COOPERATIVE EXTENSION UNIVERSITY OF CALIFORNIA
ENVIRONMENTAL TOXICOLOGY NEWSLETTER


"Published Occasionally at Irregular Intervals"

Vol. 16 No. 4, August 1996

INTRODUCTION

In June of this year, the Korean Institute of Science and Technology held a symposium in Seoul to cover recent topics in food hygiene and safety. I presented the following paper as an overview of the issues which I think will be with us into the 21st century. Most of the concerns are ones which have been with us for centuries, however the rapid development of analytical technologies has been a "modifying factor" which has driven both the improvements in food quality as well as the perceptions of needed improvement. The whole issue of safety will continue to be driven by these modifying factors in the future. Because the idea of safety is not a "fixed" constant, and as such, changes with the times, the issue will change considerably during the next 10 years and as we move into the 21st century.

A series of slides which relate to this presentation are available for use by UCCE staff upon request.

Food Safety Issues in the Twenty-first Century


Introduction

Food safety is a term broadly applied to food quality issues which may adversely affect human health. These include communicable diseases (human and zoonotic), and the acute and chronic effects of ingesting natural and human-made toxicants. Toxicologists study the interaction of endogenous and exogenous chemicals with biological systems with a focus on adverse effects. Over the years, many tools have been developed to help predict the risks of chemical exposure using risk assessment models. In recent years, risk assessment methodology has been driven by the development of exquisitely sensitive analytical methods for measuring chemicals in the environment and in food. Some of the issues which will be covered in this paper are emerging into the public view, and others are reemerging as areas of concern.

These are the issues which may be faced by affluent nations. In less affluent nations, these quality issues will continue to be secondary to the main issue; quantity. Food quality concerns are also very important when the quantity is marginal since storage and preservation may be crucial to survival. In addition, in less affluent countries, the risk-benefit trade-offs are more evident. For example, use of crop protection chemicals may be vital to the production of a sufficient quantity of food to prevent starvation, and concerns about the risk of long-term effects of pesticide exposure pale in comparison. In affluent nations, the abundance and variety of the food supply often obscure the benefits and leave only the perception of risk associated with the use of crop protection chemicals. Another example of the risk-benefit equation is cooking. The benefits include the killing of pathogenic microbes and the inactivation of some toxins. The risks include the formation of carcinogens by cooking, and the destruction of nutrients.

The issue of food safety will be addressed from the viewpoint of a toxicologist, one who studies the interaction of chemicals with the body. To avoid confusion about terminology, hazard will be defined as the possibility of an adverse effect, or the potential of a chemical or microbe to cause an adverse effect. One of the hazards associated with aflatoxin ingestion is the development of hepatic cancer. Risk will be defined as the probability of a specified adverse effect occurring under specified conditions of exposure. An example would be the probability of developing hepatic cancer after a 30 year dietary exposure to 50 ppb aflatoxin. Probability is expressed as a fraction; e.g. 1/10,000.

One definition of safety would be the "absence" of risk, which is impossible, therefore a better working definition would be 1 minus the risk, or the probability that an adverse outcome will not occur. Perfect safety would require the complete elimination of hazard. Since this is impossible, most safety programs aim to reduce risk by managing hazards. In reality, safety is acceptable risk and as such cannot be established scientifically. Thus, safety is a social decision. Science can help us to measure and predict population based risk, but it cannot set acceptable limits on risk. With this view of safety applied to food, let us examine a historical perspective of food safety and some of the issues which will probably be with us well into the twenty-first century.

