Whole Foods has made a business decision. In its responses to scientists, municipal wastewater program managers and political leaders who had written to oppose their proposed ban on selling anything grown in biosolids amended soils, the company acknowledged noted the company’s concerns regarding beneficial use of biosolids:
Concerns include greenhouse gas emissions and the persistence, mobility and impacts of contaminants found in sewage sludge and biosolids including heavy metals and other chemicals from detergents, manufacturing processes, body care products, pharmaceuticals and pesticides, as well as human disease-causing organisms in the municipal waste stream. Potent impacts include long-term contamination of agricultural land and other soils, uptake by crop plants creating dietary risk and impacts on human health and on the health of aquatic and soil organisms in the environment.
As Whole Foods also noted in its letters, biosolids are only applied to 1% of the arable land (I’ve actually heard figures as low as 0.1% from Bob Brobst at EPA). And the apprehension of many of the Whole Foods customers (who fall into a different 1% category) also contributed to its decision to ban biosolids.
How’s your blood pressure? I’m just happy that I was already on meds before I read the company letter. I ‘m getting very tired of ‘science’ being used to show how hazardous biosolids are. I was really proud of these letters that were sent to Whole Foods, proud that scientists, program managers and political leaders are starting to stand up to this purported ‘science.’
The next few libraries will be devoted to providing peer reviewed science. The vast majority of the monthly topics in the library have been centered on biosolids and wastewater. For the Whole Foods rebuttal, I think that it is time to switch gears a little bit to provide some information on the USDA Organics Rule -- the one that is held as a gold standard by Whole Foods and others who are apprehensive about biosolids. The very same rule that allows use of animal manures but prohibits biosolids.
So animal manures are the gold standard fertilizer for the USDA organics rule. Just how clean and safe are these materials? Let’s start by considering pharmaceuticals, one of the categories called out in the Whole Foods response. If you look at the Whole Foods website, all of the meat that they sell comes from antibiotic-free animals. That is worth bragging about. In fact overuse of antibiotics is a gigantic public health concern. This was recently recognized by President Obama after recommendations from a report on the growing threat of antibiotic resistance (http://www.whitehouse.gov/sites/default/files/microsites/ostp/PCAST/pcast_carb_report_sept2014.pdf). The vast majority of antibiotics used in this country are used on animals. While animals are dosed with antibiotics when they are sick, the majority of antibiotic use is prophylactic -- to prevent animals from getting sick and to accelerate weight gain. According to Wiki (granted, not a perfect source) over 90% of the antibiotics used in the U.S. are given to animals for non-therapeutic purposes. So kudos to Whole Foods for its meat department policies.
But what about produce? Here animal manures are recommended as good practice for organic farms. In the USDA rule, animal manure that is added to soils must be composted prior to use IF crops for human consumption are to be planted immediately (http://www.ecfr.gov/cgi-bin/text-idx?SID=f942530becbc168d3f72eed8fbbeca6a&node=se7.3.205_1203&rgn=div8). If the manure is not composted, then farmers must wait 120 days before crops where the edible portion is in contact with the soil are planted and 90 days for crops where the edible portion does not come into contact with the soil.
If you want to use biosolids directly on produce, you need to meet Class A standards. Composting is a traditional way to do that. A recent review of literature showed that antibiotic concentrations in composted biosolids ranged from 0.006 mg kg for Erythromycin to 0.93 mg kg for Ciprofloxin. Concentrations of antibiotics in Class B biosolids were higher, from 0.006 mg kg for Sulfamethoxazole to 3.4 mg kg for Ciprofloxin. How much of the antibiotics that animals take end up in the manure? And how much of a hazard is that for soils, plants and the people who consume those plants?
The first article in the library gives results from sampling manures, soils and waters from swine and poultry production. The researchers sampled working operations and so were not able to get all the details that would be typical for a scientific trial. For example, manure application rates and time since manure application were not known. Concentrations of several antibiotics were measured. In the swine waste lagoon, tetracycline concentrations ranged from 0.066 to 0.54 mg l, that is wet weight. On a dry weight basis, it is likely that there would be a 5 - 10 x increase in concentration. Concentrations were generally much lower in the poultry operations measured. This article was included as it was cited heavily by the authors of the second article.
