Standard reference materials — or SRMs — at the National Institute of Standards and Technology (NIST) serve as standards for many food, beverage, health, industrial and other products. There are over a thousand SRMs including peanut butter, house dust, dry cat food, soy milk, blueberries, stainless steel, fertilizer, and a DNA profiling standard. SRMs help make products safer and ensure that consumers are getting what they think they’re getting. But how do they work exactly?
In this episode of Tiny Matters, Sam and Deboki cover SRMs that are helping us accurately detect toxic substances like lead and pesticides in our house dust, fight seafood fraud, and keep PFAS out of our meat. Sam also travels to the NIST headquarters outside of Washington, DC to get a behind the scenes tour of how SRMs are made. She even gets a chance to snoop around the warehouse where SRMs are stored.
Transcript of this Episode
Sam Jones: In a large warehouse in Gaithersburg, Maryland lies … a jar of peanut butter. Well not just one jar, a bunch in fact. And they’re very expensive — $1,143 for a 3-pack — but also no one will ever eat them. This is not the beginning of some weird riddle — these expensive jars of peanut butter do exist and they serve an important purpose.
Welcome to Tiny Matters, I’m Sam Jones and I’m joined by my co-host Deboki Chakravarti.
Deboki Chakravarti: You’re probably wondering about the significance of this very expensive peanut butter. Well, peanut butter is just one of over a thousand standard reference materials produced by the National Institute of Standards and Technology, or NIST. Other standards include dry cat food, soy milk, blueberries, stainless steel, various fertilizers, a human urine standard for kidney disease diagnosis, a DNA profiling standard … the list truly does go on and on.
These standard reference materials — or SRMs — serve as, you guessed it, standards for many food, beverage, health, industrial and other products, helping make them safer and ensuring that consumers are getting what they think they’re getting. We’re going to talk about how that actually works in just a second. But first, Sam I’m a little jealous you got to go to this warehouse.
Sam: That’s fair, it was pretty cool. I got to visit not only the warehouse but one of the chemistry labs where these SRMs are developed. And I’m psyched that we can share what I learned with our listeners.
So today on the show, we’re going to talk about a handful of SRMs in particular, including shrimp and salmon and household dust, which involved collection trips to hotel and motel rooms across the country in the 90s. You’ll also become familiar with the term “beef snow.” And you might be thinking, “Can I see videos of this beef snow?” The answer is yes! We have videos showing a bunch of the SRMs. Go check out our YouTube channel @tinymatterspodcast. We’ll also put a link to our YouTube channel in the episode’s description.
Deboki: So why do we need SRMs? When you buy a product, say, baking chocolate, if you look at the back of the package there’s a nutrition label. The Nutrition Labeling and Education Act of 1990 actually requires that labels on processed foods distributed in the United States specify about a dozen nutrients that need to be listed per serving — things you’ve seen like total fat and calcium. So the manufacturer of that baking chocolate is responsible for measuring all of those things. Which means hopefully the equipment they’re using is calibrated and the measurements they’re getting are accurate. SRMs help make that possible.
When a company or academic institution or government agency buys an SRM from NIST, yes they get the product — the stainless steel or fertilizer or baking chocolate — but maybe more importantly they receive a Certificate of Analysis that provides all of the chemical or physical properties of the SRM they purchased.
Sam: Then they can use the SRM and its certificate to test their equipment or other protocols they’re using to measure their product. So if, when using their own equipment, they’re not getting the same readings on the SRM as the Certificate of Analysis says they should, then they know something is wrong that they need to troubleshoot. Once their equipment does get measurements for the SRM matching the Certificate of Analysis, they can feel confident moving forward and measuring their own products.
Kate Rimmer: So, for example, in the clinical area, we have a cholesterol standard. And pretty much all of the major laboratories in the United States use that standard to check and make sure that the measurements that they're getting when they measure your own blood and then send the results back to your physician are good. So that underpins and gives you some confidence in the measurements that you're getting.
