Ranking possible carcinogenic hazards

Meat food fraud risk in Chinese markets 2012-2021

Food fraud is a major concern worldwide, and the majority of cases include meat adulteration or fraud. Many incidences of food fraud have been identified for meat products both in China and abroad over the last decade. We created a meat food fraud risk database compiled from 1987 pieces of information recorded by official circular information and media reports in China from 2012 to 2021. The data covered livestock, poultry, by-products, and various processed meat products. We conducted a summary analysis of meat food fraud incidents by researching fraud types, regional distribution, adulterants and categories involved, categories and sub-categories of foods, risk links and locations, etc. The findings can be used not only to analyze meat food safety situations and study the burden of food fraud but also help to promote the efficiency of detection and rapid screening, along with improving prevention and regulation of adulteration in the meat supply chain markets.

Tolerance of Novel Toxins through Generalized Mechanisms: Simulating Gradual Host Shifts of Butterflies

Organisms encounter a wide range of toxic compounds in their environments, from chemicals that serve anticonsumption or anticompetition functions to pollutants and pesticides. Although we understand many detoxification mechanisms that allow organisms to consume toxins typical of their diet, we know little about why organisms vary in their ability to tolerate entirely novel toxins. We tested whether variation in generalized stress responses, such as antioxidant pathways, may underlie variation in reactions to novel toxins and, if so, their associated costs. We used an artificial diet to present cabbage white butterfly caterpillars (Pieris rapae) with plant material containing toxins not experienced in their evolutionary history. Families that maintained high performance (e.g., high survival, fast development time, large body size) on diets containing one novel toxic plant also performed well when exposed to two other novel toxic plants, consistent with a generalized response. Variation in constitutive (but not induced) expression of genes involved in oxidative stress responses was positively related to performance on the novel diets. While we did not detect reproductive trade-offs of this generalized response, there was a tendency to have less melanin investment in the wings, consistent with the role of melanin in oxidative stress responses. Taken together, our results support the hypothesis that variation in generalized stress responses, such as genes involved in oxidative stress responses, may explain the variation in tolerance to entirely novel toxins and may facilitate colonization of novel hosts and environments.

Association of Areca Nut Chewing With Risk of Erectile Dysfunction

INTRODUCTION

Areca nut chewing has been shown to increase the risk of cardiovascular disease, but its association with erectile dysfunction (ED) has not been investigated.

AIM

To investigate the association between areca nut chewing and risk of ED.

METHODS

Consecutive men at public health centers for oral malignancy screening or health checkup were invited to complete a questionnaire.

MAIN OUTCOME MEASURE

The Sexual Health Inventory for Men (SHIM).

RESULTS

Of the 2,652 respondents, 1,038 (mean age = 43.8 ± 11.1 years) were eligible for the areca nut chewing group and 1,090 non-areca nut chewers were selected as the age-matched control group. In the areca nut group, the mean duration of chewing was 13.2 ± 9.6 years, 61.7% consumed more than 10 portions per day, and 76.2% used it with betel leaf, 16.7% used it with betel inflorescence, and 7.1% used it with betel leaf and inflorescence. Smoking, alcohol drinking, obesity, hypertension, and diabetes were more predominant in areca nut chewers compared with controls. ED defined by self-report and by SHIM score was more prevalent in areca nut chewers than in controls (13.7% vs 9.8% and 48.7% vs 43.3%, respectively; P < .05 for the two comparisons). Areca nut use with betel inflorescence was associated with a higher risk of ED (odds ratio = 2.25, 95% confidence interval = 1.55-3.28) with a dose-dependent effect, whereas using it with betel leaf was not (odds ratio = 1.00, 95% confidence interval = 0.79-1.26) after adjustment of possible confounders.

CONCLUSION

Areca nut chewing with betel inflorescence was associated with an increased risk of ED. These findings warrant further studies. Huang Y-J, Jiann B-P. Association of Areca Nut Chewing With Risk of Erectile Dysfunction. Sex Med 2017;5:e163-e168.

Alternative Approaches to Pesticide Regulation

Pesticide regulation has become a topic of increasing interest in recent years, owing to rising public concerns about residues on foods, in drinking-water wells, and damage to wildlife. Public-opinion polls and political responses to incidents like the controversy over Alar suggest that demand for government intervention to protect public health and the environment from pesticides is high. Pesticides are toxic by design; survey evidence indicates that they are perceived as riskier than other, more common pollutants like auto exhaust (see, for example, Horowitz). Pesticide residues are not easily observable (short of laboratory analysis), making averting strategies by individuals extremely difficult and/or excessively costly to implement.

