Evaluation of certain food additives and contaminants.

This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, including flavouring agents, with a view to recommending acceptable daily intakes (ADIs) and to preparing specifications for identity and purity. The Committee also evaluated the risk posed by two food contaminants, with the aim of advising on risk management options for the purpose of public health protection. The first part of the report contains a general discussion of the principles governing the toxicological evaluation and assessment of intake of food additives (in particular flavouring agents) and contaminants. A summary follows of the Committee's evaluations of technical, toxicological and intake data for certain food additives (acidified sodium chlorite, asparaginase from Aspergillus oryzae expressed in Aspergillus oryzae, carrageenan and processed Eucheuma seaweed, cyclotetraglucose and cyclotetraglucose syrup, isoamylase from Pseudomonas amyloderamosa, magnesium sulfate, phospholipase A1 from Fusarium venenatum expressed in Aspergillus oryzae, sodium iron(III) ethylenediaminetetraacetic acid (EDTA) and steviol glycosides); eight groups of related flavouring agents (linear and branched-chain aliphatic, unsaturated, unconjugated alcohols, aldehydes, acids and related esters; aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances; simple aliphatic and aromatic sulfides and thiols; aliphatic acyclic dials, trials and related substances; aliphatic acetals; sulfur-containing heterocyclic compounds; aliphatic and aromatic amines and amides; and aliphatic alicyclic linear alpha, beta -unsaturated di- and trienals and related alcohols, acids and esters); and two food contaminants (aflatoxin and ochratoxin A). Specifications for the following food additives were revised: maltol and ethyl maltol, nisin preparation, pectins, polyvinyl alcohol, and sucrose esters of fatty acids. Specifications for the following flavouring agents were revised: maltol and ethyl maltol, maltyl isobutyrate, 3-acetyl-2,5-dimethylfuran and 2,4,5-trimethyl-delta-oxazoline (Nos 1482, 1506 and 1559), and monomenthyl glutarate (No. 1414), as well as the method of assay for the sodium salts of certain flavouring agents. Annexed to the report are tables summarizing the Committee's recommendations for intakes and toxicological evaluations of the food additives and contaminants considered.

Strain-specific tumorigenesis in mouse skin induced by the carcinogen, 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one, and its relation to DNA adduct formation and persistence.

The incidence of skin tumors has been studied in three strains of mice, namely, TO, C57BL, and DBA/2, after treatment with the carcinogen 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one. After either a single dose followed by croton oil promotion or a continual dose of the carcinogen, tumors were observed in the TO and C57BL strains, with the TO mice having the shorter mean latent period. The DBA/2 mice, however, appeared to be resistant to tumor formation by either treatment. To understand the mechanism of resistance, several criteria have been investigated. Metabolism of the carcinogen was assessed in terms of the total DNA adduct formation and the pattern of individual adducts after separation by high-pressure liquid chromatography, and no major differences between the three strains was found. Similarly, the rates of disappearance of the individual adducts when measured over 14 days posttreatment were not strain specific. Persistent binding of the carcinogen after 2 months was found in all three strains and could be reduced markedly if croton oil was administered throughout this period. The ability of the phorbol esters to cause biochemical changes in both sensitive and resistant strains was indicated by the induction of ornithine decarboxylase in each of the three strains after treatment with either croton oil or its active component, 12-O-tetradecanoylphorbol-13-acetate.

Repair of DNA adducts of the carcinogen 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one in mouse tissues and its relation to tumor induction.

The formation and repair of DNA adducts of the carcinogen, 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one, have been studied in three mouse tissues, liver, lung, and skin. Following a single i.m. dose of the carcinogen, DNA adduct formation was observed in all three tissues, the highest being found in liver DNA, the tissue resistant to tumor formation by this carcinogen. In skin and lung, the tissues which were susceptible to tumor formation, binding was approximately one-half that found in liver. Detailed analysis by high-pressure liquid chromatography of the adducts formed in each of the three tissues revealed no major qualitative differences in the eight adduct peaks. In vivo removal of the labeled adducts was studied over a 14-day period following initial treatment, and adducts were analyzed at each time point by high-pressure liquid chromatography. In skin and lung, active removal of the major adducts could not be measured above the normal rate of DNA turnover. By contrast, in the liver, where the rate of DNA turnover was slower, adducts were removed relatively rapidly with a half-life of approximately 2.5 days. Only one minor adduct present in both skin and liver was removed more rapidly than were the major adducts. The results suggest that the persistence of carcinogen-DNA adducts coupled with a relatively high rate of cell division may be related to tissue-specific carcinogenesis by this polycyclic ketone.

