Inter-individual variation in chlorpyrifos toxicokinetics characterized by physiologically based kinetic (PBK) and Monte Carlo simulation comparing human liver microsome and Supersome™ cytochromes P450 (CYP)-specific kinetic data as model input.

The present study compares two approaches to evaluate the effects of inter-individual differences in the biotransformation of chlorpyrifos (CPF) on the sensitivity towards in vivo red blood cell (RBC) acetylcholinesterase (AChE) inhibition and to calculate a chemical-specific adjustment factor (CSAF) to account for inter-individual differences in kinetics (HKAF). These approaches included use of a Supersome™ cytochromes P450 (CYP)-based and a human liver microsome (HLM)-based physiologically based kinetic (PBK) model, both combined with Monte Carlo simulations. The results revealed that bioactivation of CPF exhibits biphasic kinetics caused by distinct differences in the Km of CYPs involved, which was elucidated by Supersome™ CYP rather than by HLM. Use of Supersome™ CYP-derived kinetic data was influenced by the accuracy of the intersystem extrapolation factors (ISEFs) required to scale CYP isoform activity of Supersome™ to HLMs. The predicted dose-response curves for average, 99th percentile and 1st percentile sensitive individuals were found to be similar in the two approaches when biphasic kinetics was included in the HLM-based approach, resulting in similar benchmark dose lower confidence limits for 10% inhibition (BMDL10) and HKAF values. The variation in metabolism-related kinetic parameters resulted in HKAF values at the 99th percentile that were slightly higher than the default uncertainty factor of 3.16. While HKAF values up to 6.9 were obtained when including also the variability in other influential PBK model parameters. It is concluded that the Supersome™ CYP-based approach appeared most adequate for identifying inter-individual variation in biotransformation of CPF and its resulting RBC AChE inhibition.

Occurrence and Probabilistic Risk Assessment of Fumonisin B1, Fumonisin B2 and Deoxynivalenol in Nixtamalized Maize in Mexico City.

Fumonisins (FB1+FB2) and deoxynivalenol (DON) are mycotoxins produced by Fusarium species that might be present in maize and maize products. Knowledge on their occurrence in nixtamalized maize from Mexico together with an accompanying risk assessment are scarce, while nixtamalized maize is an important food in Mexico. This study presents the occurrence of FB1 + FB2 and DON in nixtamalized maize samples collected in Mexico City and analyses their distribution and resulting estimated daily intake for Mexican consumers by a probabilistic approach using a two-dimensional Monte-Carlo simulation. The results obtained reveal that for FB1 + FB2, 47% of the Mexican men and 30% of the Mexican women might exceed the provisional tolerable daily intake (PMTDI) of 2 µg/kg bw/day for fumonisins and for DON, 9% of men and 5% of women would be exceeding the PMTDI of 1 µg/kg bw/day, corresponding to the high consumers. The results raise a flag for risk managers in Mexico, to consider regulations and interventions that lower mycotoxin levels in nixtamalized maize for human consumption.

Hazard assessment of Maerua subcordata (Gilg) DeWolf. for selected endpoints using a battery of in vitro tests.

ETHNOPHARMACOLOGICAL RELEVANCE: Maerua subcordata (Gilg) DeWolf is a medicinal and wild food plant growing mainly in east Africa. Especially its root tuber is widely used in traditional medicine to treat several infectious and chronic diseases but also in some toxicity implications like use as abortifacient. AIM OF THE STUDY: the present study applied in silico and in vitro tests to identify possible hazards of M. subcordata (fruit, leaf, root, seed) methanol extracts focussing on developmental toxicity. MATERIALS AND METHODS: Ames test, estrogen receptor alpha (ERα) assay, aryl hydrocarbon receptor (AhR) assay, embryonic stem cell test (EST), and zebrafish embryotoxicity test (ZET) were employed. Besides, a Derek Nexus toxicity prediction was performed on candidate structures obtained from metabolomics profiling of the extracts using liquid chromatography coupled to multistage mass spectroscopy (LC/MSn) and a MAGMa software based structural annotation. RESULTS: Glucosinolates, which degrade to isothiocyanates, and biogenic amines were among the candidate molecules identified in the extracts by LC/MSn - MAGMa software structural annotation. Isothiocyanates and some other candidate molecules suggested a positive mutagenicity alert in Derek toxicity predictions. All the extracts showed negative mutagenicity in the Ames test. However, the Derek predictions also identified endocrine and developmental toxicity as possible endpoints of concern. This was further assessed using in vitro tests. Results obtained reveal that leaf extract shows AhR and ERα agonist activities, inhibited differentiation of ES-D3 stem cells into contracting cardiomyocytes in the EST (p < 0.001) as well as inhibited hatching (p < 0.01) and showed acute toxicity (p < 0.01) in the ZET. Also, the fruit extract showed toxicity (p < 0.05) towards zebrafish embryos and both fruit and seed extracts showed AhR agonist activities while root extract was devoid of activity in all in vitro assays. CONCLUSION: The leaf extract tests positive in in vitro tests that may point towards a developmental toxicity hazard. The current evaluations did not raise concerns of genotoxicity or developmental toxicity for the fruit, seed and root extracts. This is important given the use of especially these parts of M. subcordata, in traditional medicine and/or as (famine) food.