Deboki: That’s Kate Rimmer, a research chemist at NIST. Kate works on dietary supplements as well as foods and biological materials. Like we mentioned at the top of the episode, there are so many SRMs, over 1,100 in fact, and they sell more than 30,000 units every year.
Alix Rodowa: Keep in mind with those 1,100 that each one has to be maintained by a person.
Deboki: That’s Alix Rodowa, Kate’s colleague who is also a research chemist at NIST. Alix’s work focuses on emerging environmental contaminants of concern.
Alix Rodowa: So you're looking at people who maintain SRMs. So we make them and then also have to maintain them.
Sam with Alix and Kate: What does that mean? Maintain them?
Alix Rodowa: Yeah, so you want to make sure, right, if you go to the doctor and you get your cholesterol checked, the material that they're testing against that cholesterol SRM is consistent over time. So we need to make sure that it's shelf stable, that the contaminants we're measuring, or fatty acids or heavy metals or vitamins, are consistent, and that they don't change as the product ages.
Sam with Alix and Kate: Right. Yeah. That's a good point.
Kate Rimmer: And that's something... so if you bring up vitamins, we have a multivitamin SRM. And we actually had to go and make a different version because the vitamins themselves degrade over time. But there are also elements in multivitamin tablets. There's calcium and iron. We have an inorganic group that's analogous to us, and they measure all of those analytes in the materials. So we do the organic compound side, and they do the element side.
Deboki: The first SRM NIST ever produced was standardized iron, in 1906. In 1967, NIST produced the first SRM for clinical applications, which was cholesterol, and in 1992 they produced the world’s first DNA profiling standard. It was in 1996 that they moved into foods as well, and they began with infant formula. Kate told us that, at the time, there had been some issues with the infant formula on the market not displaying accurate nutritional information.
Kate Rimmer: Infant formula is a food where that is all that the infant is taking in. So if you don't have the proper nutritional balance in it, you cause serious harm and injury. And because of that, it's become really regulated all across the world. And we've worked hard with the infant formula manufacturers across the world to get materials so that they can prove that they have the right balance of nutrients and that they're protecting health and safety that way.
Sam with Alix and Kate: Interesting. Okay. So that's sort of how you got into food.
Kate Rimmer: Right.
Sam with Alix and Kate: And now that has evolved... rapidly.
Kate Rimmer: ... evolved, blossomed. That started to happen too when there was a labeling act that came out.
Deboki: That was the Nutrition Labeling and Education Act of 1990, which is enforced by the FDA and, like we briefly mentioned earlier, requires labels on processed foods distributed in the United States to specify total fat, cholesterol, carbs, etc.
Sam with Alix and Kate: I had no idea. I think I was too young to know at the time, but as a pretty young kid into my adult life, that's all I've known, but so fascinating to think that those labels didn't exist before.
Kate Rimmer: Right. So some companies did them voluntarily before that, but there were no rules. There was no standardization.
So we started in foods with vitamins and nutritional elements, but we've had more and more concern over time, in also being able to provide materials that work with food safety standards. So we're also looking now, at pesticides and contaminants such as PFAS, toxic elements, mycotoxins, aflatoxins, to make sure that the foods that people are taking in are safe. And that the measurements that companies are doing are valid for establishing that the foods are safe.
Deboki: And here’s where we get to that beef snow. So a few years back, as more and more data was emerging showing that so-called ‘forever chemicals,’ which you might also know as PFAS, were contaminating our soil and water and food, the FDA approached NIST.
The agency had been trying to measure PFAS in agricultural food products, but different labs were getting different results. So they asked NIST to create an SRM specifically for PFAS-contaminated meat, to help them understand what people are being exposed to and what new regulations might be needed.
Sam: If you want to really deep dive on PFAS as well as microplastics, check out episode 29 of Tiny Matters, which came out in March, 2023. But, just as a quick refresher, PFAS or perfluoro- or polyfluoroalkyl substances are a group of over 15,000 human-made chemicals that are water, heat, corrosion, and oil-resistant. That makes them useful in jet engines and firefighting foams as well as non-stick pans, microwave popcorn bags to keep them from catching fire, and the lining of fast food wrappers so that grease doesn’t soak through.