A critical theoretic look at technical risk analysis

Technical risk analysis accomplishes the activities of risk identification, risk assessment and risk management by the use of scientific rationality. As an ac tivity of the political state, it also plays a role in managing the state's legitimacy problems. Critical theory can locate these two aspects of technical risk analysis in the context of a social theory as well as provide normative guidance for cor recting the deficiencies inherently associated with them. In particular, Haber mas's concepts of communicative rationality and the ideal speech situation have immediate ramifications of risk communication.

Antimycotic Activity and Genotoxic Evaluation of Citrus sinensis and Citrus latifolia Essential Oils

The aim of this study was to evaluate the antifungal activity of essential oils (EOs) of Citrus sinensis (C. sinensis) and Citrus latifolia (C. latifolia) against five Candida species: Candida albicans, Candida tropicalis, Candida glabrata, Candida lusitaniae and Candida guilliermondii; and perform its genotoxic evaluation. The EOs of C. sinensis and C. latifolia were obtained from the peel by hydro-distillation. The major components determined by GC-MS were in C. sinensis, d-limonene (96%) and α-myrcene (2.79%); and in C. latifolia, d-limonene (51.64%), β-thujene (14.85%), β-pinene (12.79%) and γ-terpinene (12.8%). Antifungal properties were studied by agar diffusion method, where C. sinensis presented low activity and C. latifolia essential oil was effective to inhibit growing of C. lusitaniae and C. guilliermondii with IC50 of 6.90 and 2.92 μg respectively. The minimum inhibitory concentrations (MIC) for C. sinensis were in a range of 0.42-3.71 μg and for C. latifolia of 0.22-1.30 μg. Genotoxic evaluation was done by Ames test where none of the oils induced point mutations. Flow cytometry was used to measure toxicity in human oral epithelial cells, C. sinensis was not cytotoxic and C. latifolia was toxic at 21.8 μg. These properties might bestow different odontological applications to each essential oil.

What is hormesis and its relevance to healthy aging and longevity?

This paper provides a broad overview of hormesis, a specific type of biphasic dose response, its historical and scientific foundations as well as its biomedical applications, especially with respect to aging. Hormesis is a fundamental component of adaptability, neutralizing many endogenous and environmental challenges by toxic agents, thereby enhancing survival. Hormesis is highly conserved, broadly generalizable, and pleiotrophic, being independent of biological model, endpoint measured, inducing agent, level of biological organization and mechanism. The low dose stimulatory hormetic response has specific characteristics which defines both the quantitative features of biological plasticity and the potential for maximum biological performance, thereby estimating the limits to which numerous medical and pharmacological interventions may affect humans. The substantial degrading of some hormetic processes in the aged may profoundly reduce the capacity to respond effectively to numerous environmental/ischemic and other stressors leading to compromised health, disease and, ultimately, defining the bounds of longevity.

Why endocrine disrupting chemicals (EDCs) challenge traditional risk assessment and how to respond

Endocrine disrupting compounds (EDCs) are a diverse group of "chemicals of emerging concern" which have attracted much interest from the research community since the 1990s. Today there is still no definitive risk assessment tool for EDCs. While some decision making organizations have attempted to design methodology guidelines to evaluate the potential risk from this broadly defined group of constituents, risk assessors still face many uncertainties and unknowns. Until a risk assessment paradigm is designed specifically for EDCs and is vetted by the field, traditional risk assessment tools may be used with caution to evaluate EDCs. In doing so, each issue of contention should be addressed with transparency in order to leverage available information and technology without sacrificing integrity or accuracy. The challenges that EDCs pose to traditional risk assessment are described in this article to assist in this process.

The blood exposome and its role in discovering causes of disease

BACKGROUND

Since 2001, researchers have examined the human genome (G) mainly to discover causes of disease, despite evidence that G explains relatively little risk. We posit that unexplained disease risks are caused by the exposome (E; representing all exposures) and G × E interactions. Thus, etiologic research has been hampered by scientists' continuing reliance on low-tech methods to characterize E compared with high-tech omics for characterizing G.

OBJECTIVES

Because exposures are inherently chemical in nature and arise from both endogenous and exogenous sources, blood specimens can be used to characterize exposomes. To explore the "blood exposome" and its connection to disease, we sought human blood concentrations of many chemicals, along with their sources, evidence of chronic-disease risks, and numbers of metabolic pathways.

METHODS

From the literature we obtained human blood concentrations of 1,561 small molecules and metals derived from foods, drugs, pollutants, and endogenous processes. We mapped chemical similarities after weighting by blood concentrations, disease-risk citations, and numbers of human metabolic pathways.

RESULTS

Blood concentrations spanned 11 orders of magnitude and were indistinguishable for endogenous and food chemicals and drugs, whereas those of pollutants were 1,000 times lower. Chemical similarities mapped by disease risks were equally distributed by source categories, but those mapped by metabolic pathways were dominated by endogenous molecules and essential nutrients.

