Sewage sludge
{{#badges: ToxicSludge|FoodRightsNetwork}} Sewage sludge is the growing and continuous mountain of hazardous waste produced daily by city sewage plants. The sewage sludge industry has created a PR euphemism it uses in place of the words 'sewage sludge': biosolids. There is now a SourceWatch Portal on Toxic Sludge The sewage sludge industry promotes its product through front groups and stakeholders including Water Environment Federation, US Composting Council, BioCycle magazine, and others.
Contents
- 1 What is Sewage Sludge?
- 2 Why is Toxic Sewage Sludge Dumped on Farm and Gardens?
- 3 Toxic Sewage Sludge Given Away as "Organic Biosolids Compost"
- 4 EPA 2009 Toxic Sewage Sludge Survey
- 5 2008 Report from IATP
- 6 Environmental Working Group 1998 Reports on Toxic Sewage Sludge
- 7 Scientific Papers and Technical Reviews of Sewage Sludge
- 8 What's in sewage sludge
- 9 Other SourceWatch resources
- 10 PRWatch Articles
- 11 External Resources
- 12 External Articles 2008 - 2011
What is Sewage Sludge?
A list of just some of the hazardous chemicals and pathogens found in sludge can be found in the article Sludge contaminants. Sludge contaminants include Dioxins and Furans, Flame Retardants, Metals, Organochlorine Pesticides, 1,2-Dibromo-3-Chloropropane (DBCP), Naphthalene, Triclosan, Nonylphenols, Phthalates, Nanosilver, and thousands more substances.
- "Sewage is the mix of water and whatever wastes from domestic and industrial life are flushed into the sewer. To retrieve the precious water, the sewage is then 'treated,' that is, 'cleaned,' in what are called 'treatment plants.' The ideal of the treatment plant is to take out of the sewer water all the 'wastes' that sewering put into it. The water is 'cleaned' in the degree to which the pollutants which had turned the water into sewage are removed by treatment-primary, secondary, or tertiary-and concentrated in the sludge. We must note that, though the aim of sewage treatment is to produce clean water, it is never to produce 'clean' sludge. Indeed, the 'dirtier' the sludge - the more complete its concentration of the noxious wastes - the more the treatment has done its job. If there are industrial chemicals, pharmaceuticals, hormones, nano particles, prions, hospital wastes including antibiotic-resistant bacteria - and there will be all of these - you want them to end up in the sludge. Every waste produced in our society that can be got rid of down toilets and drains and that can also be got out of the sewage by a given treatment process will be in the sludge. Sludge is thus inevitably a noxious brew of vastly various and incompatible materials unpredictable in themselves and in the toxicity of their amalgamation, incalculably but certainly wildly dangerous to life." [1]
Why is Toxic Sewage Sludge Dumped on Farm and Gardens?
"The policy of disposing of sludge by spreading it on agricultural land - a policy given the benign term 'land application' - has its inception in the Ocean Dumping ban of 1987. Before 1992, when the law went into effect, the practice had been, after extracting the sludge from the wastewater, to load it on barges and dump it 12, and later 106 miles off shore into the ocean. But many people who cared about life in the ocean knew that, wherever it was dumped, the sludge was causing vast dead moon-scapes on the ocean floor. New EPA regulations for 'land application' were promulgated in 1993. With the aid of heating and pelletizing and some slippery name morphs along the way, EPA claimed sludge could be transmogrified into 'compost' ... . But the land “application” of sewage sludge ... will pollute the whole chain of life for which soil is the base." [2] In 2002, the National Research Council found that the "U.S. Environmental Protection Agency's standards that govern using treated sewage sludge on soil are based on outdated science."[3] This was again confirmed in 2011 when scientists found that noroviruses survive treatment that kills pathogens such as Salmonella.[4]
In March 2013, a study involving neighbors of land where sewage sludge had been dumped -- "living in rural and semirural areas within approximately one mile of sewage sludge land application sites in North Carolina, South Carolina and Virginia" -- found that "over half of respondents attributed physical symptoms to application events." More specifically, "Over half (18/34) of the interview respondents associated acute physical symptoms that lasted a short period of time with sludge application events near their home (Table 1). The most commonly reported symptoms were eye, nose, and throat irritations and gastrointestinal symptoms (nausea, vomiting, diarrhea). Other symptoms reported by more than one respondent include cough, difficulty breathing, sinus congestion or drainage, and skin infections or sores."[5]
