Is there scientific evidence that organic
produce is as microbiologically safe as
conventional produce?
Francisco Diez-Gonzalez, Ph. D.
Professor, Food Safety Microbiology
Current Controversies in Food Safety
2013 IAFP Annual Meeting
Organic Safety Concerns

“… people who eat organic … foods are eight times
as likely as the rest of the population to be attacked
by … E. coli O157:H7.”
(Danis Avery, ‘The hidden dangers of organic food’, Wall Street
Journal, American Outlook, 1998)
Food Safety Issues Related to
Organic Foods
A highly polarized issue
Safety Issues of Organic Crops:
Use of Manure

Synthetic fertilizers are not allowed

Animal manure



One of few allowed fertilizers
Most widely available
Pathogenic microorganisms are excreted in manure
Organic Safety
Concerns


John Stossel, ABC News “20/20”, 2000
David Mastio, The Washington Times, 2011
Organically produced fresh fruits and
vegetables are AS MICROBIOLOGICALLY
SAFE AS their conventional counterparts
Null Hypothesis
Ho: μ1 = μ2
Ha: μ1 ≠ μ2
My position in this debate
Based on microbiological safety:
Ho: Organic = Conventional
Prevalence of Pathogens in Organic Fresh
Produce
Vegetables
tested
Positive
units
Place
Ref.
Salmonella
E. coli O157
0
0
UK
Sagoo et al.,
2001
Salmonella
Listeria
E. coli O157
Campylobacter
0
0
0
0
Ireland
MacMahon and
Wilson, 2001
605
Salmonella
E. coli O157
2
0
USA
Mukherjee et
al, 2004
Organic lettuce
179
Salmonella
L. monocytogenes
E. coli O157
0
2
0
Norway
Loncarevic et
al, 2005
Organic and
conventional lettuce
108
Salmonella
L. monocytogenes
0
0
USA
Phillips &
Harrison, 2005
Salmonella
E. coli O157
0
0
USA
Mukherjee et
al, 2006
Salmonella
E. coli O157
L. monocytogenes
0
0
0
Spain
Oliveira et al,
2010
Organic varieties
Organic vegetables
Organic and
conventional
Organic and
conventional
Organic and
conventional lettuce
Total
samples
3,200
86
2,029
144
Bacteria
tested
Prevalence of Pathogens in Fresh Produce
Vegetables
tested
Total
samples
Bacteria
tested
Positive
units
Place
Ref.
Imported
1,003
Shigella
Salmonella
E. coli O157
9
35
0
USA
FDA, 1999
Domestic
1,028
Shigella
Salmonella
E. coli O157
5
6
0
USA
FDA, 200001
3,826
Salmonella
L. monocytogenes
E. coli O157
Campylobacter
6
1
0
0
UK
Sagoo et al,
2003
398
Salmonella
L. monocytogenes
E. coli O157
3
0
0
USA
Johnston et
al, 2005
Salmonella
L. monocytogenes
E. coli O157
Shigella
Salmonella
L. monocytogenes
E. coli O157
E. coli O157
Campylobacter
Salmonella
14
0
3
0
0
3
0
0
0
0
USA
Samadpour
et al, 2006
So. USA
Johnston et
al, 2006
Canada
Bohaychuck
et al, 2009
Salmonella
L. monocytogenes
0
0
Italy
Caponigro et
al., 2011
Bagged salad
mixes
Leafy greens,
cantaloupe
Sprouts
200
Mexican and
domestic
466
Local produce
673
Ready-to-eat
salads
1168
Prevalence of E. coli in Organic Fresh
Produce
Vegetables
tested
Total
samples
Prevalence
(%)
Org. vs.
Conv.
Place
Ref.
3,200
1.5
NA
UK
Sagoo et al.,
2001
86
0.0
NA
Ireland
MacMahon and
Wilson, 2001
Organic and
conventional
605
4.3 (O)
1.6 (C)
O=C
USA
Mukherjee et
al, 2004
Organic and
conventional
2,029
7.0 (O)
2.0 (C)
O=C
USA
Mukherjee et
al, 2006b
Organic lettuce
179
9.0
NA
Norway
Loncarevic et
al, 2005
Organic and
conventional lettuce
108
3.7 (O)
12.9 (C)
O < C*
USA
Phillips &
Harrison, 2005
Organic and
conventional lettuce
144
22.0 (O)
12.5 (C)
O > C*
Spain
Oliveira et al,
2010
Organic varieties
Organic vegetables
* No statistical analysis performed
Organic Foods Market
In 2011:
•$31.5 billion
•4.2% total food sales
(OTA, 2012)
Organic share:
16% of total
fresh produce
(http://www.ers.usda.gov/briefing/organic/demand.htm)
Regulatory evidence…
Based on microbiological safety:
Organic = Conventional
Food Recalls Databases
http://www.fda.gov/Safety/Recalls/ArchiveRecalls/
default.htm
http://www.fsis.usda.gov/Fsis_Recalls/Recall_Case_Arch
ive/index.asp
Organic Food Recalls
16
14
12
10
Number of
recalls
8
6
4
2
0
2004
2005
2006
2007
2008
Year
http://www.fda.gov/Safety/Recalls/ArchiveRecalls/default.htm
2009
2010
2011
2011 and 2012
Fresh Produce Recalls
40
2011
35
30
Number of
recalls
25
or %
15
2012
20
10
5
0
Conventional
Organic
http://www.fda.gov/Safety/Recalls/ArchiveRecalls/default.htm
% Organic
Conclusion
Is there scientific evidence that organic produce is as
microbiologically safe as conventional produce?
YES
Not only scientific but as well as recall data support
the idea that the safety of organic produce is
equivalent to conventional
Thanks!!