Monsanto’s Herbicide Might Be Killing Farmers

A widespread renal disorder, referred to as Chronic Kidney Disease of Unknown etiology (CKDu), has been afflicting agricultural rice paddy workers in Sri Lanka since the mid-1990s. This particular type of renal disease is distinct from the known CKD in that its victims remain asymptomatic and do not suffer from diabetes mellitus, hypertension, or glomerular nephritis; indicators normally associated with the CKD. Research groups, including the World Health Organization, have worked to determine the cause of this CKDu endemic. And while arsenic (As), cadmium (Cd), and pesticides are noted to be the disease’s main contributing factors, scientific consensus on the disease’s etiology has not been reached.

An online Vice News article reports a probable cause of CKDu based upon one study’s hypothesis recently published by the International Journal of Environmental Research and Public Health. Researchers Channa Jayasumana, Sarath Gunatilake, and Priyantha Senanayake have hypothesized that glyphosate, more commonly known under its Monsanto brand name, “Roundup,” is the primary culprit. 

However, glyphosate does not work alone. A number of other important factors, notably water hardness and nephrotoxic metals, such as arsenic, compound the chemical’s deleterious effects. For instance, in regions of Sri Lanka where water hardness is categorized as “hard” or “very hard,” prevalence of CKDu is much greater, as is illustrated in Figure 1:

Figure 1. Geographical distribution of patients with CKDu and ground water hardness in Sri Lanka. Ground water hardness data- with the courtesy of Water Resources Board of Sri Lanka.  

Glyphosate is the most widely used herbicide both in Sri Lanka, and the world. Originally patented by Stauffer Chemical Company as a descaling agent to clean calcium and other minerals from pipes, glyphosate is a well known metal binder. Rice paddy soil in CKDu endemic regions are high in metals, including Ca, Mg, Fe, Cr, Ni, and Co, which thereby combine readily to glyphosate. Exacerbating the problem is that TSP (triple super phosphate), a fertilizer which has been demonstrated to contain a significant amount of heavy metals, such as Cd, Cr, Ni, and Pb, is applied to the rice paddies within two weeks after glyphosate spraying. 

Both CKDu patients and non-CKDu afflicted individuals have been shown to have toxic levels of arsenic in their biological samples. Arsenic toxicity, primarily from the use of contaminated agrochemicals, in combination with Ca and Mg found in hard water, is what ultimately leads to significant kidney damage and CKD. While the source of the arsenic remains a contentious point, “Compound X,” dubbed by the researchers to be the unknown agrochemical at the root of the CKDu epidemic, matches the same characteristics as glyphosate. Furthermore, in the Northern Province of Sri Lanka, where ground water is particularly high but there are relatively low use of agrochemicals due to governmental prohibitions, CKDu is not prevalent.

On the whole, Vice News contributor, Neha Shastry, does a fair job representing the International Journal of Environmental Research and Public Health study. However, she does places a slightly greater attention on the role of glyphosate alone in CKDu, rather than the combined effect of the agrochemical with hard water and the nephrotoxic metals. And while Shastry omits some other pertinent information, including: glyphosate’s metal binding properties, its distinction from known CKD, the use of contaminated TSP, the statistically significant correlation between water hardness and CKDu in afflicted regions, and a greater emphasis on the absence of the disease prior to the mid-1990s, she does capture the report’s essence and relays it to a main stream audience without the use of flowery language or exaggerated claims. Lastly, Shastry’s inclusion of Monsanto’s response, as well as noting the EPA’s recent approval to raise glyphosate residue concentrations in produce, provides an interesting 360-degree view of the issue. However, I would argue that the EPA's latest ruling may or may not be relevant in this article's regard, as additional information surrounding the approval is not detailed. 

