Lars Niemann

A critical review of glyphosate findings in human urine samples and comparison with the exposure of operators and consumers

For active substances in plant protection products (PPP) with well defined urinary elimination, no potential for accumulation and virtually no metabolism, measuring of urine levels could be a powerful tool for human biomonitoring. Such data may provide reliable estimates of actual internal human exposure that can be compared to appropriate reference values, such as the ‘acceptable daily intake (ADI)’ or the ‘acceptable operator exposure level (AOEL)’. Traces of the active compound glyphosate were found in human urine samples, probably resulting either from occupational use for plant protection purposes or from dietary intake of residues. A critical review and comparison of data obtained in a total of seven studies from Europe and the US was performed. The conclusion can be drawn that no health concern was revealed because the resulting exposure estimates were by magnitudes lower than the ADI or the AOEL. The expected internal exposure was clearly below the worst-case predictions made in the evaluation of glyphosate as performed for the renewal of its approval within the European Union. However, differences in the extent of exposure with regard to the predominant occupational and dietary exposure routes and between Europe and North America became apparent.

Hepatotoxic effects of (tri)azole fungicides in a broad dose range

Abstract The toxicological relevance of effects observed at molecular stage, which occur at dose levels well below classical no-observed adverse effect levels is currently subject to controversial scientific debate. While the importance of molecular effects for the identification of a mode of action or an adverse outcome pathway is undisputed, their impact for other regulatory purposes remains uncertain. Here, we report the results of a 28-day rat-feeding study including three widely used hepatotoxic (tri)azole fungicides (cyproconazole, epoxiconazole and prochloraz) administered individually at five dose levels, ranging from slightly above the reference values to a clear toxic effect dose. Parameters analysed included pathology, histopathology, clinical chemistry and particularly effects on the molecular level. Since azole fungicides are considered to cause liver toxicity by a mechanism involving the constitutive androstane receptor (CAR), a known CAR activator (phenobarbital, PB) was administered to investigate potential similarities between triazoles and PB-mediated liver toxicity by pathway-focused gene expression analysis. Our results show an increase in liver weights and additionally histopathological changes (hepatocellular hypertrophy) for all substances at the top dose levels. The effects on liver weight were most pronounced for cyproconazole by which also the animals receiving the next lower dose were affected. In addition, vacuolisation of hepatocytes was observed at the top dose level. No such findings were obtained with any substance at lower doses to which consumers and operators might be exposed to. In contrast, the expression of sensitive marker genes (like some cytochrome-P-450 isoforms) was significantly affected also at the lower dose levels. While some of these changes, like the induction of genes related to fatty acid and phospholipid metabolism (e.g. Fasn, Fat/Cd36, Ppargc1a) or xenobiotic metabolism (Cyp1a1, Cyp2b1, Cyp3a2), could be associated with high dose effects like hepatocellular vacuolisation or hypertrophy, a histopathological correlate was lacking for others.

Epoxiconazole causes changes in testicular histology and sperm production in the Japanese quail (Coturnix coturnix japonica)

The fungicide epoxiconazole (Epox), a triazole, belongs to the group of azole compounds that are extensively used as fungicides in various fruit crops. The frequent use of agricultural lands for wintering by migrating birds can be the source of their increased dietary intake of agricultural pesticides. We investigated whether exposure to Epox causes effects on avian fertility and reproduction, using the Japanese quail (Coturnix coturnix japonica) as a model species for the assessment of reproductive effects of pesticides in wild birds. Epox was administered to adult Japanese quail for three weeks at dietary levels of 10, 50, and 500 ppm, and possible effects on reproduction were investigated. Epox administration resulted in a significantly decreased number of spermatids in the 50- and 500-ppm dose groups. Histopathology showed a reduced number of testicular canaliculi with visible germ cells and a reduction in spermatid number. However, testis weight was not affected up to the highest dose level. No impact was observed on hormone levels, fertility, and reproductive outcome, as laying rate and percentage of fertile eggs were not altered. Likewise, treatment had no influence on the egg or chick parameters evaluated. A time- and dose-related transfer of Epox into the eggs was determined in all treatment groups. We conclude that dietary treatment of Japanese quail with 50 and 500 ppm of the triazole fungicide Epox resulted in a clear impact on the testis. The evaluation of the additional endpoints spermatid count and testicular histology have proven useful and are recommended for future studies on avian reproduction.

