Sharks test positive for cocaine in Brazil’s drug-polluted waters
Sharks test positive for cocaine in Brazil’s drug-polluted waters
Richard Ma
Peer-reviewed Article: https://www.sciencedirect.com/science/article/pii/S0048969724049477?via%3Dihub
Background
Cocaine (COC), a potent psychostimulant drug of abuse, is found in aquatic systems in the ng to ug/L scale alongside the main metabolite, benzoylecgonine. It is characterized as pseudo-persistent due to continuous environmental release from sewage facilities (3.7ng to 1200ng/L for Benzoylecgonine, 29ng to 2700 ng/L for COC, 2011-2017, 37countries, 60million+ samples), illegal refining operations, and drifting cocaine packs not recovered by sellers or authorities. Those have the potential to be swallowed by large fish, including sharks. Upon consumption, more than 90% undergo metabolization, releasing metabolites including benzoylecgonine (BE) (35-43%), ecgonine methyl ester (32-49%), and norcocaine (5%).
BE is found to be a strong vasoconstrictor and can significantly change expression levels of proteins related to calcium homeostasis and oxidative emergency at low concentrations, as well as having long-term toxicity on the cardiovascular system and central nerve system. Environmental COC levels have been reported as toxic to various aquatic organisms.
Wang J, Deng X, Wu Y, Huang Y, Hou S, Zhang Y, Qiu T, Tong J, Chen X. Sub-lethal toxicity and elimination of the cocaine metabolite, benzoylecgonine: a narrative review. Ann Palliat Med 2021;10(6):6936-6947. doi: 10.21037/apm-21-243
Studies focusing on wild fish are very limited, and no reports concerning elasmobranchs are available. Araujo et al. looked at COC and BE levels in Brazilian Sharpnose sharks (n =13) (off the coast of the state of Rio de Janeiro, south-eastern Brazil, 2021-2023) using LC-MS. All samples tested positive for COC, and 92% (12/13) tested positive for BE. COC concentrations (23.0 μg kg− 1) were over 3 times higher than BE (7.0 μg kg− 1). COC levels were about 3 times significantly higher in muscle (33.8 ± 33.4 g kg− 1) compared to liver (12.2 ± 14.2 μg kg− 1). Females presented higher COC concentrations in muscle (40.2 ± 35.8 μg kg− 1) compared to males (12.4 ± 5.9 μg kg− 1).
Several positive statistical correlations were noted between COC and BE (rho = 0.84) in females, indicating systemic COC transport and metabolization, as well as between BE and weight (rho = 0.62), and between COC and the Condition Factor (rho = 0.73). A strong correlation was noted between BE and COC in the muscles of nonpregnant females (rho = 1.00).
The paper describes the methods in great detail, including sample extractions and preparations, LC setup and gradients, and method validations. The authors also included interpretations of the correlations, stating that systemic transport and metabolization of COC and BE is observed; bioaccumulation is directly correlated with weight; and COC may have a systemic effect on the shark’s growth, maturation, and fecundity.
The authors provided speculation of the causes of the observed results in the Discussion section and proposed that COC and BE are first discharged in sewage through the major channels, and due to the coastal habitats that Sharpnose sharks display, they are highly exposed to anthropogenic pollution. The data suggests a differential accumulation pattern between sexes, unlike other contaminants such as metals. They also acknowledged that the sample number is low and that all males were juvenile whereas females were adults (potential differences in metabolic rates and pathways).
More science is described with citations from other studies, including the excretion dynamics between COC and BE, the pKa difference between regions, demographic information, etc. The paper itself is a strong scientific piece that provides a comprehensive analysis of the concentration of COC and calls for action for robust legal frameworks and proactive measures to address the issue.
News Article
The article by Rachel Pannett is short, provides accurate but limited data, and doesn’t go much deeper into the research work itself. Rachel accurately described the location and time for which the sharks were captured, 3 males and 10 females, and cited the publication directly. She is careful with her wording, using “suspect”, and “probably”, when stating the source of COC in the water, and agrees with the conclusions of the paper.
She then shifts the discussion to the Cocaine Bear, before correctly stating that this work is the first-ever evidence for cocaine detection in wild sharks. Rachel then highlighted the cocaine contamination found in waters around the world and used freshwater shrimp as an example of the effects on aquatic life. In the last paragraph, (some of) the main findings were highlighted correctly, with no exaggeration.
I think this article provides a great summary of the issue of cocaine contamination in the water system, citing multiple sources and providing a concise but accurate summary of each source. It would be a good starting point for people who do have an interest in this matter but also serves well as a telling article to read. There are not many technical terms in there, and is carefully structured so that the reader keeps their attention.
