Plastic pollution has found its way from our consumer products into the ocean, and now it may have found its way back to our table. We know our oceans are polluted by giant trash gyres and tiny bits of micro plastics that prove harmful to aquatic life, but researchers have recently found that these micro plastics may also be contaminating our table salt. According to
this article from the Telegraph, researchers in China tested 15 different brands of table salt and found traces of plastics from water bottles, cellophane, and other sources. Not only was this plastic pollution found in table salt from ocean sources (though sea salt did contain the most plastic), but salt from lakes and rock salt from wells were also contaminated. These tiny pieces of plastic, most too small to see, would result in the average consumer eating about 3 pieces of plastic a day. The article also shared a quote from one of the researchers who published the original study in Environmental Science & Technology, who said that though this study only looked at Chinese salt samples, similar results could be expected elsewhere, like the US, because plastic pollution is prolific in oceans and lakes world-wide.
The ES&T article measured the plastic content in 15 salt samples in particles/kg. The most common plastics detected were
polyethylene terephthalate, polyethylene, and cellophane. The details of sample collection and analysis were discussed. The researchers found no significant different between brand of salt in terms of overall micro plastic content, though some variation in plastic types was observed. The study also compared these results to previous measurements of plastic pollution in China water bodies, which would be common sources of the salt.
Something the journal article mentioned which the Telegraph did not is how exactly plastics end up in the salt. Sea salt is usually produced by a crystallization process, essentially concentrating the salt by evaporating the water containing it. Typically, not additional processes are used to remove contaminants from the salt, plastic or otherwise. The ES&T article also had a short discussion of the implications for human health and aquatic life from ingesting these micro plastics, something the media article simply implied. The journal article did not include any discussion of this issue translating to other areas besides China, though it was mentioned that plastic pollution is a widespread problem.
Overall, I thought the Telegraph article did a good job of summarizing the study's findings without sensationalizing the issue too much. I think the study itself could be shocking, in that this pollution issue has become so widespread. The implications of table salt containing plastics were implied by both the study and news article. Plastic pollution in our oceans and lakes is definitely an issue that needs to be addressed.
I found this study to be interesting. Though it seems that the Telegraph article was meant to be short, I thought it would have been beneficial to mention how population density may play a role. The ES&T article suggested this as a potential reason why the lake salt had lower microplastic levels. Highlighting that not only sea salts may be a problem in other areas, but also salts from lakes, seems to be worth mentioning.
ReplyDeleteI thought this was a really interesting article too. I was really interested in the discussion of how microplastics actually impact human health (by retaining or absorbing other chemicals). I think a discussion of the actual health impacts would have been a nice addition to the Telegraph article, but it was a pretty short article that really seemed more focused on introducing the idea of microplastic contamination (and griping about it) than actually covering it in depth.
ReplyDeleteThe ES&T article talked about the different size and shapes of particles found. I wonder if there's any research on the impact particle shape has on how particles cycle through the environment and our bodies?
I am slightly surprised that micoplastics were found in the salts extracted from lakes and wells. The plastic found in the garbage patch located in the the North Pacific Gyre is a result of the clockwise rotation of the oceanic currents in the gyre guiding the debris to the calmer center where it becomes trapped and accumulates. Lakes and wells have stagnant water, and I would expect the plastics to settle in deep water and not undergo photodegradation – a degradation process that occurs when the plastics absorb photons from the sun. Nonetheless, plastic accumulation seems to be a global problem that needs to be addressed.
ReplyDeleteAs a chemical engineer, I'm interested in how the microplastics get entrained with the salt during the crystallization process. I had thought that the crystallization would exclude species like microplastics, but apparently that is not the case. I wonder if the manufacture of salt can be modified in a way that better excludes these materials.
ReplyDeleteI think this article does a great job addressing that plastic is found in salt that we consume, as well as in the aquatic habitats. I agree with Marina, I am interested in how plastic material is processed, and what's going wrong that it's appearing in bodies of water as well as on our kitchen tables. Considering that the daily recommendation of salt corresponds to three pieces of plastic, the accumulation of plastic in our bodies is eventually going to reach a significant amount. In addition, with obesity being a public health concern as well, the consumption of salt daily by the average American is probably more than the recommended amount. This issue is clearly complex and is intertwined with so many more environmental concerns currently.
ReplyDeleteI found this article pretty surprising, especially when it mentioned that some of the microplastics could be seen with the naked eye. I wish both articles had gone more in depth on the implications for human health. I know the ES&T article mentioned that the microplastics could absorb organic compounds, but I'd be interested to know if there is a detectable level at which the absorption effects human health. It'd be interesting to then compare cultures with varying levels of salt intake with a given health outcome.
ReplyDeleteThis article also made me wonder about the amount of microplastic intake we get from other foods and products, not just seafood or sea-derived products. It seems like plastic tupperware, bottles, and dishes could possibly produce easily-ingestible microplastics.
I agreed that the telegraph article did a fair job, as it kept its tone neutral and reported the facts as they are. I was shocked by the image in figure 1.E of the peer-reviewed article (also shown in telegraph article) though! I don't know how frequently they found plastics of this size, or if it was a singular exception to the microplastics often found, but it is very unsettling. This article was doubly interesting to me because this finding could drastically impact many Chinese people's everyday lives. Salt is one of the most important ingredients in Chinese cuisine, and the contamination could make people very hesitant to use salt generously.
ReplyDeleteNice post Rachel. The Telegraph article was brief but to the point. It was not misleading by any means, but it could have gone into more detail about health effects, where the plastics come from, etc. The ES&T article was also pretty nice. The pictures of the filters helped give a good idea of what exactly is in the salt and it is quite alarming. It was really nice that they talked about how they ran controls to control for microplastic contamination in the lab, but they can not really control for microplastic contamination during the processing period of the salt from the manufacturer. There is no doubt that there is microplastic contamination from these salt sources, but I am sure a statistically significant amount of salt contamination with microplastics may be coming from the collection and manufacturing process.
ReplyDeleteVery interesting and relevant issue. As mentioned before, the Telegraph article did a good job at summarizing the findings of the study without too much sensationalism. But they needed a paragraph on how the plastics get into the sea salt, and the human health risks. Another thing I would have liked to see in the actually ES&T article was a possible way to mitigate this issue. As Rachel mentioned, they don't process the sea salt more than just letting it crystallize out of solution so maybe an additional step of filtering or something of the sort can prevent the microplastics from ending up on our food.
ReplyDeleteInteresting post. But I am wondering if all of the micro plastics are from the ocean. Does sea salt processing procedures have the potential to introduce plastic pollution?
ReplyDeleteGreat post, I thought that the Telegraph article made its point well but was much too short. I thought it could have benefitted if it mentioned more how the plastics were ending up in our table salt as well as the health implications of ingesting this. I think it is very unlikely that the average reader will look at the study the article is quoting and this can cause the reader to fill in any gaps themselves which can lead to misunderstanding and panic.
ReplyDeleteI wonder what sort of health effects this might have. I suspect at the amounts stated probably not much. Saying someone is consume "3 pieces" of plastic a day is ambiguous. What size pieces are we talking about and how harmful could this actually be?
ReplyDeleteI think this is an incredibly interesting article, and definitely shows how anthropogenic impacts on the environment are coming back to harm us. I'm curious to how the salt industry could address this contamination? I don't know much about the salt evaporation process but I imagine that a big change to the process would have to be made to address the plastic.
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