The second article is a review article, easy to read and really helpful. It discusses how much manure is produced each year, how animal raising operations have become increasingly concentrated, and what types and how much antibiotics these animals take. The drug adsorption efficiency is also discussed with quantity of total ingested that is excreted unchanged, ranging from 25 -75%, depending on the type of antibiotic as well as the source of the estimate. The paper also includes approximate half-lives of manures and concentrations (wet weight basis) of the different compounds in manures. The authors then go on to report results from studies on soil concentrations of different compounds, persistence in soils and movement to groundwater. Some of the news is good, some is bad. For example, movement to groundwater of a number of compounds seems to occur in tile drainage systems. And groundwater contamination with animal-related pathogens is already high. Persistence in lagoons can be limited. The authors also note the potential for antibiotic resistant organisms to develop in the guts of the animals and the potential for these to be secreted in animal manures. There is a lengthy discussion of how antibiotic resistant genes are transferred in environmental samples. In general, this article is a great primer and makes it clear that there is a lot we don’t know about antibiotics in the environment and that animal manures are a significant source of them.
In case you weren’t convinced by the first review, the third article is a second review. Here the first author is Kuldip Kumar, now a proud member of the Chicago Biosolids team. This article includes separate tables for each animal type that includes the dose rate and types of antibiotics used. You can also compare dose rates for people and pigs. Pigs take 11 - 55 g of penicillin per ton of pig. An average sow weight is 0.2 tons at slaughter so about 2 - 11 g of penicillin per pig with about 120 million pigs annually, about 80% of which are prophylactically dosed. In contrast, people take about 0.2 - 0.7 g of penicillin per dose and only when they are ill. This paper also provides a discussion of expected behavior in soils with information on biodegradation. As antibiotics are widely different in properties environmental behavior and persistence also varies widely. Table 16 shows percent tage degradation and days for a number of compounds. Temperature is a very significant factor in degradation rate, so residues in manures applied in the fall will likely still be there in the spring. Table 21 includes concentrations of antibiotics found in ground and surface waters in the U.S. This review includes a section on potential impacts of antibiotics in soils on plant growth and nutrient uptake. It also includes a discussion on the emergence of antimicrobial resistance in soil plant systems and the potential impact on human health.
The last two papers in the library include Ed Topp as an author. Dr. Topp has done terrific research on pharmaceuticals and personal care products in the environment. Here he takes on the potential for antibiotic resistance in manure-amended soils (4) and biosolids amended soils (5). For the manure paper, one time applications of swine and dairy manure were added to soils at agronomic rates for two growing seasons. Vegetables that are frequently eaten raw were planted directly into the soils. Total and fecal coliforms, E coli and other pathogenic organisms were measured on the manure samples. Antibiotic resistance markers were measured in the manures, soils and on the vegetables. Resistance ranged from below detection to 64.6% for the different manures. Viable populations of the different disease causing bacteria were measured on certain of the vegetables. Manure application increased antibiotic resistance in soils in 11 cases and decreased it in 4. A similar effect was seen for the vegetables with more cases of decreased resistance than increased antibiotic resistance. There was also evidence of changes in microbial genetics in soils following manure applications. In contrast, these changes were more pronounced in vegetables grown on the control soil than on the manure amended soils. The authors conclude that the benefits of eating your vegetables, even when grown on manure amended soils, far outweigh the risks. However, they also note that in addition to antibiotic resistance, pathogens are also present and recommend that manure be treated by anaerobic digestion, lime stabilization or composting prior to land application. Sound a little like PFRP?
In fact, if you look at the Topp paper on biosolids, you’ll see that PFRP really works. Here he looked at sludge and Class B biosolids. In contrast to a very similar table in the manure paper, you will see very low concentrations of target organisms in the Class B material. You will also see much lower concentrations of antibiotic resistant response in the treated biosolids in comparison to the sludge and the animal manures.
Topp used the same approach with biosolids as he did with manure with gene targets in the control and treated soils and vegetables. Data showed that for vegetables grown immediately after application of Class B biosolids gene targets associated with antibiotic resistance were present on plants grown in CONTROL soils with one type of resistance marker on tomatoes grown in biosolids and another in carrots, lettuce and radish grown in the sludge amended soil. During the second growing season, which corresponds to the regulatory waiting period for above ground crops (20 month waiting period for crops grown in soil) in the U.S., no antibiotic markers were detected. The authors conclude that ‘managing human exposure to antibiotic resistance genes carried in human waste through judicious agricultural practice, as commonly employed in Canada and the United States and as recommended by the WHO, is prudent and should be undertaken in all jurisdictions’.
So what does this mean about the produce section in Whole Foods? What it says to me is that the USDA Organics Rule is not a gold standard. There are a great deal of unknowns about antibiotics in the environment. Antibiotic resistance is a huge concern, and animals are the primary source of these genes in the environment. Condoning this practice by calling manure application a gold standard seems to be highly hypocritical. One could say that factory farming poses a much greater risk than regulated industrial discharge, but that is just me.
More to come in the next few months.