"Establishing target and intervention guidance values for indoor air in dwellings and publicly accessible buildings: The Flemish approach".

Indoor air quality has been recognized by the Flemish authorities as an important policy field in view of protection of public health. In 2018, the revised Flemish Indoor Air Decree (Belgisch Staatsblad, 2018), entered into force in Flanders and is applicable for dwellings and publicly accessible buildings (PAB). The Decree is based on three pillars, 1) creating awareness on the importance of good indoor air quality for health, 2) a service for indoor air dwelling examination in case of health complaints that are likely provoked by bad indoor air, and 3) target and intervention guidance values for chemical, physical and biotic factors in the indoor environment. The target guidance values are set up as a measurable concentration of a chemical, physical or biotic factor in the indoor environment corresponding to a quality level which should be achieved as much as possible. For chemical factors, this level corresponds to a concentration where negative impact on health of the occupants due to the indoor environment is not expected. An intervention guidance value is a measurable concentration of a chemical, physical or biotic factor in the indoor environment requiring a remediation action because the concentrations might provoke a health risk for the occupants of the indoor environment. Target and intervention guidance values for indoor air in Flanders have been established for 23 substances, mainly Volatile Organic Compounds (VOCs), NO2, PM2.5 and asbestos. The indoor air target and intervention guidance values for these substances are based on chronic exposure since they are designed to be health protective for prolonged use of the indoor environments by the occupants, including vulnerable populations. Both a threshold-based approach, and specific for carcinogenic substances, a non-threshold-based approach is included. In this paper, we provide an overview of the methods for establishing the indoor air target and intervention guidance values for substances in the Flemish Indoor Air Decree along with the resulting values.

Assessing multimedia/multipathway exposures to inorganic arsenic at population and individual level using MERLIN-Expo.

In this study, we report on model simulations performed using the newly developed exposure tool, MERLIN-Expo, in order to assess inorganic arsenic (iAs) exposure to adults resulting from past emissions by non-ferrous smelters in Belgium (Northern Campine area). Exposure scenarios were constructed to estimate external iAs exposure as well as the toxicologically relevant As (tAs, i.e., iAs, MMA and DMA) body burden in adults living in the vicinity of the former industrial sites as compared to adults living in adjacent areas and a reference area. Two scenarios are discussed: a first scenario studying exposure to iAs at the aggregated population level and a second scenario studying exposure at the individual level for a random sub-sample of subjects in each of the three different study areas. These two scenarios only differ in the type of human related input data (i.e., time-activity data, ingestion rates and consumption patterns) that were used, namely averages (incl. probability density functions, PDFs) in the simulation at population level and subject-specific values in the simulation at individual level. The model predictions are shown to be lower than the corresponding biomonitoring data from the monitoring campaign. Urinary tAs levels in adults, irrespective of the area they lived in, were under-predicted by MERLIN-Expo by 40% on average. The model predictions for individual adults, by contrast, under-predict the biomonitoring data by 7% on average, but with more important under-predictions for subjects at the upper end of exposure. Still, average predicted urinary tAs levels from the simulations at population level and at individual level overlap, and, at least for the current case, lead to similar conclusions. These results constitute a first and partial verification of the model performance of MERLIN-Expo when dealing with iAs in a complex site-specific exposure scenario, and demonstrate the robustness of the modelling tool for these situations.

Multimedia & PBPK modelling with MERLIN-Expo versus biomonitoring for assessing Pb exposure of pre-school children in a residential setting.

This paper reports on a case study - conducted within the European FP7 project "4FUN" - focusing on exposure of pre-school children to lead resulting from past emissions by non-ferrous smelters in Belgium (Northern Campine area). Exposure scenarios were constructed and simulated with the MERLIN-Expo tool to estimate external Pb exposure as well as the Pb body burden in children living in the vicinity of the former industrial sites as compared to children living in adjacent areas and a reference area. Simulations were run for several scenarios ranging from very simple to rather complex in order to study the effect of different simulation approaches (e.g., deterministic vs. probabilistic, individual vs. aggregated population exposure) and different exposure scenarios (e.g., with vs. without considering local food consumption or time activity patterns) on the model outcomes (predicted concentrations of Pb in environmental and human matrices). This paper discusses the two most complex scenarios, namely exposure at the aggregated population level and at the individual level for a random sub-sample of subjects, respectively. In the final and most realistic exposure scenario, simulating individual lead exposure, model predictions were shown to be higher than the biomonitoring data. Blood Pb levels in children, irrespective of the area they lived in, were overpredicted by MERLIN-Expo with a factor of about 2 on average. The model predictions for individual children overlap with the prediction interval calculated by MERLIN-Expo based on population averages, demonstrating the use of probabilistic approaches in risk assessment. While these results constitute a first verification of the model performance of MERLIN-Expo dealing with inorganic pollutants in a complex real-world exposure scenario and a demonstration of the robustness of the modelling tool, further validation and benchmarking efforts are required for a larger number of inorganic pollutants and different exposure settings.

