IMPROVING MODELLING APPROACHES FOR CHILDREN EXPOSURE ASSESSMENT IN CONTAMINATED AREAS:

A CASE-STUDY IN A SMELTER SITE IN CHINA1Peizhong Li, 2Elisa Giubilato, 2Andrea Critto, 1Chunye Lin, 1Hongguang Cheng,

2Antonio Marcomini, 3Xiaoli Duan 1 State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing, China

2 Department of Environmental Sciences, Informatics and Statistics, University Ca’ Foscari of Venice, Italy 3 State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China

Area Category Medium ValueNumber of

samplesMeasurement Unit

Distance from the smelter:0-2 km

Environmental data

Soil 2240.12±1652.13 20 mg/kg

Indoor Dust 4585.19±1026.43 45 mg/kg

Outdoor dust 4338.76±1009.64 45 mg/kg

Drinking water ≤0.01 10 ug/L

Irrigation water 600 5 ug/L

Air 1.78±0.80 3 ug Pb/Nm3

Food data

Vegetable (leaf) 3.18±2.02 8 mg/kg

Meat 0.07±0.03 3 mg/kg

Fruit 6.51±3.12 5 mg/kg

Potato 0.55±0.13 7 mg/kg

Biomonitoring data(Blood lead levels)

Average (whole group, 2-14 years) 319.02±38.86 48 ug/L

2-3 years 265.88±46.90 4 ug/L

3-4 years 304.61±102.82 9 ug/L

4-5 years 283.42±141.71 5 ug/L

5-6 years 361.02±106.59 9 ug/L

6-7 years 304.03±79.14 4 ug/L

Main wind direction

0-2km

BACKGROUND METHODS

CASE-STUDY

RESULTS

REFERENCES

CONTACT: Elisa Giubilato - giubilato@unive.it

China is the largest producer and consumer of lead in the world. In the period 2006-2009, about 20major heavy metal pollution events happened and the 60% of these involved lead as one of the majorpollutants. Many cases of lead poisoning have been registered in China in recent years (Ji et al., 2011).

Children are especially susceptible to chronic lead exposure, with effects including physical,cognitive, and neurobehavioural impairment. There is no safe concentration of blood lead belowwhich children are not affected (e.g., Wilhelm et al., 2010).

Although several studies were focused on investigating the most relevant lead pollution sources (e.g.,Zhong et al., 2008; Han et al., 2012), the lack of human biomonitoring data and detailed exposureassessment hampered the identification and assessment of the significant sources and pathways toreceptors for industrial sites.

The weak knowledge on the lead sources and exposure routes limited the assessment and effectivemanagement in recent pollution and poisoning events.

In particular, there is little information about lead sources and exposure routes for children inChinese rural areas, especially for mining and smelter areas.

The study has the following main objectives: assessment of children exposure to lead in a smelter area in rural China by applying and comparing

two different exposure assessment models, to be checked against real biomonitoring data; characterization and ranking of the different exposure pathways according to their contribution to

the measured concentrations in children, as support to the identification of possible risk managementmeasures.

Results of both IEUBK and MERLIN-Expo model tend to approach real detected humanbiomonitoring data, but there are relevant differences when monitored Pb blood concentrationsare particularly high (5-6 year group).

The ranking of exposure pathways is comparable with similar studies, e.g. heavy pollutedbattery factory site in Guangdong Province in China (Chen et al., 2012).

Differences in the relative importance of exposure pathways could be attributable to differencesbetween measured (IEUBK) and modelled (MERLIN-Expo) concentrations in food and todifferences in dust exposure modelling.

Next steps: uncertainty and sensitivity analysis; MERLIN-Expo tool refinement through theapplication to other real cases.

MERLIN-EXPO is effective in predicting chemical environmental fate and human internalexposure and the coupling of multimedia + PBPK models on the same platform offers moreflexibility for integrated exposure assessments.

OBJECTIVES

One of the biggest Pb-Zn smelting sites in Southern China, it has more than 2 thousand years of history.

The area is heavily polluted by heavy metals, especially around a big 50-year smelter, which has been recently closed.