Using phytoremediation for the removal of 2,4,6-trinitrotoluene

Explosives and explosive-related materials are used in many capacities, which include mining, surface quarrying, construction and demolition, and weapons manufacturing. While explosives, such as 2,4,6-trinitrotoluene (TNT), have acted as useful avenues for the advancement of human civilization, there is a side to TNT that we rarely think about, let alone discuss: what happens to TNT after an explosion? Not all TNT is consumed during an explosion. In fact, the after-explosion TNT residues are considered pollutants that settle over millions of acres at waste sites, mining areas and conflict (war) zones. These residues are very toxic to animals, but also degrade the biodiversity in soils and severely disrupt plant foliar growth and root systems. In order to remediate these contaminated soils researchers often use phytoremediation, or the use of plants as a “filter,” to removed pollutants from soil and water medias.

In light of these issues, a recent article from The Christian Science Monitor (CSM) titled “Mutant plant munches TNT, could help solve cleanup problems,” discusses a study from the United Kingdom’s University of York recently published in Science that makes use of a mutated relative of the cabbage plant, Arabidopsis thaliana, to remediate TNT-contaminated soils. In the study, led by Rylott and Bruce, Arabidopsis was selected due to its greater root growth in the presence of TNT, thereby being more tolerant to TNT presence than most plants and a better candidate for TNT detoxification by living plant organisms. The researchers mutated a gene in the plant strain to cause a deficiency of a specific enzyme, monodehydroascorbate reductase (MDHAR6), which protects plants from oxidative stress. This enzyme generates a superoxide from TNT, which as, a reactive oxygen species, would oxidize and breakdown plant material (figure below). While the principal investigators expected the mutation would increase the performance of enzymes in the plant to detoxify TNT, the mutation instead did not produce any MDHAR6, thereby making TNT completely harmless to the plant. This increases the mutant plant’s tolerance and maintains its uptake of TNT in contaminated soils. The tolerance of the mutant Arabidopsis is specific only to TNT.

The CSM article, which is largely a summary of the peer-reviewed article, does however contribute further statements from the researchers. The researchers state that there are still a few speed bumps that need to be taken care of in the follow up research, namely the confirmation that TNT remains inactive after death and decomposition of the plant material. But they are hopeful in the article, stating he is “..fairly confident that the TNT’s been locked up in the this material…it’s incredibly difficult to extract the transformed TNT once it’s been taken up into the plant.” The articles goes on to say that the greatest issue lies in public acceptance of using these mutants to remediate soils, since there is a general public aversion to using genetically modified organisms (or GMOs).

I felt as if the journal article stated the issues with using the modified Arabidopsis very well, that is, the fixation of TNT within the plant media during decomposition of the material. However, if the TNT is not fixated, this could create disposal issues. If not fixated, TNT will continue to be present in affected areas through the plant life cycle, and other disposal methods, such as burning,  may not be applicable here due to the nature of the pollutant. Overall, I found the CSM article very representative of the peer-reviewed journal article and appreciated that it was straight science in layman’s terms without any leaning politics or “sensationalizing” incorporated by the CSM author.

  

DDT and PCBs Linked to Abnormal Sperm

It has been shown that aneuploidy, the occurrence of abnormal chromosome numbers in a cell, contributes to miscarriages and congenital abnormalities. While the causes are unknown, scientists have found that the problem occurs at nondisjunction during spermatogenesis, and suspect that environmental pollutants may play a large role in this.

In a recent journal article published in Environmental Health Perspectives, the authors aimed to investigate whether environmental exposure to persistent organic pollutants, specifically dichlorodiphenyldicholorethylene (p,p'-DDE) and polychlorinated biphenyls (PCBs), were associated with sex-chromosome disomy in men. To do so, they did a 22-year study on the males of the Faroe Islands, which is a population exposed to above-average levels of organochlorine pollutants due to their seafood-rich diet. They began with 747 Faroese men, 242 of which were part of a “birth cohort”, which consisted of people born between 1986 and 1987 and had biological samples and information on physical health and environmental exposures obtained at birth. They participated in follow-ups at age 14, and also agreed to participate in studies of semen quality at age 22. Our of all 747 participants, 90 were then randomly selected as samples, in which 40 were birth cohort, 12 were fertile (fathers cohort), and 38 were randomly selected men. In addition, data on in utero exposures via cord blood samples were available for 40 participants and at age 14 for 33 participants.

