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| Bundle of Kale (Wikimedia commons) |
Last week the Environmental Working Group (EWG) published
its annual “Dirty Dozen List” and highlighted Kale near the top of it’s list of
foods with “pesticide residue contamination.” They want you to buy your Kale as
Organic. EWG claims to base that
recommendation on data from the USDA’s
Pesticide Data Program (PDP), but a closer look at the actual data suggests
a far different conclusion – that the Kale in our food supply is quite safe and
that there is not the big difference between organic and conventional that they
imply.
Since EWG gets much of its funding from large organic
marketers, it is not surprising that their recommendation is to buy
organic, but the 2017 PDP testing included 67 samples that were labeled as USDA
organic (13% of the total for Kale).
Many of those organic samples had detectable residues representing 31
different chemicals, only one of which is approved for use on organic crops
(Spinosad).
Now the levels at which chemicals were detected on the
organic were very low and of no health concern based on the very conservative “tolerances”
set by the EPA through its extensive risk assessment process. However, the same can be said for the 455
conventional Kale samples tested the same year of. The residues we are talking about here are hundreds to
thousands of times below the relevant tolerance (see graph below).
In theory there wouldn’t be any synthetic residues on
organic, but the USDA’s certification rule allows for “inadvertent” presence of
synthetics at 5% or less of the EPA tolerance. (There is a separate
USDA-Organic compliance testing program that looks for residues, and in that
case the 5% rule applies). 98.9%
of the 2017 PDP detections for organic Kale samples would meet that standard,
but so do 98.1% of the residues on conventional samples. Not so different, eh? In the graph
above, only the red part of each bar would be a technical violation of the
organic rules and none of the Kale detections for either conventional or organic exceeded the tolerance. Note that
neither category is actually “dirty” based on a rational, scientific
assessment.
Now, there were about three times as many residues/sample
found on the conventional Kale, but the USDA does not even test for a great
many of the pesticides that are approved for and regularly used on organic. This would include “natural products”
such as mineral-based materials (e.g. sulfur or copper compounds), petroleum
oils, plant extracts, and biologicals).
Those sorts of products make up a substantial part of what gets applied
to Kale. Thus, pesticides which are not part of the PDP testing make up 65% of
the total pounds of crop protection agents applied to kale and 44% of the
treatment acres (see graph below from the most recent available year of
California use data). Approval for
organic is entirely based on what is considered to be “natural” and the USDA is
quite clear that the classification is not about relative safety.
The acreage of Organic Kale has been increasing over the
last 15 years and with it the use of the organic-allowed pesticides. (See the example of sulfur use on Kale
as linked to organic acreage in the graph below).
If the USDA tested for residues the natural product
pesticides, the number of “detections” for organic samples would certainly
increase. But as with the synthetics, the results would most likely indicate
that this is a perfectly safe vegetable to consume whether or not it is
organic. Bottom line, the wisest
thing for consumers to do is to ignore
the fear-mongering of the EWG and simply enjoy a
healthy diet including lots of this and other fruits and vegetables.