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This review compares the regulations, definitions and approval processes for substances intentionally added to or unintentionally present in human food in the following specific countries/jurisdictions: Argentina, Australia, Brazil, Canada, China, the European Union, Japan, Mexico, New Zealand, and the United States. This includes direct food additives, food ingredients, flavouring agents, food enzymes and/or processing aids, food contact materials, novel foods, and nanoscale materials for food applications. The regulatory authority of each target jurisdiction/country uses its own regulatory framework and although the definitions, regulations and approval processes may vary among all target countries, in general there are many similarities. In all cases, the main purpose of each authority is to establish a regulatory framework and maintain/enforce regulations to ensure that food consumed and sold within its respective countries is safe. There is a move towards harmonisation of food regulations, as illustrated by Australia and New Zealand and by Mercosur. The European Union has also established regulations, which are applicable for all member states, to establish a common authorisation procedure for direct food additives, flavourings and enzymes. Although the path for approval of different categories of food additives varies from jurisdiction to jurisdiction, there are many commonalities in terms of the data requirements and considerations for assessment of the safety of use of food additives, including the use of positive lists of approved substances, pre-market approval, and a separation between science and policy decisions. The principles applied are largely reflective of the early work by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) committees and JECFA assessments of the safety of food additives for human and animal foods.

Tooth whitening products (TWP) containing hydrogen peroxide (HPO) or carbamide peroxide (CPO) were evaluated in relation to potential oral cancer risk from their use. HPO is genotoxic in vitro, but such activity is not expressed in vivo. The genotoxic risk of HPO exposure of the oral mucosa encountered from TWP use is likely therefore to be vanishingly small. Available animal data on the carcinogenicity of HPO are of limited relevance to risk assessment of oral hazard of HPO exposure from TWP, and where relevant, do not indicate that there is an increased oral cancer risk for people using TWP. Clinical data on HPO-containing TWP only show evidence of mild, transient gingival irritation and tooth sensitivity, with no evidence for the development of preneoplastic or neoplastic oral lesions. Exposures to HPO received by the oral cavity, including areas commonly associated with oral cancer, are exceedingly low and do not plausibly pose a risk for the promotion of initiated cells or for induction of co-carcinogenic effects in conjunction with cigarette smoke or alcohol. The use of TWP was concluded not to pose an increased risk for oral cancer in alcohol abusers and/or heavy cigarette smokers. Furthermore, TWP were concluded to be safe for use by all members of the population, including potential accidental use by children.

Oral rinse and toothpaste products (Viadent) containing Sanguinaria extract have been shown through extensive clinical trials to be effective against plaque build-up and gingivitis. To establish safety, a comprehensive research program was conducted, including a series of clinical studies and a number of animal studies to evaluate acute, subchronic, and chronic toxicity, and the potential for irritation of mucosal tissues. In 1990 and 1993, an Expert Panel reported on reviews of these data and concluded that Viadent products are safe for their intended use. Despite the large database of information to support the safety of Viadent products, Damm et al. (1999) recently raised the possibility that their usage may be causally associated with development of oral leukoplakia. However, a critique of this recent report shows that it does not fulfil criteria for establishing causation. In particular, the study does not show that exposure to Viadent preceded the onset of leukoplakia, it does not demonstrate dose-response or biological plausibility, and it suffers from selection and information bias and from potential confounding. Furthermore, upon critical evaluation, the Damm et al. (1999) report on a case-series is inconsistent with the weight of available clinical evidence showing that Sanguinaria extract-containing oral health care products cause no cytotoxic or significant irritant effects in the oral mucosa in human studies of up to 6 months duration. The animal data similarly do not support a causal association between Viadent usage and oral leukoplakia in humans. These data demonstrate that Sanguinaria extract and whole Viadent formulations are without significant irritation potential and have no effects on the oral mucosa, even in studies with life-long dietary exposure to Sanguinaria extract. The mutagenicity and genotoxicity data do not indicate that Sanguinaria extract or its components are genotoxic in vivo. The results of 2 GLP-compliant rat oncogenicity studies provide no evidence of any carcinogenic effect of Sanguinaria extract. In conclusion, the available clinical and animal data provide no support for and in fact argue strongly against the hypothesis that the use of Viadent toothpaste and/or oral rinse products may be causally associated with the development of leukoplakia in humans.