The problem is that the carbon–fluorine bond is so stable in these perfluoro- or polyfluoroalkyl compounds that they don’t easily break down. So we find them everywhere, including our blood stream, and they’ve been linked to cancer, immune and endocrine disruption, among other things. Their causal effect in people is unclear but what is clear is that they need to be monitored. Having a PFAS standard in meat is a way of making accurate monitoring possible.
Deboki: So the FDA asked NIST for help, and was able to connect a couple of NIST researchers with a local department of public health and state veterinarian in Maine who had identified PFAS-contaminated animals on a farm. The farm, unfortunately, had to slaughter their herd as a result of the PFAS contamination. We don’t have more details on how these animals came in contact with PFAS, but a lot of times contamination can stem from groundwater polluted by industrial release of PFAS. The animals might have drunk that water from a well or eaten plants that took up that water.
NIST was shipped meat from a dairy cow, a beef cow and a pig from that farm: a total of around 300 pounds of ground beef and ground pork patties. It was then frozen at liquid nitrogen temperatures around -320 degrees F, which is -196 C for our non-American listeners, and then went through a process called cryomilling or cryogrinding where it was turned into a frozen powder. That frozen powder is the “beef snow,” and it was separated into small containers. This whole process ensures that every container of ‘PFAS-contaminated meat’ is the same.
Sam: Determining how to accurately measure concentrations of PFAS in meat has been no small task. That project is still underway. But the hope is that soon jars of beef snow or pork snow and their Certificates of Analysis can be shipped out to companies and other groups who want to make sure their equipment can accurately test for PFAS in the meat they’re buying or selling. Then, if they do see that their meat is contaminated they can begin to hunt down where the problem is coming from.
Deboki: In addition to meat, NIST is developing other PFAS SRMs. They actually already have a bunch available, including domestic sludge.
Alix Rodowa: It's exactly what you think it is. It's fecal matter. And then particulate, it could be road runoff, it could be industrial waste, anything that is solid that is going into a wastewater treatment plant.
What ultimately ends up happening is you wash your products, you throw away your products, and then they end up at the wastewater treatment plant facility. So as they are flushed, as they're used, they're washed, they go into the gray water where they're treated, and it actually acts as a sink in some places for PFAS.
Deboki: Solid particulate is sometimes collected during the wastewater treatment process because it’s super nutrient dense and can be spread on soil, used like manure.
Alix Rodowa: You would take it to a local farm, you would put it out on your field, and then you would grow crops with it. It's of importance because if we have contaminants, they end up in this and then they end up potentially on the field where they could contaminate the crops that you're growing, which are used for animal consumption and sometimes human consumption. So something to consider. It's the circle of life.
Sam: So now let’s go back to food. I know, super appealing after talking about domestic sludge, but here we are. A couple of years ago, NIST released four new seafood SRMs. Actually, at this point they’re technically RMs or reference materials, not standard reference materials which require another level of rigorous testing to become certified. One day they may become SRMs. That being said, RMs still serve the same purpose.
Deb Ellisor: This all came about because there was a lot of media attention and reports of a lot of seafood products that are available to the US consumer at grocery stores or markets that were actually not what they are labeled as. The label may say one thing, but it's actually either a different species or it's from a different source or something like that.
Sam: That’s Deb Ellisor, a research biologist in the Biospecimen Sciences Group at NIST. She’s in Charleston, South Carolina.
Deb Ellisor: And this can have a number of implications, obviously, it can affect the economy if we're paying for things, imported goods, for example, that are not exactly the quality or the high level of quality that we might be expecting. It also has an effect on the honest business person in the US, the honest fisherman that's trying to make a living, or someone catching and raising seafood. It’s for the good of the consumer as well. So are we not only paying for what we should be getting or also, from the health side, we're ingesting these things and we think the food is one thing, but it's actually something else.
Deboki: Deb is currently in charge of four seafood RMs: wild caught coho salmon, aquacultured coho salmon, wild caught shrimp and aquacultured shrimp.