The study found that both adult and age 14 DDE and PCBs serum concentrations were associated with significantly increased rates of chromosomes XX18, XY18, and total disomy. But cord blood concentrations were not significant with sperm disomy. There was also evidence of a negative association between DDE and YY18, but results for PCBs and YY18 were inconsistent.

In the popular media article from Scientific American, I was pleasantly surprised by their accurate reporting and concise usage of language. They made the science more readable and related the findings to how they can impact our lives, specifically sperm abnormality and governmental policies.

They gave a general overview of the study by stating the sample sizes and findings, but it did so selectively. It noted that the scientists "examined sperm and blood samples from 90 men from the Faroe Islands... [and] for 33 of the men, they also had blood samples at age 14". They failed to mention the three different "cohorts" that the scientists randomly selected these men from, and how they controlled for the experiment. The article also generalized the findings, saying that "men with higher levels of DDE... and... PCBs... at 14 years old had higher rates of abnormal sperm". It's important to remember that only specific aneuploidies were found, and that results for PCBs and YY18 was actually inconsistent.

Agricultural insecticides threaten surface waters at the global scale

Over the past six decades, there has been an incredible increase in the volume and intensification of agriculture throughout the world. Recently, the majority of this transformation has occurred, and is occurring, in developing nations. As a result, pesticides are applied over an increasing share of the Earth’s surface, placing more and more ecosystems at risk of pollution, warns this Washington Post article by Kollipara, citing this study by Stehle and Schulz published in PNAS. Although pesticide usage is prevalent in many areas, there is a scarcity of data on the amounts and effects of these chemicals on surface waters, which has the potential for dire ecological and human health consequences.

Stehle and Schulz compiled data from 838 studies on pesticide concentrations in surface waters globally and determined which of these concentrations exceeded regulatory threshold limits (RTLs) for 28 different insecticides. From this meta-analysis, the two most striking conclusions were:

1. There is no data on pesticide concentrations in surface waters near about 90% of global cropland.
2. Over 50% of the measured insecticide concentrations (MICs) exceeded their respective RTLs.

Fig. 1.

Global crop area and the distribution of regulatory threshold level (RTL) exceedance rates for reported measured insecticide concentrations (MICs, n = 10,659) aggregated in 1° grid cells.

The Washington Post article effectively communicates these two points, without ‘overselling’ the results. In fact, the author makes sure to elucidate what is and isn’t implied by these results. Regarding the exceedance of regulatory limits, the author explains how this doesn’t necessarily translate directly to risk: “Just because pesticides are toxic doesn’t mean they’ll actually pose risk – of causing a disease or damage to the environment”. The researchers made sure to caution against applying their risk predictions to the 90% of remaining cropland, which is also communicated well by the Washington Post author: “That doesn’t mean that these lands’ surface waters are tainted with pesticides, much less that the pesticide levels are too high.”

Overall, the Washington Post article does an adequate job of communicating the major conclusions of the study without exaggerating the analysis, and also of explaining the researchers’ methods in simpler language. However, there were a few shortcomings of the article. One inconsistency I found was that the article stated that the exceedances occurred in “similar amounts” between countries with weak regulatory systems (designated as LERQ countries in the study) and countries with strong regulatory systems (designated as HERQ countries in the study), while the study indicated that these amounts were significantly different (p<0.001). Still, 39.9% exceedance in HERQ countries compared to 42.4% in LERQ countries is similar enough to be concerning. Also the article failed to explain the challenges in assessing environmental risk from pesticide exposure, which the study attributed to the fact that organisms’ exposure is limited to acute amounts near the time of application and also that organisms are exposed to a number of different pesticides simultaneously, and the interaction effects were not accounted for. Finally, the researchers in their analysis urge the need for better regulation of pesticide usage, citing their results as evidence that the current regulation schemes are not effective. This agenda is, perhaps purposefully, not included in the Washington Post article.

Plastics found in table salt

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.