3-Monochloro-1,2-propanediol (3-MCPD) is a by-product found in trace amounts, generally less than 1 mg/kg (

This study compared the compositional changes in mushrooms exposed to sunlight with those occurring after commercial ultraviolet (UV) light processing. Button mushrooms (75 kg) were processed in the presence or absence of UVB light; a third group was exposed to direct sunlight. Mushroom composition was evaluated using chemical analyses. Vitamin D concentrations were 5, 410, and 374 μg/100 g (dw) in control, UVB, and sunlight groups, respectively. On a dry weight basis, no significant changes in vitamin C, folate, vitamins B(6), vitamin B(5), riboflavin, niacin, amino acids, fatty acids, ergosterol, or agaritine were observed following UVB processing. Sunlight exposure resulted in a 26% loss of riboflavin, evidence of folate oxidation, and unexplained increases in ergosterol (9.5%). It was concluded that compositional effects of UVB light are limited to changes in vitamin D and show no detrimental changes relative to natural sunlight exposure and, therefore, provide important information relevant to the suitability and safety of UVB light technology for vitamin D enhanced mushrooms.

The term chlorinated chemicals is used to describe diverse groups of chemicals of varying chemical structure, including those used in water disinfection, as well as numerous aliphatic, aromatic, and polycyclic chlorinated substances. This report elaborates a number of scientific principles that govern the evaluation of the potential for chlorinated organic chemicals to cause adverse effects on the environment and to human health. The purpose of the report is to demonstrate the importance of applying these scientific principles in the evaluation of potential adverse effects of chlorinated organic chemicals. The four major principles upon which such a scientific analysis must be based are: (1) the fate and biological activity of a compound are determined by the chemical properties of the compound; (2) compounds do not show adverse effects below certain threshold concentrations, and the magnitude of response is related to dose; (3) inherent metabolic processes allow organisms to accommodate low doses of chlorinated organic chemicals; (4) observations associated with the presence of a certain compound must be biologically plausible effects, based on the specificity of the compound's activity in experimental systems. With respect to the first of these principles, there is abundant scientific evidence that the physical and chemical properties of chlorinated organic chemicals govern their bioaccumulative potential, toxicological properties, and thus their potential behavior and effects in the environment. Chemicals that have low solubility in water are highly lipophilic and have low vapor pressure, tend to accumulate in biological systems, and degrade slowly in the environment. Chlorinated organic chemicals that possess these characteristics include those having a carbon ring structure and multiple chlorine substitution. Other chlorinated organic chemicals with lesser degrees of chlorine substitution, such as 2,4-dichlorophenoxyacetic acid (2,4-D), trichlorophenol, chloroform, and dichloroethane, do not share the physical and chemical properties of the high molecular weight, cyclic, polychlorinated compounds and, as such, do not have the same potential to bioaccumulate. These differences among chlorinated organic chemicals with respect to their physical and chemical properties and behavior in the environment preclude the generalization that all organic chemicals containing chlorine behave similarly in the environment and act as persistent, bioaccumulative chemicals. The reactivity of chlorinated organic chemicals and hence their potential to produce biological effects depends on their specific molecular features. The substitution of chlorine into an organic molecule may increase or may reduce its biological activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Publisher Summary This chapter provides a brief summary and overview of the data available on 2,4-D. 2,4-dichlorophenoxyacetic acid (2,4-D), the most common of the phenoxy herbicides, is one of the best-studied agricultural chemicals. It is the most widely used herbicide and the majority of the literature on phenoxy herbicides pertains to studies with 2,4-D. The basic form of 2,4-D is the acid, but 2,4-D is often formulated as an inorganic salt, amine, or ester through various manufacturing processes and is used in many commercial products. 2,4-D is primarily used as an herbicide in agriculture, forestry, and lawn care practices, with the majority of the total usage in the United States being reported for use as weed control in agriculture. Exposure to it can occur via inhalation, ingestion, and dermal contact. Respiratory exposure to 2,4-D is less than 2% of total exposure, and residual levels in foodstuffs or drinking water are essentially nondetectable or only detected in trace amounts. 2,4-D is rapidly absorbed through the gastrointestinal tract following oral exposure, with peak plasma levels being reached in as little as 10 minutes or up to 24 hours depending on the dose and chemical form of 2,4-D. In occupationally exposed humans, dermal absorption was reported to occur rapidly based on the detection of 2,4-D in urine within 4 hours. 2,4-D is highly water-soluble and therefore is widely distributed, but does not accumulate, in the body. It also does not readily cross lipid membranes, and at physiological pH, it exists predominantly in the ionized form. 2,4-D uses active transport systems to enter tissues and cross the blood/brain barrier. The extensive database of metabolic, toxicological, and epidemiological studies on 2,4-D has provided no evidence that 2,4-D poses any health risk to humans when used according to label directions.