Application of omics data in regulatory toxicology: report of an international BfR expert workshop.

Abstract Advances in omics techniques and molecular toxicology are necessary to provide new perspectives for regulatory toxicology. By the application of modern molecular techniques, more mechanistic information should be gained to support standard toxicity studies and to contribute to a reduction and refinement of animal experiments required for certain regulatory purposes. The relevance and applicability of data obtained by omics methods to regulatory purposes such as grouping of chemicals, mode of action analysis or classification and labelling needs further improvement, defined validation and cautious expert judgment. Based on the results of an international expert workshop organized 2014 by the Federal Institute for Risk Assessment in Berlin, this paper is aimed to provide a critical overview of the regulatory relevance and reliability of omics methods, basic requirements on data quality and validation, as well as regulatory criteria to decide which effects observed by omics methods should be considered adverse or non-adverse. As a way forward, it was concluded that the inclusion of omics data can facilitate a more flexible approach for regulatory risk assessment and may help to reduce or refine animal testing.

Combination effects of azole fungicides in male rats in a broad dose range

Two 28-day feeding studies were performed in male rats to investigate combination effects of azole fungicides in a broad dose range. Following separate administration of cyproconazole, epoxiconazole, prochloraz, propiconazole, and tebuconazole at five dose levels, the first three compounds were selected to be administered in two different mixtures at three dose levels including very low doses. Here we present the data obtained by clinical observations, pathology, histopathology, clinical chemistry and haematology. The liver was the common main target organ of all compounds and their mixtures. In addition, epoxiconazole exhibited an effect on the adrenals. Furthermore, food consumption and efficiency and body weight (gain) were affected. Adverse effects of the combinations were observed at dose levels at which the individual substances caused similar effects. No evidence of adverse effects was found at dose levels below the previously established NOAELs. Our findings indicate that the concept of dose additivity appears sufficiently protective for risk assessment of the fungicides examined. Besides toxicological testing, tissue residues of the azole compounds in liver, testis and kidney were determined revealing remarkable differences following administration of the single substances and of the mixtures.

Relevance and reliability of experimental data in human health risk assessment of pesticides

ABSTRACT Evaluation of data relevance, reliability and contribution to uncertainty is crucial in regulatory health risk assessment if robust conclusions are to be drawn. Whether a specific study is used as key study, as additional information or not accepted depends in part on the criteria according to which its relevance and reliability are judged. In addition to GLP‐compliant regulatory studies following OECD Test Guidelines, data from peer‐reviewed scientific literature have to be evaluated in regulatory risk assessment of pesticide active substances. Publications should be taken into account if they are of acceptable relevance and reliability. Their contribution to the overall weight of evidence is influenced by factors including test organism, study design and statistical methods, as well as test item identification, documentation and reporting of results. Various reports make recommendations for improving the quality of risk assessments and different criteria catalogues have been published to support evaluation of data relevance and reliability. Their intention was to guide transparent decision making on the integration of the respective information into the regulatory process. This article describes an approach to assess the relevance and reliability of experimental data from guideline‐compliant studies as well as from non‐guideline studies published in the scientific literature in the specific context of uncertainty and risk assessment of pesticides. HIGHLIGHTSRelevant (appropriate) and reliable (trustworthy) data are needed for regulatory decision making.Selection of data used in risk assessment and weight of evidence can directly influence the decision making process.Transparent evaluation criteria are essential to understand why and how certain data are relied on.Specific requirements for experimental data from different sources for health risk assessment of pesticides are described.Adherence to good scientific and reporting practice is key to facilitate regulatory use of published research results.