The troubling reason why deep ocean mercury is reaching California’s coast

There are many ways for putting toxic mercury into the environment to cause pollution. The most common ways are releasing gaseous mercury into the atmosphere and dump waste into water. When microbes in the seawater absorb mercury, they convert it into a powerful neurotoxin called “methylmercury”, which can be transferred among predators, until it reaches the top of the food chain - human. That’s why scientists pay very close attention to this issue.

                                                                                                      

A recent article in The Washington Post discusses a new study published in Proceedings of the National Academy of Sciences, which suggests that the water in coastal areas can be contaminated by mercury from the fur of seals coming from the ocean. The article describes the results of the research done by Cossaboon and his team at Año Nuevo – the area that elephant seals reside. The research shows that the seawater at Año Nuevo has an eight times higher level of methylmercury than that of other sites along the California coast, and there is a peak during the elephant seal molting season. Researchers then tested the molted fur, and found mercury in it. Giving the fact that elephant seals don’t eat at the coast, it’s reasonable to assume that they carry the mercury all way from the ocean. However, because there have been no obvious signs of other marine organisms being damaged, and Año Nuevo is not used for fishing, it’s still unclear how much impact the mercury in this area have on human.

  Nearshore seawater sampling locations. (A) Locations of Año Nuevo and comparison sites along the Central California coast. (B) Detailed map showing the sampling stations at the south end of the Año Nuevo mainland breeding rookery during the 2012 Northern elephant seal molting season (M1–M6) and 2013 breeding season (B1–B6), as well as the Cove Beach Año Nuevo State Reserve sampling site.

   MeHg and HgT in nearshore unfiltered seawater samples. (A) MeHg concentrations for the Año Nuevo mainland rookery during the 2012 molting season (M1–M6), 2013 breeding season (B1–B6), and Central California comparison sites. (B) HgT concentrations for the rookery during the 2012 molting season, 2013 breeding season, and Central California comparison sites. Error bars (±1 SD) indicate the sample was analyzed at least three times. HgT for B5 (1,650 pM) was considered contaminated and is not graphed.

The study measured the concentration of total Hg (HgT) and methylmercury (MeHg) at Año Nuevo and nearby shores that don’t have great marine mammal populations, respectively. Data showed that the concentrations of HgT at Año Nuevo (3.1~34.0 pM ) and nearby shores (9.2~41.7 pM) had no distinct difference. On the contrary, the MeHg level had an obvious increase at Año Nuevo during molting season (0.28~9.5 pM) compared to that of breeding season (0.39~0.83 pM) and that of nearby shores (0.16~0.41 pM). Scientists then tested the molted fur samples from Northern elephant seals and found that they contained a high level of HgT concentrations, >80% of which are presumed to be MeHg. The results indicate a strong relationship between the increasing concentration of MeHg at Año Nuevo and the molted fur of Northern elephant seals.

One big concern for scientists is that along the shoreline of the U.S. Pacific Coast reside hundreds of thousands of seals and sea lions, all of which have the potential to increase the MeHg concentration in the seawater. So it’s important to understand the mercury cycling in the ocean and its effect on human.

Generally, I think that the article did a good job at objectively summarizing the main idea of the study. It didn’t use exaggerated language to spark unnecessary concern. Also, it pointed out the limitation to the research: Because scientists only tested methylmercury levels in the seawater, instead of other marine organisms, it’s still not clear how much havoc can mercury cause to wildlife and human. However, I think that the author could have used some numbers and simplified figures, instead of conceptual words like “higher” or “increase”, to make the conclusions more intuitive and powerful. For example, putting the concentration levels of total Hg and methylmercury and the diagrams of the comparative tests, which are not hard to be understood by the general public, into the article. Furthermore, the study discussed the role of M. angustirostris, other pinnipeds and marine birds in releasing mercury into the seawater at Año Nuevo, and the reason why their contribution can be ignored. But the author failed to mention these things, which I think could have strengthen the article and help people to understand why molted fur of sea seals are so important and should be pay close attention to.