Toxic Sewage Sludge Given Away as "Organic Biosolids Compost"
In 2009 a major controversy erupted in San Francisco when the Center for Food Safety and the Organic Consumers Association called on the SFPUC to end its give-away of toxic sewage sludge as free "organic biosolids compost" to gardeners. A March 4, 2010, demonstration at City Hall by the OCA forced a temporary halt to the program. (See articles below)[6] [7][8][9] [10] The misleading labeled "organic compost," which the PUC has given away free to gardeners since 2007, is composed of toxic sewage sludge from San Francisco and eight other counties. Very little toxicity testing has been done, but what little has been done is alarming. Just the sludge from San Francisco alone has tested positive for 1,2-Dibromo-3-Chloropropane (a.k.a. DBCP), Isopropyltoluene (a.k.a. p-cymene or p-isopropyltoluene), Dioxins and Furans. [11] The controversy spread to the famous Berkeley chef Alice Waters and her Chez Panisse Foundation. Waters and the Foundation advocate growing organic food and creating organic schoolyard gardens; toxic sewage sludge fertilizer is forbidden under the National Organic Standards Act in the production of commercial organic food. The executive director of the Water's Chez Pannise Foundation is Francesca Vietor, the vice-president of the SFPUC, the agency promoting and giving away toxic sewage sludge as "organic biosolids compost." Waters and her foundation have refused to publicly oppose the practice of growing food in toxic sludge.
EPA 2009 Toxic Sewage Sludge Survey
Targeted National Sewage Sludge Survey results are described in two EPA reports published in 2009. EPA found that dozens of hazardous materials , not regulated and not required to be tested for, have been documented in each and every one - ALL - of the sludge samples EPA took around the USA.[12] Hundreds of communities across the U.S. sell sludge products that are renamed biosolids and sold or given away as "organic fertlizer."
2008 Report from IATP
- Marie Kulick, Smart Guide on Sludge Use and Food Production, Institute for Agriculture and Trade Policy, 2008.
Environmental Working Group 1998 Reports on Toxic Sewage Sludge
- Environmental Working Group, Dumping Sewage Sludge On Organic Farms? Why USDA Should Just Say No, April, 1998.
- Environmental Working Group, Routes of Exposure sewage sludge: EWG Research on Chemicals in sewage sludge, April 30, 1998.
Scientific Papers and Technical Reviews of Sewage Sludge
Dozens of peer reviewed scientific studies examine and confirm the many hazards of sewage sludge See: Scientific Studies of Sewage Sludge for a synopsis of leading studies and a PDF of each
What's in sewage sludge
A list of just some of the hazardous chemicals and pathogens found in sludge can be found in the article Sludge contaminants. Sludge contaminants include Dioxins and Furans, Flame Retardants, Metals, Organochlorine Pesticides, 1,2-Dibromo-3-Chloropropane (DBCP), Naphthalene, Triclosan, Nonylphenols, Phthalates, Nanosilver, and thousands more substances.
From the 1995 book, Toxic Sludge Is Good for You, with permission:
The HarperCollins Dictionary of Environmental Science defines sludge as a "viscous, semisolid mixture of bacteria- and virus-laden organic matter, toxic metals, synthetic organic chemicals, and settled solids removed from domestic and industrial waste water at a sewage treatment plant."
Over 60,000 toxic substances and chemical compounds can be found in sewage sludge, and scientists are developing 700 to 1,000 new chemicals per year. Stephen Lester of the Citizens Clearinghouse for Hazardous Wastes has compiled information from researchers at Cornell University and the American Society of Civil Engineers showing that sludge typically contains the following toxins:
- Polychlorinated Biphenyls (PCBs);
- Chlorinated pesticides--DDT, dieldrin, aldrin, endrin, chlordane, heptachlor, lindane, mirex, kepone, 2,4,5-T, 2,4-D;
- Chlorinated compounds such as dioxins;
- Polynuclear aromatic hydrocarbons;
- Heavy metals--arsenic, cadmium, chromium, lead, mercury;
- Bacteria, viruses, protozoa, parasitic worms, fungi;
- Miscellaneous--asbestos, petroleum products, industrial solvents.
In addition, a 1994 investigation by by the US General Accounting Office found that "the full extent of the radioactive contamination of sewage sludge, ash and related by-products nationwide is unknown." Most of the radioactive material is flushed down the drain by hospitals, businesses and decontamination laundries, a practice which has contaminated at least nine sewage treatment plants in the past decade.