DNA synthesis with methylated poly(dC-dG) templates. Evidence for a competitive nature to miscoding by O(6)-methylguanine.

The alternating copolymer poly(dC-dG) has been methylated with either dimethyl sulphate or N-methyl-N-nitrosourea and the levels of the various methylation products determined. In addition to the 3-methylcytosine, 3-methylguanine and 7-methylguanine (produced by both agents) reaction with N-methyl-N-nitrosourea also yielded easily detectable amounts of O(6)-methylguanine and phosphotriesters. These methylated polymers were then used as templates in an in vitro assay with Escherichia coli DNA polymerase I measuring the incorporation of complementary (dCMP and dGMP) and noncomplementary (dAMP and dTMP) nucleotides. When the dimethyl sulphate-methylated polymer was used as template there was virtually no detectable incorporation of non-complementary nucleotides indicating that no miscoding could be attributed to the presence of 3-methylcytosine, 3-methylguanine or 7-methylguanine. However, when the N-methyl-N-nitrosourea-methylated polymer was used as template there was a specific incorporation of dTMP but not of dAMP. The amount of dTMP incorporated was always less than the level of O(6)-methylguanine in the template and was found to vary with the relative concentrations of the deoxynucleoside 5'-triphosphates in the assay. As the amount of dCTP present in the assay was decreased the wrong incorporation of dTMP increased and approached the level that would have been expected for a one-to-one miscoding by O(6)-methylguanine as the concentration of dCTP approached zero. The results indicate that O(6)-methylguanine is capable of miscoding with a DNA polymerase but the miscoding is competitive with the normal incorporation of dCMP: when the 5'-triphosphate precursors are present in equal amounts approximately one O(6)-methylguanine in three miscodes leading to the incorporation of dTMP.

The formation of acetylaminofluorene adducts in poly(dC-dG) and poly(dA-dT) on reaction with N-acetoxy-2-acetylaminofluorene and the effect of such modification upon the polymers as templates for DNA polymerases.

N-Acetoxy-2-acetylaminofluorene (AcO-AAF) reacts with the alternating DNA-like polynucleotides poly(dC-dG) and poly(dA-dT) in vitro to give adducts of the guanine and adenine bases similar to those reported to be formed in DNA. A previously unobserved guanine adduct was detected in the poly(dC-dG). Using a double-labelled [U-14C-dG, 8-3H-G]-poly(dC-dG) we show that this adduct does not involve the 7- or 8-positions of the guanine. Similarly a thymine adduct of unknown structure was observed in poly(dA-dT). Modification of the polymers with AcO-AAF inhibits their capacity to act as templates for Escherichia coli DNA polymerase I and mammalian DNA polymerase alpha although the binding of the polymerases to the polynucleotides is unaffected. Such modification also leads to an increase in the levels of non-complementary nucleotides incorporated into newly synthesised DNA.

Mutational and recombinational events in carcinogen-modified plasmid DNA. Influence of host-cell repair genes.

A plasmid containing the STR operon has been modified in vitro (i) by irradiation with UV light, (ii) by reaction with ethyl methanesulphonate (EMS), (iii) by reaction with N-acetoxy-2-acetylaminofluorene (AcO-AAF), (iv) by reaction with (+/-)trans-benzo[a]pyrene-7, 8-dihydrodiol-9,10-epoxide (BPDE), and (v) by heating at 70 degrees C to produce apurinic sites. Suitably modified plasmid DNA was then used to transform both repair-proficient and repair-deficient strains of Escherichia coli, and the mutation frequency in the plasmid-encoded rspL+ gene measured. The influence of host mutations in the uvrB+, recA+, umuC+ and lexA+, genes on the mutation frequency have been investigated. Transformation into a uvrB strain significantly decreased survival and increased the level of mutations observed for UV- and AcO-AAF-modified plasmid DNA, while only a small increase in mutation frequency was seen with EMS-modified DNA and no increase in mutation frequency with plasmid DNA containing apurinic sites. Mutagenesis in UV- and BPDE-modified DNA (and probably also DNA containing apurinic sites) was totally dependent on he recA+ gene product, while EMS and AcO-AAF induced mutagenesis was only partially independent on the recA+ gene. Transformation of UV- or BPDE-modified DNA into a umuC or lexA strain, on the other hand, showed no change in mutation frequency from that observed with wild-type strain. Pre-irradiation of the wild-type host with UV light before transformation led to a significant increase in mutation frequency for UV- and BPDE-modified plasmid DNA. These results are discussed in terms of mutational or recombinational pathways which may be available to act on modified plasmid DNA, and suggest that the majority of the mutational events measured in this system are due to recombination between homologous regions on the plasmid and chromosomal DNA.