CONCLUSIONS

For studies of disease etiology, the complexity of human exposures motivates characterization of the blood exposome, which includes all biologically active chemicals. Because most small molecules in blood are not human metabolites, investigations of causal pathways should expand beyond the endogenous metabolome.

Cytogenetics in benzene-associated myelodysplastic syndromes and acute myeloid leukemia: new insights into a disease continuum

Hematopoiesis in health and disease results from complex interactions between primitive hematopoietic stem cells (HSCs) and the extrinsic influences of other cells in the bone marrow (BM) niche. Advances in stem cell biology, molecular genetics, and computational biology reveal that the immortality, self-renewal, and maintenance of blood homeostasis generally attributed to individual HSCs are functions of the cells' behavior in the normal BM environment. Here we discuss how these advances, together with results of outcomes-based clinical epidemiology studies, provide new insight into the importance of epigenetic events in leukemogenesis. For the chemical benzene (Bz), development of myeloid neoplasms depends predominantly on alterations within the microenvironments in which they arise. The primary persistent disease in Bz myelotoxicity is myelodysplastic syndrome, which precedes cytogenetic injury. Evidence indicates that acute myeloid leukemia arises as a secondary event, subsequent to evolution of the leukemia-initiating cell phenotype within the altered BM microenvironment. Further explorations into the nature of chemical versus de novo disease should consider this mechanism, which is biologically distinct from previous models of clonal cytogenetic injury. Understanding alterations of homeostatic regulation in the BM niche is important for validation of models of leukemogenesis, monitoring at-risk populations, and development of novel treatment and prevention strategies.

Risk assessment of 'endocrine substances': guidance on identifying endocrine disruptors

The European regulation on plant protection products (1107/2009) and other related legislation only support the marketing and use of chemical products on the basis that they do not induce endocrine disruption in humans or wildlife species. This legislation would appear to make the assumption that endocrine active chemicals should be managed differently from other chemicals presumably due to an assumed lack of a threshold for adverse effects. In the absence of agreed scientific criteria and guidance on how to identify and evaluate endocrine activity and disruption within these pieces of legislation, a European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) task force was formed to provide scientific criteria that may be used within the context of these three legislative documents. The first ECETOC technical report and associated workshop, held in 2009, presented a science-based concept on how to identify endocrine activity and disrupting properties of chemicals for both human health and the environment. Specific scientific criteria for the determination of endocrine activity and disrupting properties that integrate information from both regulatory toxicity studies and mechanistic/screening studies were proposed. These criteria combined the nature of the adverse effects detected in studies which give concern for endocrine toxicity with an understanding of the mode of action of toxicity so that adverse effects can be explained scientifically. A key element in the data evaluation is the consideration of all available information in a weight-of-evidence approach. Both sets of data (evidence of the adverse effect in apical studies and conclusive mode of action knowledge) are essential in order to correctly identify endocrine disruption according to accepted definitions. As the legislation seeks to regulate chemicals on a mode of action rather than the more traditional approach of adverse endpoints, then conclusive evidence of the mode of action of concern should be presented. From a human safety perspective and in the absence of any compelling data that endocrine active chemicals exert their adverse effects through anything other than a threshold mechanism there is no scientific justification for not using a margin of exposure approach to risk assessment in order to best protect human health.

Cancer Risk and Behavioral Factors, Comorbidities, and Functional Status in the US Elderly Population

About 80% of all cancers are diagnosed in the elderly and up to 75% of cancers are associated with behavioral factors. An approach to estimate the contribution of various measurable factors, including behavior/lifestyle, to cancer risk in the US elderly population is presented. The nationally representative National Long-Term Care Survey (NLTCS) data were used for measuring functional status and behavioral factors in the US elderly population (65+), and Medicare Claims files linked to each person from the NLTCS were used for estimating cancer incidence. The associations (i.e., relative risks) of selected factors with risks of breast, prostate, lung and colon cancers were evaluated and discussed. Behavioral risk factors significantly affected cancer risks in the US elderly. The most influential of potentially preventable risk factors can be detected with this approach using NLTCS-Medicare linked dataset and for further deeper analyses employing other datasets with detailed risk factors description.

