1,721,288 research outputs found
Application of the threshold of toxicological concern (TTC) to the safety evaluation of cosmetic ingredients
No full textThe threshold of toxicological concern (TTC) has been used for the safety assessment of packaging migrants and flavouring agents that occur in food. The approach compares the estimated oral intake with a TTC value derived from chronic oral toxicity data for structurally-related compounds. Application of the TTC approach to cosmetic ingredients and impurities requires consideration of whether route-dependent differences in first-pass metabolism could affect the applicability of TTC values derived from oral data to the topical route. The physicochemical characteristics of the chemical and the pattern of cosmetic use would affect the long-term average internal dose that is compared with the relevant TTC value. Analysis has shown that the oral TTC values are valid for topical exposures and that the relationship between the external topical dose and the internal dose can be taken into account by conservative default adjustment factors. The TTC approach relates to systemic effects, and use of the proposed procedure would not provide an assessment of any local effects at the site of application. Overall the TTC approach provides a useful additional tool for the safety evaluation of cosmetic ingredients and impurities of known chemical structure in the absence of chemical-specific toxicology dat
EUROTOX's view regarding the ROLE and TRAINING of certified European registered toxicologists (ERT))
No full textToxicology's evolution from a traditional science of poisons to an extensive discipline has introduced complications and ambiguity in the definition of a scientific area of qualification and training. The need to define toxicology and to identify and standardise the roles and the profiles of practising toxicologists in order to certify the professional credibility of toxicologists has been recognised by national registries and certifying boards across the USA, Europe and Asia. Established in 1994, the EUROTOX Model (www.eurotox.com) has promoted the harmonisation of educational differences, practical experiences and common visions and requirements for the accreditation of toxicologists in Europe. Such harmonisation should be seen as an indispensable step towards the mutual recognition of registered toxicologists at a global level and to promote the development of shared educational and training programmes on a regional basis. A description of typical professional roles for toxicologists with required educational background, training and experience are presented in this paper and serve as the basis for the ERT templates, a self-evaluation tool for individuals seeking ERT recognitio
Can methylmercury present in fish affect human health?
No full textNo abstract available - Non disponibil
Integrated environmental risk characterisation
No full textRisk characterisation is the final phase of the health risk assessment process. It integrates the three phases: Hazard Identification, Dose-Response Assessment, and Exposure Assessment. This phase determines the probability of an adverse effect to a human population by a toxic substance and outlines permissible exposure levels from which standards of exposure are set. Characterizing Risk for Non-carcinogens
The first step is to consider the Admissible Daily intake (ADI) as was defined in the dose-response phase of the risk assessment, compared to the maximum exposure occurring within the target population, and which is calculated in the exposure assessment phase. There are far too many uncertainties associated with our knowledge of the effects of substances and individual human sensitivities.
Characterizing Risk for Carcinogens
Considering that carcinogens are considered to pose a risk at any dose and the probability of developing cancer would increase with dose, we can state that the probability can range from being negligibly low at low dose ranges or unacceptably high at high dose ranges. Currently the risk value of one in a million is considered an insignificant risk and is used as a maximum value for defining permissible environmental concentrations. The Margin of Exposure (MoE) and the Threshold of Toxicological Concern (TTC) will also be addressed.
Combined Exposure
There is increasing need to address the potential risks of combined exposures to multiple residues from pesticides in the diet. The available evidence suggests that the main concern is from dose addition of those compounds that act by the same mode of action. The possibility of synergy needs to be addressed on a case-by-case basis, where there is a biologically plausible hypothesis that it may occur at the levels of residues occurring in the diet.
