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Pesticides Seeping Into Urban Streams

Pesticide Stream Monitoring MapPesticides are seeping into an increased number of urban streams, according to a scientific report. The report looks at pesticide levels at USGS National Water-Quality Assessment sites. The sites are shown on the map at right. Some are urban, some are rural, and some are at mixed urban/rural sites.

(For larger view, click on map.)





Source: Stone, Wesley, Robert Gilliom and Karen Ryberg, 2014.

Source: Stone, Wesley, Robert Gilliom and Karen Ryberg, 2014.

The report focuses on pesticide levels during the decade from 2002-2011, and compares them to levels during the decade from 1992-2001. The report focuses on streams where pesticides were present at least 95% of the year. The first chart at right shows the percentage of streams in which at least one pesticide exceeded maximum aquatic-life benchmark. An aquatic-life benchmark is the level above which the pesticide is believed to be toxic for aquatic life.

From 2002-2011, pesticides exceeded aquatic benchmarks in 61% of agricultural streams, a decrease of 8%. They exceeded aquatic benchmarks in 90% of urban streams, an increase of 37%. And they exceeded aquatic benchmarks in 46% of mixed use streams, an increase of 1%.

In considering this information, it is important to understand that not all pesticides were included. Thus, results represent a minimum, and actual levels of contamination are almost certainly higher.

The stunning result here is the increase in the percentage of contaminated urban streams. The report states that the increase is primarily due to the use of fipronil and dichlorvos. Fipronil is an insecticide that did not come into common use until the late 1990s, so it has spread into streams relatively quickly. It is highly effective because it is slow acting. Thus, it is carried back to roach and ant nests, affecting the entire nest, not just a single individual. However, it has been found to be toxic to aquatic life, and the compounds into which it degrades in the environment may be even more toxic.

Dichlorvos is a popular insecticide in commercial use since the 1960s. The EPA lists it as a probable carcinogen and has restricted its used, but not banned it.

The report is national in scope, and unfortunately does not break out data for Missouri.


Stone, Wesley, Robert Gilliom, and Karen Ryberg. 2014. Pesticides in U.S. Streams and Rivers: Occurrence and Trends During 1992-2011. Environmental Science & Technology, 48,(19), 11,025-11,030. http://pubs.acs.org/doi/abs/10.1021/es5025367.

Weston, D.P. and M.J. Lydy. 2014. “Toxicity of the Insecticide Fipronil and its Degradates to Benchic Macroinvertebrates of Urban Streams.” Abstract. Environmental Science and Technology. 48,(2); 1290-97.

EPA. “Dichlorvose.” Air Toxics Web Site. http://www.epa.gov/ttnatw01/hlthef/dichlorv.html.

Eighty-Four Percent of Missouri Toxic Waste Is “Managed”

Releases by Category ChartIn my previous post I discussed the EPA’s Toxics Release Inventory, and provided a chart showing the total amount of toxic materials released in Missouri for the years 2002-2012.

Toxic materials can be released into the air, they can be discharged into surface water, they can be held in impoundments, they can be injected into wells, and they can be landfilled or spread on the land. The first chart at right shows Missouri toxic releases by category in 2012. The vast amount of releases occur at the site where the toxics are generated (vs. being transported off-site for disposal). Almost 2/3 of the releases involve release into an impoundment of one sort or another. The next largest amount involves emission into the air.


Managed by CategoryToxics can also be managed by recycling, by energy recovery, by treatment, or by other methods. The second chart at right shows Missouri managed toxic wastes in 2012. The largest amount is recycled for reuse. The next largest amount is treated to make it less toxic.

The total amount of managed toxic waste in Missouri in 2012 was 360 million pounds. The total amount of toxic releases were 70 million pounds. Thus, about 84% of Missouri toxics were managed in some fashion in 2012, while 16% were released. Nationally, about 23.5 billion pounds of toxic waste were managed in 2012 (87% of the total) , while 3.6 billion pounds were released (13% of the total).


Top Releasing IndustriesThe industries responsible for releasing the largest amounts of toxic chemicals are shown in the third chart. Releases in Missouri are shown as the blue line and should be read on the left vertical axis. Releases in the United States are shown as red bars, and should be read on the right vertical axis. Metal mining is the largest, both in Missouri and nationwide, with more than double the releases of the next largest releasing industry. In Missouri, electric utilities are second, but nationwide it is the chemicals industry. I was surprised to see how much toxic material was released by the food, beverage, and tobacco industry. That it releases more than the petroleum and the plastics & rubber industries blows my mind!