Levels of methyleugenol and eugenol in instant herbal beverages available on the Indonesian market and related risk assessment.

The presence and accompanying risks of methyleugenol and eugenol in herbal beverages available on the Indonesian market were evaluated. Methyleugenol was detected in 49 out of 114 samples, at levels amounting to 2.6-443.7 µg/g, while 4 samples contained eugenol at 21.4-101.2 µg/g. The EDI resulting from drinking these preparations amounted to 0.1-51.2 µg/kg bw/day and 1.1-3.3 µg/kg bw/day, respectively for samples targeted at adults and children. A BMDL10 value of 22.2 mg/kg bw/day for methyleugenol was defined using literature data and model averaging. MOE values were below 10,000 for 46 samples (40.4%), indicating a priority for risk management when assuming daily lifelong consumption, while the EDI for 4 samples containing eugenol did not exceed the ADI of 2.5 mg/kg bw thus did not raise a concern for human health. Using Haber's rule to correct for less than lifetime exposure, consumption of methyleugenol via these beverages would be of low concern when consumed for less than 2 weeks/year during a lifetime. This conclusion holds for herbal beverages collected by targeted sampling, not for all herbal beverages on the Indonesian market. The study provides data that can support establishment of a maximum permitted level (MPL) for methyleugenol in herbal beverages in Indonesia.

Aflatoxin B1 in nixtamalized maize in Mexico; occurrence and accompanying risk assessment.

Maize is a staple food in Mexico that might contain Aflatoxin B1 (AFB1). Nonetheless, data on the exposure and risk assessment of AFB1 from maize for the Mexican population are limited. The aim of the present study was to analyse the occurrence of AFB1 in Mexican nixtamalized maize samples, and to assess the accompanying exposure and risk. Four out of 88 samples contained AFB1 at levels above the limit of detection (1 ng/g). AFB1 occurrence values obtained in this study and additional occurrence values from literature were combined with available literature data for mean and P95 consumption of maize based products. For a 70 kg body weight person, lower bound and upper bound exposure assessments resulted in estimated daily intakes (EDI) of 0.7-8.5 ng/kg bw/day, based on a mean maize consumption. Based on the P95 maize consumption these EDI values amounted to 3.3-11.7 ng/kg bw/day. The corresponding Margin of Exposure (MOE) values amounted to 257-20 for the mean and 50-15 for the P95 consumers. The estimated increased cancer risks were 9-320 and 43-439 cases/106 individuals/lifetime of 75 years for the mean and P95 consumers, respectively. Altogether, the assessment reveals the need for continued risk management of AFB1 in Mexico.

Natural occurrence of genotoxic and carcinogenic alkenylbenzenes in Indonesian jamu and evaluation of consumer risks.

