Regulatory aspects of bound residues (chemistry)

Kovacs, Martin F

doi:10.1007/978-1-4612-4934-4_1

Cited by 18 publications

(15 citation statements)

References 4 publications

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“…These values were 0.05 mg parent pesticide equivalent kg −1 plant material, or 10% (US Environmental Protection Agency)6 or 25% (Commission of the European Communities)7 of the total radioactive residue. Previous reviews had proposed trigger values at incorporation rates of 0.5 mg kg −1 or 10%8 and 0.1 mg kg −1 or 10% 9. At the time the various trigger values were proposed, they were already known to be often exceeded, but progress in this area of research has been slow.…”

Section: Introductionmentioning

confidence: 99%

Bound and unextractable pesticidal plant residues: chemical characterization and consumer exposure

Sandermann

2004

Pest Management Science

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Plants are well known to incorporate pesticides into bound and unextractable residues that resist solubilization in common laboratory solvents and are therefore not accessible to standard residue analysis. A characterization of such residues has been proposed for incorporation rates above trigger values of 0.05 mg kg(-1) parent pesticide equivalents, or percentage values of 10% (United States Environmental Protection Agency, 1995) or 25% (Commission of the European Communities, 1997) of the total radioactive residue. These trigger values are often exceeded. The present review describes the current status of the chemical characterization and animal bioavailability of bound and unextractable residues that may be xenobiotic in nature or result from natural recycling of simple degradation products. The latter case represents a mechanism of detoxification. Bound residues have been shown to be covalent or non-covalent in nature. With regard to the plant matrix molecules involved, incorporation into proteins, lignins, pectins, hemicelluloses and cutins has been demonstrated, and four covalent linkage types are known. Animal feeding experiments have revealed cases of low as well as high bioavailability. Many of the studies are limited by experimental uncertainties and by results only being reported as relative percentage values rather than absolute exposure. A preliminary value of absolute exposure from bound and unextractable residues is derived here for the first time from eight case studies. The mean exposure (ca 1.5 mg kg(-1) pesticidal equivalents) exceeds some of the existing maximum residue levels (MRLs) of residual free pesticides that are typically in the range of 0.05-1 mg kg(-1). A mathematical framework for the correction of current maximum residue levels is presented for cases of highly bioavailable bound residues. As bound pesticidal residues in food plants could represent a source of significant consumer exposure, an experimental test scheme is proposed here. It consists of basic chemical characterization, model digestibility tests and, in exceptional cases, animal bioavailability and additional toxicological studies.

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Section: Introductionmentioning

confidence: 99%

Bound and unextractable pesticidal plant residues: chemical characterization and consumer exposure

Sandermann

2004

Pest Management Science

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“…In most of the studies reported in the literature, quantification of 14C-bound residues in plants has been achieved by combustion (39). This method is limited to the determination of total 14C-bound residues and cannot be used to identify the chemical form of the bound residues.…”

Section: Methodology For Determination Of the Nature And Quantity Of mentioning

confidence: 99%

Bioavailability of Bound Pesticide Residues and Potential Toxicologic Consequences

Akhtar

Khan

Kacew

1992

Experimental Biology and Medicine

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“…The first definition of bound residues in plants was published about 20 years ago in a IUPAC Pesticide Commission Report 1, 2. Other, similar, approaches were published later 3–8. Accordingly, the term non‐extractable residues is employed to identify the fraction of (pesticide‐derived) radioactivity remaining in the plant residuum (debris) after application of (exhaustive) extraction procedures, which, however, do not significantly alter the chemical nature of these residues.…”

Section: Introductionmentioning

confidence: 99%

“…In the EU, trigger values for the evaluation of residues in general are 10% of the total 14 C detected or 0.05 mg kg −1 , depending, however, on their respective toxicities 9–11. Comparable values hold true for the USA 6, 12, 13. Above these trigger values, residues have to be characterized and evaluated.…”

Section: Introductionmentioning

confidence: 99%

“…Above these trigger values, residues have to be characterized and evaluated. In the case of bound residues, this may imply the use of accelerated extraction methods (eg supercritical fluid extraction, microwave‐assisted extraction), chemical treatment with acids and bases, sequential fractionation procedures, as well as enzymatic digestion 1, 4–6, 9, 11, 13. Findings from these procedures together should render possible the evaluation of the bioavailability of potentially toxic pesticidal moieties in humans and animals.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the bound residues of the fungicide cyprodinil formed in plant cell suspension cultures of wheat

Sapp

Ertunç

Bringmann

et al. 2003

Pest Management Science

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The non-extractable residues of the fungicide cyprodinil formed in heterotrophic cell suspension cultures of wheat were studied by application of [2-pyrimidyl-14 C] or [2-pyrimidyl-13 C]cyprodinil. The main objective was to examine whether solid-state and liquid 13 C NMR spectroscopy can be used to examine plant bound residues of pesticides. For 14 C experiments, wheat suspensions grown on glucose as carbon source were treated with 10 mg litre −1 of 14 C-cyprodinil. After incubation for 12 days, 20% of applied 14 C was detected as non-extractable residues. The cell debris were treated with 0.1 M HCl (reflux), 1.0 M HCl (reflux), buffer, or 2 M NaOH (50 • C); Björkman lignin and acidolysis lignin fractions were also prepared from the debris. Radioactivity liberated and solubilized by these procedures was examined by thin-layer chromatography and high-performance liquid chromatography. The results showed that cyprodinil and primary metabolites contributed to the fungicide's bound residues. Most of the residues (12% of applied 14 C) remained associated with polar or polymeric/oligomeric endogenous cell materials in a stable manner. For the study with 13 C-cyprodinil, wheat suspensions were cultivated on 13 C-depleted glucose for four growth cycles, resulting in maximum 13 C depletion of the natural cell components to about 0.10%. During the fourth cycle, 13 C-labelled cyprodinil was applied, and cells were incubated (12 days). Cell debris was prepared and examined by solid-state 13 C NMR spectroscopy. Debris was then treated as described above in the 14 C experiment. Solubilized fractions were analyzed by liquid 13 C NMR spectroscopy. However, none of the 13 C NMR spectra recorded gave utilizable or unambiguous results, and all exhibited large inconsistencies, especially concerning the data from the conventional 14 C experiment.

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Regulatory aspects of bound residues (chemistry)

Cited by 18 publications

References 4 publications

Bound and unextractable pesticidal plant residues: chemical characterization and consumer exposure

Bound and unextractable pesticidal plant residues: chemical characterization and consumer exposure

Bioavailability of Bound Pesticide Residues and Potential Toxicologic Consequences

Characterization of the bound residues of the fungicide cyprodinil formed in plant cell suspension cultures of wheat

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