Historical Perspective

In prehistoric times, the primary food safety issues included establishing the edibility of plants and animals, and who was to be the food and who was to be the consumer. As humans advanced to the top of the food chain and became producers of agricultural products, concerns about food storage and preservation became more important. In medieval times, new concerns were added as poisoning became an established procedure for dealing with difficult people, or people whose wealth or position you desired more than their company. As the sciences progressed, chemists discovered how to detect many of the most common poisons, thereby adding another level of assurance to dining, and leading to unemployment of many tasters. In the late 1800’s and early 1900’s the advances in chemistry led to the development and addition of many chemicals to foods, some with dire results. Food adulteration problems led to the establishment of regulations and government agencies to oversee food and drug quality. In the 1940’s and 1950’s, further advances in organic chemistry associated with the world war produced numerous pesticides for control of vectors of human disease. DDT was one of many chemicals which were later utilized for crop protection until their adverse effects on wildlife were discovered and their environmental fate better defined. The 1980’s and 1990’s have seen further concerns develop about synthetic chemicals and human health and the institution of intensive monitoring programs to insure the proper use of crop protection chemicals, animal drugs, and food additives.

During the 1960’s and well into the 1980’s, concerns about the effects of pesticides and environmental contaminants dominated the food safety programs. In the late 1980’s, almost all of the food safety educational programs in the USA were presented in response to consumer concerns about synthetic chemical residues in food. Despite overwhelming evidence that food handling (storage and preparation) were the most significant elements of food safety, chemical residue concerns were still number one on the public’s list. Table 1 shows the food safety concerns in 1989 in relation to the documented problems and the perception of the problems. The concern was based primarily on chronic exposure to residues which might later cause cancer. All of the predictions were based on toxicological risk assessments using animal test data, and the risks were far below any which could be measured epidemiologically. The fear was fueled by special interest groups opposed to synthetic chemical use, and culminated in the Alar crises of 1989.

Table 1. U.S. Food Safety Concerns, 1989

Documented Problems Perceived Problems
Storage and preparation Pesticide and drug residues
Diet Contaminants
Contaminants Diet
Natural toxicants Storage and preparation
Pesticide and drug residues Natural toxicants

In 1995, most of the USA food safety education programs were focussing on microbial contamination issues related to processing, handling and storage, and chemical residues were not even mentioned at several national conferences on food safety. Indeed, Hazard Analysis Critical Control Point (HACCP) management of microbial contamination and food storage problems are the topics of the day.

In 1988, I was asked to project into the 1990’s and list what I thought would be the significant food safety issues. In addition to the continuing (eternal) problems associated with handling and storage, I listed the following five areas which were of concern at that time, and which seemed destined to last; 1) pesticide and drug residues, 2) natural toxicants, 3) products of cooking and preservation, 4) diet, and 5) zoonoses. Pesticide and drug residues continue to be a major public perception issue, however they no longer dominate educational programs. Concerns about natural toxicants and products of cooking and preservation have not become major issues during the 1990’s, however they continue to be the topics of research, much of it focussed on the beneficial effects of some of the natural constituents (toxicants) of foods. By diet, I mean the modification of nutrient intake to affect human health. (This is a sure bet in any case, and there are plenty of willing experimental subjects ready to follow the most recently published books on the subject. It is interesting to note that the observation that experimental animals fed diets severely restricted in calories live substantially longer than those fed ad libitum has attracted widespread interest in societies where up to 30% of the population are overweight.) The zoonotic diseases will be with us as long as we consume animal products, and the most recent concern is about the possibility that a disease suspected to be caused by a prion (bovine spongiform encephalopathy), may be zoonotic as well.

One might postulate that contemporary food safety issues of concern are those which are in some way connected with the major causes of mortality at the time. Consider, for example, the top ten causes of death in the USA (Table 2) in 1900, 1970, and 1993. In 1900, communicable diseases were the primary cause of mortality. Dietary risk factors for heart disease, stroke and cancer were not known. After the advent of antimicrobial drugs, communicable diseases were replaced by heart disease, stroke and cancer in 1970, and continue to be the major causes of mortality in the US population. Diet is a factor in the top three causes of death in the US, however it is probably not the most important factor. The synthetic chemicals which helped to eliminate communicable diseases as a major cause of death are now suspected of being the cause of at least one of the top three; cancer.

