ORGANIC VS' CONVENTIONAL FOODS: A Look at Food Safety Risks

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ORGANIC VS. CONVENTIONAL FOODS A Look at Food
Safety Risks

• Dr. Carl K. Winter
• Department of Food Science and Technology
• University of California, Davis
• ckwinter_at_ucdavis.edu

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OUTLINE

• Growth of organic food industry
• Organic food regulations and standards
• Comparisons of organic and conventional foods
• Pesticide residues
• Nutritional composition
• Natural toxins
• Microbiological contamination
• Summary and conclusions

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ORGANIC FOOD INDUSTRY GROWING RAPIDLY
Source Whole Foods Market, 2005
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Why do consumers choose organic foods?

• Perceived health and nutrition benefits
• Avoidance of pesticides (70)
• Freshness (68)
• Health and nutrition (67)
• Avoidance of genetically modified foods (55)
• Willing to pay typical 10 to 40 price premiums

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ORGANIC FOODS

• Not just fresh fruits and vegetables anymore

U.S. Organic Food Sales by Category, 2005 (Mil)
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ORGANIC REGULATIONS AND PRACTICES

• Systems based on minimal use of off-farm inputs
  and on management practices that restore,
  maintain, and enhance ecological harmony.
• Ecological production systems that promote and
  enhance biodiversity, biological cycles, and soil
  biological activity.

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ORGANIC REGULATIONS AND PRACTICES

• Prohibited in organic production
• Synthetic pesticides
• Growth hormones
• Antibiotics
• Genetically modified crops
• Irradiation
• Chemical fertilizers
• Sewage sludge

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ORGANIC REGULATIONS AND PRACTICES

• Synthetic materials only allowed if they are on
  the National List of Allowed and Approved
  Substances
• Typically naturally-occurring
• Some EPA-approved pesticides are allowed in
  organic production (i.e. sulfur, chrysanthemum
  extracts)

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ORGANIC REGULATIONS AND PRACTICES

• Conversion from conventional to organic
  agriculture takes time
• Fields cannot be certified for organic production
  until 3 years have elapsed since last use of
  prohibited substances
• Animal herds - must be fed 80 organic feeds for
  9 months and then 100 organic feeds for another
  3 months

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REGULATORY TIMELINE

• 1990 - Organic Foods Production Act (OPFA)
  introduced by USDA
• 2000 - National Organic Program Standards
  announced
• 2002 - National Organic Program Standards fully
  implemented
• USDA Secretary Glickman organic certification
  expresses a production philosophy and organic
  labeling did not imply a superior, safer, or
  healthier product than food not labeled as
  organic

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ORGANIC SEAL
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ORGANIC SEAL USES

• Products containing only organically produced
  ingredients may use seal and be labeled 100
  organic
• Products containing at least 95 organically
  produced ingredients may use seal and be labeled
  organic
• Products that contain at least 70 organic
  ingredients can be labeled made with organic
  ingredients but cannot use USDA seal

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PESTICIDE RESIDUES FROM ORGANICS ARE LOWER, BUT
NOT ZERO

• Pesticides, typically naturally-occurring, are
  permitted for use in organics if approved by
  National Organic Standards Board
• Some pesticides may inadvertently contaminate
  organic foods
• Some organic growers may use pesticides not
  allowed by organic rules

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Baker, et al, 2002

• Organic foods 127 samples, 23 positive for
  pesticide residues
• 10 of positives due to persistent chlorinated
  hydrocarbon insecticides
• Remaining 13 showed detectable residues of
  pesticides not approved for organic use
• Foods with no market claim 26,571 samples, 73
  positive for pesticide residues

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PESTICIDE RESIDUES - CONVENTIONAL VS. ORGANIC
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WHAT ARE THE RISKS FROM PESTICIDE RESIDUES IN
FOODS?
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NO ADVERSE EFFECTS ARE OBSERVED
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Food Safety in Perspective
Food safety priorities of FDA and WHO

• Microbiological contamination
• Nutritional imbalance
• Environmental contaminants
• Naturally-occurring toxins
• Pesticide residues
• Food additives

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NUTRITION DIFFERENCES

• Very little research directly comparing
  nutritional value of organic vs. conventional
  foods
• There is some limited evidence suggesting that
  organic foods have higher nutrient levels than
  conventional foods
• Worthington (2001) analyzed results from 41
  comparative studies