A detailed monitoring survey was carried out in the area in 2010, including the collection and analysis of environmental samples (soil, indoor and outdoor dust, different food items, drinking water) as well as blood samples from children living in the area (2 to 7 years old).

This research has received funding from the European Union’s FP7 under 4FUN project

(grant agreement No 308440) and GLOCOM project (grant agreement No 269233)

It contains a library of models for exposure assessment that can be combined allowing to:

build complex exposure scenarios involving several pollution sources and multiple exposurepathways, both for organic and inorganic chemicals;

Couple dynamic environmental multimedia and physiologically-based pharmaco-kinetic(PBPK) models to link concentrations in environmental media to internal dose in targetorgans/tissues;

conduct exposure assessment for different human populations (general population, childrenat different ages, pregnant women) over a wide range of time periods (e.g. lifetime, specificwindows of sensitivity, short/long periods);

perform both deterministic and probabilistic simulations;

perform advanced sensitivity analyses.

An interaction matrix allowscombining and connecting theselected compartmental modelsin a flexible way to build up thespecific exposure scenario.

The figure illustrates the chainof models selected for theassessment of childrenexposure to lead in the smelterarea. The arrows representlinkages between the models(compartments) in terms ofinputs/outputs.

The exposure pathways and routes considered in the exposure assessment are illustrated in the exposure diagram.

Ji AL, Wang F, Luo WJ, et al.,2011 Lead poisoning in China: a nightmare from industrialisation. The Lancet 377(9776): 1474-1476.

Han ZX, Bi XY, Li ZG, et al., 2012. Occurrence, speciation and bioaccessibility of lead in Chinese rural household dust and the associated health risk tochildren. Atmospheric Environment 46:65-70.

Zhong K, Zhang JL, 2008. Sources and influencing factors of children blood lead in China. Journal of Environment Health 25(7): 651-654 [in Chinese].

USEPA, 1994. Technical support document: parameters and equations used in the integrated exposure uptake biokinetic model for lead in children.

Wilhelm M., Heinzow B., et al. 2010. Reassessment of critical lead effects by the German Human Biomonitoring Commission results in suspension ofthe human biomonitoring values(HBM I and HBM II) for lead in blood of children and adults. International Journal of Hygiene and EnvironmentalHealth, 213:265-269.

MERLIN-Expo tool has been developed and validated within 4FUN EUproject (2012-2015; http://www.4funproject.eu/). It is implemented onthe Ecolego platform (http://en.wikipedia.org/wiki/Ecolego).

Monitored lead concentrations in soil, air, irrigation and drinking water from the smelter area areused as input data to MERLIN-Expo model. Time-dependent concentrations in food (leafyvegetables, grain and potato) are calculated by the tool, and are used to calculate dietary dailyintakes. The model calculates total Pb daily intake by considering total ingestion and inhalationcontributions (see exposure diagram). Then, time-dependent concentrations in children blood aresimulated by the man model (PBPK).

Lead concentration in children blood for different age classes are estimated also by applying theIEUBK model (Integrated Exposure Uptake BioKinetic Model for Lead in Children; USEPA, 1994).IEUBK is a model developed specifically for assessment of lead exposure of children up to 7 years ofage. Monitored lead concentrations in environmental compartments and in food items arerequired by the model to estimate lead concentration in children blood.

MODEL AGEBlood concentration

CALCULATEDBlood concentration

DETECTEDMeasurement

Unit

IEUBK

2 - 3 28.5 26.6 ug/dL

3 - 4 28.2 30.5 ug/dL

4 - 5 24.8 28.3 ug/dL

5 – 6 22.0 36.1 ug/dL

6 - 7 19.9 30.4 ug/dL

MERLIN-Expo

2 - 3 25.4 26.6 ug/dL

3 - 4 23.4 30.5 ug/dL

4 - 5 21.9 28.3 ug/dL

5 - 6 20.5 36.1 ug/dL

6 - 7 19.2 30.4 ug/dL

IEUBK MERLIN-Expo

Relative contribution of the different exposure pathways to the total exposure