In 1977, EPA Administrator Douglas Costle estimated that by 1990 treatment plants would be generating 10 million tons of sludge per year, a thought that "gives us all a massive environmental headache." In 1995 there were about 15,000 publicly-owned wastewater treatment works in the United States, discharging approximately 26 billion gallons per day of treated wastewater into lakes, streams and waterways. Before treatment, this wastewater contains over a million pounds of hazardous components. Sewage plants use heat, chemicals and bacterial treatments to detoxify 42 percent of these components through biodegradation. Another 25 percent escapes into the atmosphere, and 19 percent is discharged into lakes and streams. The remaining 14 percent--approximately 28 million pounds per year--winds up in sewage sludge.
Once created, this sludge must be disposed of somehow. Available methods include: incineration (which pollutes the air), dumping into landfills (which is expensive, and often leaches contaminants into groundwater), and ocean dumping (where it has created vast underwater dead seas). A fourth method --gasification, using sludge to generate methanol or energy--is described by EPA's Hugh Kaufman as the "most environmentally sound approach, but also the most expensive." A fifth approach --using sludge as plant fertilizer--was considered hazardous to health and the environment until the 1970s, but it has the advantage of being inexpensive. As budget concerns mounted in the late 1970s, the EPA began to pressure sewage plants to adopt the cheapest method available--spreading sludge on farm fields.
Other SourceWatch resources
- Sewage Sludge Portal
- Food Rights Network
- Biosolids
- You say biosolids, I say sewage sludge
- Scientific Studies of Sewage Sludge
- Sludge contaminants
- Targeted National Sewage Sludge Survey
- The EPA's plan to bypass opposition to sewage sludge disposal
- Sewage sludge giveaways, producers, and brands
- Water Environment Federation
- US Composting Council
- BioCycle
- Sludge News
- Sewage Sludge Primer
PRWatch Articles
- Rebekah Wilce, "Don't Ask, Don't Tell": Concerned Citizen Uncovers Whole Foods' Policy on Selling Food Grown in Sewage Sludge, PRWatch.org, December 18, 2012.
- Sara Jerving, New Toxic Sludge PR and Lobbying Effort Gets Underway, PRWatch.org, March 16, 2012.
- Rebekah Wilce, More Free Sludge! Calabasas, California Offers Free Sewage Sludge, PRWatch.org, March 6, 2012.
- Sara Jerving, Sewage Sludge Rash: Texas Musical Fest-Goers Blame "Dillo Dirt", PRWatch.org, March 2, 2012.
- Rebekah Wilce, Neighbors Occupy Road, Blockade Sludge Trucks, PRWatch.org, January 2, 2012.
- Rebekah Wilce, Sludge Industry Reveals "Resource Recovery" Spin, PRWatch.org, December 15, 2011.
- Rebekah Wilce, Meet Kellogg's Sludge Puppet, PRWatch.org, November 9, 2011.
- Lisa Graves, Children Gardening in Sewage Sludge: Los Angeles Schools Alerted, PRWatch.org, October 11, 2011.
- Jill Richardson, Los Angeles and Kern County's Epic Sewage Sludge Battle, PRWatch.org, October 5, 2011.
- Jill Richardson, Would you "Like" Sewage Sludge on Facebook?, PRWatch.org, September 12, 2011.
- Jill Richardson, ALEC Exposed: Protecting Factory Farms and Sewage Sludge?, PRWatch.org, August 4, 2011.
- Jill Richardson, Why is Monterey Bay Aquarium Greenwashing Sewage Sludge?, PRWatch.org, May 20, 2011.
- John Stauber, San Francisco's Free "Organic Biosolids Compost" is Toxic Sludge, and Not Good For You!, PRWatch.org, August 17, 2010.
- John Stauber, Gavin Newsom Hopes to Leave his Sludge in San Francisco, PRWatch.org, July 27, 2010.
- John Stauber, Chez Sludge: Complaint Filed Regarding Francesca Vietor's Threat to the Guardian, PRWatch.org, July 13, 2010.
- John Stauber, Chez Sludge: How the Sewage Sludge Industry Bedded Alice Waters, PRWatch.org, July 9, 2010.
- John Stauber, ACSH Makes Alice Waters a Poster Child for Toxic Sludge, PRWatch.org, April 13, 2010.
- Jill Richardson, Toxic Sludge Taints the White House, PRWatch.org, March 29, 2010.
- John Stauber, Waiter, There is Toxic Sludge in my Soup!, PRWatch.org, March 16, 2010.