Can we use indoor fungi as bioindicators of indoor air quality? Historical perspectives and open questions

Microbiological analysis of atmospheres witnessed substantial technical improvements in the 1940s to 1960s. May's cascade impactor and Hirst's spore trap allowed the counting of total cells but had limited capacity for identification of the spores. Bourdillon's sampler enabled the counting of cultivable fungi and their identification. A great step forward was given with the Andersen's six-stage impactor, which allowed discrimination of particles by size, counting of cultivable cells, and species identification. This period also witnessed the development of impingers, namely, the AGI-30 described by Malligo and Idoine, and the three-stage model designed by K. R. May. The 1990s to 2000s witnessed innovative discoveries on the biology of indoor fungi. Work carried out in several laboratories showed that indoor fungi can release groups of spores, individual spores and fungal fragments, and produce volatile organic compounds and mycotoxins. Integrating all findings a holistic interpretation emerged for the sick building syndrome. Healthy houses and buildings, with low indoor humidity, display no appreciable indoor fungal growth, and outdoor Cladosporium dominates. On the contrary, in sick houses and buildings, high indoor humidity allows fungal growth (mainly of Penicillium and Aspergillus), with concomitant release of conidia and fragments into the atmosphere. The intoxication probably results from a chronic exposure to volatile organic compounds and mycotoxins produced by Penicillium, Aspergillus, and Stachybotrys. Very clean atmospheres are difficult to study by conventional methods. However, some of these atmospheres, namely, those of hospital rooms, should be monitored. Sedimentary sampling, chemical methods applied to impinger's collection liquid, and selected molecular methods can be useful in this context. It was concluded that fungi can be useful indicators of indoor air quality and that it is important to deepen the studies of indoor atmospheres in order to promote air quality, the health and well-being of all, and a better understanding of the biology of indoor fungi.

Setting Standards in the Presence of Developing Scientific Understanding

The setting of standards for potential hazards as result of the application of a new technology depends on both the philosophy with respect to risk and the state of knowledge about the circumstances under which the technology can cause damage. Typically, biological damage is first observed for high levels of exposure and short times. As our understanding of the technology and its effects on the biology improve, biological effects are observed at lower levels and longer exposure times. For extended low-level exposures it also becomes more difficult to demonstrate a hazard that is independent of other influences. This has been true for electric and magnetic fields both at low and radio frequencies. In this article it is recognized that a set number is needed for both manufactures and system operators to meet if the technology is to serve the public. It is also recommended that the public be presented with tables of relative risks that include levels of exposure and other risks for comparison. Three tables of relative risks are included as a possible starting point.

An analysis of cocaine powder in the Netherlands: content and health hazards due to adulterants

AIMS

To report on trends in the content and adulterants present in street cocaine (powder) in the Netherlands and to describe the associated health hazards.

DESIGN AND PARTICIPANTS

Drug consumers handed in samples of cocaine powder from 1999 to 2007 for analysis. Reports were compiled of users' experiences with the samples received.

MEASUREMENTS AND ANALYSIS

Linear regression analysis was used to assess the trend in adulterated cocaine powder across the study period, and comparison of reported adverse effects of adulterated with those of unadulterated cocaine by Fisher's exact test.

FINDINGS

There has been a statistically significant upward trend in the occurrence of adulterated cocaine powder over the years. Adulterated cocaine was associated more frequently with reported adverse effects than unadulterated cocaine. Phenacetin, hydroxyzine and diltiazem appeared to be three adulterants contributing to these adverse effects.

CONCLUSIONS

An increase in adulterants was detected in the analysed cocaine powder between 1999 and 2007. This increase is associated with relatively more adverse effects with cocaine use. The cardiac and hallucinatory effects that were reported more frequently are not understood clearly. Adverse effects are likely to be due to several factors, including interactions of adulterants with cocaine and the route of administration.

Allium cepa chromosome aberration and micronucleus tests applied to study genotoxicity of extracts from pesticide-treated vegetables and grapes

The Allium cepa assay is an efficient test for chemical screening and in situ monitoring for genotoxicity of environmental contaminants. The test has been used widely to study genotoxicity of many pesticides revealing that these compounds can induce chromosomal aberrations in root meristems of A. cepa. Pesticide residues can be present in fruit and vegetables and represent a risk for human health. The mutagenic and carcinogenic action of herbicides, insecticides and fungicides on experimental animals is well known. Several studies have shown that chronic exposure to low levels of pesticides can cause birth defects and that prenatal exposure is associated with carcinogenicity. This study evaluated the potential application of plant genotoxicity tests for monitoring mutagens in edible vegetables. The presence of pesticides and genotoxic compounds extracted from 21 treated vegetables and eight types of grapes sampled from several markets in Campania, a region in Southern Italy, was monitored concurrently. The extracts were analysed for pesticides by gas chromatography and high-performance liquid chromatography, and for genotoxicity using two plant tests: the micronucleus test and the chromosomal aberration test in A. cepa roots. Thirty-three pesticides were detected, some of which are not approved. Genotoxicity was found in some of the vegetables and grapes tested. Allium cepa tests proved to be sensitive in monitoring genotoxicity in food extracts. The micronucleus test in interphase cells gave a much higher mutagenicity than the chromosomal aberration test in anaphase-telophase cells.