Table 2. Top Ten Recorded Causes of Death in the United States

Rank 1900 1970 1993
1 Pneumonia and Flu Heart Diseases Heart Diseases
2 Tuberculosis Malignant neoplasms Malignant neoplasms
3 Gastritis Stroke Stroke
4 Heart Diseases All accidents Respiratory disease
5 Stroke Pneumonia and Flu All accidents
6 Chronic nephritis Early infant diseases Pneumonia and Flu
7 All accidents Diabetes Diabetes
8 Malignant neoplasms Arteriosclerosis HIV
9 Early infant diseases Cirrhosis Suicide
10 Diphtheria Respiratory disease Homicide

Current Food Safety Issues

All of the food safety issues which will be covered in this section will undoubtedly still be of concern in the 21st century, and others which cannot be foreseen will arise, most likely in one of the broad categories presented below. The focus of this discussion will be on chemical constituents, however, microbial elements must be addressed briefly because of their major importance. It is important to keep in mind that the microbial issues are principally associated with acute exposure and disease onset in which the causative agent can be found (the "smoking gun"). The chemical concerns are primarily about chronic exposure and are based on toxicological risk assessment predictions and epidemiological studies.

Microbial Issues

It is generally agreed that microbes are the cause of most foodborne illness. In 1994 the US Economic Research Service reported on the costs associated with foodborne illness in the USA. Table 3 shows the data on the estimated cases of illness for 1993.

Table 3. Estimated morbidity and mortality associated with foodborne illness in the United States, 1993

Causative Agent (% foodborne) Morbidity Mortality
Salmonella (87-96%) 696,000 - 3,840,000 696 - 3,840
Campylobacter (55-70%) 1,418,494 - 1,805,356 110 - 511
E. coli 0157:H7 (80%) 8,000 - 16,000 160 - 400
Listeria monocytogenes (85-95%) 1,526 - 1,767 377 - 475

The total number of foodborne cases for the four pathogens was 3,390,875-6,600,940 and 1,644-5,730 deaths. Total foodborne illness losses from lost productivity and medical expenses were estimated at 1.9 to 6.2 billion dollars. Untermann (1995) reported that while public perception is still focussed on chemical issues, the perception is slowly changing and the importance of microorganisms is being recognized. He also estimated the incidence of acute gastroenteritis caused by microbes to be 100 to 150 per 1,000 inhabitants in Holland. Also of interest is the observation of McIntosh et al. (1994) that with respect to eating undercooked hamburger, awareness of the danger, and knowledge of the pathogens and food safety practices had no effect on the subject’s willingness to change behavior.

For several years the United Kingdom has been struggling with a newly discovered disease in cattle termed Bovine Spongiform Encephalopathy (BSE), or Mad Cow Disease. It appears that the disease was transferred through the recycling of farm animal protein back into animal feed, a practice which has been stopped. In recent weeks, the British government published a warning that there might be a connection between BSE and several newly diagnosed cases of Creuzfeldt-Jakob’s Disease (CJD) in humans. The connection between the BSE agent (prion) and CJD in humans has not been proven, and indeed the evidence for transmission to humans through meat is quite weak, however the reaction to the possibility of a connection has been overwhelming. This issue has emerged as a major food safety issue within the last two years, and will certainly continue into the 21st Century, especially considering the long "incubation" period for most prion induced diseases.

Chemical Issues

Toxicologists view food as an assortment of chemicals which may be classified as nutrients, inerts and toxicants. For purposes of this discussion, consider the following assumptions:

1. Food is composed of chemicals.

2. Chemicals may be nutrients, inerts or toxicants.

3. Nutrients may be toxic at high doses (vitamins).

4. Toxicants may be nutrients at lower doses (ethanol).

5. Adverse effects of chemicals in foods will follow toxicological/nutritional mechanisms.

6. True food allergy is rare, usually due to allergy to protein, and is a malfunction of the immune system; it’s not the food’s fault.

