UNL's AgBiosafety for Educators

IS THIS STUFF SAFE TO EAT?

How Foods from Biotech Crops are Evaluated for Human Safety in the United States

Dr. Robert K. D. Peterson
Agricultural & Biological Risk Assessment
Montana State University
bpeterson@montana.edu

Before reading this chapter, you may want to read, "Plant Biotechnology Regulation: Science-Based and Consumer Accessible from Plow to Plate,” which provides a brief overview of how biotech crops are regulated in the United States.

In the first chapter, we discussed why scientists can never prove that biotech crops are safe. But that does not mean that regulatory agencies and society at large can’t determine that those crops are safe for humans and for the environment. To make that determination, society relies on the scientific weight-of-evidence regarding how risky these crops are.

In the United States, there are three federal regulatory agencies that primarily regulate biotech crops: the Environmental Protection Agency (EPA), the Food and Drug Administration (FDA), and the United States Department of Agriculture (USDA). Although their responsibilities overlap considerably, each agency is responsible for a single overriding question:

• EPA asks, “Is it safe for the environment?”

• USDA asks, “Is it safe to grow?”

• FDA asks, “Is it safe to eat?”

In this chapter, we take a closer look at the roles of the FDA (and to a lesser extent the USDA and EPA) in evaluating and making decisions about human-health risks from biotech crops and the foods derived from them.

Based on the questions posed above, in the United States, determining whether human health risks from consuming foods derived from biotech crops are acceptable or unacceptable is the primary responsibility of the FDA. In the first chapter, we discussed how science and the scientific method form the foundation upon which the societal decision of “is it safe enough” is made. For crops produced using recombinant DNA technology, the FDA evaluates the new protein that has been introduced into the crop and whether the nutritional and compositional aspects of the crop have been changed. The EPA also is involved in this process, especially if the new protein protects the plant from pests (what EPA calls a “Plant-Incorporated Protectant”).

The department within the FDA that primarily is responsible for assessing the safety of consuming foods derived from biotechnology is the Center for Food Safety and Nutrition (CFSAN). CFSAN enforces allowable residues of pesticides (called tolerances) in food and feed, oversees all new plant varieties derived from biotech not covered by the EPA, and oversees biotech pesticidal substances that appear in food and feed.

Currently, all regulated biotech products or substances fit into three FDA categories: Whole Foods, Food Additives, and GRAS (Generally Recognized as Safe) Substances. “Whole Foods” must ensure that there are no changes in nutritional profile and no introduction of foreign substances that might present health hazards. “Food Additives” must receive pre-market approval of substances intentionally added to foods that are significantly different in structure, function, or amount than in current food substances. “GRAS Substances” must demonstrate that the substances generally appear in nature, have been consumed for long periods without recorded hazards, and are scientifically found to have no undesirable effects on humans.

To date, foods derived from biotech crops have fallen into the Whole Foods and GRAS Substances categories. Why these foods have not been placed into the Food Additives category will be discussed below.

Proteins that typically are considered safe (or that pose negligible risk) have the following characteristics:

They are from sources with no history of toxicity or allergy
They do not resemble known toxins or allergens
They have well understood functions
They are expressed at low levels (major allergens are usually found in large amounts in allergenic foods)
They are rapidly degraded in the stomach (within minutes)
There is a lack of adverse effects in mice at high levels of consumption
Animal feeding studies (such as a 42-day poultry trial) do not reveal any adverse effects

To evaluate the characteristics described above, the FDA regulator evaluates data from the following studies:

Acute oral toxicity in mice (Is the protein toxic when ingested by a mouse?)
In vitro digestibility under simulated gastric conditions (How quickly does the protein break down in conditions that mimic the human stomach?)
Comparison of amino acid sequence similarity of insecticidal protein to known protein allergens (Is the protein structurally similar to proteins that we know are allergenic?)
Heat stability of the protein (Does heat, such as we might see in food processing or cooking, break down the protein?)
Protein expression in plant tissues (Where in the plant does the protein occur and in what amounts?)
Protein fate in parts of the plant and in processed food fractions (How do the amounts of protein in different parts of the plant change over time and how much protein is present as the harvested crop is being processed into food?)
Poultry feeding studies (Are there any differences between chickens fed the biotech crop and those fed a non-biotech crop over a 42-day period? This type of study gives the regulator some idea of potential long-term dietary risks associated with humans eating food with ingredients from biotech crops.)

In addition to the risk associated with the protein, there is the question of how the insertion of the foreign gene has altered compositional and nutritional properties of the crop. To evaluate this, there are a number of analyses that are required. They include:

Protein, crude fiber, oil, carbohydrate, ash
Amino acid composition
Fatty acid composition
Antinutritional factors such as phytic acid, trypsin inhibitor, sachyose, raffinose
Isoflavones

What is important to recognize here is that none of the results from the studies alone or in combination prove anything. In particular, they do not prove that human health risks from biotech crops are acceptable or that they are safe. Each study tests a hypothesis. For example, the acute oral toxicity in mice study is centered on the initial hypothesis that the dose or doses of protein administered to the mice will not result in mortality or any signs of toxicity. The results from all of the study are evaluated by the FDA regulator, who makes a decision about the food safety of the biotech crop. The regulator, therefore, utilizes a weight-of-evidence approach when making his or her decision. The results either provide a weight-of-evidence that the protein is safe to consume or that it is not.

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