Toxicology and Remediation in Agroecology Systems

“In the 21st Century, every garden is a bioremediation project”

Ben Falk, Whole Systems Design, LLC

The Problem points to the Solution.

As human populations increase and spread outwards from urban areas, trails of industrial toxicity follow our every move.  Urban and suburban areas are constantly exposed to toxins from industrial manufacturing that seep into our soils, leach into our water sources, and hover in the air we breathe.  Our farmland is treated like an industrial production site, soaked with chemicals in the form of agro-fertilizers, pesticides, and herbicides that stick to the food we eat and wash into the water we consume daily.  These toxins include carcinogens (cancer-forming chemicals), endocrine disrupters (chemicals that disrupt hormone functioning), neurotoxins (attack nerve cells), mutagens (chemicals that change DNA in cells) and teratogens (that  cause abnormalities during embryonic development) that take on familiar forms throughout our homes and communities.

In 1962, Rachel Carson’s Silent Spring served as the voice of the canary in the mine shaft, exposing the toxic biomagnification of pesticides like DDT on the food chain.  Today, the siren is still ringing and has reached popular media.  In 2008, Dr. Joseph Mercola, founder of http://www.mercola.com, the second most popular wellness site after WebMD, published a listing of the most common household items that pose serious environmental and human health concerns over continued exposure.   In 2010, TIME magazine published a full listing of 10 most common toxins found in U.S. households, warning parents of the risks for exposure.  The following is a summary comprised by Professors William P. and Mary Ann Cunningham (2012):

Atrazine most widely used herbicide in America.  More than 60 million pounds are applied per year, mainly on corn and cereal grains, but also on golf courses, sugarcane, and Christmas trees.  Disrupt endocrine hormone functions in mammals, resulting in spontaneous abortions, low birth weights, and neurological disorders.  In 2003 the European Union withdrew regulatory approval for this herbicide, and several countries banned its use altogether. 

Phthalates are found in cosmetics, deodorants, and many plastics (such as polyvinyl chloride and PVC) used for food packaging, children’s toys, and medical devices.  Known to be toxic to laboratory animals, causing kidney and liver damage and possibly some cancers.  Endocrine disruptors have been linked to reproductive abnormalities and decreased fertility in humans.

BPA (BIsphenol A) a key ingredient of both polycarbonate plastics and epoxy resins, is one of the world’s most widely used chemical compounds.  Used in items ranging from baby bottles, automobile headlights, eyeglass lenses, CDs, DVDs, water pipes, the lings of cans and bottles, and tooth-protecting sealants.  Traces of BPA are found in humans nearly everywhere…In one study of several thousand adult Americans, 95% had measureable amounts of this chemical in their bodies.  Unbound molecules can leach out, especially when plastic is heated, washed with harsh detergents, scratched, or exposed to acidic compounds, such as tomato juice, vinegar, or soft drinks.  BPA is linked to a myriad health effects, including mamary and prostate cancer, reproductive organ defects, cardiovascular disease, type 2 diabetes, liver-enzyme abnormalities.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA or C8) used to make nonstick, waterproof, and heat stable, stain-resitant products such as Teflon, Gortex, Scotchguard, and Stainmaster, in airplanes and computers to cosmetics and household cleaners.  Shown to cause liver damage as well as various cancers and reproductive and developmental damage.  In 2005, EPA announced the start of a study of human health effects of these chemicals.

Polybrominated diphenyl etheres (PBDEs) is a flame retardant used in textiles, foam in upholstery and plastic in appliances and computers.  150 million metric tons (330 million lbs) of PBDEs are used every year worldwide. European Union has already banned PBDEs.

Perchlorate is a waterborne contaminant left over from propellants and rocket fules.  Tests of cow’s milk and human breast milk detected perchlorate in nearly every sample from throughout the U.S.  Can intefere with iodine uptake in the thyroid gland, disrupting adult metabolism and childhood development.

Persistent Organic Pollutants (POPs) are found in pesticides and are extremely widespread: found from Tropics to the Arctic.  POPs bioaccumulate in food webs and reach toxic concentrations in long-living top predators such as humans, sharks, raptors, swordfish, and bears.

One year after Japan’s Fukushima nuclear power reactors were severely damaged by climactic earthquakes and subsequent tsunamis that ravaged the island nation, they are still emitting high quantities of radioactive cesium, radioactive strontium, and other isotopes that cause cancer and birth deformities.  Arnold Gunderson, Energy Advisor from Fairewinds Associates in Vermont, found that areas from 30-60 km from the site are so contaminated with radioactivity that “people should not ever return.” In Tokyo, 250 km away, five samples were taken from soils and all were found to contain radioactivity strong enough to be considered nuclear waste by U.S. standards.  Despite the warnings provided by Fukushima, over 60 nuclear energy plants continue to be built today with no means for mitigating nuclear disasters.

“The question is whether any civilization can wage relentless war on life without destroying itself, and without losing the right to be called civilized.”
― Rachel Carson

One would think that such a glaring problem that affects so many areas of our lives would bring instant reform of industrial and agricultural practices. Despite widespread scientific research, analysis and stark evidence of the environmental and human health impact of these industrial chemicals,  these toxins are still being used daily.

What is the Solution to this toxic mess?