Despite the overwhelming evidence that microbes are the primary causes of foodborne illness, there is a continuing concern about the presence of synthetic chemicals in foods. This concern is focussed on chronic exposure effects rather than acute toxicity. There have been a few instances of acute toxicity from synthetic chemicals in food, all related to accidental contamination or blatant misuse of the chemicals involved. Accidental contamination of grains (usually during shipping) by pesticides has been responsible for numerous cases of illness, and many deaths. In California, in 1985, the criminal misuse of the pesticide aldicarb caused hundreds of cases of acute carbamate toxicity, but no deaths (Goldman et al., 1990). In 1992, misuse of the growth promoting drug clenbuterol in cattle, led to 113 reported cases of acute toxicity in Spain. (Salleras et al., 1995) In this instance, veal liver was the vehicle of intoxication, and there were no deaths.

There are no papers in the literature which demonstrate human chronic toxicity effects from synthetic chemicals ingested in foods. One might conclude that pesticide and drug residues in foods do not have a significant effect on human health. Such residues are however perceived as being of great importance, even at the very low levels at which they are found in foods. While chronic toxicity from low level ingestion has been a concern, the possibility of drug residue induced allergic reactions have been the focal point. Sundlof (1989) reviewed the literature about drug related allergic reactions and found few documented cases, all of them for reactions to -lactam antibiotics. Dewdney et al. (1991) reported that a review of the literature uncovered only 6 documented cases of allergic reactions to penicillin in milk over the last 25 years, and all of the reactions were benign. They also reported that the induction of allergy through ingestion of residues has never been documented and is highly unlikely since most -lactam induced allergies are more frequently due to parenteral therapeutic use rather than oral therapy.

Chemical Residues

Pesticides

In the United States, there are several national pesticide and animal drug residue monitoring programs, and many state programs which specifically look at pesticide residues in food and feed. The US Environmental Protection Agency (USEPA) establishes tolerances for pesticide residues. Tolerances are similar to Maximum Residue Levels (MRLs) in that they are the maximum level allowed in a product. Tolerances are established to reflect good agricultural practices for pesticides and are monitored to insure that pesticides are used legally. The setting of a tolerance for a pesticide in a particular crop does however involve the protection of human health by insuring that consumption of residues in all commodities will not exceed the EPA established Reference Dose (RfD), which is similar in concept to the World Health Organization (WHO) Acceptable Daily Intake (ADI). In practice, many of the RfDs are substantially lower than the corresponding ADI.

Table 4 shows data from the California Department of Pesticide Regulation for the last 8 years. There has been virtually no change in the percentage of samples which show illegal residues, however there has been an increase in the number of samples with detectable residues, which is a reflection of the increasing sensitivity of the analytical procedures. In California, Certified Organic produce may contain pesticide residues up to 10% of tolerance, to account for accidental crop contamination. The results presented are for conventionally grown produce, approximately 90% of which contains less than 10% of tolerance.

Table 4. Results of California State Department of Pesticide Regulation residue monitoring programs, 1987-1994

Year Sample
Number
Percent of Total,
Non-Detectable
Residue
Percent of Total
with 0-10%
Tolerance
Percent of Total with
Nondetectable, or
0-10% Tolerance
1987 7,010 80 12 92
1988 9,293 78 13 91
1989 9,403 78 13 91
1990 8,278 80 12 92
1991 7,446 75 16 91
1992 7,319 69 21 90
1993 6,066 66 23 89
1994 5,588 66 22.5 88.5

The US Food and Drug Administration (USFDA) conducts a monitoring program every year called the Total Diet Study (TDS). In this survey, foods are bought once per year at 4 regions throughout the USA, from three cities within the region. The foods are prepared for consumption, and then analyzed for pesticides residues and environmental contaminants. This very comprehensive survey is the most complete study available for measuring the levels of residues in foods as they are consumed. Most monitoring programs measure the levels in the foods at harvest or at the wholesale market. In 1991 the Market Basket Survey showed that the consumption of residues was far below the ADIs for all detectable residues (Table 5). Gunderson (1995) presented similar data for the 1984-1986 TDS data showing very similar results. In some cases, the RfD is up to 2 orders of magnitude lower than the ADI. For these very low RfD’s, actual residue consumption could approach the RfD and still be way below the ADI. It should be understood that if residue consumption approaches the RfD or the ADI, it does not mean that toxic effects will be seen, in fact, the RfDs in most cases are 500 to 1000 times lower than the no observable adverse effect level. The data presented above is for a series of organophosphate and carbamate insecticides which are considered "neurotoxicants".

