A chronic study of artificial sweeteners in Syrian golden hamsters

Non-sugar sweeteners and cancer: Toxicological and epidemiological evidence

Several toxicological and epidemiological studies were published during the last five decades on non-sugar sweeteners (NSS) and cancer. Despite the large amount of research, the issue still continues to be of interest. In this review, we provided a comprehensive quantitative review of the toxicological and epidemiological evidence on the possible relation between NSS and cancer. The toxicological section includes the evaluation of genotoxicity and carcinogenicity data for acesulfame K, advantame, aspartame, cyclamates, saccharin, steviol glycosides and sucralose. The epidemiological section includes the results of a systematic search of cohort and case-control studies. The majority of the 22 cohort studies and 46 case-control studies showed no associations. Some risks for bladder, pancreas and hematopoietic cancers found in a few studies were not confirmed in other studies. Based on the review of both the experimental data on genotoxicity or carcinogenicity of the specific NSS evaluated, and the epidemiological studies it can be concluded that there is no evidence of cancer risk associated to NSS consumption.

The potential developmental neurotoxicity of calcium cyclamate in CD rats

The developmental neurotoxicity of calcium cyclamate was evaluated in Sprague Dawley [Crl:CD(SD)] rats, administered in drinking water, in comparison to a concurrent control group (water) and a positive control group given propylthiouracil (PTU). Calcium cyclamate was administered to F0 females for 4 weeks prior to pairing, throughout mating, gestation and lactation and to F1 offspring from weaning to 12 weeks of age, PTU was administered by gavage to F0 females from Day 6 of gestation up to Day 20 of lactation. Target calcium cyclamate doses were 0, 250, 500 and 1,000 mg/kg bw/day, while the PTU dose was 0.5 mg/kg bw/day. No treatment-related effects of cyclamate were observed in either the F0 or F1 generations on reproductive performance or neurobehavioral development. In comparison, PTU exposure resulted in developmental delays, memory impairment and a number of neuropathological and morphometric outcomes. The results from the unique developmental neurotoxicity study design, corroborate the absence of hyperactivity and any other neurotoxic effects following cyclamate administration at levels up to 878 mg/kg bw/day in F0 females and 784 mg/kg bw/day in F1 animals. This demonstrates the suitability of PTU as a positive control and confirms the safe use of cyclamate as a no-calorie sweetener.

Saccharin mechanistic data and risk assessment: urine composition, enhanced cell proliferation, and tumor promotion

Sodium saccharin (NaSac) produces bladder tumors consistently in male rats only after lifetime exposure that begins at birth. NaSac is not metabolized and is negative in most genotoxicity tests. NaSac-induced cell damage and proliferation have been proposed as important factors in tumor promotion, and dose-response information demonstrating a threshold for these parameters is available. One theory proposes that high levels of NaSac, combined with protein in a high Na+, high pH environment found only in the male rat, form toxic microscopic crystals; therefore, NaSac-induced tumors may not be relevant to human carcinogenesis.

Assessment of the carcinogenicity of the nonnutritive sweetener cyclamate

The weight of the evidence from metabolic studies, short-term tests, animal bioassays, and epidemiological studies indicates that cyclamate (CHS) is not carcinogenic by itself; however, there is evidence from in vitro and in vivo studies in animals that implies it may have cancer-promoting or cocarcinogenic activity. Epidemiological studies indicate that the use of nonnutritive sweeteners (CHS and saccharin) has not resulted in a measurable overall increase in the risk of bladder cancer in individuals who have ever used these products. No epidemiological information exists on the possible associations of these sweeteners and cancers other than those of the urinary tract. It is recommended that (1) no further studies on the metabolism of CHS to evaluate its carcinogenicity are required since no potentially hazardous metabolites have been appreciably detected in humans; (2) no further animal bioassays to test for the carcinogenicity of CHS by itself are necessary; (3) the studies in rodents that suggest a promotional or cocarcinogenic effect of CHS should be repeated because they cannot be ruled out; (4) because the significance to human health of a positive outcome of such studies is uncertain, additional research aimed at understanding the predictive value for human health of such results and more generic studies to develop well-validated systems that can be relied on in the assessment of cancer-promoting agents are recommended; (5) in populations where CHS continues to be used, epidemiological monitoring should be continued to determine whether there is an increased risk of cancer in humans who are heavy or long-term users or for those observed long after first exposure. In such monitoring, other cancer sites--in addition to the bladder--should be considered.