I think a bit more data will help, but given the targeted audience this is around a reasonable level of detail. The data would not help with the understanding of the research work but rather distract the readers. Rachel also picked sources that are open to the public, which is beneficial for the readers to follow up.
Overall, I would give this article a 6/10 for the concise summaries, easy-to-access citations, and overall level of detail (just right for the targeted audience). It does lack an explanation of the observed trends as well as the uncertainty in the data, and it may be beneficial to include at least one chart to help the reader understand the drawbacks of this study (limited number of samples, high standard deviation, the difference in the life stage of the shark, etc.).
1. Gabriel de Farias Araujo, Luan Valdemiro Alves de Oliveira, Rodrigo Barcellos Hoff, Natascha Wosnick, Marcelo Vianna, Silvani Verruck, Rachel Ann Hauser-Davis, Enrico Mendes Saggioro, “Cocaine Shark”: First report on cocaine and benzoylecgonine detection in sharks, Science of The Total Environment, https://doi.org/10.1016/j.scitotenv.2024.174798.
2. Wang J, Deng X, Wu Y, Huang Y, Hou S,
Zhang Y, Qiu T, Tong J, Chen X. Sub-lethal toxicity and elimination of the
cocaine metabolite, benzoylecgonine: a narrative review. Ann Palliat Med
2021;10(6):6936-6947. doi: 10.21037/apm-21-243
3. Thomas
H. Miller, Keng Tiong Ng, Samuel T. Bury, Sophie E. Bury, Nicolas R. Bury, Leon
P. Barron, Biomonitoring of pesticides, pharmaceuticals and illicit drugs in a
freshwater invertebrate to estimate toxic or effect pressure, Environment
International, https://doi.org/10.1016/j.envint.2019.04.038.
4. Iolana
Campestrini, Wilson F. Jardim, Occurrence of cocaine and benzoylecgonine in
drinking and source water in the São Paulo State region, Brazil, Science of The
Total Environment, https://doi.org/10.1016/j.scitotenv.2016.10.089.
5. J.P
García-Cambero, H. García-Cortés, Y. Valcárcel, M. Catalá, Environmental
concentrations of the cocaine metabolite benzoylecgonine induced sublethal
toxicity in the development of plants but not in a zebrafish embryo–larval
model, Journal of Hazardous Materials, https://doi.org/10.1016/j.jhazmat.2015.08.019.
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ReplyDeleteI really enjoyed your summary and analysis, Richard. However, I disagree with your rating of this Washington Post (WP) article as 6/10. Yes, it is true that the article does not go into the nitty-gritty details of the statistics and uncertainties in their data. However, broadly speaking, I think a general audience would not gain much from a high standard deviation. Instead, the uncertainty may be clear by a small sample size, which the WP article mentioned in the second paragraph. To your point about graphs and figures, I believe a general WP audience would struggle to find meaning in the box-and-whiskers plot as these plots require more attention. As per trends, the WP article describes the gendered differences in its concluding paragraph. Despite the lack of trend discussion for juvenile vs. mature sharks, I believe that due to the small sample size this exclusion may be justifiable if intended. Overall, the WP article faithfully reproduces the science, connects it to popular media, and describes why we should care. In my eyes, this is a perfect 10/10 article.
ReplyDeleteHi Joe, thanks for the reply! I would agree with your rating as well. I was very conservative in my ratings, and I would agree that it deserves a higher grade given your reasoning. I read it through again without using my science part of the brain, and it conveys the point nicely as well as underlining the importance of this topic very clearly. I think Rachel did a great job of picking what should be included, probably after reading the publication a couple of times, and has done an outstanding job of thinking from an audience's perspective.
DeleteThe topic of the scientific paper and the journal report is really astounding. There is so much cocaine being produced that it is becoming a pollutant and affecting aquatic wildlife. I knew that there are environmental impacts from legal pharmaceutical production, but I guess it never occurred to me that illegal drug production would also play a role.
ReplyDeleteI would have given the Washington Post article a higher rating like 8/10. I felt like it was a good summary of the research article because the study is pretty cut and dry. In the study, I think the clear point is made: there is a significant concentration of cocaine and its metabolite in a sampling of Brazilian Sharpnose sharks. Would it have made the article stronger to discuss the statistics? In my opinion, no. However, I think including a small discussion about the differences between pregnant female sharks and non-pregnant female sharks would have raised additional concerns to the reader about the cocaine's long-lasting impact on the ecosystem. I do agree with you though that the study itself seems rather limited. Is the sample size of 13 sharks, 10 of which are female, truly representative of the shark population? I don't think the burden is on the Washington Post to say one way or another. I liked how the Washington Post explained why the researchers chose the Brazilian Sharpnose sharks to study. Adequate context was given, even if some of it was the fabled Cocaine Bear. Quotes were taken directly from the research article. I think this is what should be done in news reports so as to minimize misinterpretation to the public.