Fortunately for humans, Nature has been practicing sound ecological remediation and restoration for ions and can provide a model for dealing with our self-imposed mess.  In a 2007 workshop intensive with microbiologist Dr. Elaine Ingham of the Soil Food Web, Ingham introduced the concept of restoring deadened soils by following natural succession models of landscape regeneration.  For example, when a natural disaster hits (such as a volcanic explosion), the first pioneer species to inhabit the deadened areas are bacteria, soon followed by cyanobacteria, protozoa, nematodes, microarthopods and fungi, who break down toxicities left in the soil and make it suitable for plant growth (Ingham 2007).  Catering to these early successional microorganisms and/or innoculating soils with key pioneer microorganisms can accelerate the process of restoration in damaged landscapes.

When it comes to toxic landscapes, Paul Stamets, author of Mycelium Running, and other mycologists have come to understand that fungi in particular “are adept as molecular disassemblers, breaking down many recalcitrant, long-chained toxins into simpler, less toxic chemicals…Since many of the bonds that hold plant material together are similar to the bonds found in petroleum products, including diesel, oil, and many herbicides and pesticides, mycelial enzymes are well suited for decomposing a wide spectrum of durable toxic chemicals” (Stamets 2005).  Harnessing this unique ability and innoculating poisoned landscapes with mushroom species is the work involved in mycoremediation, using fungi to degrade or remove toxins from the environment.     

Oyster Mushroom (Pleurotus ostreatus) breaking down bunker C oil (PAH) in soil test, Battelle Pacific Northwest Laboratories, 1999 (Stamets 2005)

In 1998, Stamets and a small research group from Batelle Pacific Northwest Laboratories in Sequim, Washington set aside 4 piles of diesel-contaminated soils from a maintenance yard operated by the Washington State Department of Transportation (WSDOT) in Bellingham, WA.  The group placed the piles onto 4 large sheets of 6 mm black plastic polyethylene tarps at the Bellingham site.  Each pile was 3-4 ft tall by 20 ft long and 8 ft wide, and in one of the piles they included a layer of oyster mushroom sawdust spawn that was roughly 30% of the pile (Stamets 2005).  Two other piles received bacterial treatments and the last pile was an untreated control.  Four weeks later, only the fourth pile infused with mycelium showed any signs of life.  Not only were there large oyster mushrooms growing out of the pile (some as large as 12 inches in diameter), but the soil was sprouting seeds and showing clear signs of recovery.  Batelle Laboratory reported that total petroleum hydrocarbons (TPHs) had plummeted from 20,000 ppm to less than 200 ppm in 8 weeks, making the once heavily contaminated soil acceptable for highway landscaping (Stamets 2005).  Even more interesting, upon further testing of the oyster mushrooms sprouting from the pile determined that no petroleum residues were detected n the oyster mushroom itself.

This trial, one of but hundreds conducted by Stamets and his associated mycologist research team, demonstrates the potential in utilizing mycoremediation techniques in urban, suburban, and even rural settings where chemical toxins have contaminated soils.  Many mushrooms naturally absorb radioactivity and some species are even hyperaccumulators, with an ability to absorb and concentrate radioactive elements at thousands of times above levels in the surrounding areas.  In Mycelium Running (2005), Paul Stamets provides an introductory list of no less than 18 species and the common chemical toxins that they break down (96).  He then goes on to cite 36 species that bioaccumulate six heavy metals, including arsenic, cadmium, radioactive cesium, lead, mercury and copper (106).  Many of these potent mycoremediators are familiar to most households.  For example, the North American masutake (Tricholoma magnivelare) accumulate arsenic, and shaggy manes (Coprinus comatus) accumulate both arsenic and lead.  Button mushrooms (Agaricus bisporus), found in grocery stores around the country, hyperaccumulate cadmium.  Wild turkey tail mushrooms (Trametes versicolor) and oyster mushrooms (Pleurotus pulmonarius) remove mercury from soils and aquatic systems (Stamets 2005).  Japan’s Fukushima nuclear disaster can look to these fungi friends for answers to the grave radioactive contamination still facing their nation, one year later.  For further information regarding specific species, refer to www.fungi.com.

In areas where water is contaminated due to runoff or leaching of chemical toxins, mycofiltration systems can be inexpensively built.  Stamet’s use of mycorrhizal-infused filters has been shown to filter:

  • pathogens including protozoa, bacteria, and viruses
  • silt
  • chemical toxins

and has been shown favorable results in reducing contamination when installed around:

  • farms and suburban/urban areas
  • watersheds
  • factories
  • roads (Stamets 2005).

References.

Cunningham, William P. and Mary Ann.  Environmental Science:  A Global Concern, Twelfth Edition.  New York:  McGraw-Hill Companies, Inc., 2012.  76-93. PRINT.

Gunderson, Arnold.  Gundersen: One Year Anniversary of Fukushima Daiichi.  RT, March 2012.  (VIDEO)

Ingham, Dr. Elaine.  Soil Food Web Course.  Davis, California.  2007.

Mercola, Dr. Joseph.  http://www.mercola.com

Stamets, Paul.  Mycorrhizal Running.  Berkeley:  Ten Speed Press, 2005.  PRINT.

Walsh, Bryan.  “Environmental Toxins:  The Perils of Plastic”  TIME magazine. 2010.  http://www.time.com/time/specials/packages/article/0,28804,1976909_1976908_1976938,00.html

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