- John Stauber, San Francisco's Toxic Sludge: It's Good for You!, PRWatch.org, February 8, 2010.
- John Stauber, Toxic Sludge: Better than Ever!, PRWatch.org, May 3, 2009.
- John Stauber, Toxic Sludge is Still Good for You!, PRWatch.org, April 28, 2009.
External Resources
- Sludge News, a project of RILES, an independent nonprofit organization founded in 1990 to protect health and the environment.
- Biosolids Applied to Land: Advancing Standards and Practices, National Research Council, 2002.
- Sludge Victims, informational website compiled by researcher and activist Helane Fields.
- Sludge Blog, a resource website compiled by "Sludgeblog Beth."
External Articles 2008 - 2011
Articles below are arranged from oldest to newest:
2013
- Dr. Steve Suppan, Institute for Agriculture and Trade Policy, Nanomaterials In Soil: Our Future Food Chain?, organizational report, March 28, 2013.
2012
- Xoco Shinbrot, Beyond Pesticides, "Biosolids or Biohazards?, Pesticides and You, organizational quarterly magazine, Volume 32, Number 3, Fall 2012, pp. 9-15.
2011
- Murray McBride, "No solid evidence that biosolids are safe to disperse," The Chronicle Herald, August 27, 2011.
2010
- Rebekah L. Cowell, Sludge, a free fertilizer for farmers, can pose health and environmental risks, Durham Independent Weekly, July 28, 2010.
- Louis Sahagun, City of LA, Kern County Battle Over Human Waste Disposal, LA Times, June 7, 2010.
- James Burger, Kern wins again as U.S. Supreme Court refuses to hear sludge case, Bakersfield.com , June 1, 2010.
- Barry Estabrook, Composted Sewage Stirs Up Bay Area Food Fight, The Atlantic, May 3, 2010.
- Susan Galleymore, The Green Mayor Has Toxic Sludge on His Hands, Op-Ed News, April 25, 2010.
- John Stauber, ACSH Makes Alice Waters a Poster Child for Toxic Sludge, PRWatch.org, April 12, 2010.
- Leora Broydo Vestel, Food Groups Clash Over Compost Sludge, New York Times Green Inc. blog, April 9 2010.
- Jill Richardson, What San Francisco Found in Their Own Sludge, La Vida Locavore blog, April 8, 2010.
- Peter Fimrite, Groups make stink over S.F. 'biosolid' compost, SF Chronicle, April 7, 2010.
- Brady Welch, The Shit Show's Extended Run SF Bay Guardian, April 7, 2010.
- Jill Richardson, Francesca Takes Legal Action over Sludge Article, La Vida Locavore blog, April 7, 2010.
- Suzanne Goldenberg, US chef Alice Waters criticised over sewage fertiliser: Top US healthy-eating chef Alice Waters attacked for supporting fertiliser made of sewage that activists say contains toxins, UK Guardian, April 1, 2010.
- Tracey Taylor, Toxic sludge demonstrators picket Chez Panisse, April 1, 2010.
- Raymond Barglow, Organic Consumers Association Pickets Chez Panisse, The Berkeley Daily Planet, April 1, 2010.
- John Birdsall, Alice Waters Demands Apology from Sewage Sludge Protestors, SF Weekly, April 1, 2010.
- Organic Consumers Association, The Organic Consumers Association To Picket Chez Panisse Restaurant on Thursday, April 1st, Noon, in Berkeley, CA Alice Waters, World Famous Organic Food Chef and Promoter of Safe School Gardens, Does Not Oppose Growing Food on Toxic Sewage Sludge, News Release, March 31, 2010.
- John Stauber, Chef Alice Waters and Chez Panisse the Targets of a Toxic Sludge Protest, PRWatch.org, March 31, 2010.
- Brady Welch, Alice Waters protested for supporting using human waste as compost San Francisco Bay Guardian, March 31, 2010.
- Brady Welch, Shit show: What has the SFPUC has been dumping in city gardens?, San Francisco Bay Guardian, March 23, 2010.
- Louis Sahagun, Counties ask high court to rule on Kern County's human waste ban, LA Times, March 18, 2010.
- John Stauber, Waiter, There Is Toxic Sludge in my Organic Soup!, PRWatch.org, March 16, 2010.
- Ian Fortely, San Francisco Gives Away Organic Toxic Sludge, Asylum, March 9, 2010.
- Tom Joyce, Protesters rally against sewage sludge, York Daily Record, March 9, 2010.