The safety of 2,4-D to farm and forestry workers, commercial applicators and the general public has been of continuing concern because certain epidemiological studies of groups potentially exposed to 2,4-D have suggested a relationship between 2,4-D use and increased risk of soft tissue sarcoma, Hodgkin's disease or non-Hodgkin's lymphoma. This review on 2,4-D is unique in that the approach taken was to integrate data from worker exposure studies, whole animals, metabolic and other relevant laboratory studies with the epidemiological findings to assess the extent to which there is scientific support for the hypothesis that 2,4-D exposure is associated with any increased risk of human cancer.The case-control epidemiological studies that have been the source of the cancer risk hypothesis are inconclusive. Problems in assessing exposure based on patients' memories make these studies difficult to interpret. Cohort studies of exposed workers do not generally support the specific hypothesis that 2,4-D causes cancer. Taken together, the epidemiological studies provide, at best, only weak evidence of an association between 2,4-D and the risk of cancer.Importantly, the cancer hypothesis is not supported by other data. A critical evaluation of the exposure data indicates that exposure to 2,4-D in user groups is intermittent and much lower than the doses tested chronically in long-term animal studies that have not shown evidence of tumor induction. Moreover, the structure of 2,4-D does not suggest it would be a carcinogen. 2,4-D is a simple organic acid, that is largely excreted unchanged, and there is no evidence that it is metabolized to critically reactive metabolites or accumulates in tissues. This evidence is supported by a large body of negative studies on genotoxicity, which taken together with the metabolic studies, clearly indicates that 2,4-D is highly unlikely to be a genotoxic carcinogen. Furthermore, 2,4-D has no known hormonal activity and does not induce proliferative changes in any tissue or organ, indicating that it does not possess any of the characteristics of non-genotoxic animal carcinogens. Thus the available mechanistic studies provide no plausible basis for a hypothesis of carcinogenicity.In this review, data relating to potential neurotoxicity, immunotoxicity and reproductive toxicity also were evaluated. There is no evidence that 2,4-D adversely affects the immune system and neurotoxic and reproductive effects only have been associated with high toxic doses that would not be encountered by 2,4-D users.Historical exposures to 2,4-D by user groups, particularly farmers, forestry workers and commercial applicators, would be higher than those sustained under present rigorous standards for application which involve the use of protective clothing and other measures to reduce exposure. Proposed label changes indicate that in the future exposures will be even further reduced. Viewed in this context, the available data indicate that the potential public health impact of 2,4-D, including the risk of human cancer, was negligible in the past and would be expected to be even smaller in the present and future.

The risk assessment of migration products resulting from packaging material has and continues to pose a difficult challenge. In most jurisdictions, there are regulatory requirements for the approval or notification of food contact substances that will be used in packaging. These processes generally require risk assessment to ensure safety concerns are addressed. The science of assessing food contact materials was instrumental in the development of the concept of Threshold of Regulation and the Threshold of Toxicological Concern procedures. While the risk assessment process is in place, the technology of food packaging continues to evolve to include new initiatives, such as the inclusion of antimicrobial substances or enzyme systems to prevent spoilage, use of plastic packaging intended to remain on foods as they are being cooked, to the introduction of more rigid, stable and reusable materials, and active packaging to extend the shelf-life of food. Each new technology brings with it the potential for exposure to new and possibly novel substances as a result of migration, interaction with other chemical packaging components, or, in the case of plastics now used in direct cooking of products, degradation products formed during heating. Furthermore, the presence of trace levels of certain chemicals from packaging that were once accepted as being of low risk based on traditional toxicology studies are being challenged on the basis of reports of adverse effects, particularly with respect to endocrine disruption, alleged to occur at very low doses. A recent example is the case of bisphenol A. The way forward to assess new packaging technologies and reports of very low dose effects in non-standard studies of food contact substances is likely to remain controversial. However, the risk assessment paradigm is sufficiently robust and flexible to be adapted to meet these challenges. The use of the Threshold of Regulation and the Threshold of Toxicological Concern concepts may play a critical role in the risk assessment of new food packaging technologies in the future.

