Scientist Found an Unexpected Toxin Floating in Oklahoma Sky
By Seth Morandini
News Article https://www.yahoo.com/news/scientists-found-unexpected-toxin-floating-120000739.html?fr=sycsrp_catchall
Peer Reviewed Study
https://pubs.acs.org/doi/10.1021/acsenvironau.5c00038
Background
This study focuses on chlorinated paraffins (CPs), which are alkanes that have had chlorine unselectively added to the molecule. The paraffins are produced on a large scale and are used for many industrial purposes such as flame retardants, fertilizers, and high pressure/temperature lubricants. Depending on their chain length, CPs fall into different categories with 10-13 carbons being short chain CPs, 14-17 carbons being medium chain length CPs and 18 or more being long chain CPs. Short Chained CPs were recently regulated after their propensity for long range atmospheric transport combined with their toxicity were discovered, however, medium chain CPs have been much less studied and lack the same strict regulation.
In this article the first real time measurement of gas phase medium chain CP’s were made using a form of chemical ionization mass spectrometry. Chemical ionization mass spectrometry is a form of mass spectrometry where particles are ionized using specific reactive ions. Once the particles are ionized, they are accelerated and detected by the spectrometer revealing information about their mass/charge ratio. In this research, the mass spectrometry was used to determine the atomic composition of the CPs
Lastly, gas partitioning is an important concept in this article. Gas partitioning describes the equilibrium between a particle in the gas phase and the condensed phase. An important factor in this equilibrium is temperature, and as temperature increases the equilibrium shifts toward the gas phase.
News Article
In the Yahoo article, “Scientists found an Unexpected toxin Floating in the Oklahoma Sky”, begins by relating the molecule in question, chlorinated paraffins, to a well known pollutant PFAS. The article describes how PFAS and CPs share a long lifetime in the environment and are very hard to break down. Next the article dives into the peer reviewed study describing the novel mass spectrometry approach used to detect the gas phase medium chain CP’s. A large part of this article was used to explain the government action taken in regards to this research. The EPA and the Stockholm convention began strictly regulating production of short chained CPs while disregarding its larger counterpart. The News article wraps up by providing recent legislation news of Oklahoma banning biosolids, a type of fertilizer and a known medium chain CP pollutant, from use in the state.
Peer Reviewed Study
The peer reviewed article primarily focused on the detection method of gas phase medium chain CPs. The research team combined ambient air from the environment with vaporized nitric acid within a nitrate anion chemical ionization mass spectrometer to ionize medium chain CPs and record them using time of flight analysis. This was the first time medium chain CPs were measured in the gas phase. Using the measurements gathered from the mass spectrometer the researchers were able to determine the most abundant medium chain CPs in the atmosphere. It was found that medium chain CPs continuing 14-16 carbons and 6-8 chlorines were the most abundant species.
The researchers then decided to collect data throughout the day to determine if there were any noticeable trends between incoming solar radiation, air temperature and mass concentration of the medium chain CPs. This time series collection revealed that all medium chain CPs had a large increase in mass concentration during the day, and their peaks aligned with the time of the day in which the incoming shortwave radiation and air temperature was the highest. This fits with what is known about gas particle partitioning, where increasing temperatures increase the amount of particles in the gas phase vs the condensed phase. However in the time series analysis they noticed an increase in the mass concentration of medium chained CPs in the early morning which doesn’t follow what was predicted. In the morning, as temperatures rise, the boundary layer, or the layer of the atmosphere influenced by the surface of the earth begins to increase. It was believed that this increase in volume would dilute the concentration of medium chain CPs and cause a dip in the graph. Instead there was a steady increase in the morning meaning there must be an external medium chain CP source, actively polluting in the area.
Finally the researchers mentioned an anomaly they saw where a sudden wind switch brought cool air. This should have resulted in a larger amount of medium chained CPs to partition into their condensed phase but instead they saw an increase in gas phase mass concentration. This gave further evidence for an active medium chain CP pollutant source nearby.
The paper ends with a section on the atmospheric implications of their findings. It is noted that America is the largest producer of medium chain CPs in the world and given the confirmation of gas phase medium chain CPs in the atmosphere it is probable that significant quantities of these toxic paraffins have partitioned into the air.
Article Rating
I would rate the news article 8.5/10. I believe the news article did a great job summarizing the important findings of the research article. I was impressed by the inclusion of specific details from the peer reviewed study in the news article, such as the exact mass spectrometry technique used. Also, providing the health impacts related to medium chain CP exposure, which was absent in the peer reviewed study, allowed for the reader to understand the impact of this research. Finally the addition of the current legislature surrounding this issue was very informative.
One issue I had with the news article was the fixation it had on PFAS. I understand that this is a much more known pollutant, but other than their long lifetime in the environment, there weren't any other similarities mentioned between chlorinated paraffins and PFAS. It seemed to me like it used PFAS almost as a buzzword to entice the reader rather than use it to help explain the results of the study.
Hi Seth. Great post! I like how your introduction does a good job setting the stage for your analysis of both the article and peer study. I do agree that the news article could have done a better job focusing on the issue at hand and cut out the many mentions of PFAS (even though these are more well known). I think the article could have done a better job digging deeper into CP's and focus more on the size and effects of these CP's. My first question is what kinds of health hazards or environmental impact does the short chain CP's have and do you know when these were first discovered? Also, do these health hazards remain the same with medium and long chain CP's, or is it a matter of chain length where the shorter CP's are more dangerous and longer ones are not as hazardous?
ReplyDeleteThanks for the comment Cody, Both the short and long chain CPs have similar effects on human health and the atmosphere their identical atomic compositions allow them to take part in the same chemistry. The main reason why they were regulated before the medium chained CPs is because they had a much higher volatility than their larger counterparts so there was a large concern for large concentrations of them to be found in the atmosphere. There wasn't as large a concern for the medium and long chains because it wasn't believed at first that they would be able to sustain a large enough concentration in the atmosphere to be dangerous.