The consumer risks of jamu, Indonesian traditional herbal medicines, was assessed focussing on the presence of alkenylbenzene containing botanical ingredients. Twenty-three out of 25 samples contained alkenylbenzenes at levels ranging from 3.8 to 440 µg/kg, with methyleugenol being the most frequently encountered alkenylbenzene. The estimated daily intake (EDI) resulting from jamu consumption was estimated to amount to 0.2-171 µg/kg bw/day for individual alkenylbenzenes, to 0.9-203 µg/kg bw/day when adding up all alkenylbenzenes detected, and to 0.9-551 µg/kg bw/day when expressed in methyleugenol equivalents using interim relative potency (REP) factors. The margin of exposure (MOE) values obtained were generally <10,000 indicating a priority for risk management when assuming daily consumption during a lifetime. Using Haber's rule it was estimated that two weeks consumption of these jamu only once would not raise a concern (MOE >10,000). However, when considering use for two weeks every year during a lifetime, 5 samples still raise a concern. It is concluded that the consumption of alkenylbenzene containing jamu can be of concern especially when consumed on a daily basis for longer periods of time on a regular basis.

Determination and risk assessment of naturally occurring genotoxic and carcinogenic alkenylbenzenes in basil-containing sauce of pesto.

A risk assessment of basil-based pesto sauces containing methyleugenol and related alkenylbenzenes was performed based on their levels detected in a series of pesto sauces available on the Dutch market. The estimated daily intake (EDI) values of alkenylbenzenes as a result of consumption of the different pesto sauces amounted to 1.2-44.3 µg/kg bw for individual alkenylbenzenes, 14.3-43.5 µg/kg bw when adding up the alkenylbenzene levels assuming equal potency, and 17.3-62.9 µg/kg bw when expressed in methyleugenol equivalents using alkenylbenzenes defined toxic equivalency factors (TEF). The margin of exposure approach (MOE), used to evaluate the potential risks, resulted in MOE values that were generally lower than 10000 indicating a priority for risk management when assuming daily consumption. The levels of methyleugenol detected in the pesto sauces would allow consumption of 1.1-29.8, 7.5-208, 15.1-416.5, and 32.4-892.5 g of pesto sauce on a daily basis, once a week, once every two weeks, and once a month, respectively, to achieve MOE values above the 10000 limit indicating low priority for risk management. It is concluded that consumption of pesto sauces would only be of concern if consumed on a daily basis over longer periods of time.

Risk assessment of combined exposure to alkenylbenzenes through consumption of plant food supplements containing parsley and dill.

A risk assessment was performed of parsley- and dill-based plant food supplements (PFS) containing apiol and related alkenylbenzenes. First, the levels of the alkenylbenzenes in the PFS and the resulting estimated daily intake (EDI) resulting from use of the PFS were quantified. Since most PFS appeared to contain more than one alkenylbenzene, a combined risk assessment was performed based on equal potency or using a so-called toxic equivalency (TEQ) approach based on toxic equivalency factors (TEFs) for the different alkenylbenzenes. The EDIs resulting from daily PFS consumption amount to 0.74-125 µg kg-1 bw for the individual alkenylbenzenes, 0.74-160 µg kg-1 bw for the sum of the alkenylbenzenes, and 0.47-64 µg kg-1 bw for the sum of alkenylbenzenes when expressed in safrole equivalents. The margins of exposure (MOEs) obtained were generally below 10,000, indicating a priority for risk management if the PFS were to be consumed on a daily basis. Considering short-term use of the PFS, MOEs would increase above 10,000, indicating low priority for risk management. It is concluded that alkenylbenzene intake through consumption of parsley- and dill-based PFS is only of concern when these PFS are used for long periods of time.

Determination and risk assessment of naturally occurring genotoxic and carcinogenic alkenylbenzenes in nutmeg-based plant food supplements.

A risk assessment of nutmeg-based plant food supplements (PFS) containing different alkenylbenzenes was performed based on the alkenylbenzene levels quantified in a series of PFS collected via the online market. The estimated daily intake (EDI) of the alkenylbenzenes amounted to 0.3 to 312 µg kg-1 body weight (bw) for individual alkenylbenzenes, to 1.5 to 631 µg kg-1 bw when adding up the alkenylbenzene levels assuming equal potency, and to 0.4 to 295 µg kg-1 bw when expressed in safrole equivalents using toxic equivalency factors (TEFs). The margin of exposure approach (MOE) was used to evaluate the potential risks. Independent of the method used for the intake estimate, the MOE values obtained were generally lower than 10000 indicating a priority for risk management. When taking into account that PFS may be used for shorter periods of time and using Haber's rule to correct for shorter than lifetime exposure it was shown that limiting exposure to only 1 or 2 weeks would result in MOE values that would be, with the presently determined levels of alkenylbenzenes and proposed uses of the PFS, of low priority for risk management (MOE > 10000). It is concluded that the results of the present paper reveal that nutmeg-based PFS consumption following recommendations for daily intake especially for longer periods of time raise a concern. Copyright © 2017 John Wiley & Sons, Ltd.

