Being a Scientist is a Job
At the 2016 Biofest, Andrew Carpenter (Northern Tilth) and I had the pleasure of doing a joint presentation on carbamazepine, the anti-convulsive medication that has received a lot of attention in the scientific literature as an emerging constituent of concern in biosolids. I went first. sporting a lab coat and showing black and white slides. I presented data from high visibility peer review journals that ‘clearly’ show the hazard of this compound in land applied biosolids. As I finished my portion of the talk with dire warnings of impending doom, Andrew raised his hand and thanked me for my work. He then proceeded to take apart my presentation slide by slide, using simple math and some very solid, if less melodramatic science. He pointed out that many of the ‘high alarm’ studies had used pure carbamazepine added to soils, not carbamazepine in biosolids. He pointed out that the studies that had seen some plant uptake had high enough concentrations in soils that you couldn’t even find biosolids anywhere near them. He quoted studies with real biosolids that showed no plant uptake and negligible risk. He finished by putting the minimal risks associated with this compound into the context of the significant benefits associated with biosolids. His slides were all in color. The talk (first item in the library) showed both how much of the ‘sky is falling’ science related to biosolids is structured and then followed it with tools to both interpret that science and respond to it.
Before you get angry at the scientists who publish the sky is falling work related to biosolids, you have to understand that they are just doing their jobs as they understand them. Being a scientist is a job, not quite the same as driving a truck but it also is not completely different. Yes, you need to get a PhD, but just like driving a truck, you don’t show up, you don’t produce; you don’t have a job. A job that you had to spend 4 years in college, two getting an MS and typically more than three for the PhD plus the post doc before you actually got it. Once you have the job, it is part of your duty to bring in grant funding and to publish your results in high impact factor journals. These journals are the scientific equivalent of getting front- page coverage. In certain cases, if your work is ‘splashy’ enough, you can even make it from those journals to the real news. If not quite an ivory tower, then academia is often far removed from the real world, so sometimes the relationship between your research and the real world is vast. That makes it difficult to make that ‘splash’.
Biosolids has come to represent a sweet spot for many of these scientists. So few of us in the US are aware of wastewater treatment and the decades of work and good practice that have gone into developing biosolids programs, that it is easy to sound the alarm about constituents in biosoilids. Biosolids are a mirror of how we live and talking about scary things that we see in that reflection is one way to hit the trifecta: grant funding, publications in peer review journals, and even occasional coverage in the news. A good portion of the scientists that work with biosolids inhabit that ivory tower, or at least have a lab in a building a long way from a land application site.
When these or any scientist starts to work on developing an understanding of the behavior of a potential contaminant in the soil plant system, the first thing that they typically do uses a ‘proof of concept’ approach. This is the metals added as metal salts, compounds added without the biosolids, sometimes not even using soils- to see if plants will take up the compound. Andrew and I picked carbamazepine for our presentation because it is a compound that fits the bill for high potential for plant uptake. It has a relatively low formula weight (how much one unit of the compound weighs), it is ubiquitous in biosolids, takes a relatively long time to mineralize (decompose) and has characteristics that suggests that plants may take it up. We have had two libraries on carbazapine (June 2013 and November, 2015) that include a lot of this preliminary type research with plenty of alarm bells sounding. As a reminder of this kind of work, we go to the second article in the library where plant uptake of carbamazepine was demonstrated yet again. Here the authors used real biosolids- spiked with the drug. So, a little bit better than the direct spiking but not much. In fact the final concentrations in their spiked soil were about the same as in pure biosolids. They justify this by saying that they wanted to be sure to be above detection. So while some plant uptake was detected, take these findings with a grain of salt.
After you prove the concept or potential threat, the next step in research is typically to move to more realistic field conditions to see if what you have demonstrated in the lab holds true in a setting that resembles reality. For the third paper this month, the scientists have gone one step past that. The study focuses on plant uptake of carbamazipine and adsorption by people that eat those plants. The source here is reclaimed water and the work was done in Israel, a nation that depends on reclaimed water to grow a significant portion of their food. The authors did find plant uptake and found some carbamazepine in urine in the test group. Some was also found in the control, likely because of the widespread use of reclaimed water to grow truck crops in Israel. The authors note that reclaimed water is a resource and that the levels found in urine were several orders of magnitude lower than those in people that actually take the drug- suggesting that risk to the population as a whole is likely minimal.
Finally, when you have enough data, you can use that to develop models of potential risk to the population from these compounds in biosolids. The last two papers both present risk assessments associated with carbamazepine and other compounds in biosolids. The both conclude that the risk is minimal. So maybe this signals that it is time to turn the page on pharmaceuticals. My recent perusing of Environmental Science and Technology – one of those high impact journals that loves to cry wolf- showed very few papers on these compounds. In fact a new paper by Rolf Halden (one of the big alarmists on the topic) in the journal is focused on these compounds in household dust.
But don’t get too relaxed, there were an awful lot of papers on nanomaterials in the environment. Move over carbamazepine, and make room for nano silver.