Determination of contamination pathways of phthalates in food products sold on the Belgian market.

As numerous studies have indicated that food ingestion is the most important exposure pathway to several phthalates, this study aimed to determine possible contamination pathways of phthalates in food products sold on the Belgian market. To do this, concentrations of eight phthalates (dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), benzylbutyl phthalate (BBP), dicyclohexyl phthalate (DCHP), di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP)) were determined in 591 foods and 30 packaging materials. In general, the four most prominent phthalates in Belgian food products were DEHP, DiBP, DnBP and BBP. Special attention was given to the origin of these phthalates in bread, since high phthalate concentrations (especially DEHP) were determined in this frequently consumed food product. Phthalates seemed to occur in Belgian bread samples due to the use of contaminated ingredients (i.e. use of contaminated flour) as well as due to migration from phthalate containing contact materials used during production (e.g. coated baking trays). Also the results of the conducted concentration profiles of apple, bread, salami and two cheese types revealed the important role of processing - and not packaging - on phthalate contents in foods.

Key aspects of a Flemish system to safeguard public health interests in case of chemical release incidents.

Although well-established protocols are available for emergency services and first-responders in case of chemical release incidents, a well-developed system to monitor and safeguard public health was, until recently, lacking in Flanders. We therefore developed a decision support system (DSS) to aid public health officials in identifying the appropriate actions in case of incidents. Although the DSS includes human biomonitoring as one of its key instruments, it also goes well beyond this instrument alone. Also other, complementary, approaches that focus more on effect assessment using in vitro toxicity testing, indirect exposures through the food chain, and parallel means of data collection (e.g. through ecosurveillance or public consultation), are integrated in the Flemish approach. Even though the DSS is set up to provide a flexible and structured decision tree, the value of expert opinion is deemed essential to account for the many uncertainties associated with the early phases of technological incidents. When the DSS and the associated instruments will be fully operational, it will provide a valuable addition to the already available protocols, and will specifically safeguard public health interests.

Phthalates dietary exposure and food sources for Belgian preschool children and adults.

Numerous studies have indicated that for phthalates, the intake of contaminated foods is the most important exposure pathway for the general population. Up to now, data on dietary phthalate intake are scarce and - to the authors' knowledge - not available for the Belgian population. Therefore, the purpose of this study was: (1) to assess the long-term intake of the Belgian population for eight phthalates considering different exposure scenarios (benzylbutyl phthalate (BBP); di-n-butyl phthalate (DnBP); dicyclohexyl phthalate (DCHP); di(2-ethylhexyl) phthalate (DEHP); diethyl phthalate (DEP); diisobutyl phthalate (DiBP); dimethyl phthalate (DMP), di-n-octyl phthalate (DnOP)); (2) to evaluate the intake of BBP, DnBP, DEP and DEHP against tolerable daily intake (TDI) values; and (3) to assess the contribution of the different food groups to the phthalate intake. The intake assessment was performed using two Belgian food consumption databases, one with consumption data of preschool children (2.5 to 6.5 years old) and another of adults (≥15 years old), combined with a database of phthalate concentrations measured in over 550 food products sold on the Belgian market. Phthalate intake was calculated using the 'Monte Carlo Risk Assessment' programme (MCRA 7.0). The intake of DEHP was the highest, followed by DiBP. The intake of BBP, DnBP and DEP was far below the TDI for both children and adults. However, for DEHP, the 99th percentile of the intake distribution of preschoolers in the worst case exposure scenario was equal to 80% of the TDI, respectively. This is not negligible, since other exposure routes of DEHP exist for children as well (e.g. mouthing of toys). Bread was the most important contributor to the DEHP intake and this may deserve further exploration, since the origin of this phthalate in bread remains unclear.