P.E. Boon

Dietary exposure to dioxins and dioxin-like PCBs in The Netherlands anno 2004

In this study, representative occurrence data for PCDD/Fs and dioxin-like PCBs in food were obtained and used to estimate dietary exposure of the Dutch population. Food composite samples were analyzed as well as single fish and vegetables samples. Total dioxin concentrations in animal products ranged from 0.05 pg TEQ/g product in poultry to 2.5 pg TEQ/g product (using TEF(2006)) in fish (shrimp), with 0.12pg TEQ/g product being the lowest concentrations measured in fish (tuna). In vegetable products, concentrations ranged from 0.00002 pg TEQ/g product (white kale) to 0.19 pg TEQ/g (oils and fats). A long-term dietary exposure distribution was calculated using Monte Carlo Risk Assessment software. The lower bound median exposure of the Dutch population to PCDD/Fs and dioxin-like PCBs was estimated at 0.8 pg WHO-TEQ/kgbw/d, half of which were dioxin-like PCBs. Dairy was the main source (38%) due to its high consumption. Time-trend analysis shows that the exposure to dioxins has further decreased by 35% over the past five years. This is due to lower levels of dioxin-like compounds in most of the foods, mainly influenced by lower levels in meat and milk. The use of the new TEFs gives an exposure reduction of 10% with respect to TEF(1998). Still, 4% of the Dutch population exceeds the exposure limit of 14 pg/kgbw/week as set by the EU.

Dietary exposure assessments for children in europe (the EXPOCHI project): rationale, methods and design.

Background/purposeThe number of dietary exposure assessment studies focussing on children is very limited. Children are however a vulnerable group due to their higher food consumption level per kg body weight. Therefore, the EXPOCHI project aims [1] to create a relational network of individual food consumption databases in children, covering different geographical areas within Europe, and [2] to use these data to assess the usual intake of lead, chromium, selenium and food colours.MethodsEXPOCHI includes 14 food consumption databases focussed on children (1-14 y old). The data are considered representative at national/regional level: 14 regions covering 13 countries. Since the aim of the study is to perform long-term exposure assessments, only data derived from 24 hr dietary recalls and dietary records recorded on at least two non-consecutive days per individual were included in the dietary exposure assessments. To link consumption data and concentration data of lead, chromium and selenium in a standardised way, categorisation of the food consumption data was based on the food categorisation system described within the SCOOP Task report 3.2.11. For food colours, the food categorisation system specified in the Council Directive 94/36/EC was used.ConclusionThe EXPOCHI project includes a pan-European long-term exposure assessment of lead, chromium, selenium and food colours among children living in 13 different EU countries. However, the different study methods and designs used to collect the data in the different countries necessitate an in-depth description of these different methods and a discussion about the resulting limitations.

Cumulative risk assessment of the exposure to organophosphorus and carbamate insecticides in the dutch diet

We report the acute cumulative exposure to organophosphorus insecticides (OPs) and carbamates in the Dutch population and young children (1-6 years) via the diet. Residue data were derived from Dutch monitoring programmes performed during 2003-2005, and food consumption levels from the Dutch National Food Consumption Survey 1997/1998. The relative potency factor (RPF) approach was used to cumulate the exposure to OPs and carbamates using acephate and oxamyl as index compound respectively. The exposure was estimated using the probabilistic approach, including unit variability and processing effects. We demonstrate that about 3% of the composite samples analysed for OPs and 0.2% for carbamates contain combinations of these pesticides. The P99.9 of exposure to OPs and carbamates in the total Dutch population equals 23 and 0.64microg/kg BW/d respectively. For young children the corresponding exposure levels are 57 and 1.47microg/kg BW/d. When comparing the P99.9 of exposure with the ARfD, 50 and 9microg/kg BW/d for acephate and oxamyl respectively, there is only a possible health risk for young children. Spinach contributed most to the exposure to OPs in both age groups, followed by orange and mandarin. For carbamates apple (sauce) was the main product determining the exposure.

Comparison of two models for the estimation of usual intake addressing zero consumption and non-normality.