Upper extremity snowboarding injuries. Ten-year results from the Colorado snowboard injury survey.

A survey of snowboarding injuries was conducted over 10 seasons (1988 to 1998). A questionnaire evaluating 20 variables was used to collect data from 47 medical facilities near Colorado ski resorts. A total of 7430 snowboarding-related injuries were seen. A control group consisted of 3107 noninjured snowboarders. Most of those injured were 30 years of age or younger; 74% of injuries occurred in men and 26% in women; 39% of injured snowboarders were beginners and 61% were intermediate or experts. Men rode at more advanced levels than women. Injured snowboarders were more likely than noninjured snowboarders to be beginners. There were 3645 (49.06% of total) upper extremity injuries; 56.43% were fractures, 26.78% sprains, and 9.66% dislocations. The most common site of injury was the wrist (21.6% of all snowboarding injuries). Wrist fractures (except to the scaphoid) and sprains were more common in beginners, women, and younger age groups. Intermediate and expert men were more likely to sustain hand, elbow, and shoulder injuries, as well as more severe injuries. Falling was the predominant mechanism of upper extremity injuries. Snowboarders who wore protective wrist guards were half as likely to sustain wrist injuries as those who did not wear guards.

The biomechanics of lateral knee bracing. Part I: Response of the valgus restraints to loading.

To better understand the role of preventive knee braces in injury prevention, a biomechanical study using fresh frozen cadaveric knees (N = 18) was conducted. Ligament tensions and joint displacements were measured at static, nondestructive valgus forces as well as low-rate destructive forces. After quantifying and establishing individual ligament contributions to valgus restraining function, knees were then braced with two different laterally applied preventive braces, the McDavid Knee Guard and the Omni Anderson Knee Stabler. The effects of lateral bracing were analyzed according to valgus force, joint line opening, and ligament tensions. Valgus applied forces, with or without braces, consistently produced medial collateral ligament (MCL) disruptions at ligament tensions surprisingly higher than the anterior cruciate ligament (ACL) and higher than or equal to the posterior cruciate ligament (PCL). Although large joint displacements were necessary for complete ligament failure, bundle disruption in the MCL, ACL, and PCL was noted at much smaller joint openings. In Part I of this study, no significant protection could be documented with the two preventive braces used. Also, four potentially adverse effects were noted: MCL preload, center axis shift, premature joint line contact, and brace slippage.

Carcinogenic chemicals in food: evaluating the health risk.

The presence of a low level of potentially harmful chemicals in food continues to be a concern to many individuals. A major concern is that these chemicals, which can be synthetic or naturally occurring, may be a causative factor in human cancer. Synthetic chemicals in food may be present either as specific additives or as contaminants derived from environmental or agricultural chemicals. Food also contains a variety of naturally occurring chemicals derived from vegetables or other plants. These may in some cases be considered as contaminants, and are occasionally used as specific additives. New chemicals can also be formed during the cooking or preserving processes. The capacity of any of these chemicals to induce cellular damage and mutation is minimized by natural defence systems such as an efficient cellular detoxification system and DNA repair. The factors influencing tumour formation in humans are numerous and interrelated and exposure to minor dietary chemicals needs to be considered in this context. Thus, the results of animal carcinogenicity assays on individual chemicals need to be interpreted with care, taking into account the mechanisms by which mutagenic and other chemicals initiate cancer, as well as the level of human exposure to these chemicals. Further research is necessary to determine the role, if any, of minor dietary components in tumour formation. Meanwhile, there needs to be a more holistic approach to the multitude of factors, including total diet, that may influence human cancer incidence. In this way, the relative risk of dietary chemicals may be given a more meaningful perspective for health professionals and consumers alike.

Retrospective analyses of additional services for methadone maintenance patients.

We report on the 6-month outcome of a retrospective analysis of additional treatment services for patients entering a methadone maintenance program who transferred from community methadone treatment programs (n = 83) or entered off the street (n = 83) not currently on methadone. Patients were participating in a clinical treatment trial examining the effectiveness of Community Reinforcement Approach and Relapse Prevention. Patients in the methadone transfer group were using less heroin at intake than patients newly initiated onto methadone and both groups improved from additional treatment services in the following problem areas specifically: drug, alcohol, legal, employment, social, and in some measures of psychiatric distress. Therefore, both groups of patients in this study benefited from additional treatment services.