- Jill Richardson, Food Sunday: Toxic Sludge as 'Organic Fertilizer', FireDogLake, March 7, 2010.
- Anna Werner, Concern Over SF Compost Made from Sewage Sludge, CBS Channel 5, March 3, 2010.
- Chris Roberts, News Farmers Call PUC's Shit, Will Dump it on City Hall Today, San Francisco Appeal, March 4, 2010.
- What SF calls compost, activists call 'toxic sludge, San Francisco ABC affiliate KGO TV, March 4, 2010.
- Josh Harkinson, A Backlash After San Francisco Labels Sewage Sludge Organic, Mother Jones magazine, March 4, 2010.
- Photo Gallery: Activists Praise Poop, Deliver Dirt to Mayor's Office, SF Appeal, March 4, 2010.
- Evelyn Nieves, Claim: San Francisco giving gardeners toxic sludge, Associated Press in the Boston Globe, March 5, 2010.
- John Upton, The City’s free compost causes stink SF Examiner, March 5, 2010.
- Charlie Reid, There's a reason towns ban sludge spreading, Foster's Daily Democrat, February 21, 2010.
- Harrison Haas, Belmont, New Hampshire, puts the banning of sludge on town warrant, Laconia Citizen, January 12, 2010.
- Gayathri Vaidyanathan, Biosolids Tracking Efforts a Jumble of Research With No Clear Answers, New York Times, Greenwire, August 26, 2010.
2009
- Barry Estabrook, Sludge Fest: Center for Food Safety vs. San Francisco. It’s a battle that may be coming soon to a city near you, Politics of the Plate, November 30, 2009.
- Barry Estabrook, Free Compost--Or Toxic Sludge?, The Atlantic, December 1, 2009.
- Eric Fleishauer, Fed to test 200 for DU toxic waste, The Decatur Daily (Alabama), December 2, 2009.
- CFS Petitions San Francisco Mayor to Stop Giving Away Poison Compost to Public, Center for Food Safety Website, September 23, 2009.
- Heather Knight, Nonprofit calls PUC's compost toxic sludge, San Francisco Chronicle, September 27, 2009.
- Laura Bauer, Farmers perplexed over free fertilizer’s health issues, Kansas City Star, April 24, 2009.
- Lawsuit Links Chemical To Cameron Tumors Brockovich Report Says Hexavalent Chromium Used As Fertilizer, KMBC-TV, April 23, 2009.
- Mark Schultz, Biosolids concerns bubble to surface Neighbors say sewage sludge spread on fields may be making them sick, Chapel Hill News, April 19, 2009.
2008
- Editorial, Kern wins again as U.S. Supreme Court refuses to hear sludge case, Mobile Press Register, September 19, 2008.
- Mike Silvestri, Is sewage sludge, Angelos’s next asbestos?, Baltimore Examiner, September 14, 2008 .
- Patrick Lynch, Inspections are up, but is sludge safe? Tests for 9 metals done before shipments, The farm fertilizer contains traces of toxic chemicals, studies find, Daily Press, September 15, 2008.
- Jasmin Melvin, Group to Sue EPA Over Sewage Sludge, Reuters, September 12, 2008.
- Ben Raines, Sludge Sprayed on Grand Bay Fields Contains Pollutants, Mobile Press-Register, September 12, 2008.
- Ben Evans, Senate Cancels Hearing on Georgia Sludge Findings, Associated Press, September 12, 2008.
- Ben Raines, Mobile Sludge Fight Has National Attention, Mobile Press-Register, September 11, 2008.
- Jasmin Melvin, Congress to Address Dumping of Sewage Sludge, Reuters, September 10, 2008.
- Stacey Shepard, Group Seeks Community Input for National Sludge Fight, The Bakersfield Californian, September 8, 2008.
- Sara Miller, Shrewsbury Township passes sludge ordinance, The York Dispatch, September 4, 2008.
- Ben Raines, Grand Bay residents upset that farmland is fertilized with processed sewage, Mobile Press-Register, Alabama, August 31, 2008.
- Rose George, Reports that sludge from sewage plants is routinely used to fertilise edible crops have caused outrage. Is this simply a prudent use of so-called 'biosolids' or a grave threat to our health?, The Guardian, August 29, 2008.
- Greg Bluestein, Ex-EPA scientist fights agency over sewage sludge, Associated Press, August 9, 2008.
- Carola Vyhnak, Biosolids a ‘disaster in waiting’, The Independent, July 17, 2008
- Zachary Gorchow, The Synagro Sludge Deal Federal grand jury probes possible payoffs in Synagro sludge deal, Detroit Free Press, July 17, 2008.