Various models exist for estimating the usual intake distribution from dietary intake data. In this paper, we compare two of these models, the Iowa State University Foods (ISUF) model and the betabinomial-normal (BBN) model and apply them to three different datasets. Intake data are obtained by aggregating over multiple food products and are often non-normal. The ISUF and BBN model both address non-normality. While the two models have similar structures, they show some differences. The ISUF model includes an additional spline transformation for improving the normality of the intake amount distribution, while the BBN model includes the possibility of addressing covariates, such as age or sex. Our analyses showed that for two of the example datasets both models produced similar estimates of the higher percentiles of the usual intake distribution. However, for the third dataset, where the intake amount distribution appear to be multimodal, both models produced different percentile estimates.

An integrated probabilistic framework for cumulative risk assessment of common mechanism chemicals in food: an example with organophosphorus pesticides.

This paper presents a framework for integrated probabilistic risk assessment of chemicals in the diet which accounts for the possibility of cumulative exposure to chemicals with a common mechanism of action. Variability between individuals in the population with respect to food consumption, concentrations of chemicals in the consumed foods, food processing habits and sensitivity towards the chemicals is addressed by Monte Carlo simulations. A large number of individuals are simulated, for which the individual exposure (iEXP), the individual critical effect dose (iCED) and the ratio between these values (the individual margin of exposure, iMoE) are calculated by drawing random values for all variable parameters from databases or specified distributions. This results in a population distribution of the iMoE, and the fraction of this distribution below 1 indicates the fraction of the population that may be at risk. Uncertainty in the assessment is treated as a separate dimension by repeating the Monte Carlo simulations many times, each time drawing random values for all uncertain parameters. In this framework, the cumulative exposure to common mechanism chemicals is addressed by incorporation of the relative potency factor (RPF) approach. The framework is demonstrated by the cumulative risk assessment of organophosphorus pesticides (OPs). By going through this example, the various choices and assumptions underlying the cumulative risk assessment are made explicit. The problems faced and the solutions chosen may be more generic than the present example with OPs. This demonstration may help to familiarize risk assessors and risk managers with the somewhat more complex output of probabilistic risk assessment.

Validation of a probabilistic model of dietary exposure to selected pesticides in Dutch infants

A probabilistic model for dietary exposure to pesticides was validated. For this, we evaluated the agreement of dietary exposure to six pesticides as estimated with the model with exposures measured in duplicate diet samples (=‘real intake’) and those calculated with the point estimate. To calculate the exposure with the model and point estimate, consumption data of the duplicate diet survey and pesticide residue measurements from Dutch monitoring programmes in 2000 and 2001 were used. The model was considered validated when the outcome was both higher than the real intake and lower than the point estimate. Results showed that exposures estimated with the model were closer to the real intake than those of the point estimate, and that the model outcome was lower than the point estimate. Furthermore, it was shown that the probabilistic approach can address the exposure to a pesticide via the consumption of different food products, while the point estimate only estimates the exposure through the consumption of one product. The model validated is a valuable asset when estimating the dietary exposure to pesticides in both the authorization of new pesticides and the evaluation of exposures using monitoring data.

A model for probabilistic health impact assessment of exposure to food chemicals.

A statistical model is presented extending the integrated probabilistic risk assessment (IPRA) model of van der Voet and Slob [van der Voet, H., Slob, W., 2007. Integration of probabilistic exposure assessment and probabilistic hazard characterisation. Risk Analysis, 27, 351-371]. The aim is to characterise the health impact due to one or more chemicals present in food causing one or more health effects. For chemicals with hardly any measurable safety problems we propose health impact characterisation by margins of exposure. In this probabilistic model not one margin of exposure is calculated, but rather a distribution of individual margins of exposure (IMoE) which allows quantifying the health impact for small parts of the population. A simple bar chart is proposed to represent the IMoE distribution and a lower bound (IMoEL) quantifies uncertainties in this distribution. It is described how IMoE distributions can be combined for dose-additive compounds and for different health effects. Health impact assessment critically depends on a subjective valuation of the health impact of a given health effect, and possibilities to implement this health impact valuation step are discussed. Examples show the possibilities of health impact characterisation and of integrating IMoE distributions. The paper also includes new proposals for modelling variable and uncertain factors describing food processing effects and intraspecies variation in sensitivity.