IARC monographs program on carcinogenicity of combined hormonal contraceptives and menopausal therapy

The World Health Organization International Agency for Research and Cancer (IARC), in June 2005, has classified combination hormone contraception and menopausal therapy as carcinogenic in humans. The IARC's distinction is to identify potential carcinogens associated with nutrition, environment and pharmaceutical products. They do not produce risk-benefit analyses for any country or population. Their conclusions are highly controversial in that no proof is presented for a causal relation of estrogens with reproductive cancer, be it plausibility according to mechanisms of action or experimental evidence in the animal model. Equating natural compounds like estradiol with defined carcinogens like asbestos, tobacco smoke as well as indispensable drugs such as aspirin and tamoxifen is of no substantial clinical relevance. Thus, there are no new reasons to change current management principles with combination hormone contraception and therapy.

Organic Food: Buying More Safety or Just Peace of Mind? A Critical Review of the Literature

Consumer concern over the quality and safety of conventional food has intensified in recent years, and primarily drives the increasing demand for organically grown food, which is perceived as healthier and safer. Relevant scientific evidence, however, is scarce, while anecdotal reports abound. Although there is an urgent need for information related to health benefits and/or hazards of food products of both origins, generalized conclusions remain tentative in the absence of adequate comparative data. Organic fruits and vegetables can be expected to contain fewer agrochemical residues than conventionally grown alternatives; yet, the significance of this difference is questionable, inasmuch as actual levels of contamination in both types of food are generally well below acceptable limits. Also, some leafy, root, and tuber organic vegetables appear to have lower nitrate content compared with conventional ones, but whether or not dietary nitrate indeed constitutes a threat to human health is a matter of debate. On the other hand, no differences can be identified for environmental contaminants (e.g. cadmium and other heavy metals), which are likely to be present in food from both origins. With respect to other food hazards, such as endogenous plant toxins, biological pesticides and pathogenic microorganisms, available evidence is extremely limited preventing generalized statements. Also, results for mycotoxin contamination in cereal crops are variable and inconclusive; hence, no clear picture emerges. It is difficult, therefore, to weigh the risks, but what should be made clear is that 'organic' does not automatically equal 'safe.' Additional studies in this area of research are warranted. At our present state of knowledge, other factors rather than safety aspects seem to speak in favor of organic food.

Evaluation of genotoxic effects of Apitol® (cymiazole hydrochloride) in vitro by measurement of sister chromatid exchange

Apitol, with cymiazole hydrochloride as the active ingredient, is used in bee-keeping against the ectoparasitic mite Varroa destructor. The preparation was evaluated for genotoxicity in cultured human peripheral blood lymphocytes. Sister chromatid exchange, the mitotic index and the cell proliferation index were determined for three experimental concentrations of Apitol (0.001, 0.01 and 0.1 mg/ml). All concentrations significantly (p < 0.001) increased the mitotic index (MI = 7.35+/-0.18%, 8.31+/-0.20% and 12.33+/-0.25%, respectively), the proliferative index (PI = 1.83+/-0.01, 1.84+/-0.01 and 1.88+/-0.02, respectively) and the frequency of sister chromatid exchange (SCE = 8.19+/-1.81, 8.78+/-1.80 and 13.46+/-1.88, respectively), suggesting that cymiazole hydrochloride has genotoxic potential.

Are tumor incidence rates from chronic bioassays telling us what we need to know about carcinogens?