Risk assessment of plant food supplements and other herbal products containing aristolochic acids using the margin of exposure (MOE) approach.

After the incidences of induction of aristolochic acid nephropathy after consumption of herbal weight loss preparations that accidentally contained aristolochic acids (AAs), several countries defined national restrictions on the presence of AAs in food, including plant food supplements (PFS) and herbal products. This study investigates whether the risks associated with exposure to AAs via PFS and herbal products are at present indeed negligible. Data reported in literature on AA levels in PFS and other herbal products and also obtained from a new series of PFS in the present study were used to calculate the estimated daily intakes (EDIs) and corresponding margins of exposure (MOEs). Available literature data revealed that 206 out of 573 samples were found to contain aristolochic acid I (AAI) and/or aristolochic acid II (AAII). The results obtained from recently collected PFS revealed that both AAI and AAII were detected in three out of 18 analysed PFS at levels up to 594.8 and 235.3 µg g-1, respectively, being in line with the levels reported in literature. The EDIs resulting from intake of these PFS resulted in MOEs that were generally below 10,000, corroborating the priority for risk management. Although these results refer to PFS collected by targeted sampling strategies, the data reveal that AA-containing PFS are still freely available. When considering that the use of these samples may be limited to shorter periods of time, the EDIs might be lower, but MOE values would still be lower than 10,000 for more than 50% of the AA-containing PFS and herbal products. In conclusion, the presence of AAs in PFS and herbal products even several years after instalment of the legal restrictions still raises concern, especially for people who frequently use the respective PFS and herbal products.

Level of Alkenylbenzenes in Parsley and Dill Based Teas and Associated Risk Assessment Using the Margin of Exposure Approach.

Risk assessment of parsley and dill based teas that contain alkenylbenzenes was performed. To this end the estimated daily intake (EDI) of alkenylbenzenes resulting from use of the teas was quantified. Since most teas appeared to contain more than one alkenylbenzene, a combined risk assessment was performed based on equal potency of all alkenylbenzenes or using a so-called toxic equivalency (TEQ) approach through defining toxic equivalency factors (TEFs) for the different alkenylbenzenes. The EDI values resulting from consuming one cup of tea a day were 0.2-10.1 µg/kg bw for the individual alkenylbenzenes, 0.6-13.1 µg/kg bw for the sum of the alkenylbenzenes, and 0.3-10.7 µg safrole equiv/kg bw for the sum of alkenylbenzenes when expressed in safrole equivalents. The margin of exposure (MOE) values obtained were generally <10000, indicating a concern if the teas would be consumed on a daily basis over longer periods of time.

Mode of action based risk assessment of the botanical food-borne alkenylbenzene apiol from parsley using physiologically based kinetic (PBK) modelling and read-across from safrole.

The present study developed physiologically-based kinetic (PBK) models for the alkenylbenzene apiol in order to facilitate risk assessment based on read-across from the related alkenylbenzene safrole. Model predictions indicate that in rat liver the formation of the 1'-sulfoxy metabolite is about 3 times lower for apiol than for safrole. These data support that the lower confidence limit of the benchmark dose resulting in a 10% extra cancer incidence (BMDL10) that would be obtained in a rodent carcinogenicity study with apiol may be 3-fold higher for apiol than for safrole. These results enable a preliminary risk assessment for apiol, for which tumor data are not available, using a BMDL10 value of 3 times the BMDL10 for safrole. Based on an estimated BMDL10 for apiol of 5.7-15.3 mg/kg body wt per day and an estimated daily intake of 4 × 10(-5) mg/kg body wt per day, the margin of exposure (MOE) would amount to 140,000-385,000. This indicates a low priority for risk management. The present study shows how PBK modelling can contribute to the development of alternatives for animal testing, facilitating read-across from compounds for which in vivo toxicity studies on tumor formation are available to compounds for which these data are unavailable.