Table 5. Intake of pesticide residues in the 1991 Total Diet Study, g residue/kg body weight per day compared to established WHO Acceptable Daily Intakes (ADI) and USEPA Reference Doses (RfD), g residue/kg body weight per day.

Pesticide FAO/WHO ADI USEPA RfD 6-11 mo. 14-16 year 60-65 year
Acephate 30 4 0.089 0.0113 0.0165
Azinphos-methyl 5 1.5 0.0028 0.0033 0.0029
Carbaryl 10 14 0.181 0.09 0.0811
Carbofuran 10 5 0.0002 0.0001 0.0004
Chlorpyrifos 10 3 0.0082 0.0034 0.0024
Chlorpyrifos-methyl 10 10 0.0104 0.0126 0.0066
Diazinon 2 0.09 0.0049 0.0022 0.0022
Dichlorvos 4 0.5 <0.0001 <0.0001 0.0001
Dimethoate 10 2 0.034 0.0022 0.0035
Fenitrothion 5 1.3 <0.0001 <0.0001 <0.0001
Fonofos none 2 <0.0001 <0.0001 <0.0001
Malathion 20 20 0.0779 0.0487 0.0275
Methamidiphos 4 0.05 0.012 0.0102 0.019
Methomyl 30 25 0.0053 0.0037 0.0068
Mevinphos 1.5 0.25 0.0066 0.0026 .00081
Omethoate 0.3 none 0.0144 0.0013 0.0019
Parathion 5 0.33 0.0097 0.0016 0.0042
Parathion-methyl 20 0.25 0.0007 0.0001 0.0001
Phosalone 6 2.5 0.0073 <0.0001 <0.0001
Pirimiphos-methyl 30 10 0.0007 0.0006 0.0006

Drugs

The United States Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) monitors drug and pesticide residues in animals which are slaughtered at inspected facilities. Table 6 shows the results of residue monitoring for 1991. The violation rate is very low for most species; less than 1%. The inspection programs are designed to target the most suspect animals (sick, lame, etc.) and hold the meat until the tests show it to be "clean".

Table 6. Food animal residue testing results for 1991 collected by the USDA FSIS

Chemical Class Tested Number Number Violative
Antibiotics 4,044 17
Sulfonamides 8,109 50
Arsenic 1,140 4
Benzimidazoles 2,627 0
Carbadox 649 0
Carbamates 1,087 0
Chlorinated Hydrocarbons and Organophosphates 7,099 7
Halofuginone 612 1
Ivermectin 3,253 6
Pyrethrins 656 0
TOTAL 29,276 85

The US Food and Drug Administration (FDA) recently began collecting national data on residue testing of milk. Throughout the USA, virtually every truck tanker load of milk is tested using a rapid screening test for antimicrobial residues. The violation rate for samples from the first quarter of 1995 ranges from a low of 0.029% of pasteurized fluid milk and milk product samples, to a high of 0.107% of bulk milk tankers (a total of 811 tanker loads). There is considerable concern that the sensitive tests which are being used may detect residues which are actually within established safe levels, and that a significant portion of the milk which is condemned may be legal.

Another recent concern about drug residues is their role in the development of bacterial drug resistance. The concern was that low level feeding of antimicrobials might lead to human pathogen antimicrobial resistance. This has carried over to the low residue levels which might occur in animals treated with antimicrobials having an effect on bacterial resistance development in the human gastrointestinal tract. While this seems extremely farfetched, research has been funded to examine this question.

