A guest post by agricultural scientist Steve Savage,
proprietor of Applied Mythology.
(This post first appeared on Applied Mythology 6/19/2012)
Each year, the Agricultural Marketing Service of the USDA (USDA-AMS) conducts an extensive sampling and analysis of items from the actual US food supply to determine what, if any, pesticide residues are present at the consumer level. This information is published each year, and the actual raw data is also available for download. The data for 2010 was just recently released.
What Does The Data Actually Tell Us?
For 2010, as for preceding years, the data demonstrates is that pesticide residues are only present at very low levels, usually dramatically below the conservative ‘tolerances’ set during the risk analysis by the EPA. This is quite remarkable considering that pesticide use on crops depends on many thousands of independent decisions by many thousands of individual farmers both in the US and in dozens of countries from which we import food.
This year the USDA provided several summaries in an effort to be clear about what they have found. In this years press release one finds the following, unambiguous statements:
The 2010 PDP report confirms that food does not pose a safety concern
based upon pesticide residues.
Statement from the EPA ‘The data confirms EPA’s success in phasing- out pesticides used in children’s food for safer pesticides and pest control techniques. The very small amounts of pesticide residues found in the baby food samples were well below levels that are harmful to children.’
Statement from FDA: ‘Based on the PDP data from this report, parents and
caregivers can continue to feed infants their regular baby foods without being concerned about
the possible presence of unlawful pesticide chemical residues.’
Statement from the USDA: ‘Age-old advice remains the same: eat more fruits and vegetables and wash them before you do so. Health and nutrition experts encourage the consumption of fruits and vegetables in every meal as part of a healthy diet…’
What Does The Press Tell Us?
As a typical example, CNN starts with the headline, ‘Watch out for the 2012 Dirty Dozen,’ and continues, ‘Apples and celery are still agricultures dirtiest pieces of produce according to the Environmental Working Groups annual ‘Dirty Dozen’ report.’ Its version of the baby food findings are, ‘For the first time this year, the USDA also collected data on pesticide residue in baby food, finding many of the studies samples to be contaminated with organophosphate pesticides.’
How can CNN report something so radically different than what the USDA said? They simply are repeating what the Environmental Working Group has said in its press release of 6/19 and make no effort to compare it with the official document.
HuffPost Healthy Living starts with the headline, ‘Dirty Dozen: EWG Reveals List of Pesticide-Heavy Fruits and Veggies.’ Nowhere in this article is there even a reference to what the USDA, EPA and FDA said about the data. It simply passes along the EWG interpretation as if it were gospel.
This is the mainstream media. You can well imagine what is said on various organic and Food Movement sites and blogs.
In contrast, Jon Hamilton writing for an NPR blog uses the headline, ‘Why you shouldnt panic about pesticide in produce.’ Jon notes that the EWG sends a ‘mixed message,’ saying ‘you should be concerned about pesticide residues in fruits and vegetables, but not so concerned that you stop eating these foods.’ Rather than simply parroting EWG, this writer demonstrates some journalistic mettle by interviewing a scientist at McGill University who can provide some perspective. He also demonstrates that he read at least some of the USDA documentation by quoting specific numbers on apples and the non-alarm assessment for the baby food data. Such efforts at balance are unfortunately rare.
Why Does The EWG’s Version Get So Much Attention vs The USDA’s?
Although sensationalism, low journalistic standards, and limited scientific background are certainly involved in the largely uncritical magnification of the EWGs message by the press (and particularly the blogosphere), Im afraid that UDSA-AMS is partially to blame. Dont get me wrong, they do a rigorous collection and analysis of the data. They are extremely clear in what they conclude with sound reasoning. They are definitely transparent and unbiased in their presentation. What what USDA does not do is provide a summary version of the data that is easily digestible by ordinary readers, including typical members of the press. EWG provides a simple list with a one dimensional ranking. It is a gross and misleading simplification, but that makes it easy to relay as if it was a real analysis. Unfortunately, the summaries that the USDA presents are extremely detailed, extremely long, and not easy to interpret even for someone who wants to. Let me explain.
A Document That I Doubt Many People Really Read and Digest
The annual summary document for each years PDP data is huge, in the range of 200 pages as a pdf (it is hard to tell, the appendices are numbered independently). It starts with 28 pages of background on methodology and summary of sample types etc. Then there are 9 pages of a historical appendix. Finally the actual data begins in a 77 page appendix, but this is organized by chemical – nothing that most people would even begin to relate to. For each chemical there is no information about whether that product is something toxic or not, nor is there information on any other dimension of its environmental profile. To get that, someone would have to search for an MSDS and maybe an EPA RED – none of which are easy for any layman to interpret. All this table lists are the number of samples, the number and percent of ‘detections,’ the range of those detections in PPM, the LOD (limit of detection), and the EPA tolerance (an extremely conservative level set by an elaborate risk analysis). Most people would have no idea what to do with those numbers. In fact they show that the vast majority of ‘pesticide detections’ are at levels well below the tolerances, but it is tedious to do the comparisons by eye and there is nothing in the table to give the message of how far below any level of concern the vast majority of samples are actually shown to be. Im not surprised that no independent journalistic interpretation of these data occur.
Below the chemical-by-chemical summary there are dozens of pages summarizing commodities other than fruits and vegetables. That is followed by an appendix J which unhelpfully simply compares the ‘percent detections’ for imported and domestic samples (a summary level as seriously unhelpful as that by the EWG).
Finally, at the very end of this huge document there is a crop-by-crop summary with the same data columns as for each chemical (#samples, #detections…) which has the same tedious requirement to compare detections and tolerance that are all usually numbers to several decimal points. I have never seen anyone in the press do much if anything with this data set.
What Does This Report Need?
To be fair, USDA-AMS has amassed such a huge body of data. It is difficult to summarize it in a way that is intuitively meaningful. Their bottom line conclusion, ‘produce is safe,’ is a perfectly valid, but some visual representation could go a long way towards getting that message across. I acknowledge that this is difficult. I have made some attempts to do so in the past. I plan to do so again with this years data, but that will take time. The same would be true for even an ambitious reporter, while simply reporting what the EWG says allows less ambitious reporters to keep up with the instant news cycle.
A Mountain of Data
It is a wonderful thing that the USDA makes the effort to analyze so many samples of so many crops and looks for so many different chemicals. The downside is that this generates a database that is beyond what most of us even know how to process. The file that one can download with the raw data has been getting bigger every year and has now reached 85MB. Im used to dealing with large files, but none of my ordinary software can deal this this. Ive gotten my son to write a program in RUBY to parse the data and only give me the tiny fraction which contains ‘detections’ and discard the millions of rows of data that effectively say, ‘we didnt find this chemical in this sample.’ Im going to ask him to modify the program this year with some additional summaries.
When and if I get this done, I plan to make this available to anyone interested in doing an actually meaningful analysis of the data and to explore ways to present it graphically in ways that can compete with the egregiously trivialized ‘analysis’ done by EWG.
You are welcome to comment here, and/or email me at email@example.com
Produce stand image from Steve Savage
(Via Steve Savage Applied Mythology.)