Methylcyclopentadienyl manganese tricarbonyl (MMT) in petrol: the toxicological issues.

Methylcyclopentadienyl manganese tricarbonyl (MMT), when used as an octane improver in petrol, leads to increased airborne levels of manganese in the form of Mn3O4. The potential health effects of increased airborne manganese are considered in this paper. Manganese, unlike lead which it can replace in petrol, is a normal and essential component of the human diet and the intake from airborne manganese is slight by comparison to the normal dietary intake. The major toxicological effects of manganese, observed after long occupational exposure, are on the lung (manganese pneumonia) and the central nervous system (manganism). The small increase in airborne manganese from the use of MMT in petrol is 3-4 orders of magnitude lower than the level required to produce toxic symptoms of manganese exposure, even in areas of high traffic density, and no health risk from the use of MMT is likely.

Psychiatric disorders of opioid addicts entering treatment: preliminary data.

Psychiatric disorders have become an increasing concern in the treatment of substance abusers. The introduction of the Human Immunodeficiency Virus (HIV) into this population has further complicated treatment. This study examines the prevalence of psychiatric disorders in an opioid dependent population maintained on methadone. Results from this preliminary analysis show high rates of psychiatric disorders in this population. Additionally, needle sharing behavior appears to be increased in patients with a diagnosis of dysthymia. These findings have direct implications for aggressive screening and treatment of psychiatric disorders in methadone maintenance clinics.

AIDS risk behavior in opioid dependent patients treated with community reinforcement approach and relationships with psychiatric disorders.

This study examined the Community Reinforcement Approach's (CRA) effect on AIDS risk behaviors and the relationship between comorbid psychiatric disorders and the risk for AIDS behavior in opioid dependent patients entering methadone maintenance treatment. Additionally, we looked at AIDS risk behaviors as they related to the Addition Severity Index (ASI), Beck Depression Inventory, Symptom Checklist-90-Revised (SCL-90-R), and the Social Adjustment Scale-Self Report (SAS-SR). Subjects (N = 227) were drawn from a large clinical trial that examined the effectiveness of a Community Reinforcement Approach for treatment of opioid dependence. Both CRA and standard treatment demonstrated a significant effect on reduction of AIDS risk behaviors. There was no relationship found regarding comorbid psychiatric disorders with the risk for AIDS behavior. However, there were correlations with other psychiatric, social, and substance abuse variables. Multivariate analyses indicated that increased drug and legal ASI composite scores were the primary predictors of increased AIDS risk behavior.

American Indian and Alaska native aboriginal use of alcohol in the United States.

Alcohol beverages prior to White contact originated with the Mayan and the Aztec Nations and spread to the American Indians of the Southwest. Surprisingly, there are a number of accounts of alcohol use among other American Indians and Alaska Natives. Beverages were limited to wine and beer, and included: balche, pulque, and "haren a pitahaya" wines, tulpi beer and other beverages. White contact brought dramatic shifts in the use and function of alcoholic beverages in American Indian and Alaska Native societies.

Caffeine: a toxicological overview.

The health effects of caffeine have been examined in a review of its toxicological and pharmacological properties together with its effect on children. Caffeine commonly causes symptoms of an acute overdose and withdrawal symptoms. These may be identified as anxiety in moderate consumers and can lead to severe central nervous system effects in heavy consumers. Pharmacological effects occur even at low doses but their severity is influenced by wide individual variation and the development of tolerance. Nevertheless, chronic consumption of caffeine is implicated in various minor symptoms of ill health and is associated with elevated serum cholesterol levels. At the doses that are consumed by humans, there is little evidence at present to suggest effects on reproduction, teratogenesis, tumour formation or the incidence of myocardial infarction. A reduced consumption of caffeine is advocated for all age groups.

Traditional and western healing practices for alcoholism in American Indians and Alaska Natives.