Sucralose is a non-nutritive sweetener used in a broad range of foods and beverages and is the non-nutritive sweetener in retail SPLENDA Sweetening Products, composed of sucralose and common food ingredients. A review of the extensive body of evidence that supports the safety of sucralose is provided. The results of an independent review of a new study investigating the safety of a sucralose-mixture retail product, Granulated SPLENDA No Calorie Sweetener, are also discussed. The collective evidence supports the conclusion that the ingredient, sucralose, is safe for use in food and that the sucralose-mixture product, Granulated SPLENDA No Calorie Sweetener, is also safe for its intended use.

Tooth whitening products containing hydrogen peroxide or carbamide peroxide were evaluated in this review for potential oral cancer risk from their use. Hydrogen peroxide is genotoxic in vitro, but not in vivo. Hydrogen peroxide was not considered to pose a genotoxic risk to humans. The animal toxicology data relevant to the assessment of the carcinogenicity of hydrogen peroxide do not indicate that it has significant carcinogenic activity at any site, including the oral cavity. Hydrogen peroxide was found to enhance the carcinogenic effects of potent DNA reactive carcinogens in experimental animals. However, these experimental conditions are artificial as they are related to high exposures and are of no relevance to potential human exposures to low quantities of hydrogen peroxide from the use of tooth whitening products. Clinical data on hydrogen peroxide-containing tooth whitening products show no evidence for the development of preneoplastic or neoplastic oral lesions. Exposures to hydrogen peroxide received by the oral cavity are exceedingly low, of short duration (30–60 minutes), and could not plausibly enhance any carcinogenic risk associated with exposure of the oral cavity to chemicals in cigarette smoke or to alcohol, both known risk factors for the development of oral cancer. CLINICAL SIGNIFICANCE Based on a comprehensive review of the available literature and research, the use of tooth whitening products containing hydrogen peroxide or carbamide peroxide does not appear to pose an increased risk of oral cancer in the general population, including those persons who are alcohol abusers and/or heavy cigarette smokers.

This paper is intended to present the background and general principles embodied in the model for the risk assessment of nutrients of the Food and Nutrition Board (FNB) of the Institute of Medicine, National Academies. Because no one had previously developed a comprehensive approach to the risk assessment of nutrients, the FNB Subcommittee on Upper Reference Levels of Nutrients first looked at various options that could be used to accomplish this task. During initial meetings, the committee considered a variety of options for setting tolerable upper intake levels and settled on the risk assessment approach described in this paper.

The current status of the GRAS evaluation program of flavoring substances operated by the Expert Panel of FEMA is discussed. The Panel maintains a rigorous rotating 10-year program of continuous review of scientific data related to the safety evaluation of flavoring substances. The Panel concluded a comprehensive review of the GRAS (GRASa) status of flavors in 1985 and began a second comprehensive review of the same substances and any recently GRAS materials in 1994. This second re-evaluation program of chemical groups of flavor ingredients, recognized as the GRAS reaffirmation (GRASr) program, is scheduled to be completed in 2005. The evaluation criteria used by the Panel during the GRASr program reflects the significant impact of advances in biochemistry, molecular biology and toxicology that have allowed for a more complete understanding of the molecular events associated with toxicity. The interpretation of novel data on the relationship of dose to metabolic fate, formation of protein and DNA adducts, enzyme induction, and the cascade of cellular events leading to toxicity provides a more comprehensive basis upon which to evaluate the safety of the intake of flavor ingredients under conditions of intended use. The interpretation of genotoxicity data is evaluated in the context of other data such as in vivo animal metabolism and lifetime animal feeding studies that are more closely related to actual human experience. Data are not viewed in isolation, but comprise one component that is factored into the Panel's overall safety assessment. The convergence of different methodologies that assess intake of flavoring substances provides a greater degree of confidence in the estimated intake of flavor ingredients. When these intakes are compared to dose levels that in some cases result in related chemical and biological effects and the subsequent toxicity, it is clear that exposure to these substances through flavor use presents no significant human health risk.

This publication is the seventh in a series of safety evaluations performed by the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA). In 1993, the Panel initiated a comprehensive program to re-evaluate the safety of more than 1700 GRAS flavoring substances under conditions of intended use. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, pharmacokinetics and toxicology. Flavor ingredients are evaluated individually and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of cinnamyl derivatives as flavoring ingredients is evaluated.