Also, apparently you can buy deuterated cocaine as an internal standard for LCMS analysis??? Wild.
Thanks for the reply and for reading my post! I would agree with your rating and your reasonings for the score, and I do see that the statistics would not help the reader by much. It's also fair that it is not up to the Wash post to say weather the sample set is representative or not. I love the direct quotes as well, they give more trustworthiness to this article and offer the audience a peek into the article without actually reading them.
DeleteI didn't know you could do that as well and it's cheaper than I thought. The deuterated one is about ~$120 per mg in MeCN, but the nondeuterated COC is restricted (obviously).
Richard, great analysis. I thought the news article did a great job reporting the facts and making the content relatable to general readers. I found myself disappointed that Pannett didn’t end the article with a more impactful, “going-forward” sentence or call to action like the scientific article; therefore, I agree with your rating (6/10). I also I really liked the pictures included in the news article and thought they kept the audience captivated in the subject.
ReplyDeleteIn the concluding paragraph of the scientific article, the authors gives great examples/actions that people can implement to prevent further environmental pollution: incorporate monitoring & mitigation strategies into existing environmental legislation, increase public awareness through education & more collaborative initiatives. I found the scientific article much more impactful then the news article which I find disappointing because the WP has a lot more power in reaching larger general audiences.
What do you think? Do you think the WP article was impactful enough to create or inspire change/action among readers?
Hi Mia, thanks for reading! I too think that the news article could and should have included the part that the authors wanted for this work: make a general awareness of this problem so that policies or regulations could be made. Given how much influence (audiences) the WP has, they could have turned this into a more serious "This is happening and we should do something about it" article. I understand that it could be beneficial to the click counts to keep the piece away from policies and more toward entertainment, but it does not harm to at least include a few sentences at the end.
DeleteLike Mia said, I'm also a bit surprised that the news article didn't have a stronger call to action. The comparisons between juvenile and adult female shark samples could've led to a stronger discussion on the pollutant impact and supplemented a call to action. The author does a good job of conveying the overall facts, especially given that her previous work consists of more global political news. Given the relatively small sample size and the skewed female to male ratio, do you think they should've used a different sampling methodology for shark capture?
ReplyDeleteHi Teresa, thanks for replying! It's a good point that other sampling methodologies or analytical methods could be used. Their sample preparation is multi-step and requires multiple transfers, which could have led to sample loss and falling below the 1ug/kg detection limit. I do think they have strings attached when it comes to shark capturing, due to local or global laws and policies. But it would be very beneficial if improvements could be made for capturing, increasing n, and balancing different ages and life stages of the sharks.
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ReplyDeleteRichard, this is a really interesting topic. Its surprising to me that there wasn't more research in this area for the authors to reference. It would be very interesting to see future work in this area. The news article briefly mentions the idea of cocaine entering the food chain as the sharks are fished for their meat. I would be curious to know more about the metabolic lifetime of cocaine in different fish species and whether or not the amount poses any risks for human consumption. Pannett quotes the paper, describing how the amount of cocaine and metabolites in the sharks “exceeded levels reported in the literature for fish and other aquatic organisms by up to two orders of magnitude,” but does not report the actual magnitude of contamination. I think that is a weakness of the article as the title is so eye-catching, it seems vital to be precise with what claims are being made. I think the article leaves the reader in a precarious position where it is not clear how concerned they ought to be.
ReplyDeleteThanks for the reply! Although outside the scope of this paper, I think human consumption is possible, and I've found a few papers elsewhere that talked about the inability of the regular water process to completely filter out cocaine. However, the concentration is low when considering human consumption (after process). It is definitely interesting to see the comparison between different fish species, and maybe a longitudinal study would also be beneficial.
DeleteI really enjoyed your analysis of the news and academic article. I think it is just the right amount of detail for the average reader to understand and does get across the major points of the article. I also agree with your rating of a 6/10. Although there were not any factual inaccuracies, I do think that the article focused more on the "silly" nature of a cocaine shark rather than a call to action. I saw "Cocaine Bear" (2023) and it was not at all accurate, but nonetheless it was a slasher comedy horror movie that I really enjoyed. I felt that this article was focusing on the ridiculous nature of sharks on cocaine by drawing this parallel to the movie, but did little to address the issue at hand. Rather than drawing parallels to this movie, I think that the Washington post article should have stated a stronger call to action and included more of the negative implications of cocaine in waters surrounding Brazil. Cocaine in the oceans is causing environmental harm and writing about it in the context of its ridiculousness, rather than the root issue, makes the problem seem less servere.
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