COMMENTS OF ANNE R. BRIDGES, Ph.D.
American Association of Cereal Chemists, Biotechnology Committee

PRESENTED TO THE UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY,
FIFRA Scientific Advisory Panel

on Bt Plant Pesticides: Risk and Benefit Assessments

October 20, 2000 - Arlington, Virginia

Good afternoon. My name is Anne Bridges. I am here today in my role as Chair of the American Association of Cereal Chemists, Technical Committee on Biotechnology Methodsⁱ. My trip here today, is supported by the American Association of Cereal Chemists (AACC)ⁱⁱ and the Council for Agricultural Science and Technology (CAST)ⁱⁱⁱ. My comments are based on my experience in the development and quality assurance of testing methods for grains and cereals. In my current work with General Mills, Inc., my responsibilities include providing technical expertise for the monitoring and measurement of biotechnology events in our consumer food products.

In my comments to the Panel, I will touch upon four topics, which are pertinent to your discussions on human health and product characterization including (1) Safety of the US food supply, relative to the presence of Cry9C. (2) What test methods are appropriate to detect or quantify DNA or proteins at various points in the food supply chain. (3) What efforts are underway to develop and implement appropriate test methods and (4) finally to confirm that checks and balances are in the system to insure that this testing is robust and reliable.

First, I want to say that there is testing and auditing of the food in the US food supply chain and from all indications the quality of our food supply is very good.While recent events have raised questions, those questions really lie in the regulatory arena - in particular, in the implementation of regulations rather than in questions of safety.

Recent recalls, of processed consumer foods containing the Cry9C biotech event, have been an appropriate regulatory response to the registration status of Cry9C. Cry9C has a tolerance exemption for animal feed and industrial uses, while the food use tolerance exemption is still pending. The voluntary cancellation of Cry9C registration earlier this month ensures that no further Cry9C containing seeds will be planted. Once the current batch of Cry9C containing grain works its way through the food chain no more will be available. There will in fact be a limited length of time for which human exposure will even be possible.

(2) What test methods are appropriate to detect or quantify proteins or DNA at various points in the food supply chain? What can we tell from current testing of grains and cereals?

We know that there are differences in the testing methods needed for seeds, grains, mixed grains and the complex food matrices found in finished consumer goods. This is why the same test is not appropriate for all applications. In the best situation the testing method is fast, accurate, sensitive, reproducible and economical. It is not always possible to meet all of these objectives at the same time.

The methods used to detect the protein expressed by the enhanced DNA are best used early in the food chain when we can be relatively certain that the protein has not been changed in any significant way.

As the food product becomes more complex, either through blending of ingredients or processing it is more difficult to use a protein analysis method, and the more complex analysis of the DNA is often used.

The DNA analysis is known as the polymerase chain reaction or PCR method. In either case, the method requires validation for the particular sample matrix material.

The sensitivity of the flow strip or ELISA protein method can be adjusted by changing the number of samples in the sampling protocol used and depends on the level of confidence required for the test. Appropriate sampling protocols are well established and can be obtained from a number of qualified sources, such as USDA- Grain Inspection, Packers and Stockyards Administration (GIPSA). Technicians can perform these analyses with a minimum of training. The major limitation of ELISA protein methods is that each protein or part thereof requires a specially prepared antibody. There is no general screening method available today to detect all agbiotech events. However, a highly specific antibody is available for detection of the Cry9C protein in grain through Strategic Diagnostics, Inc.

The PCR analysis can be an extremely sensitive analysis and herein lies its challenge. There is no margin for error. Contamination is multiplied along with the target DNA. It can be a challenge to keep even the basic equipment clean. Electric coffee grinders are considered disposable in some labs performing the analysis. The cost for analysis reflects this concern. The time taken to complete the analysis can be a hindrance to the movement of products through the system. However, in the best hands different versions of the method can be used as a general screening tool, as a trait identification tool and in some laboratories as a trait quantification tool.

EXAMPLE: Cereal Cycle Stages- cereal grains can go through up to five life cycle stages as they make their way along the food supple chain. Testing methods, which are appropriate for grains prior to processing, are often not appropriate once those same grains that have been mixed, blended and/or heat processed.

Methods can be developed in individual laboratories but when transportation or trade is required it is imperative that the tests and the interpretation of those tests can be transferred with confidence between laboratories conducted for a limited number of methods. The most successful studies have measured soy protein using both protein and DNA type methods, and most recently a quantitative ELISA method for MON810 corn containing the Cry1Ab protein has been successfully completed by AACC. Up to 40% variability in the amounts reported, has been observed in other studies quantifying DNA in processed foods – this is clearly not an acceptable situation for regulation. More work needs to be done. The AACC has new method validations in the planning stages and we believe that other organizations such as the Joint Research Centre, Ispra of the European Commission and AOAC International have similar studies planned.

Two ways to monitor competency and reliability for a laboratory are first to use an accreditation program with an ongoing check sample requirement and second to develop appropriate reference materials.

The USDA-GIPSA lab is working on both of these objectives. The Institute for Reference Materials and Measurements (IRMM) of the EU has some limited types of reference materials available today.

In conclusion, test methods are feasible, but in need of validation and standardization to ensure consistent, reliable results. Despite the need for additional work to ensure good quality in all cereal products, from the grain to the finished breakfast cereal, there is testing and auditing of the food in the US food supply chain. All indications are that the quality of our food is very good.

ⁱ The role of the AACC Biotechnology Committee is to provide methods and a set of quality-standards for methods to test grains derived using modern biotechnology techniques. Robust, reliable standard methods and protocols to ensure consistency in the quality of testing are vital to consumer confidence, regulation and commerce. To that end, the AACC has conducted a collaborative study on "Bt Modified Corn in Corn Flour MON810/ ELISA Method", with 40 collaborators worldwide. The method has been approved by the AACC Biotechnology Methods Technical Committee and is pending First Approval status, it will be included as a standard method in the AACC Approved Methods book.

ⁱⁱ AACC is an international organization of cereal science and other professionals studying the chemistry of cereal grains and their products or working in related fields. It publishes journals and books on cereal and food science, including the textbook Principles of Cereal Science and Technology. AACC strives to be the premier world-wide cereals organization with a commitment to advancing cereal science and related technologies; creating, interpreting and disseminating cereals information; and providing personal and professional development opportunities for the cereal chemist. AACC website: http://www.scisoc.org/aacc

ⁱⁱⁱ CAST is a nonprofit organization composed of over 180,000 scientists from 38 scientific societies and many individual, student, company, nonprofit, and associate society members. CAST assembles, interprets, and communicates science-based information regionally, nationally, and internationally on food, fiber, agriculture, natural resources and related societal and environmental issues to our stakeholders (legislators, regulators, policy makers, the media, the private sector, and the public). CAST website: http://www.cast-science.org

©AACC International - 3340 Pilot Knob Road - St. Paul, MN 55121 U.S.A.
Phone: +1.651.454.7250 or Fax: +1.651.454.0766
Privacy Policy | Disclaimer | Copyright |  Contact AACC International  |  Webmaster