Cumulative risk assessment is a resource-intense activity and hence a tiered approach to both toxicological evaluation and intake estimation is recommended, and the European Food Safety Authority (EFSA) has recently published such a proposal
Oral toxicity of formaldehyde and its derivatives
No full textFormaldehyde (FA) has been commercially produced since the early 1900s. Its widespread use in a variety of applications is known to result in appreciable exposure of workers and of a section of the general population. Formaldehyde is a normal metabolite in mammalian systems. It occurs in air as a product of the natural photooxidation of automobile exhaust, combustion processes, incinerators; formaldehyde has been found in municipal and industrial effluents and is present in food either naturally (fruits and vegetables, in the order of parts per million), or as a result of its use as a food additive. The use of FA and its derivative, hexamethylenetetramine (HMT), which gradually decomposes to FA under acidic conditions as antimicrobial agents in food, raises questions about their potential chronic oral toxicity. Furthermore, since FA is a very reactive compound and reacts with different macromolecules such as proteins and nucleic acids, the safety evaluation of FA as a cheese additive must take into account the toxicity of the reaction products between FA and milk components. Biochemical aspects, acute and short-term toxicity studies including mutagenicity, miltigeneration, and reproduction studies, long-term carcinogenicity studies after oral administration of FA and HMT are reviewed in this paper. The results of these studies indicate that repeated oral exposure of a relatively large amount of FA that could overwhelm the normal metabolic capacity of animals to convert FA into formiate, CO2, and water produces histopathological gastric changes. This paper correlates the hazard caused by the exposure to low levels of FA, as far as its carcinogenic potential by oral route is concerned per se or regarding its use as a food additive. Based on the evidence that FA is formed naturally in food and is a normal mammalian metabolite and that a threshold for carcinogenicity exists both after exposure by inhalation and oral administration, it may be deduced that FA is not carcinogenic at low levels of exposure
Risk assessment of multiple pesticide residues
No full textRisk assessment of multiple pesticide residues means an analysis, characterization, and possible quantification of the combined risks to health or the environment from multiple agents. The framework itself is conceptually similar to the approach used in both human health and ecological assessments. Its focus on the combined effects of more than one agent makes it different from many assessments conducted today, in which, if multiple chemicals are evaluated, they are usually evaluated individually and presented as if the others were not present. Because multiple stressors are affecting the same population, there is increased focus on the specific populations potentially affected rather than on hypothetical receptors and the requirement is that the risks from multiple agents or stressors be combined. This does not necessarily mean that the risks should be “added,” but rather that some analysis should be conducted to determine how the risks from the various agents or stressors interact. It also means that an assessment that covers a number of chemicals or other stressors but that merely lists each chemical with a corresponding risk without consideration of the other chemicals present is not an assessment of cumulative risk under this definition. The European Food Safety Authority (EFSA) published the results of on-going work to develop methodologies to assess the cumulative effects resulting from consumer exposure to pesticides. The work looks at a group of pesticides that have similar chemical structure and toxic effects to see if their impact on human health can be assessed collectively rather than just on an individual basis. The EFSA Panel concluded that only cumulative effects from concurrent exposure to substances which have a common mode of action raised concerns and needed further consideration. In order to evaluate methodologies the Panel selected some pesticides from the group of triazole fungicides on the basis of their similar chemical structure and mode of action, which are considered prerequisites for the assessment of cumulative effects. In order to address uncertainties, the application of new cumulative risk assessment methodologies required further work and that guidance on appropriate methodologies for exposure assessment was also still needed
NANOTECHNOLOGY SAFETY CONCERNS REVISITED
No full textRisk characterization is the process of the qualitative/quantitative estimation of the probability of the occurrence and severity of known or potential adverse health effects in a given population based on hazard identification, hazard characterization and exposure assessment.
The definition includes quantitative risk assessment, which emphasizes reliance on numerical expressions of risk, and also qualitative expressions of risk, as well as an indication of the attendant uncertainties.
The introduction of nanostructured materials for biomedical and electronics applications opens tremendous opportunities for biomedical applications as therapeutic and diagnostic tools as well as in the fields of engineering, electronics, optics, consumer products, alternative energy, soil/water remediation, and others.
However, very little is yet known about their potential to cause adverse effects once they are introduced into the organism—unintentionally or intentionally.
The regulators are focussing their attention on the gaps in knowledge relating to the properties of NPs that might determine toxicity and in understanding the most appropriate ways both to measure this in the laboratory and to assess the real exposure in the workplace and for the consumer.
Unsolved problems till remain the charcterization of the materials, the dosimetry, the transformation when included in a biological matrix, as well as which test protocol and to what extent could be applied
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