Chronic bioassays for over 500 chemicals have been conducted under the auspices of the National Cancer Institute and/or the National Toxicology Program (NTP) to screen chemicals for carcinogenicity, providing a wealth of information about bioassays. Typically, chemicals are administered for two years to both sexes in each of one strain of rats and mice generally at the maximum tolerated dose (MTD), MTD/2, MTD/4 (in recent years), as well as unexposed control animals. In an attempt to ascertain the sensitivity of this bioassay to detect animal carcinogens tested at the MTD for the current experimental design, the false negative rate (failure to detect increased tumor rates) was investigated. This was accomplished by examining the tumor incidences from over 150 NTP bioassays and estimating the probability that a statistically significant (P0.01) dose-response trend would be obtained at one or more tissue sites in either sex of rats or mice if 200, rather than 50, animals were used per dose group. This provides an estimate of the proportion of chemicals that were not declared high-dose animal carcinogens due to the limited sample size of 50 animals per species-sex-dose group. In this series of chemicals tested, 97/156 (62%) were identified by the NTP to show some or clear evidence of carcinogenicity. With an increase of the number of animals per dose group from 50 to 200, it is estimated that 92% of these chemicals would show statistically significant (P0.01) dose-response trends at one or more tissue sites in either sex of rats or mice. Many of these chemicals are not genotoxic. Some chemicals had no structural alerts for carcinogenicity, but were tested because of potentially high human exposure. This analysis suggests that almost all of the chemicals selected would produce a statistically significant increase in tumor incidence at the MTD with larger sample sizes. Hence, this MTD bioassay screen is not distinguishing between true carcinogens and non-carcinogens. Rather, the screen is simply failing to detect the weaker carcinogens at the MTD. More than 30% of chemicals tested failed to detect statistically significant dose-response trends for tumors because of inadequate sample sizes of 50 animals per dose. Presumably, little or no action would have been taken to regulate exposures to these chemicals as potential carcinogens due to lack of a positive test result. This analysis does not suggest that most chemicals are carcinogenic at human exposure levels nor does it suggest that more than 50 animals should be tested per dose group. With an MTD that may produce a difference (up to 10%) in weight gain between treated and control animals, there quite possibly is cytotoxicity at the MTD. Increased carcinogenicity would be expected from increased opportunities for mutagenic activity during regenerative cell replication to compensate for cytotoxicity. Since it appears that almost all chemicals tested adequately at the MTD will demonstrate carcinogenicity, it is tempting to surmise that this is due in large part to one or more nearly universal modes of action, such as, regenerative cell replication at the MTD rather than due to some unique carcinogenic property of a chemical. That is, the current bioassay possibly is just primarily a screen for the more potent cytotoxins at the MTD, rather than a screen specifically for carcinogenicity. This issue should be examined and suggests that cytotoxicity and cell proliferation should be considered in setting the MTD, particularly for non-genotoxic (non-DNA reactive) chemicals. From a public health view, it is prudent to assume that most chemicals could demonstrate increased tumor incidence rates at the MTD in rodents. The current standard NTP bioassay provides sufficient data to estimate a benchmark dose associated with a specified low tumor incidence to be used as a point-of-departure for cancer risk assessments. The question that should be investigated by a bioassay is not whether a chemical is a carcinogen at the MTD, but what is the relationship between dose and cytotoxicity and/or other modes of action that could produce an excess of tumors?

Health risk communication using comparative risk analyses

The ability to communicate effectively the degree or magnitude of public exposures or health risks is essential for risk assessors and risk managers. Various guidelines exist for communicating environmental and public health risks, including recommended approaches for putting risk data into proper context. Although it remains unclear as to which approach is the most useful or appropriate under different circumstances, risk comparisons are a popular choice for conveying the significance of or providing a better perspective on a particular chemical exposure or health risk. In this paper, several different types of risk comparisons are described that are frequently used in the private and public sectors, and these are illustrated using a variety of examples from the literature. These approaches include: (1) intrachemical comparisons, (2) interchemical comparisons, (3) comparisons to background levels of risk, (4) comparisons to theoretical risks or safety levels, and (5) comparisons to other actions or activities. The primary purpose of this paper is to summarize and briefly discuss the advantages and limitations of these risk communication approaches. The evolving field of risk communication is also discussed, including ongoing research on public risk perceptions and alternative methods for communicating risk magnitudes and data uncertainties.

Preference for natural: instrumental and ideational/moral motivations, and the contrast between foods and medicines

Preference for natural refers to the fact that in a number of domains, especially food, people prefer natural entities to those which have been produced with human intervention. Two studies with undergraduate students and representative American adults indicate that the preference for natural is substantial, and stronger for foods than for medicines. Although healthfulness is often given as a reason for preferring natural foods, even when healthfulness or effectiveness (for medicines) of the natural and artificial exemplars is specified as equivalent, the great majority of people who demonstrate a preference for natural continue to prefer natural. In addition, when the natural and artificial exemplars are specified to be chemically identical, a majority of people who prefer natural continue to prefer it. This suggests that a substantial part of the motivation for preferring natural is ideational (moral or aesthetic), as opposed to instrumental (healthiness/effectiveness or superior sensory properties).

Isothiocyanates as novel cytotoxic and cytostatic agents: molecular pathway on human transformed and non-transformed cells

Cancer chemoprevention is a new approach in the management of cancer. Traditional cytotoxic chemotherapeutic approaches cannot cure most advanced solid malignancies. Chemoprevention can be defined as the use of non-cytotoxic drugs and natural agents to block the progression to invasive cancer. Recently, isothiocyanates, natural products found in the diet of humans, has been shown to function as cancer chemopreventive agents. They are strong inhibitors of phase I enzymes and inducers of phase II enzymes. They can also induce apoptosis and modulate cell-cycle progression of highly proliferating cancer cells. This commentary will review the mechanism of apoptosis and growth inhibition mediated by different isothiocyanates. Particular attention will be given to the effects of the new isothiocyanate 4-(methylthio)butylisothiocyanate (MTBITC). Since selective targeting and low toxicity for normal host tissues are fundamental requisites for proposed chemopreventive agents, we will also review the effects of different isothiocyanates on non-transformed human cells.

