I have been pretty consistent on calling bullshit on a particular left-wing rallying cry of Roundup as an environmental issue. The demonization of this herbicide started as a way of opposing Monsanto's quest to take over the world's food supply, a worthy endeavor that was defeated a long time ago, but the bad science persisted. (This campaign directly affected my life in my scientist days, so one day I'll blog on it.) No, Roundup does not look like a carcinogen of any importance. It is the only herbicide licensed for use near water, as it doesn't move in the soil, and the alternative--plowing--leads to erosion and leaching of toxins. Up until now, I had considered it by far the least of evils for agriculture, environmentally, although I always maintained the caveat that it might disrupt microbial populations because some of them had the target enzyme EPSP synthase, and that further studies of effects on microbes were merited.

Well, the first such study came out that might be of concern today. Here's the link to the PNAS paper. I emphasize might. I emphasize might because this is going to be headlines in every left or environmentally-oriented news outlet.

The study: feed honeybees Roundup at concentrations that they might encounter from feeding on flowering weeds near an agricultural field, and one particular type of bacteria in their gut microbiome (Snodgrassella alvi) is depleted. This change in the gut microbiome of the bees leads to susceptibility to pathogenic bacteria. So, Roundup might be a contributory cause to bee decline.

What I liked most about the study was that they used newly hatched worker bees. These bees have near-sterile guts, as the microbiome is acquired socially. Older bees would be misleading, as dead bacteria accumulate in the gut. (Bees don't defecate.)

However, there is one experiment missing. I believe that the concentrations of Roundup used are found in agricultural fields. I believe that if you feed Roundup at these concentrations directly to bees in a lab, the deleterious changes to the gut microbiome take place. I believe that if these changes take place, there is enough likelihood of a contribution to bee decline that new regulation of agriculture is essential.

But two experiments are missing from this line of thought: one highly feasible, and one near-impossible. The near-impossible experiment is to prove that the bees that die under field conditions had these changes in the microbiome occur prior to death. You just can't find the remnants of dead bees in a field and assay their gut contents. They're dead. Their gut has already been rotting away, even if you could find them. It's not reasonable to demand an experiment that can't be done.

On the other hand, I'm not going to buy this line of reasoning until it can be shown that when Roundup is sprayed on a field such that the relevant amount of it is on flowering weeds at the side of the field, the expected concentrations of Roundup are later found in the guts of the bees that feed on the flowers. Easy experiment: (1) Spray Roundup and put a large cage over an entire field that includes honeybees; (2) Capture bees; (3) Dissect the guts out and measure Roundup content in them; (4) Do the required math to adjust for size of bee gut and report the concentrations found. If bees guts never experience Roundup at the relevant concentrations, we have a non-issue that should not be considered in regulation of agriculture.

With that one experiment and perhaps confirmation of the current work by an independent lab, it will be time for government action, but still not likely time for protest signs. There does not exist another herbicide that can be used near water. You can't demand immediate use of technology that doesn't exist.

Here's what I would do if I was US Secretary of Agriculture: (1) Immediately fund the studies needed to be sure of the science by a Congressional Appropriation. Do them in the ARS facilities of USDA, paid for directly. I can't imagine this is more than a few hundred thousand dollars of money required. (2) If the studies say action is necessary, impose a huge fine on all agricultural interests still using Roundup in ten years. (3) Provide match money to chemical companies/ag companies for research designed to produce a Roundup replacement: an herbicide that doesn't move in the soil, so it can be used near water, that is at least as environmentally and biologically safe as Roundup. (4) In the meantime, ban Roundup use on fields that are not near sources of ground water. There are plenty of other herbicides that can be used in those situations.

Environmental policy must be science-based. Even as we pillory the right-wing in the US for dooming much of the planet with short-sighted climate and other policies, the left cannot be allowed a pass on this issue. Sure, Monsanto has an evil history, but scoring a minor victory against evil capitalists is not worth a major loss for the environment.