Comparison of human health risks resulting from exposure to fungicides and mycotoxins via food.

The interest in holistic considerations in the area of food safety is increasing. Risk managers may face the problem that reducing the risk of one compound may increase the risk of another compound. An example is the potential increase in mycotoxin levels due to a reduced use of fungicides in crop production. The Integrated Probabilistic Risk Assessment (IPRA) model was used to compare the estimated health impacts on humans caused by crops contaminated with the fungicides spiroxamine (SPI) and tebuconazole (TEB) or with the mycotoxins deoxynivalenol (DON) and zearalenone (ZEA). The IPRA model integrates a distribution characterising the exposure of individuals with a distribution characterising the susceptibility of individuals towards toxic effects. Its outcome, a distribution of Individual Margins of Exposure (IMoE), served as basis to perform comparisons of compounds, effects, countries, and population groups. Based on the available data and the assumptions made, none of the four compounds was found to have impact on human health in the addressed scenarios. The IMoE distributions were located as follows: DON<TEB=ZEA<SPI, showing DON to be the compound with the highest potential for negative health impacts. The presented approach can help risk managers to prioritise risk-reduction measures.

Determination of trichothecenes in duplicate diets of young children by capillary gas chromatography with mass spectrometric detection.

Trichothecenes are mycotoxins produced by several fungal genera, mainly Fusarium species, that can contaminate a wide range of cereals used for human and animal consumption. They are associated with various adverse health effects in animals and humans such as feed refusal, vomiting and immunotoxic effects. A method based on capillary gas chromatography with mass spectrometric detection was developed and validated in-house for the determination of nine trichothecenes in duplicate diets of young children. The trichothecenes were extracted from the sample matrix by water/ethanol (90/10). The extracts were cleaned by means of ChemElut® and Mycosep® columns. The cleaned extracts were evaporated to dryness and derivatized to trimethylsilyl ethers at room temperature. The residues were dissolved in iso-octane and washed with water. The final extracts were analysed for trichothecenes by GC-MS. The response was linear in the range tested (1–10 μg kg−1). Recoveries for the trichothecenes were between 70 and 111%, with the exception of nivalenol, which had a low recovery (34%). The limit of quantification for all trichothecenes was below 0.4 μg kg−1. Seventy-four food samples from young children collected by 74 respondents in a duplicate diet study were analysed for trichothecenes with the developed method. The mean levels of deoxynivalenol, nivalenol, HT-2 toxin and T-2 toxin were 5.8, 0.3, 0.3 and 0.1 μg kg−1, respectively. Based on the individual results, dietary intake calculations were made. For deoxynivalenol, the tolerable daily intake of 1 μg kg−1 body weight was exceeded by nine respondents. For the combined intake of T-2 and HT-2 toxin, the temporary tolerable daily intake of 0.06 μg kg−1 body weight was exceeded by nine respondents.

The MCRA model for probabilistic single-compound and cumulative risk assessment of pesticides

Pesticide risk assessment is hampered by worst-case assumptions leading to overly pessimistic assessments. On the other hand, cumulative health effects of similar pesticides are often not taken into account. This paper describes models and a web-based software system developed in the European research project ACROPOLIS. The models are appropriate for both acute and chronic exposure assessments of single compounds and of multiple compounds in cumulative assessment groups. The software system MCRA (Monte Carlo Risk Assessment) is available for stakeholders in pesticide risk assessment at mcra.rivm.nl. We describe the MCRA implementation of the methods as advised in the 2012 EFSA Guidance on probabilistic modelling, as well as more refined methods developed in the ACROPOLIS project. The emphasis is on cumulative assessments. Two approaches, sample-based and compound-based, are contrasted. It is shown that additional data on agricultural use of pesticides may give more realistic risk assessments. Examples are given of model and software validation of acute and chronic assessments, using both simulated data and comparisons against the previous release of MCRA and against the standard software DEEM-FCID used by the Environmental Protection Agency in the USA. It is shown that the EFSA Guidance pessimistic model may not always give an appropriate modelling of exposure.