Deb Ellisor: This issue, it's been reported along many different species and seafood products, but we chose salmon and shrimp specifically in this case because they are two of the three most consumed seafood products in the US, the third being tuna, which is a little bit more expensive, but also difficult to get our hands on as far as from different sources and being sure that we have what we want.
Deboki: So each of the four salmon and shrimp RMs is a blend of either multiple fish or crustaceans. Similar to the meat, the blended mixture is frozen and cryomilled, and then that frozen powder is stored at super cold temperatures before being shipped out to buyers along with the appropriate Certificate of Analysis.
Sounds pretty straightforward, but in addition to any technical challenges they faced, making these RMs had the added hurdle of ensuring that these shrimp and salmon came from verified sources.
Deb Ellisor: So we couldn't just go to the grocery store and buy, for example, wild caught salmon, because that's part of the issue, we're not 110% sure if that's what it is based on these media reports. So we really had to work with some folks at NOAA in the marine forensics division in order to help us identify vendors that we were certain we were going to get what we were intending.
Sam: I feel like we just can’t get away from forensics with Tiny Matters. And I’m not complaining. NOAA, or the National Oceanic and Atmospheric Administration, has a Marine Forensics Laboratory in Charleston that will work with law enforcement to analyze evidence collected during the investigation of civil and criminal cases, including violations of the Endangered Species Act.
For example, they would step in if a restaurant is caught serving an endangered whale species on the menu, which does happen. The Marine Forensics Laboratory is also involved in enforcing domestic seafood labeling laws, and so Deb told us that they were fully on board to help out in getting these RMs made.
Deb Ellisor: Right now we're really focusing on the protein content and the fatty acid profiles. And it's just to say that they're different.
Deboki: We should be clear that NIST is not here to tell you one is better than the other. Their purpose is to ensure that companies are labeling that shrimp or salmon accurately so that you are eating what you are told you are eating. Beyond that, your food choices are up to you.
And as a real left turn to close out this episode, we want to talk about dust. More specifically, household dust.
Jessica Reiner: In the late '90s, researchers started really getting interested in what we now call the built environment, sort of the indoor environment and how you might be exposed to different chemicals because of your indoor environment.
Deboki: That’s Jessica Reiner, a research chemist at NIST who is also located in Charleston.
Jessica Reiner: NIST started talking with EPA because they had this National Human Exposure Assessment Survey at EPA that they were starting out, and there was a field program associated with that, going out to homes and actually really understanding the characteristics of house dust and maybe how people might be exposed. So talking with EPA, NIST did realize that there was a need to make sure measurements of different chemical contaminants in house dust were of high quality. This was especially important for things like lead.
Deboki: Lead exposure is linked to nervous system disorders, cardiovascular effects, issues with kidney function, and other negative health outcomes. It’s dangerous, so having a standard to make sure you’re able to accurately detect it is a very good thing. But soon NIST was looking for a lot more than lead in house dust.
Jessica Reiner: If you start off with the initial dirty dozen that was on the list of things that were regulated by the EPA: PCBs, a bunch of different pesticides, PAHs, those were on the original list.
Sam: PCBs or polychlorinated biphenyls are, like PFAS, a group of human-made organic chemicals. They’re toxic and carcinogenic. Although they were banned in the US in 1979, they were used a lot in transformers and different electrical equipment, and so if something was built before then all bets are off. PAHs or polycyclic aromatic hydrocarbons are a class of chemicals that are found in coal, crude oil, and gasoline and will float around in the air.
There are three different SRMs for house dust: an original two that were high level lead and baseline lead in house dust, and then a third was added for those organic contaminants like pesticides and PCBs. Jessica told us there are actually over 160 different compounds in that SRM.
Deboki: But what would a representative dust SRM look like? People live in vastly different environments and use different cleaning products and have different air filtration systems. There are so many variables, so to get a good mix of samples, it means collecting a lot of them from a lot of places.