DeleteHi Seth. Excellent review. I strongly agree with your critique of the news article's "fixation on PFAS." While the comparison is an easy way to grab a reader's attention, it risks conflating two distinct chemical issues. As you noted, beyond their shared persistence, their sources, properties, and regulatory histories are quite different.
ReplyDeleteHowever, the news article's comparison does inadvertently highlight a critical systemic failure: the problem of regrettable substitution. Just as the regulation of legacy PFAS like PFOA and PFOS led to the proliferation of novel, unregulated alternatives, the regulation of SCCPs contributed to the rise of MCCPs.
This pattern demonstrates that a substance-by-substance approach is often a losing battle. The only effective path forward seems to be a shift toward class-based regulation, addressing the entire chemical family at once. Now that MCCPs are also slated for global elimination, it will be interesting to see what future atmospheric monitoring reveals: will we see a successful phase-out, or will a new "longer-chain" chlorinated paraffin simply take its place?
Thanks for the comment Siyu, I wasn't aware that PFAS had the same problem of new chemicals replacing the old when once it was regulated. I agree that a class based approach would save the environment from the countless iterations of the same group of molecule being used to replace its banned counterpart. Its unfortunate that many smart chemists use their knowledge to bypass environmental regulations and create new toxins that are not yet regulated. As for these chlorinated paraffins, the larger the chain gets, the less volatile they become and therefor there will be a smaller and smaller concentration in the atmosphere. This doesn't take into account others ways the larger chains could pollute the environment such getting into water sources or the soil.
DeleteGreat analysis, Seth! I'm curious about how CP's get released into the atmosphere-- are they combusted then released, or are they disposed of as waste and end up escaping into the atmosphere? In general, if you have any knowledge of how the molecule changes during its industrial use and the mechanism of its release into the atmosphere I would be really interested to know more about that. For example, does it react with atmospheric molecules to create reactive chlorine species, similar to how CFCs operate? I agree with your rating of the article, but also agree that the inclusion of PFAS in the Yahoo article doesn't add anything to the piece. Do you know of another pollutant that is more analogous to CP's in terms of structure and reactivity that they could maybe have compared it to?
ReplyDeleteThanks for the comment Eliza, The main way in which CPs get into the the atmosphere is from them evaporating into the atmosphere from waster products that contain CPs. Combustion is also another cause. When these CP containing products are disposed of and then incinerated, they are released into the atmosphere as well. The article and study did not mention any sort of ozone depleting chemistry, such as the kind that cfc and other halogenated species participate in. After some research I found that CPs relatively low volatility, along with their high molecular weight keeps them closer to earths surface when they make their way into the atmosphere, preventing them from reaching the stratosphere and interacting with ozone.
ReplyDeleteHi Seth, great job! Was there any information given on medium chained CPs on health or something of that nature? Like I would assume its not great based on them being toxic paraffins but I would think the smaller chains are worse based on size implications. I do find it interesting that medium chained CPs are the most abundant but far less studied and regulated. I wonder if it was a detecting issue at first or something along those lines.
ReplyDeleteNice work, Seth! I like your analysis of the article and agree that a lot of the details that it included were a great addition to it. However, I do disagree with the fixation on PFAS. The article does mention them a good bit, but I think it provides a good connection for the general public. There are a ton of acronyms that get thrown around in chemistry, especially with atmospheric and environmental chemistry, and I can imagine that people outside chemistry might have a difficult time keeping track of them or relating them to each other. Although it may not be the most accurate at times, I think having that connection and getting the public to understand *why* they should care is much more important than being 100% accurate. Obviously, having both is the best case scenario, but p values and confidence intervals don't get people to click on an article.
ReplyDeleteI definitely agree about the over mention of PFAS felt a little out of place and didn’t directly relate to the medium chain CP’s being focused on in the research article, but otherwise I agree that it did a really good job at introducing the chemicals at play, how they might get into the atmosphere, and why and how they are being regulated/eliminated. I especially liked the links throughout the article that not only linked to the research article but also other articles that provided more information and context to some of the content being described. I did find it meaningful about how they described regulation like a “whack a mole” and how regulating one type of harmful chemical just leads to other chemicals being used that are also harmful. Curious to if there could be a more proactive approach to try and understand chemicals before they are used in mass? Also, not sure if I missed it, but you mention that there was great evidence of an active medium chain CP pollutant source nearby, did they figure out what it was specifically in this case?
ReplyDeleteThanks for the comment Evan. I also found the whack a mole reference to be very insightful. Its very easy for these pollutants to be released into the environment and much harder for the EPA and other organizations to get enough research done to get legislation passed. Every time and pollutant important to industry get regulated another one normally takes its place which is very unfortunate. For the question, they never explicitly mention where they source is coming from, they just generally say that according to the data there must be an active source of emission putting medium chain CPs into the atmosphere.
DeleteFirstly. I have to agree with you on the PFAS usage in your news article commentary. For me I think it actually confused me into thinking they are more similar and have the same issues as we are seeing with either SCCPs or MCCPs when to my understanding the only similarity is their ability to stay in environment for a long time and similar-esque health concerns. Based on the description it gave for where both come from they don't sound similar in either composition or usage/how they were spread. Your background explanation was much better at explaining the relevant details and how critically with longer chains the concentration in the atmosphere was found to go down. Also I don't fully understand the relevance of the concentration by mass rising in the morning counter to what was predicted. Does this means that it pollutes more in the morning in general or was this part of the study to better help determine a cause, as they postulate sewer sludge for fertilizers and I assume that happens relatively early in the day.
ReplyDelete