Over 20 years have elapsed since aspartame was approved by regulatory agencies as a sweetener and flavor enhancer. The safety of aspartame and its metabolic constituents was established through extensive toxicology studies in laboratory animals, using much greater doses than people could possibly consume. Its safety was further confirmed through studies in several human subpopulations, including healthy infants, children, adolescents, and adults; obese individuals; diabetics; lactating women; and individuals heterozygous (PKUH) for the genetic disease phenylketonuria (PKU) who have a decreased ability to metabolize the essential amino acid, phenylalanine. Several scientific issues continued to be raised after approval, largely as a concern for theoretical toxicity from its metabolic components--the amino acids, aspartate and phenylalanine, and methanol--even though dietary exposure to these components is much greater than from aspartame. Nonetheless, additional research, including evaluations of possible associations between aspartame and headaches, seizures, behavior, cognition, and mood as well as allergic-type reactions and use by potentially sensitive subpopulations, has continued after approval. These findings are reviewed here. The safety testing of aspartame has gone well beyond that required to evaluate the safety of a food additive. When all the research on aspartame, including evaluations in both the premarketing and postmarketing periods, is examined as a whole, it is clear that aspartame is safe, and there are no unresolved questions regarding its safety under conditions of intended use.

Bisphenol A (BPA) is a monomer component of polycarbonate plastics and epoxy resins. These resins are used in numerous consumer products, including food-contact plastics. There has been considerable scientific debate about the relevance to humans of reported estrogenic actions of BPA. Much less attention has been focused on the carcinogenic potential of BPA. The carcinogenic potential of BPA was assessed through a review of metabolic data, genetic toxicity studies, long-term toxicity/carcinogenicity studies, and estimates of consumer exposure. Following a weight-of-evidence approach as recommended by IARC and U.S. EPA, it was concluded that BPA is not likely to be carcinogenic to humans. The bases for this conclusion included: (a) the results of an NTP study which provided no substantive evidence to indicate that BPA is carcinogenic to rodents; (b) the lack of activity of BPA, at noncytotoxic concentrations, in standard in vitro genetic toxicity tests; (c) the lack of genotoxic activity of BPA in a GLP-compliant in vivo mouse micronucleus assay; and (d) the results of metabolism studies showing BPA is rapidly glucuronidated without evidence of formation of potentially reactive intermediates, except possibly at high doses that could saturate detoxication pathways. In addition, exposure assessment reveals that current use of BPA would result in only a trivial human exposure.

This chapter provides an overview of the available studies on 2,4-Dichlorophenoxyacetic acid (2, 4-D). . 2, 4-D is the most common of the phenoxy herbicides and is one of the best-studied agricultural chemicals. It is primarily used as a herbicide in agriculture, forestry, and lawn care practices and is effective against a wide variety of broadleaf plants. Occupational exposure to 2, 4-D is mainly through dermal contact but can also occur, to a lesser extent, via ingestion and inhalation. Studies in humans have shown exposures to be extremely low even in all occupational groups. The extensive database of metabolic, toxicological, and epidemiological studies on 2, 4-D has provided no evidence that 2, 4-D poses any health risk to humans when used according to label directions. The majority of human studies have been conducted with farmers, forestry workers, and other similar groups of potential users of herbicides. In most of the studies, there were methodological shortcomings in conducting exposure assessments specifically related to 2,4-D. Moreover, majority of the studies involved occupational exposures to a wide variety of chemical, physical, and biological agents, including phenoxy herbicides, and it was difficult to discern specific exposure to 2,4-D.

The IARC Monographs (Vols 1–70) were studied to determine the time of onset of treatment-related tumorigenicity in long-term rodent studies for chemicals classified by IARC as having sufficient evidence of carcinogenicity in animals. The analysis excluded studies on metals and their salts, studies on particulates, studies by parenteral routes of administration that resulted in tumours only at the site of exposure, and studies that did not approximate to the current standard long-term rodent carcinogenicity bioassay, for instance transplacental or multigeneration studies, initiator-promoter studies, lung tumour assays in Strain A mice and studies in newborn animals. Data from a total of 210 chemicals revealed that, overall, evidence of treatment-related tumorigenicity was first apparent within 12 months for 66% of the chemicals and for only 7% were studies of longer than 18 months necessary. All IARC Group 1 chemicals were detected in animals within 18 months, and most within 12 months. Most of the tumour types that required more than 18 months for detection were of dubious relevance to human risk assessment. Termination of rodent carcinogenicity studies at 18 months or earlier would greatly reduce the complications that arise in interpreting the findings in aged animals which often have defective hepatic or renal function and would also markedly reduce the time required for histopathological examination of dozens of tissues taken from the approximately 500 animals routinely employed in these studies.