Environmental Contaminants

Environmental contaminants can have a major adverse effect on human health, and none are more striking than the heavy metals. Intensive and extensive research has not yet established adverse human health effects caused by very low level exposure to many of the chlorinated hydrocarbon contaminants (PCBs, dioxins). While the adverse effects of these chemicals is well documented in laboratory and wildlife animals, the postulated human connection is under intensive examination and the data are not conclusive. At the 1996 Society of Toxicology Meeting, there were three major sessions devoted to the consideration of xenobiotics acting as hormones. A large body of evidence has been collected and continues to be collected, much of it from in vitro experiments.

A book was published in early 1996 titled "Our Stolen Future" in which concerns about hormonal effects of environmental chemicals were hypothesized to be damaging our ability to reproduce (and many other things as well). The book has not generated the reaction many activists would like to see, and in fact has been soundly discredited by most environmental reporters in the media. This concern will continue well into the 21st Century as more research is published about potential hormonal effects of synthetic and natural chemicals. We can expect a US federal agency to establish guidelines for testing for potential hormonal activity. In addition, look for environmental hormonal risk assessment paradigms to be developed and used in regulatory programs.

Packaging

Transfer of chemicals from packaging into foods has recently become a greater concern, particularly the transfer of plasticizers which might have estrogenic activity (phthalates, others). One of the more recent concerns is the potential transfer of chemicals from recycled packaging into foods.

Supplements and Additives

Vitamins

There have been many studies looking at the effects of "mega-dose" uses of vitamins to help prevent heart disease, stroke and cancer. A recent clinical trial in which large doses of vitamin A were being given was halted when increased mortality in the vitamin treated group was seen. Other studies have shown beneficial effects from additional intake of water soluble vitamins (e.g. folic acid and it’s inhibitory effect on neural tube defects).

Natural substances

Most of the current studies in progress are looking at the protective effects of natural constituents of foods. The isoflavones are an example of natural substances which are being considered for use as food additives. Some of these substances influence metabolic enzyme activity, and others appear to have hormonal effects. The potential beneficial and the potential toxic effects of natural substances in foods will continue to be an active area of research and speculation.

Preservatives, flavorings, etc.

All chemicals which are used for preserving and flavoring foods are now tested extensively before they can be used. Suspicion of these chemicals still abounds however. Aspartame is one of the most toxicologically studied food additives of all time, and yet it is still distrusted by many consumers. Monosodium glutamate (MSG) has been the recent focus of extensive review which has found that most people who report MSG sensitivity do not show a response when studied using double-blind testing. There is evidence of a small subpopulation of asthmatics who may be sensitive to MSG, however sensitivity is not widespread. The search for additional fat replacements will undoubtedly continue and the use of the one approved fat substitute, olestra, will undoubtedly expand as will concerns about it’s widespread use.

Natural Toxicants

The inorganic natural toxicants, which may also be considered as environmental contaminants, (primarily the metals and the transition element selenium) are what I consider to be real problems in the sense that there is measurable contamination and the effects can be severe. We are at the top of the food chain, and when the source of food is geographically limited, there is a greater potential for problems to develop. Itai-Itai disease caused by cadmium and Minemata Disease caused by mercury are two examples. Aluminum has come under suspicion as being a contributor to Alzheimers Disease, causing many US consumers to give up their aluminum cookware despite the lack of evidence. Natural organic toxicants are often the same ones considered for use as natural food additives!

Allergens and Biotechnology

Most food allergens are proteins, and most food allergies occur in children. Only 1-2% of adults have verifiable food allergies, however the allergies may be severe and exposure to allergens life-threatening. Allergies to soybeans and milk are common in children and usually outgrown. Nut, peanut, and seafood allergies are rarely outgrown. Many adults who believe they have a food allergy, do not. For some time, concerns have been expressed that genetic engineering of foods might result in the transfer of allergens from one species to another.

