November 19, 2009 | General

Climate Change Connections

BioCycle November 2009, Vol. 50, No. 11, p. 44
Sally Brown

MY son has a friend whose mother loves him very much. She loves him so much that she is terrified, absolutely terrified, that something might hurt him. Because she loves him so much and is so afraid that something bad might happen to him, she seems determined not to let anything happen to him. He is not allowed to take city buses, go to his high school football games or ride his bike in the city and the list goes on. I worry about this kid. I worry that in his mom’s well-intentioned attempts to protect him from anything and everything, that when he finally leaves the nest, all sorts of hell will break loose. Hell that he has no tools to deal with.
So I do my best to help out. One of the things that he hadn’t been able to do was go swimming off of our housebarge because of the high potential to drown. I invited the kid, his mom and dad and some other kids over. The mom got to see the boat, got to see the other kids jump off and grudgingly agreed to let her son give it a shot. Not from the roof like the others, but at least from the lower level. She saw the happy kid coming up the ladder. He was fine. He had a great time. I like to think that doing this helped give him some tools for that flight out of the nest.
What, you are likely thinking, does this have to do with climate change?
Lately people have been asking me about contaminants in organics. I got an email from composters in San Luis Obispo about public concerns that the cadmium in the compost was a health threat to children at the school garden. A letter to the editor in the paper ended up getting the compost taken away from the schoolyard.
At this year’s USEPA Brownfields Conference, I’m the one slated to give a talk on contaminants and why it is or isn’t safe to garden at these sites. In getting ready for this talk, I’ve spoken to one EPA official who is very concerned about potential hazards related to contaminants in the soils and who is not sure that gardening is safe.
At our recent regional biosolids conference, one of our guest speakers talked about her risk assessment for triclocarbon, an antimicrobial used in hand soaps. There is a potential she said that land application of these biosolids could harm a group of birds over a 100 year period. This is a risk that needs further research and should be given due attention.


These concerns are each expressed by individuals and/or scientists who care about human and ecosystem health and safety. But I find myself getting as frustrated with these individuals I have with Homer’s mom. By focusing on perceived risks – rather than a broader understanding of risks and benefits associated with different practices – these well intentioned individuals have the potential to derail projects or practices that (within this industry) have a very high potential to provide an effective tool against climate change.
John Holdren, the President’s science advisor, described our approach to climate change like this: “We’re driving in a car with bad brakes in a fog and heading for a cliff. We know for sure that cliff is out there. We just don’t know exactly where it is. Prudence would suggest that we should start putting on the brakes.”
Land application of organic residuals is a way to put on the brakes. We know that organics on land:

Increase soil carbon concentrations: Soil carbon is the third largest pool of carbon behind the ocean and fossil deposits. Up until about 1980, losses of carbon from soils were the primary source of elevated CO2 in the atmosphere.

Provide an effective alternative to synthetic fertilizers: Fertilizers are highly energy intensive to produce. In addition, phosphorus ore reserves are nearing depletion.

Improve soil tilth and reduce erosion: Soil is a key resource to ecosystem stability. Soils help store and filter water and are the basis for terrestrial ecosystems. Soil is the living skin of the earth and is a resource that needs attention and protection.

Improves plant yields: Research has shown that organic amendments improve soil productivity. Soil productivity, particularly in light of the ramifications of climate change, is essential to survival (our ability to produce food).

For me, much of the concern about contaminants is like worrying about what radio station to listen to in the car and by so doing, neglecting the brakes altogether. Not using organics in soils because of a perceived risk related to contaminant concentration is a well-intentioned disaster. It is like not letting Homer out of the house until he is 18 because once someone got hurt on the steps. I say this because there has been a lot of excellent science on risk assessment of contaminants.
In last month’s issue I wrote an article that goes into detail on risk assessment for contaminants in urban soils. (See “Urban Soil Contaminants and Remediation,” BioCycle October 2009.) Risk is a function of both the frequency of exposure as well as the dose or concentration of the contaminant. Risk assessment is usually carried out to determine if there is a potential for harm to occur due to the presence of a particular contaminant. This assessment process includes an evaluation of the different ways that a contaminant has the ability to cause harm to an end receptor.
In the case of the San Luis Obispo schoolyard, a risk assessment analysis would include factors such as how much soil the kids are likely to eat, how much of the cadmium would be taken up by plants and what fraction of the kids’ total diet the plants grown in the school garden would comprise. For biosolids, the risk assessment process was based on an individual who grew 59 percent of their food in biosolids, ate meat grazed on biosolids amended pasture and did this for 70 years. The number that they came up with for cadmium was 39 parts per million (ppm). The compost in the school had 3.5 ppm.
So what is your role in this discussion about risk? For me, your job is to get the general public’s version of Homer’s mom over to your house. Understand enough about contaminants that you can answer questions in a coherent and respectable way. Don’t just call these questions stupid.
At the same time, you need to invite the public in to see what you do and explain the benefits of what you do. Let them try your material. Be willing to show them how to use these materials; classes and demonstration gardens are wonderful tools. You can even go to their house or neighborhood. Offer to hold workshops with different stakeholders. Always bring some of your product to these workshops. Land application of organics may not be the whole answer to the car driving towards the cliff. But as far as our industry goes, it is the tool that we have that lets you stop on a dime.

Sally Brown – Research Associate Professor at the University of Washington in Seattle – is a member of BioCycle’s Editorial Board, and authors this regular column on the connections of composting, organics recycling and renewable energy to climate change. Email Dr. Brown at

Sign up