Myocardial effects of calcium cyclamate in the BIO F1D Alexander Syrian golden hamster

In a subchronic 90-day oral toxicity study, 5 groups (20 males, 20 females each) of F2-descendants of BIO F1D Alexander hamsters received 0, 275, 550, 1,100 and 2,200 mg/kg b.w./day doses, respectively, of calcium cyclamate in the drinking water. These doses caused no adverse health effects in any treated animal and the multifocal myocardial calcifications, detectable at a 100% incidence in the male and female control hamsters (20 males, 20 females), were not exacerbated by the sweetener. Instead, the myocardial lesions exhibited a striking negative dose-response relationship with a 0% incidence in the males and a 5% incidence in the female hamsters of the highest dose group.

Toxicological aspects of cyclamate and cyclohexylamine

In the late 1960s the artificial sweetener cyclamate was implicated as a bladder carcinogen in rats. This finding and other concerns about its safety ultimately led to a ban on cyclamate in the U.S. and restrictions on its use in many other countries. Since that time, the carcinogenic potential of cyclamate and cyclohexylamine, its principal metabolite, has been reevaluated in a group of well-controlled, well-designed bioassays that have failed to substantiate the earlier findings. This review of the published and unpublished literature on cyclamate attempts to evaluate the carcinogenicity question and other important aspects of the toxicity of cyclamate and cyclohexylamine, including their effects on various organ systems, their genotoxic potential, and their effects on reproduction. In addition, the physiological disposition of cyclamate is reviewed, with particular attention directed toward the site and extent of its conversion to cyclohexylamine.

Highlights in the history of saccharin toxicology

Saccharin has successfully survived a half century of scrutiny of its safety. Experience during almost 60 years of common use in foods, as well as several rat feeding studies including that conducted by the FDA, established its GRAS status under the 1958 Food Additives Amendment. Many chronic one-generation and three (unvalidated) two-generation rat studies subsequently conducted by regulatory and independent agencies in the USA and elsewhere have been interpreted by expert committees, especially those of the National Academy of Sciences/National Research Council, as supportive of saccharin's non-carcinogenicity under possible conditions of use. Not convinced of saccharin's safety, because of the (inconsistent) evidence of bladder tumours in saccharin-treated F1 male rats, the FDA proposed a ban on its use as a food additive. This ban has been temporarily postponed by Congressional moratoria, while better designed and executed studies into the mode of action of this unmetabolized non-genotoxic substance are in progress.

Effect of short-term administration of sodium saccharin on rhesus monkeys

Sodium saccharin (NaS) was incorporated into biscuits or the drinking-water and fed to rhesus monkeys at progressively increasing doses in order to determine the maximum dose that the monkeys would voluntarily consume and/or tolerate. Very little rejection of NaS-treated biscuits or drinking-water was observed. However, severe diarrhoea which precluded further treatment occurred when the dose of NaS reached 8.0% (approximately 1600 mg/kg body weight/day) in the biscuits and 0.48% (approximately 900-2400 mg/kg/day) in the drinking-water. An increase in fluid intake occurred in monkeys in both treatment groups. An increase in urine volume and a decrease in urine osmolality occurred in monkeys fed NaS in the drinking-water. No effects on body weight, food consumption or urine pH were observed in monkeys in either treatment group. All animals rapidly recovered when they were given untreated biscuits or water. Therefore, although monkeys will voluntarily consume rather high doses of NaS incorporated into biscuits or drinking-water, adverse effects on their general well-being preclude such administration for more than a few days.

Saccharin: a toxicological and historical perspective

Saccharin, first synthesized in 1879, eventually became popular as an inexpensive substitute for sugar, particularly as a non-caloric sweetner. The dispute concerning the safety of saccharin for human consumption is almost as old as saccharin itself. In this article, the history concerning the uses of saccharin and the accompanying controversy are reviewed. In addition, the spectrum of toxicological and epidemiological studies to which saccharin has been subjected are also examined. While the toxicological data indicate that saccharin is probably the agent solely responsible for the bladder tumors observed in second generation male rats, the epidemiological studies provide, at best, an equivocal relationship between the consumption of saccharin and bladder cancer. A benefit-risk evaluation for saccharin showed few, if any documentable benefits from the use of saccharin and much genuine uncertainty concerning the potential risks for ingestion by man. This element of genuine uncertainty as to the extent of human risk posed to man is the crux of saccharin's past and its foreseeable future.

Experiments on the carcinogenic effect of ortho-toluol-sulfonamid (OTS)

Ortho-toluol-sulfonamid was applied to male and female Sprague-Dawley rats in daily doses of 200 mg/kg and 20 mg/kg bodyweight respectively. The maximum dose applied amounted to 17 g/kg. A shortening of the average life expectation was not observed in comparison to the control animals. The incidence of malignant tumors in the animals treated with OTS was identical with the one of the control animals. We did, however, find one animal in the test groups that had a carcinoma of the urinary bladder and seven animals with papillomas of the bladder.