In a very recent paper, Nordlee et al. (1996) reported the transfer of a Brazil nut allergen into transgenic soybeans. The allergen appears to be 2S albumin which was being "imported" to provide a higher methionine content in the soybeans. They demonstrated the transfer of the allergen to soybeans with IgE serum binding and skin prick testing using known sensitized human subjects. This is the first time that this has been noted, and the discovery is being heralded by opponents as proof of the dangers of genetic engineering, and by advocates as proof that the system works, since it was discovered long before the soybeans were released into the market. Brazil nut allergy was known to occur, and therefore could be taken into account in the testing of the transgenic soybeans. In the future, the concern will probably focus on the transfer of allergens from known allergenic foods to nonallergenic ones, transfer from nonfood genetic sources (of unknown allergenicity), and genetic engineering to remove the allergenic potential from foods known to cause allergy.


Future Food Safety Issues

In the 21st century, all of the issues which were listed as current will still be with us to varying degrees. In this section I would like to list some modifying factors which I think will influence future issues with respect to regulatory programs and public perception.

1. Rapid Screening Tests

At the 1996 American Chemical Society Meeting in March, a session devoted to pesticide residue hazards and HACCP brought mixed responses from industry and governmental participants. The Director of the FDA Center for Food Safety and Applied Nutrition (CFSAN) recommended that food processing companies continue to monitor for pesticide residues since it continues to be a major consumer concern. The representative from the National Food Processor’s Association agreed that monitoring for residues was necessary but should not be part of HACCP programs since HACCP should be reserved for significant food safety threats (such as microbiological pathogens, natural toxicants, food allergens, nutritional imbalances and environmental contamination.) An independent consultant recommended that food companies should consider pesticides, toxic metals, natural toxicants, additives, environmental contaminants, allergens, hormones, and contamination from packaging, and recommended development and use of better test kits to check each shipment for chemical hazards thereby saving money for processors and providing safety assurance to consumers.

The food industry should examine carefully the impacts of these tests on the dairy industry before promoting an overall program for expansion and adoption of rapid screening tests. While the testing of individual milk tankers assures that antimicrobial residues will be below established safe levels, there is growing concern that the sensitivity of these tests results in too many "false violative" results, and too much economic loss to producers. There is a tremendous economic incentive for rapid test manufacturers to promote their development and use since they may sell hundreds of thousands of them in a single year. When so many may be used to determine the quality of large numbers of large lots of food, a very small false positive rate may have major economic impacts. There is a Generally Held Over-confidence in Screening Tests (GHOST) which may come to haunt us in the future. One must question the wisdom of implementing such widespread testing programs when there is no indication that there are human health problems, and when in fact it is impossible to measure the very low incidence of these problems predicted by risk assessment. Most of the proposed "safety" measures for chemical residues are targeting chemicals whose uses are already highly regulated and which require substantial premarketing toxicity testing.

2. Microbiological Zero Tolerances

For chemical residues found in foods, our current ability to measure extremely small quantities has led to a situation in which toxicologists are forced to make predictions about toxic effects far beyond our ability to measure such effects. The process of toxicological risk assessment has expanded so rapidly and into so many areas that some people think that toxicology is a science meant to support risk assessment rather than as a science from which risk assessment sprouted. Of particular concern is the possibility that the enhanced ability to detect extremely small numbers of microbes may lead to a "zero-tolerance" mentality similar to what has occurred with chemical residues. For microbes, the situation is also strikingly similar to the 1950’s attitude about chemical contamination. The development of "zero-tolerance" standards for pathogens may have the same effects as the Delany Clause zero tolerance for carcinogens, except for the fact that pathogens are unintentional "additives". Microbiological tests may end up chasing an ever vanishing zero, just like analytical chemistry tests have.

3. Increasing number of sensitive individuals

Over the last several decades, there has been an increase in the number of "highly susceptible" individuals in the US population. Examples include AIDS patients, individuals with severe allergies, patients undergoing cancer chemotherapy, and organ transplant recipients. Regulatory programs have often focussed on protecting these extremely sensitive individuals, and this seems likely to continue into the 21st Century.