The American Indian and Alaska Native population is a culturally diverse population with a current census of 1,959,000. Prior to White contact, there was historically little use of alcoholic beverages except for American Indians in the Southwest. After White contact, use and misuse of alcohol escalated rapidly; however, the prevalence, patterns, and problems of drinking alcoholic beverages vary enormously even in tribes closely linked geographically. American Indians and Alaska Natives have preserved and revitalized a number of traditional healing practices and applied these to the treatment of alcohol-related problems. These healing practices include the following: nativistic movements, sacred dances, sweat lodges, talking circle, four circles, and cultural enhancement programs. Additionally, Western treatment approaches have been applied in the treatment of problems related to alcohol, such as medication for detoxification, disulfiram (Antabuse), Alcoholics Anonymous, and behavioral interventions. Several investigators have completed a small number of naturalistic follow-up studies, but no one has undertaken a randomized controlled trial looking at specific methods of alcohol treatment in American Indians or Alaska Natives. American Indian and Alaska Native communities have adapted and integrated both Traditional and Western approaches to fit their own unique sociocultural needs.

Stimulation of recombination between homologous sequences on carcinogen-treated plasmid DNA and chromosomal DNA by induction of the SOS response in Escherichia coli K12.

Previous studies have shown that transformation of Escherichia coli by plasmid DNA modified in vitro by carcinogens leads to RecA-dependant recombination between homologous plasmid and chromosomal DNA sequences. The mechanism of this recombination has now been studied using recombination-deficient mutants, and the influence of induction of the SOS response on the level of recombination investigated. Plasmid pNO1523, containing the str+ operon (Sms), has been modified in vitro by either irradiation with UV light, or by reaction with (+/-) trans-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) and used to transform streptomycin-resistant hosts. The formation of Ampr transformants which also carry streptomycin resistance was used as a measure of the level of recombination between plasmid and chromosomal DNA. Transformation of recB and recC mutants produced no change in the level of recombination while in the recF mutant a significant decrease was observed compared to the wild type host. Thermal induction of the SOS response in tif-1 and tif-1 umuC mutants followed by transformation led to a four-fold increase in recombination in both cases. The results suggest that the streptomycin-resistant transformants arise exclusively via a recombinational pathway which is largely dependant on the recF gene product, and that this pathway is influenced by induction of the SOS response. These results are discussed in terms of the mechanism of this recombination.

Comfrey: assessing the low-dose health risk.

The regular use of comfrey as part of the diet or for medicinal purposes may be a potential health risk as a result of the presence of naturally-occurring pyrrolizidine alkaloids. The majority of these alkaloids are hepatotoxic in both animals and humans, and some have been shown to induce tumours in experimental animals. In this article, the toxic properties of pyrrolizidine alkaloids are reviewed briefly, with particular reference to their presence in comfrey. The acute and long-term health risks at the normally-low levels of comfrey consumption are evaluated and discussed. On the basis of the data that are available currently, the small but significant long-term risk that is associated with the consumption of comfrey justifies the need to limit its intake. This is being achieved by controls under various state Poisons Acts, but also requires further education on the potential dangers of naturally-occurring chemicals of plant origin.

Formation of O2-methylthymine in poly(dA-dT) on methylation with N-methyl-N-nitrosourea and dimethyl sulphate. Evidence that O2-methylthymine does not miscode during DNA synthesis.

The alternating co-polymer has been methylated with either N methyl-N-nitrosourea (MNU) or dimethyl sulphate (DMS) and the levels of the various methylated thymidines (O2-methylthymidine, 3-methylthymidine and O4-methylthymidine) measured. MNU produced all three compounds whereas DMS only produced 3-methylthymidine and O2-methylthymidine at detectable levels. These results have been combined with our earlier results concerning the misincorporation of dGMP with E. coli DNA polymerase using MNU-methylated poly(dA-dT). These results indicate that O2-methylthymidine does not miscode during DNA synthesis.

DNA-synthesis with methylated poly(dA-dT) templates: possible role of O4-methylthymine as a pro-mutagenic base.

The alternating copolymer poly(dA-dT) has been methylated with either dimethyl sulphate (DMS) or N-methyl-N-nitrosourea (MNU) and the levels of the various methylation products determined. In addition to the methylated adenines formed by both methylating agents, MNU resulted also in the formation of 3-methylthymine, O4-methylthymine and phosphotriesters. The methylated polymers have been ution of complementary and non-complementary nucleotides determined. With the DMS methylated template no wrong nucleotide incorporation was detectable, but with the MNU methylated polymer the incorporation of dGMP was observed. The amount of dGMP incorporated correlated with the level of O4-methylthymine in the template over the range of methylation studied. The results indicate that O4-methylthymine is capable of miscoding on a one-to-one basis while the products of DMS methylation (1-, 3- and 7-methyladenines), and also possibly the phosphotriesters, do not lead to any misincorporation.