Jessica Reiner: With coordination with the EPA, we went to different locations throughout the whole country to get a representative sample of what people might have in their homes. North Carolina, Maryland, Ohio, New Jersey, Montana and Wyoming, those were the different states that were visited. Vacuum cleaner bags were collected between 1993 and 1994.
Deboki: And those vacuum cleaner bags came from homes, cleaning services, motels and hotels.
Jessica Reiner: So really trying to get a range of different types of places you would get dust from and different locations across the country so it could be hopefully representative of what someone may have in their house, even if it's not exactly what you have in your location.
Deboki: A lot of dust was collected back in the 90s, so much that there is still plenty of it left.
Jessica Reiner: I think we probably still have, based on current sales, about 50 years left, but maybe it's time to think about making a contemporary material. Because if you now think about what is in our homes or in a motel or in a hotel, it's very different than it was in the 1990s. The different products, especially back in the '90s there weren't so many computers. There were TVs, but they were different TVs. They weren't the liquid crystal TVs that we have now. So we've actually been talking and there's thought of maybe a contemporary house dust that's more like what people have in their house today, might be worth investing to make a new material.
Sam: So whether it’s a case of accurately detecting contaminants in house dust or beef or knowing that you’re buying wild caught salmon if the label says “wild caught salmon,” I think of NIST as this somewhat silent but crucial entity in the background like “hey, here’s the data to be sure of that.” So the next time you go to the grocery store and pick up a jar of peanut butter, think about how there’s a good chance you’re getting what you think you’re getting because of NIST. And also be grateful that that jar of peanut butter does not cost $1,143.
I never remember who’s going first. I am happy to, unless you’re raring to go. So a study just came out looking at kidney health post space flight. I’ve always been really fascinated in what happens to the human body when you leave Earth… which makes it sound like when you die how I just said that… but in astronauts, really, like people who have spent time in the International Space Station or in the astronauts that went to the moon. It's cool. Anyway, as soon as I saw that this was a new study that came out, I had to read about it. The goal of this work was to understand what would happen to the kidneys should astronauts go on a Mars mission. Which would mean somewhere around two and a half, three years in space to go there and back. Since the 1970s, researchers have known that space flight causes certain health issues: loss of bone mass, weakening of the heart and eyesight, development of kidney stones. A lot of this stuff is reversible. It takes some time, but it comes back. Kidney stones, you just got to pass them. It's the way it is.
So space radiation, including solar winds from the sun and galactic cosmic radiation from deep space, those have been considered potentially the greatest health threats. There was this team led by University College London, or UCL, researchers, and it included over 40 institutions. And they conducted a bunch of different experiments related to investigating how kidneys respond to space flight. This included biomolecular, physiological, and anatomical assessments and used data from both humans and mice. And the humans, the samples from people or the data that was collected, I'll get into it a little bit, but the data was collected from people, most of those people were astronauts who had been in the International Space Station for however amount of time.
They found that both human and animal kidneys are remodeled by the conditions in space. And so kidney tubules responsible for keeping calcium and salt levels balanced appeared to actually shrink after less than a month in space. And what they concluded was that it was actually more likely due to microgravity, not space radiation in part because they're really not going super far into space. They're pretty protected in that low orbit. But kidney stones developing during space missions, like I mentioned a second ago, that's not uncommon. And so now it looks like, actually, that might be because the kidneys are not effectively processing salt, which is good to know, right?
And then the big and worrisome finding came from mice. And so what they did was they looked at the kidneys of mice exposed to radiation that would simulate the galactic cosmic radiation for about two and a half years. And what they saw was that these mice experienced permanent damage and loss of function in their kidneys. Around two and a half years — that's the amount of time that astronauts would be in space in order to get to Mars and back. And because they'd be going so deep into space, they would be subjected to the galactic cosmic radiation.
And so yeah, that's not great, but the researchers seem pretty optimistic. It's good to identify issues before they occur, or potential issues before they occur. And so this is where, really, drug development could kick in. Are there medications that would allow the kidneys to be more resilient, maintain homeostasis? And one of the researchers also pointed out that drugs developed for astronauts to help protect them from space radiation could also be really beneficial to cancer patients because a lot of times the limiting factor in terms of how much radiation they can be given is related to kidney function and not damaging the kidneys. Actually, it could potentially allow patients to tolerate higher doses of radiation if there's some sort of way of protecting the kidneys from any harm from that. Yeah, I just thought this was really fascinating.