MO Chemicals ChartThe top 10 toxic chemicals released in Missouri in 2012 are shown in the third chart at right. The top five are all associated with the metal mining industry.

Chemicals that are persistent, bioaccumulative, and toxic (PBT) are of most concern to the EPA. Lead accounts for 98% of PBT releases nationwide. Lead emissions are driven by mining activities, and more lead was released in Missouri in 2012 than any other toxic compound. Mercury is also a PBT of concern. Coal burning power plants are the largest source of mercury emissions in the United States. Nationwide, mercury emissions have been falling, from over 140,000 lb. in 2004 to under 80,000 in 2012. It was the 57th most heavily released chemical in Missouri in 2012. Information about all these chemicals can be found on the EPA website or on Wikipedia.


Environmental Protection Agency. 2014. Missouri State Fact Sheet, TRI Explorer. http://iaspub.epa.gov/triexplorer/tri_broker_statefs.broker?p_view=STCO&SFS=YES&trilib=TRIQ1&state=MO&year=2012

Environmental Protection Agency. 2014. 2012 Toxics Release Inventory National Analysis Overview. http://www2.epa.gov/toxics-release-inventory-tri-program/2012-tri-national-analysis.

Information on specific industries and specific chemicals releases came from the EPA TRI Explorer data portal. The data was viewed 3/13/14 at http://iaspub.epa.gov/triexplorer/tri_release.chemical.

Missouri Toxic Releases Down 2% in 2012

In February, 2013, I published a post on the Toxic Release Inventory with data through 2011. This post updates the information for 2012, the most recent year available.

Many industrial processes use or produce toxic substances. These substances must be properly handled to prevent harm to people, land, and water. After a series of disasters in the 1970s and 1980s, Congress passed the Emergency Planning and Community Right-to-Know Act in 1986, and the Pollution Prevention Act in 1990. These laws require facilities to report releases, transfers, and waste management of toxic material.

The Toxics Release Inventory (TRI) of the EPA gathers this information and makes it available to the public on their website. In addition, they publish annual fact sheets and analyses. The TRI data does not cover all toxic materials or facilities, but it does cover an important set of them. New for 2012, releases of hydrogen sulfide, a poisonous gas that smells like rotten eggs, have been included in the data.

Toxic substances are recycled, burned to generate electricity, injected into wells, stored, landfilled, emitted into the air, discharged into surface water, and spread over the land. They can be handled either on-site or off-site. Determining whether any of these activities represents a potential hazard to people, land, or water is complex. One cannot simply assume that on-site means safe, or that emission or discharge means that there is toxic exposure. The statistics in the TRI are only a starting point.

Missouri Toxic Releases 2012In the graph at right, the blue line shows total releases and disposal of toxic materials in Missouri from 2002-2012. In 2007, the EPA changed the minimum reporting threshold from 2,000 to 5,000 pounds, suggesting that comparisons between years may not be valid. Over the entire time period, toxic releases and disposal decreased by 4%. While there does not appear to be a significant discontinuity in the data following 2007, the data shows a rapid increase until 2005, followed by a rapid decrease. The percentage differences are very large: between 2002 and 2004 the increase was 56% From 2004-2012, the decrease was 39%. Such large , rapid changes may, indeed, reflect changes in data gathering rather than actual changes in the amount of toxic materials. A report tracking the changes and making an “apples-to-apples” comparison across years would be most welcome. If you know of one, let me know about it by posting a comment.

Interestingly, Missouri releases declined 2% between 2011 and 2012, despite the addition of sulfur dioxide to the list. Some other data suggests that Missouri may lag the nation by a couple of years in implementing changes, so it will be interesting to follow this trend in upcoming years.

My next post will explore the industries and the chemicals that account for the most toxic releases.


State Fact Sheet, TRI Explorer, 2012. http://iaspub.epa.gov/triexplorer/tri_broker_statefs.broker?p_view=STCO&SFS=YES&trilib=TRIQ1&state=MO&year=2012.

Manufacturing Employment in Missouri, FRED Economic Data, Federal Reserve Bank of St Louis, http://research.stlouisfed.org/fred2/graph/?s[1][id]=MOMFGN.