Oxidative effects induced by dediazoniation of the p-hydroxybenzenediazonium ion in a neutral aqueous medium

The toxicity of arenediazonium ions is believed to result from the appearance of very reactive compounds during the dediazoniation process. In the case of the p-hydroxybenzenediazonium ion (PDQ), radical species generated during dediazoniation could potentially initiate lipid peroxidation. The data obtained in spectrophotometric experiments suggest that an interaction between PDQ and linoleic acid (LA) gives rise to the characteristic absorption of oxidized products deriving from LA, both in the presence and absence of a mixed micellar medium containing the surfactant Tween 20 (Tw20). Spectroscopic evidence also clearly points to the interference of these processes in the dediazoniation of PDQ. Analysis by reverse-phase, high-pressure liquid chromatography (HPLC) confirms that the decomposition of PDQ in a mixed micellar medium induces the peroxidation of both LA and methyl linoleate (MEL), thus causing the appearance of peaks characteristic of dienic conjugated hydroperoxides. The same products are observed after interaction between LA and the water-soluble 2,2'-azobis (2-amidinopropane), a frequently used initiator of lipid peroxidation. The proportion of isomers produced during the peroxidation process agrees well with that reported for reactions mediated by free radicals. A further chromatographic analysis of the decomposition of PDQ in the presence of 2-methylcyclohexa-2,5-diene-1-carboxylic acid (CHD) shows that phenol and quinone are the main products of the reaction. These results are discussed on the understanding that aryl and peroxyl radicals abstract a hydrogen atom from CHD, in accordance with our general scheme for PDQ dediazoniation described in a previous publication.

Toxaphene residues from cotton fields in soils and in the coastal environment of Nicaragua

Toxaphene (camphechlor) was intensively used in the cotton growing fields of Nicaragua for decades with application rates as high as 31 kg ha(-1) in 1985. Although the use of this compound has recently been discontinued in the country, its intensive use in the past and its long persistence in soil allowed for the build up of large reservoirs of toxaphene in agriculture soils and a wide dispersal of residues in the environment. Measurements of toxaphene in coastal areas on the coast of the Pacific Ocean show that environmental concentrations are particularly high in the district of Chinandega, the traditional cotton growing region. Toxaphene residues measured in soils attained 44 microg g(-1) (dry weight) while concentrations in lagoon sediments attained 6.9 microg g(-1) (dry weight) near the mouth of the rivers flowing across the agricultural region. Measurements in aquatic biota showed concentrations as high as 1.6 microg g(-1) (dry weight) in the soft tissues of clams. The toxaphene reservoir in soils combined with the obvious persistence of this compound in soils and lagoon sediments allows predicting that toxaphene will remain in the coastal ecosystem at relatively high concentrations for many years. Toxic effects in lagoon fauna are likely to be observed especially in benthic species that may recycle this compound from sediments. Consumption of seafood, in particular of clams (Anadara spp.) from the more contaminated areas, may expose the population to unacceptably high intake of toxaphene, 30 microg d(-1) per person, with the diet.

Ozonation of drinking water: part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine

Ozone is an excellent disinfectant and can even be used to inactivate microorganisms such as protozoa which are very resistant to conventional disinfectants. Proper rate constants for the inactivation of microorganisms are only available for six species (E. coli, Bacillus subtilis spores, Rotavirus, Giardia lamblia cysts, Giardia muris cysts, Cryptosporidium parvum oocysts). The apparent activation energy for the inactivation of bacteria is in the same order as most chemical reactions (35-50 kJ mol(-1)), whereas it is much higher for the inactivation of protozoa (80 kJ mol(-1)). This requires significantly higher ozone exposures at low temperatures to get a similar inactivation for protozoa. Even for the inactivation of resistant microorganisms, OH radicals only play a minor role. Numerous organic and inorganic ozonation disinfection/oxidation by-products have been identified. The by-product of main concern is bromate, which is formed in bromide-containing waters. A low drinking water standard of 10 microg l(-1) has been set for bromate. Therefore, disinfection and oxidation processes have to be evaluated to fulfil these criteria. In certain cases, when bromide concentrations are above about 50 microg l(-1), it may be necessary to use control measures to lower bromate formation (lowering of pH, ammonia addition). Iodate is the main by-product formed during ozonation of iodide-containing waters. The reactions involved are direct ozone oxidations. Iodate is considered non-problematic because it is transformed back to iodide endogenically. Chloride cannot be oxidized during ozonation processes under drinking water conditions. Chlorate is only formed if a preoxidation by chlorine and/or chlorine dioxide has occurred.