Deboki: Yeah. At first when you were like, "And they're feeling optimistic," I was like, "Hmm. How?" That's not what my reaction was. But I feel like that point at, oh, actually, this has a lot of overlap with research for patients, that makes a lot of sense. That's really interesting. Still don't want to go to Mars.
Sam: Yeah, I have no interest. I'm good. I'm good on Earth.
Deboki: Absolutely not.
Sam: Do I want to go to the bottom of the ocean? Also no. Leave me here. I'm good. Please. Let me live my life.
Deboki: Keep me where the humans are supposed to be and I will be content.
For my Tiny show and tell, I'm also here to present a little bit of a medical study. This was presented to the American Society of Clinical Oncology, and it's about palliative care for cancer patients. And so basically what they wanted to know is: can palliative care work as well virtually as it does in person? Palliative care is about helping patients and families navigate serious illness. It's not necessarily about the treatments itself, it's more focused on quality of life, things like managing symptoms and emotions, understanding the disease.
So in the past, oncologists have shown that when patients have gotten palliative care early on, they also tended to live longer compared to patients who didn't. And that's a pretty big deal. It's, I think, really important to be able to know that giving this kind of care that's not just about what medicine they're giving can be really helpful for patients. One of the challenges, though, is also how do you make this more accessible to patients? A lot of these patients have serious illness, so whether or not they can always make it into an appointment, maybe it makes more sense to have an appointment be virtual so they can access it from a place that's comfortable for them.
This study was started around seven years ago, and they looked at 1,250 patients with advanced lung cancer. And they had half of the patients receive virtual palliative care and half had monthly visits in a cancer center. And they found no statistically significant differences between these groups when it came to depression and anxiety, coping skills, and understanding of their treatment and prognosis. And so the hope is that maybe this will lead to an expansion of telehealth palliative care programs. Yeah, this study is really just about expanding strategies to help patients access palliative care.
Sam: This is another example, I think, of how people were forced, in a lot of ways, when the pandemic started to go virtual in a number of situations. Certain things I really much prefer doing in person, but it's so nice to know that that's an option for so many things now when it wasn't before. And it just increases access in a way where it's like, maybe I wouldn't go to that appointment for another six months because I'm just so busy and I have this thing going on, but if I can do it at noon on a Monday when I'm working at home, great. Perfect. You know?
Deboki: Yep.
Sam: Palliative care also is just so, so important. I've talked with some palliative care doctors before, and they're just amazing. You know?
Deboki: Right. Yeah.
Sam: Yeah, they're so-
Deboki: Yeah, I didn't really know much about palliative care. And I think it was a talk that Atul Gawande was giving about palliative care that really was the first time I had really learned about it. It's one of those facets of healthcare that I think just makes so much sense to expand on. It's like, what's the point of healthcare? It's to take care of people. And there are a number of ways to do that, including, yes, the drug side, but also these quality of life discussions are so important.
Thanks for tuning in to this week’s episode of Tiny Matters, a production of the American Chemical Society. This week’s script was written by Sam, who is also our executive producer, and was edited by me and by Michael David. It was fact-checked by Michelle Boucher. The Tiny Matters theme and episode sound design is by Michael Simonelli and the Charts & Leisure team.
Sam: Thanks so much to Deb Ellisor, Jessica Reiner, Alix Rodowa and Kate Rimmer for joining us. Very soon we’re introducing a new bonus series called “Tiny Show and Tell Us.” Write in to tinymatters@acs.org with science news you’re itching to share, a science factoid you love telling friends about, or maybe even a personal science story. We want to hear about it! And then talk about it. Again, email tinymatters@acs.org. Maybe there will even be some giveaways, ya never know! You can find me on social at samjscience.
Deboki: And you can find me at okidokiboki. See you next time.
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