Investigations on the possible impact of a glyphosate-containing herbicide on ruminal metabolism and bacteria in vitro by means of the 'Rumen Simulation Technique'.

This study was performed in a well‐established in vitro model to investigate whether the application of a glyphosate‐containing herbicide might affect the bacterial communities and some biochemical parameters in a cows rumen.

Die Vorgehensweise des Bundesinstitutes für Risikobewertung bei der Abschätzung der dermalen Absorption von Wirkstoffen in Pflanzenschutzmitteln und Biozidprodukten

ZusammenfassungFür die Bewertung des gesundheitlichen Risikos von Pflanzenschutzmitteln (PSM) und Biozidprodukten (BP) ist die korrekte Abschätzung der Aufnahme der darin enthaltenen Wirkstoffe über die Haut erforderlich. In dieser Veröffentlichung wird dargestellt, wie das Bundesinstitut für Risikobewertung (BfR), in Abhängigkeit von den verfügbaren Daten, die dermale Absorption von Wirkstoffen in PSM und BP ableitet. Dabei finden zwei neue Bewertungsleitfäden der EFSA und der OECD Verwendung. Grundlegende Prinzipien der Studienauswertung werden ebenso beschrieben wie Möglichkeiten zur Abschätzung der Hautabsorption, wenn keine produktspezifischen experimentellen Daten vorliegen. Die Publikation dieser Vorgehensweise stellt einen ersten Schritt für die Harmonisierung der Bewertung in den Zulassungsverfahren von PSM und BP dar.AbstractA correct estimate of dermal absorption of the contained active ingredients is needed for the health risk assessment of plant protection and biocidal products. In this paper, the approach is reported that is currently taken by the Federal Institute for Risk Assessment to derive the dermal absorption rate of active substances in plant protection or biocidal products, depending on the available data. It is explained what use is made of two new guidance documents that were recently released by EFSA and OECD. Basic principles of the assessment of dermal absorption studies are described but also opportunities for estimations in the absence of product-specific experimental data. This publication is considered a first step towards harmonisation of assessment in the authorisation processes for plant protection and biocidal products.

Chapter 8:Insecticides of Natural Origin, Other than Pyrethrum and Nicotine

This chapter gives a detailed overview on the history, use and toxicology of substances of biological origin such as plant extracts (rotenone, azadirachtin, quassin, anabasin) and fermentation products from soil microorganisms (avermectins and spinosins) that are more or less widely used as insecticides in plant protection products or biocides but may also play a role in public health to prevent spread of infectious diseases or even to cure them.

Examination of Japanese quail chicks in one-generation feeding studies for effects of the agrochemicals dimethoate, fentin hydroxide, and vinclozolin on skeletal development

An established method for evaluation of skeletal anomalies was successfully adapted to Japanese quail (Coturnix coturnix japonica) and performed on 793 untreated 1-day old chicks to develop an historical control database. Incomplete ossification of the pelvic bones and irregular position of the toes were rather frequently observed. Subsequently, 702 chicks from the treatment groups in three one-generation reproduction studies with the pesticides dimethoate, triphenyltin (fentin) hydroxide, and vinclozolin were compared to their respective controls and the whole historical database. Presumed treatment-related effects were confined to a higher number of chicks with incomplete ossification of vertebrae and pelvis when the hens had been administered fentin hydroxide at a dietary level of 30 ppm for up to 6 weeks, corresponding to a mean daily substance intake of 3.1-3.9 mg kg−1 body weight (bw). Thus, inclusion of teratological findings as a further endpoint confirmed the previously established NOAEL of 3 ppm (equal to 0.28-0.35 mg kg−1 bw/day) based on reproductive effects in this study. No effects on skeletal development were seen with dimethoate and vinclozolin up to the highest dietary concentrations of 70 and 500 ppm, corresponding to estimated mean daily intakes of about 8 or 56 mg kg−1 bw. The suitability of the method for reliable detection of skeletal anomalies was proven. The established method can be considered useful in providing additional information for ecotoxicological risk assessment.