Risk analysis, life cycle assessment--the common challenge of dealing with the precautionary frame (based on the toxicity controversy in Sweden and The Netherlands)

Life cycle impact assessment (LCIA) and comparative risk assessment (RA) use the same building blocks for analyzing fate and potential effects of toxic substances. It is tacitly assumed that emission-effect calculations can give uniform and decisive answers in debates on toxicity problems. For several decades, mainstream policy sciences have taken a different starting point when analyzing decision making on complex, controversial societal issues. Such controversies in essence are thought to be caused by the fact that different actor coalitions adhere to a different, but in scientific terms equally reasonable, conceptualization or "framing" of the problem. A historical, argumentative analysis of the Dutch chlorine debate and the Swedish PVC debate shows that this is also true in the discussions on toxic substances. Three frames have been identified, which were coined the "risk assessment frame," "the strict control frame," and the "precautionary frame." These frames tacitly disagree about the extent of knowledge/ignorance about the impacts of substances, the robustness/fallibility of emission-reduction schemes, and the robustness/vulnerability of nature. The latter frame, adhered to by environmentalists, seeks to judge substances mainly on their inherent safety. Under the current institutional arrangements and practices, RA and LCIA are executed mainly in line with the philosophy expressed by the risk assessment frame. This article gives various suggestions for dealing with framing in debates on toxic substances. One of the options is elaborated in somewhat more detail, i.e., the development of multiple indicators and calculation schemes for RA and LCIA that reflect the different frames. An outline is given for a possible indicator system reflecting the precautionary principle.

Toxicology review and risk assessment of resorcinol: thyroid effects

Resorcinol administered at high doses to rodents can disrupt thyroid hormone synthesis and can produce goitrogenic effects. These effects were not seen in a 2-year bioassay at doses of up to 520 mg/kg/day. There are species-specific differences in synthesis, binding, and transport of thyroid hormone that complicate interpretation of goitrogenesis in rodents. Clinical case reports from patients undergoing resorcinol therapy for dermatological indications reveal thyroid side effects when copious amounts of resorcinol-containing ointments are applied to integrity-compromised skin for months to years. Effect levels were greater than 34 mg/kg/day. Occupational epidemiology studies provide no evidence that exposure to resorcinol at levels greater than found in the general environment causes thyroid dysfunction. Studies investigating the relationship between endemic goiter and exposure to "phenolics," including resorcinol, in drinking water do not fulfill accepted scientific criteria for establishing resorcinol as a cause of thyroid disease. Those reports neither quantify exposure levels nor demonstrate dose-response relationships or rule out confounding by the multiple other chemicals present in water supplies, by bacterial contamination of water, or by nutritional factors. A risk assessment comparing potential worst-case exposures to resorcinol through its use in dermatological preparations supports the conclusion that under real-world conditions, human exposures to resorcinol are not expected to cause adverse effects on thyroid function.

Carcinogenic risk of toluene diisocyanate and 4,4'-methylenediphenyl diisocyanate: epidemiological and experimental evidence

Diisocyanates are highly reactive compounds widely used, for example, in the production of polyurethane foams, elastomers, paints, and adhesives. The high chemical reactivity of these compounds is also reflected in their toxicity: diisocyanates are one of the most important causes of occupational asthma but also other adverse effects, such as irritation and toxic reactions, have been described in exposed subjects. One of the open questions is whether occupational isocyanate exposure is a carcinogenic hazard. The few epidemiological studies available have been based on young cohorts and short follow-up and are not conclusive. Toluene diisocyanate (TDI) has been classified as carcinogenic in animals on the basis of gavage administration studies, but no conclusions are available on inhalation exposure. For 4,4'-methylene diphenyldiisocyanate (MDI) there is suggestive evidence for carcinogenicity in rats. The possible carcinogenic mechanism of TDI and MDI is not clear. Both chemicals have been positive in a number of short-term tests inducing gene mutations and chromosomal damage. The reactive form could be either the diisocyanate itself or may derive from the metabolic activation of the aromatic diamine derivatives formed by hydrolysis. TDI and MDI react with DNA in vivo and in vitro. However, the structure of the adducts has not been identified. Especially from the in vivo experiment it is not known if the adducts are a product from the reaction with the isocyanate or the corresponding amine. In conclusion, both TDI and MDI are highly reactive chemicals that bind to DNA and are probably genotoxic. The alleged animal carcinogenicity of TDI and MDI would suggest that occupational exposure to these compounds is a carcinogenic risk. The few epidemiological studies available have not, however, been able to clarify if TDI and MDI are occupational carcinogens.