4. Risk assessment paradigms

The risk assessment models which have been used for the last decade to set chemical exposure levels are termed "conservative", meaning, the models definitely overestimate the risks. In many cases, these "conservative" models are actually extreme, utilizing assumptions that grossly overestimate risk, and which ignore mechanistic data which is of great importance. For example, saccharin causes bladder cancer in male rats through a metabolic mechanism which does not even exist in humans, yet it is regulated as a probable human carcinogen. The linearized multistage model for predicting cancer risk has been the standard for the last decade, and it is very conservative.

There are steps being taken to allow the use of mechanistic data in regulatory risk assessment, which will result in revised risk predictions which, for many chemicals, will be lower than the previous estimates. This change offers chemophobic activists the opportunity to attack the revisions by stating that the government is putting the public at higher risk for the financial benefit of big business. It is always harder to relax the standards than it is to tighten them, at least from the public perception viewpoint. It is no wonder there is distrust of regulatory standard setting procedures, after all, if they were wrong once, might they not be wrong again?

5. Contamination issues and politics

The presence of low level chemical or microbiological residues is also a political and a trade issue. In the US, the slightly higher incidence of detectable residues on foreign vegetables has led some US producers to state that US grown produce is safer! The EEC countries do not allow the use of natural hormones (estrogens) as growth promoters in food animals, nor will they accept the use of bovine somatotropin (BST) for improving milk production. The issues can be stated as food safety issues when in reality they are trade and political issues; contamination is simply an ever available excuse.


Conclusion

Food quality embraces aspects of nutrition, toxicology, communicable diseases, and aesthetics. Food safety is an element of food quality which includes all of the above except aesthetics. Regulatory food safety programs have become very political and are now driven more by perception of hazard than by actual risk. This will continue into the 21st Century as the quest for increased safety is unending. In this quest we should remember the words of Warren Burger, a United States Supreme Court Justice in 1980.

"Perfect safety is a chimera. Regulation must not strangle human activity in a search for the impossible."

References:

Dewdney, JM; Maes, L; Raynaud, JP; Blanc, F; Scheid, JP; Jackson, T; Lens, S; and Verschueren, C. Risk assessment of antibiotic residues of -lactams and macrolides in food products with regard to their immuno-allergic potential. Food Chem. Toxic. 29(7):477-483, 1991.

Goldman LR; Smith DF; Neutra RR; Saunders LD; Pond EM; Stratton J; Waller K; Jackson RJ; Kizer KW. Pesticide food poisoning from contaminated watermelons in California, 1985. Archives of Environmental Health, 45(4):229-36, 1990.

Gunderson, EL. Dietary intake of pesticides, selected elements, and other chemicals: FDA Total Diet Study, June 1984-April 1986. Journal of AOAC International, 78(4):910-921, 1995.

McIntosh WA; Christensen LB; Acuff GR. Perceptions of risks of eating undercooked meat and willingness to change cooking practices. Appetite, 22(1):83-96, 1994.

Nordlee JA; Taylor SL; Townsend JA; Thomas LA; Bush RK. Identification of a Brazil-nut allergen in transgenic soybeans. New England Journal of Medicine, 334(11):688-92, 1996.

Salleras L; Dominguez A; Mata E; Taberner JL; Moro I; Salva P. Epidemiologic study of an outbreak of clenbuterol poisoning in Catalonia, Spain. Public Health Reports, 110(3):338-42, 1995.

Sundlof SF. Drug and chemical residues in livestock. Veterinary Clinics of North America. Food Animal Practice, 5(2):411-49, 1989.

Untermann F. Risk assessment of microorganisms relevant to food hygiene. Zentralblatt fur Hygiene und Umweltmedizin, 197(1-3):222-31, 1995.


Art Craigmill
Extension Toxicologist
UC Davis