- Elie Dolgin, UW-Madison study says Prions can survive sewage treatment, Journal Sentinal, July 13, 2008
- Carola Vyhnak, Soiled Land (four part series in the Toronto Star) Part I. Is sewage fertilizer safe? Worries grow over 'stew' of chemicals spread on farmland, The Toronto Star, July 12, 2008.
- Carola Vyhnak, Part II. Farmers split over safety, The Toronto Star, July 13, 2008.
- Carola Vyhnak, They started to become ill when a farmer spread sludge on his fields, then their wells became contaminated, The Toronto Star, July 13, 2008.
- Carola Vyhnak, Oakville family files suit over treated sewage lagoon near their home, The Toronto Star, July 13, 2008.
- Carola Vyhnak, Part III. When sludge disposal rules are broken, The Toronto Star, July 14, 2008.
- Carola Vyhnak, Federal workplace safety agency recognizes sewage sludge disease, The Toronto Star, July 14, 2008.
- Carola Vyhnak, Part IV. Food firms shun sludge use, The Toronto Star, July 15, 2008.
- Joel Bliefuss, Piling It High, In These Times, May 21, 2008.
- Kevin S. Vineys, "No one knows what makes up sewage sludge," Associated Press, May 11, 2008.
- Mike Silvestri, NAACP officials continue probe into sludge study, Baltimore Examiner, June 30, 2008.
- Critics Cry Racism over Baltimore Sludge, NPR, April 28, 2008.
- Dennis O’Brien, NAACP questions sludge study methods, Baltimore Sun, April 23, 2008.
- Mike Silvestri, NAACP seeks probe into sludge spreading in black communities, Baltimore Examiner, April 16, 2008.
- John Heilprin and Kevin S. Vineys (AP),"Sludge Tested As Lead-Poisoning Fix," FOX News, April 14, 2008,
- John Heilprin, Senate Plans Hearing on Sludge, Associated Press Writer, April 14, 2008.
- John Heilprin, Probes wanted on sludge research in poor neighborhoods, Associated Press, Apr 13, 2008.
- John Heilprin and Kevin S. Vineys, Sludge fertilizer program spurs concerns, Associated Press Writers, April 13, 2008.
- "National policy brought sludge to Augusta farms: Ruling for farmer disputes government data," Associated Press March 9, 2008.
- John Heilprin and Kevin S. Vineys,"Sewage-Based Fertilizer Safety Doubted," Associated Press, March 7, 2008.
References
- ↑ About Sewage Sludge, SludgeNews.com, Accessed June 18, 2010.
- ↑ About Sewage Sludge, SludgeNews.com, Accessed June 18, 2010.
- ↑ Sewage Sludge Standards Need New Scientific Basis, National Research Council, July 2, 2002, Accessed June 22, 2011.
- ↑ Emily Gertz, Safety Rules For Sewage Sludge May Be Outdated, Chemical & Engineering News, June 15, 2011, Accessed June 22, 2011. Link broken, but part of article archived here.
- ↑ Amy Lowman, Mary Anne McDonald, Steve Wing, and Naeema Muhammad, "[https://www.sourcewatch.org/images/7/7a/March_2013_Land_Application_Study.pdf Land Application of Treated Sewage Sludge: Community Health and Environmental Justice," Environmental Health Perspectives, March 11, 2013 (online).
- ↑ Heather Knight, Nonprofit calls PUC's compost toxic sludge, San Francisco Chronicle, September 27, 2009.
- ↑ Barry Estabrook, Free Compost--Or Toxic Sludge?, The Atlantic, December 1, 2009
- ↑ Anna Werner, Concern Over SF Compost Made from Sewage Sludge, CBS Channel 5, March 3, 2010
- ↑ Leora Broydo Vestel, http://greeninc.blogs.nytimes.com/2010/04/09/food-groups-clash-over-compost-sludge/ Food Groups Clash Over Compost Sludge, New York Times Green Inc. blog, April 9 2010.
- ↑ Chris Roberts, Farmers Call PUC's Shit, Will Dump it on City Hall Today, San Francisco Appeal, March 4, 2010.
- ↑ Jill Richardson, What San Francisco Found in Their Own Sludge, La Vida Locavore blog, April 8, 2010.
- ↑ TNSSS: EPA-822-R-08-016 and EPA-822-R-08-018. Published by EPA, January 2009.