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WORTHINGTON CONCLUSIONS

• Organic foods had higher levels of vitamin C,
  iron, calcium, phosphorus, sodium, potassium,
  magnesium and beta-carotene than conventional
  foods
• Nitrate levels were lower in organics relative to
  conventional foods

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OTHER REVIEWS

• Woese, et al (1997)
• 150 comparative studies between 1926 and 1994
• No major differences between organics and
  conventional, or contradictory findings, with the
  exception of nitrates, which were lower in
  organics
• Bourn and Prescott (2002)
• Looked at differences from organic vs.
  conventional fertilizers
• Study designs and results too variable to provide
  definitive conclusions

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INTERESTING STUDY

• Davis, et al (2004)
• Compared USDA nutrient content for 43 crops
  between 1950 and 1999
• Statistically reliable declines for protein,
  calcium, potassium, iron, riboflavin, and
  ascorbic acid

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DAVIS CONCLUSIONS

• Differences primarily due to cultivars (plant
  varieties) used
• Selection of cultivars primarily made for
  resource-using functions such as growth rate,
  yield, and pest resistance
• Tradeoffs that limit cultivars abilities to
  incorporate soil minerals, transport them within
  the plant, or synthesize nutrients such as
  proteins and vitamins

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SPECIFIC STUDIES

• Large number of comparative studies reported in
  the past ten years
• Frequently look at plant polyphenolics
• Suggestive that plant polyphenolic levels are
  increased in organic production

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Asami, et al JAFC 51 1237 (2003)
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REASONS FOR INCREASED PLANT POLYPHENOLICS

• Use of synthetic fertilizers promotes plant
  growth at the expense of synthesis of plant
  secondary metabolites
• Plant stress due to insect, weeds, or plant
  pathogens may increase synthesis of plant
  secondary metabolites more likely with organics
  if other pest management tools are not available

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Naturally-occurring toxins

• Many chemicals produced by plants themselves show
  signs of toxicity in animal testing
• Examples
• Potatoes glycoalkaloids
• Celery furanocoumarins
• Many plants alkaloids
• May be produced as a means for the plant to
  defend itself

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MYCOTOXINS

• Toxins produced naturally by fungi that live on
  food plants
• Examples aflatoxins, fumonisins
• Frequently found in crops like corn and nuts that
  are stored in humid environments
• Epidemiological correlations between eating
  mycotoxin-contaminated foods and human cancers
• Best method of control often is to control insects

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EFFECT OF PRODUCTION PRACTICES ON LEVELS OF
NATURAL TOXINS

• Very little direct research comparing plant
  toxins in organic vs. conventional foods
• Logical that natural toxin levels could be
  elevated in organics
• Some evidence suggests mycotoxin levels could be
  lower in conventional produce

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Food Safety in Perspective
Food safety priorities of FDA and WHO

• Microbiological contamination
• Nutritional imbalance
• Environmental contaminants
• Naturally-occurring toxins
• Pesticide residues
• Food additives

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MICROBIOLOGICAL RISKS

• US Estimates - 76 million cases of foodborne
  illnesses annually, including 320,000 cases of
  hospitalization and 5,000 deaths
• Is organic food more or less safe than
  conventional food in terms of microbiological
  safety?
• More manure use in organics, but more stringent
  regulation of manure in organic agriculture

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MICROBIOLOGICAL RISKS

• Mukherjee et al (2004)
• Compared 476 organic food samples and 129
  conventional food samples for various
  microorganism contamination levels

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MUKHERJEE FINDINGS (generic E. coli contamination)

• Conventional produce - 1.6 of samples positive
• Certified organic produce - 4.3 of samples
  positive
• Noncertified organic produce - 11.4 of samples
  positive
• Statistically, certified organic and conventional
  had no significant difference contamination of
  noncertified organic produce was significantly
  higher than on conventional or certified organic

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SUMMARY

• Organic foods have lower pesticide residue and
  nitrate levels than convention foods
• Polyphenolics are higher in organics in some
  cases
• Naturally occurring toxins may be higher in
  organics in some cases
• There is concern about the microbiological safety
  of organic produce if it is not handled properly
• TRADEOFFS!

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HEALTH SIGNIFICANCE?

• Differences in chemical/microbiological
  compositions of foods do not necessarily imply
  health differences
• Need to know the magnitude of the differences and
  whether the magnitude is of significance

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