorb decreases as the pH goes up. Therefore, the fact that the Idaho groundwater used in the tests had a pH >7 and contained silica is significant, says Patrick Brady with Sandia National Laboratories, which is also developing arsenic removal technologies. But he is waiting for the field tests that Tranter says he hopes to conduct “soon.” A few other companies have also made resins that remove arsenic by capitalizing on its affinity for iron oxide. But INL’s new material surpasses the others on more than one count, Tranter says. “We have created nanoparticles [that] have a lot higher surface area . . . increased by a factor
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through June, Royer says. “Our job is to derive nutrient standards to protect Illinois water. Right now, we’re definitely not thinking of what we need to do to protect the Gulf of Mexico,” adds Bob Mosher at the Illinois EPA. Excess nitrogen is not seen as a problem for freshwater streams, Dennis McKenna of the Illinois Department of Agriculture explains. Even if the state were to set water-quality standards for nitrogen, they are usually based on concentrations averaged over a 3-month period and might be meaningless in a situation where most of the nitrogen comes off during a handful of storm events, he says. —JANET PELLEY
of 3–4 over current technologies,” Tranter explains. That means more reactant sites for arsenic to adsorb on the iron oxide. The material also contains much more adsorbent—85% iron oxide by mass, compared with 20–40% for competing technologies. In Tranter’s lab tests, 10–12 mg of arsenic were sorbed on each gram of resin. This is a fairly high adsorbing capacity, says Paul Westerhoff, a civil and environmental engineering professor at Arizona State University, who calls the INL technology “promising.” Depending on the water an adsorbent is treating, he says, capacities can go up to 20 mg/g. The spent adsorbent passes the U.S. EPA’s Toxicity Characteristic Leaching Procedure test; this means it is not a hazardous waste and can be safely disposed. The resin should be cheap to make because the raw material is inexpensive, Tranter adds. The INL says that using it will cost utilities ~$0.10/1000 gal water. Plus, operating costs will be lower compared with other adsorbents. The higher cost of water resulting from the use of arsenic treatment technologies that meet the EPA standard is an “acute” problem in rural communities, Brady says. —PRACHI PATEL-PREDD
EnvironmentaltINTERVIEW George Gray
Gray sat down with ES&T to talk about his priorities.
CHERYL HOGUE, C&EN
George Gray was sworn in as the U.S. EPA’s newest science adviser on January 25. He carries out this role while also overseeing the agency’s Office of Research and Development (ORD). Before joining EPA, Gray was the executive director of the Harvard Center for Risk Analysis, an academic think tank that he joined almost at its inception in 1991. He became di-
George Gray will push his plan to highlight uncertainty analysis in the agency’s risk assessments.
rector shortly after the center’s founder, John Graham, (Environ. Sci. Technol. 2003, 37 [19], 365A– 368A) stepped up in 2001 to head the White House Office of Management and Budget’s top regulatory review office. While at the Harvard School of Public Health, Gray lectured on risk analysis. His research focused on the scientific bases of human-health risk assessment and its application to risk policy and risk management. Soon after being sworn in as ORD assistant administrator, Gray laid out five priority areas: enhancing human capital within ORD, improving the agency’s popular Integrated Risk Information System (IRIS), nanotechnology, communicating ORD science to more people who can use it, and focusing on outcomes.
In April, ORD announced plans to hire up to 5 new “world-class” scientists and engineers per year for the next 6 years. These individuals will specialize in areas such as bioinformatics, nanotechnology, and microbiology and will be employed for a limited time. They will also be paid more; the Federal Register notice says that EPA will offer salaries that compete with the private sector and other federal agencies, including the National Institutes of Health. Why is this necessary? One of the things that struck me in a recent meeting with our lab director at our National Risk Management Research Laboratory is that right now at least half of the people in our laboratories could retire and walk out the door today. We have to think about our workforce of the future. . . . It’s important for the agency to have the people in place to call upon [who] have the tools and the techniques to bring that cutting-edge science and that cutting-edge analysis to the mission of this agency. So I’m going to work on . . . [hiring] world-class scientists that will help us bring in some new techniques and skills. One of the things I’m [also] trying to do is to make sure that I am supporting the people at ORD. One of the simple things that we’re doing is helping to make sure the scientists have the latest and newest equipment. We are putting in a new state-of-the-art nuclear magnetic resonance facility [at ORD’s Ecosystems Research Division of the National Exposure Research Laboratory] in Athens, Ga. . . . I want ORD to be an attractive place for scientists to come to work—and that is because it is being recognized as a place where you are doing the best science and it matters. How might you change IRIS? [Note: IRIS is the chemical database maintained by the agency that lists the toxic properties of chemicals and estimates of each chemical’s level of exposure, can-
cer-causing strength, and whether it may be a carcinogen.] One of the things I want to do is to make the most of all the work we do [at ORD]. For example, IRIS, as one of our big risk-assessment databases, supports lots of different uses—some in this agency, some in state agencies, some in academia, and some around the world. We know that roughly a third of all of the [web] hits that come to [IRIS] are international. . . . So I’m going to make changes to the process and the content of IRIS. For the process, I think it’s important to improve the [data’s] transparency so folks know what is going on, people know what is involved. . . . We want to make sure it is known that we are open to all of the scientific information that is out there in the world, and the scientific expertise, so that we can do the best possible job when we characterize the [toxicity of these compounds]. We are also going to increase our uncertainty analysis in our assessments. That means that rather than, as is the case now, there being a single value for exposures for a compound, we are going to recognize that the levels of exposure that we are [expecting] in the environment are usually hundreds to thousands of times lower than what we know about now. And we don’t actually know what is going to happen at those low levels of exposure. We expect there will be nothing that happens, but we are somewhat uncertain. We are going to recognize that uncertainty qualitatively.