Traditional toxicological procedures have only limited application to the safety assessment of macronutrient substitutes. Experience indicates that spurious effects are often encountered when macronutrients or their replacements are fed to rodents at high dietary levels. These effects may result in nutritional imbalances that lead secondarily to adverse physiological consequences including cancer, renal disease, or reproductive effects. In approaching the safety assessment of macronutrient substitutes, consideration needs to be given to designing and implementing a safety assessment program which acknowledges the physical, chemical, and biological properties of the substance. Factors such as molecular size, physical state, solvent properties, hydrolysis potential, digestibility, absorption potential, and metabolic fate must be well established prior to selection of appropriate test models. Armed with this information, many potential undesirable physiological effects of the substances can be predicted, thus precluding the need for a full spectrum of animal testing. Predicted physiological and metabolic effects, however, should be characterized usingin vitromethods and confirmed within vivomodels. Initial short-term toxicity screening tests with rodents should be carried out to identify unanticipated systemic toxicity. Testing in laboratory animals and trials in humans should then proceed with more appropriate models that are specially selected to assess the significance of predicted outcomes, to characterize dose–response relationships, and to identify possible needs to modify the product to mitigate adverse physiological consequences. These might include physical changes to alter particle size, chemical changes to modify digestibility, or nutrient supplementation to overcome impacts on nutrient availability. Thoughtful selection of appropriate and relevant models based on the physical, chemical, and biological properties of test substances will provide more rational approaches to safety assessments and avoid the pitfalls of routine application of traditional tests.

For decades, it has been known that a number of different factors (e.g., species, metabolism, age, animal husbandry, diet) may exhibit a significant modulating effect on the process of carcinogenesis. Often, however, these modulators have been largely uncontrolled and thus have made uncertain the results of many carcinogenicity bioassays. Fortunately, current research into molecular carcinogenesis is beginning to provide methods, not only to understand the molecular basis of known modulators of carcinogenesis, previously described only in empirical terms, but also to allow genetic modulation of carcinogenesis in experimental systems. An expanding body of knowledge regarding the role of oncogenes and tumor suppressor genes in neoplastic events is leading to a better understanding of carcinogenic mechanisms and points to the use of transgenic animal species in carcinogenicity bioassays. The transgenic animal provides methods to examine the molecular basis of carcinogenesis in experimental systems in addition to enhancing the sensitivity of carcinogen identification and the biological specificity of chemical risk extrapolation.

In order to characterize the human health risks of exposure to a chemical substance or mixture of substances, it is necessary to identify the health effects that the substance(s) cause(s) in exposed humans (hazard evaluation) and then determine a quantitative relationship between the specific exposure and the incidence or severity of the effects (dose-response characterization). Ideally, information from studies of exposed human populations is used for risk characterization. In practice, in the absence of adequate data on human health effects, information from studies in experimental animals is used. This is especially true for dose-response characterization.

o-Toluenesulfonamide (o-TS) was found to be a major impurity in 9 of 10 different saccharin samples used for carcinogenicity tests in animals in various laboratories. Isolation of o-TS from sodium saccharin was achieved by extraction with ethyl acetate, and separation was accomplished by using thin layer chromatography. Saccharin samples obtained in the free acid form were first converted to their sodium salts. o-TS was identified by Rf and ultraviolet, infrared, and mass spectra. Quantitative determination of o-TS was performed by gas chromatography. The concentration of o-TS in the samples ranged from 2.5 to 5050 ppm.

Pesticides and other agricultural chemicals are now widely used throughout the world as a means of improving crop yields in order to meet the increasing demands being placed upon the global food supply. In Canada, the use of such chemicals is controlled through government regulations established jointly by the Department of Agriculture and the Department of National Health & Welfare. Such regulations require a detailed evaluation of the toxicological characteristics of the chemical prior to its being cleared for use. In this paper, procedures for assessing the carcinogenic potential of agricultural and other chemicals are discussed. Consideration is given to both the classical long-term in vivo carcinogen bioassay in rodent or other species and the more recently developed short-term in vitro tests based on genetic alterations in bacterial and other test systems.

Carcinogenicity is a major consideration in the assessment of risks due to environmental chemicals. The carcinogen bioassay therefore is a very important component of the battery of toxicological tests used in hazard evaluation. The strengths and limitations of this bioassay are discussed with emphasis upon the unresolved practical considerations, the interpretation of negative results, the significance of tumors induced in the presence of a high background incidence of naturally occurring tumors, and the difficulties in transspecies extrapolation. These factors, in combination with consideration of the biological mechanisms of chemical cancer induction, will be valuable in assessing the potential risk to man posed by individual chemicals.