Structure-based thresholds of toxicological concern-guidance for application to substances present at low levels in the diet
Structure-based thresholds of toxicological concern-guidance for application to substances present at low levels in the diet
Health-based guidance values, such as the ADI, use chemical-specific data to determine the highest intake that would be without significant adverse health effects. A threshold of toxicological concern (TTC) is a level of intake predicted to be without adverse effects based on the toxicity of structurally related compounds. The main advantage of the use of TTCs is that the risk of low exposures can be evaluated without the need for chemical-specific animal toxicity data. TTCs have been used for many years for screening the safety of packaging migrants by the FDA in the USA, and of flavoring substances, by the JECFA. A recent reassessment of the use of TTCs, organized by ILSI Europe, has developed a decision tree which allows a systematic approach to the evaluation of low levels of diverse chemicals in food. The decision tree incorporates a series of increasing TTC values into a step-wise approach. Potentially genotoxic carcinogens are considered first, based on the presence of known structural alerts. Aflatoxin-like, azoxy- and nitroso-compounds are removed from consideration because they are the most potent, and a practical TTC could not be established. Other compounds with structural alerts for genotoxicity are allocated a TTC of 0.15 ?g/person per day. Compounds without structural alerts for genotoxicity are evaluated based on chemical structure and intake using a series of TTC values derived by the application of a 100-fold uncertainty factor to the 5th percentile of the distribution of NOAELs from chronic studies on compounds sharing similar structural characteristics.
structure–activity, risk assessment, toxicity database, intake estimates
585-591
Renwick, A.G.
596705ab-5418-4e02-9ad7-c4309326df46
2005
Renwick, A.G.
596705ab-5418-4e02-9ad7-c4309326df46
Renwick, A.G.
(2005)
Structure-based thresholds of toxicological concern-guidance for application to substances present at low levels in the diet.
Toxicology and Applied Pharmacology, 207 (2 Supplement 1), .
(doi:10.1016/j.taap.2005.01.034).
Abstract
Health-based guidance values, such as the ADI, use chemical-specific data to determine the highest intake that would be without significant adverse health effects. A threshold of toxicological concern (TTC) is a level of intake predicted to be without adverse effects based on the toxicity of structurally related compounds. The main advantage of the use of TTCs is that the risk of low exposures can be evaluated without the need for chemical-specific animal toxicity data. TTCs have been used for many years for screening the safety of packaging migrants by the FDA in the USA, and of flavoring substances, by the JECFA. A recent reassessment of the use of TTCs, organized by ILSI Europe, has developed a decision tree which allows a systematic approach to the evaluation of low levels of diverse chemicals in food. The decision tree incorporates a series of increasing TTC values into a step-wise approach. Potentially genotoxic carcinogens are considered first, based on the presence of known structural alerts. Aflatoxin-like, azoxy- and nitroso-compounds are removed from consideration because they are the most potent, and a practical TTC could not be established. Other compounds with structural alerts for genotoxicity are allocated a TTC of 0.15 ?g/person per day. Compounds without structural alerts for genotoxicity are evaluated based on chemical structure and intake using a series of TTC values derived by the application of a 100-fold uncertainty factor to the 5th percentile of the distribution of NOAELs from chronic studies on compounds sharing similar structural characteristics.
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Published date: 2005
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Review Article
Keywords:
structure–activity, risk assessment, toxicity database, intake estimates
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Local EPrints ID: 27361
URI: http://eprints.soton.ac.uk/id/eprint/27361
PURE UUID: f0a53038-b66c-4b9d-b175-8fa01df3f65e
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Date deposited: 27 Apr 2006
Last modified: 15 Mar 2024 07:18
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Author:
A.G. Renwick
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