Would the introduction of more uncertainty analysis be a change for the agency in terms of the final product? Well, as I’ve said, the agency’s actually for a long time done a good job of characterizing uncertainty. Sometimes, it’s qualitative or it’s talked about. Other times, [for example,] that huge stack [of papers on my desk] over there is the National Ambient Air Quality Standards for Particulate Mat-
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EnvironmentaltINTERVIEW ter background work. It includes the criteria document that’s done in our office. [EPA’s Office of Air and Radiation] does the staff paper and risk assessments. Those have quantitative estimates of uncertainty all over the place. I think that sometimes we haven’t made that kind of information as available to people as we could, and I want to push that out into IRIS. To me, part of this [effort] is being suitably humble about our science. . . . Often, we can’t make multiple-decimal-point predictions about anything with any kind of confidence. I think recognizing uncertainty is sort of a sign of this kind of humility that says, “We’re doing the best we can with what we’ve got. As we learn more, those uncertainty boundaries will change. But here’s our best characterization of what we know today.”
When you spoke to the National Academy of Sciences (NAS) Board on Environmental Studies and Toxicology in January, you explained how EPA would implement this focus on uncertainty in science. How might this change the way you see EPA doing its job? To me, it’s not going to change the way EPA does its job a lot. It’s going to change the way ORD does its job. It’s going to make clearer the distinction between what the science can tell us and what it can’t tell us. And it may make some sorts of decision making a little more explicit. What are all those other factors at the table when we’re making a decision, which we know are there? Science plays an important role, but other things are involved. I want to be sure we are being as true to the science as we can. President Bush has requested $557.2 million for ORD for fiscal year 2007. If approved, that comes out to a 14% drop in ORD funding in 3 years (Environ. Sci. Technol. 2006, 40 [7], 2078–2079). At the same time, you’ve mentioned your interest in a few new projects. How are you going to be im-
plementing these? Where are you going to be making cuts? One of the things I have thought of . . . is making more out of what we do. And many of these [initiatives] aren’t things that are going to require a huge amount of new funding. They’re going to require somebody taking the lead to push and make sure we’re getting our message out to our communications group and help people understand the work that’s done at ORD. We are now in a place [in history] where there are a lot of smaller sources of pollution. Well, I want us to think about what we in the agency are calling stewardship— this means that we are doing a better job of taking care of things. . . . I’m interested in things that we can do on a small scale. If we can get information about a particular technology into the hands of 100 million households, each of which makes just a small difference in the problem, [then] small changes times big numbers should make a big difference in the state of our environment and human health. . . . I really do believe that people want to help. You’ve also talked some about recharging some old ORD programs. Which ones will you focus on? ORD in the past had supported and been part of a program called [Strengthening] Science-Based Decision Making in Developing Countries. And what I’m trying to do is sort of reinvigorate that. And also to look for other opportunities, maybe through the National Academies, [in which] we can take the really good work that is done in ORD and help to spread it—both to benefit people in other countries and sometimes to benefit us as we recognize how little pollution respects lines on maps. I’ll be making a trip to China sometime in the next couple of months as part of that [effort]. I’m working with the National Academy of Sciences on a program helping to transfer information and approaches to developing countries.
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So, a lot of these are things that don’t have big price tags. They require a little bit of push and a little bit of energy and the engagement of people in ORD.
An NAS panel recently revised EPA’s reference dose for perchlorate in drinking water, saying it can be 20× higher than the agency’s proposal (Environ. Sci. Technol. 2005, 39 [5], 96A– 97A). In my memory, this is the first time NAS has overturned a major EPA risk assessment. How might this affect the way EPA does its risk assessment in the future? This was settled before I came here, so I can’t speak to this authoritatively. But what I would say is that the perchlorate risk assessment that was done by ORD was really very good. It was state of the art. It turns out that there were differences within the scientific community [concerning] the appropriate weight to give to animal evidence versus human evidence. Those things happen. To me, that is a reflection of the uncertainty that wasn’t properly reflected in our reference dose. I do think that it is sort of an argument for us doing a better job of characterizing uncertainty, and I think that is something we’ll see. You’ve said that you want ORD to begin collecting data on environmental and public-health progress, or in other words to begin working on the agency’s State of the Environment report. Why? I attended the 35th anniversary of the agency, where we brought together the previous [EPA] administrators, and one of the things that struck me is that they feel that people don’t know about all of the good things that EPA does. There is actually a good reason for that. We don’t do a very good job of collecting data to help us make our case. I want ORD to be the one to measure, to access, and to describe the environmental and health conditions as they exist today and how they might improve in the future. —CATHERINE M. COONEY
