(7f) Determination of Persistent Organic Pollutants in Silicone Wristbands: A Case Study of 6 European Cities

The aim of this study was to identify the the concentrations of 27 chemicals including PAHs, phthalates and some consumer and personal care products in silicone wristbands worn by 120 participants from 6 different European cities. Our ultimate objective was to test and optimize the use of silicon wristbands as comprehensive personal exposure assessment tool covering a large chemical space. All samples were collected during a 7 days period. To our knowledge, this is the first study to provide a novel personal exposure data at various types of microenvironments and seasons across European cities captured by silicone wristbands for three groups of environmentally relevant chemicals. The seasonal and spatial variations were also investigated. Silicone wristbands have been used increasingly to provide personal exposure assessments, and are often partnered with demographic data assessed by questionnaires to infer lifestyles and behaviors that are associated with chemical concentrations (Kile, Scott et al. 2016). They can continuously record a person’s chemical exposure even as they sleep, jog, eat, work, pet a dog or perform any other activity. Silicone wristbands are able to absorb organic chemicals from the environment. Their most important characteristic is that they mimic the way human cells absorb organic chemicals as they contain long chainlike structures that create channels similar in size (about 1 nm) to pores created by biological polymers in a human cell membrane(Huckins, Petty et al. 2006). Measurement of chemical exposure is a critical component for estimating health effects, wristbands can complement current methods for personal chemical exposure (Anderson, Points et al. 2017).

METHODS

In this study, 120 personal silicone samplers were collected from participants after they have been worn for 7 days in winter and summer at Thessaloniki, Athens, Ljubljana, Madrid, Basel and Milan. The silicone samplers were extracted and analyzed by means of gas chromatography coupled to mass spectrometry. All silicone wristbands before use were cleaned with different organic solvents. A quantity of 65g of silicone wristbands was cleaned with 800 mL of mixed solvent with 5 rinses using ethyl acetate, methanol, and hexane (O’Connell et al. 2014). The first three exchanges were performed with the mixture of ethyl acetate/ hexane (1:1, v:v) and the last two were performed with ethyl acetate/methanol (1:1, v:v) with a minimum shaking of 2.5 hours at 60 rotations per minute in an orbital shaker. After pre cleaning extraction, wristbands were placed under a nitrogen stream. Finally, dried wristbands were stored in amber jars at 4 °C until the sampling procedure. Silicone wristbands, before being sent to each partner city, were individually packaged in amber glass vials with caps coated (inside) with Teflon and marked with a unique serial number which was the same as the one of the enclosed wristbands. For every 10 samples, one field blank (i.e. a pre-cleaned silicone wristband) was collected. After sampling, silicone wristbands were extracted with 100 mL of hexane on an orbital shaker for 2.5 h. The extract was concentrated until 0.5 mL with a nitrogen evaporator system. Samples were transferred and stored in amber chromatography vials at -20 °C prior to analysis. Analysis was performed by a Thermo Trace Ultra Gas Chromatograph coupled to a Thermo TSQ Quantum XLS MS spectrometer operated in MS/MS mode. Two (2) μl of each sample were injected into the GC in PTV Splitless mode where the inlet temperature was ramped from 70 upwards to 300. A fused silica capillary column (30 m×0.25mm×0.25 μm i.d., HP-5MS Ultra Inert Agilent) was used for the separation of the 16 PAHs, 7 phthalates and 4 consumer products with helium as carrier gas (flow of 1.3 ml/min). The GC oven temperature was 55 ^oC for 1 min, increased with a rate of 12 ^oC min^-1 to 320 ^oC held for 5min. Total run time was 28 min. Ion source temperature was kept at 240^oC while the transfer line was maintained at 280^oC.

RESULTS

A wide range of compounds was identified from the ambient wristband extracts from 120 participants. In total, 27 different compounds were identified in our study, including PAHs, consumer and personal care products and phthalates. The compounds with the highest detection frequency were phenanthrene and acenaphthene. Total PAHs concentrations ranged from 0.14 to 1050 ng/wristband. The highest average PAH concentration between the six cities was found in Ljubljana (290 ± 200 ng/wristband) during the winter campaign but the lowest during the summer campaign. PAHs were detected in 80% of the total number of silicone wristbands. The two most detected compounds among phthalates were bis(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP). The highest average phthalate concentration was in Athens (72 ± 67 μg/wristband) during the winter campaign while the lowest was in Ljubljana during the summer campaign. Phthalates were detected in 85% of the total number of silicone wristbands. Milan had the highest number of total chemicals detected compared with all other cities. The silicone wristbands from the winter campaign had a high percentage of PAHs detections (77%) compared with the ones from summer campaign which was expected due to more frequent use of biomass burning for space heating.

CONCLUSION

Silicone wristbands were used as samplers of personal exposure to a wide range of chemical compounds. The chemical exposure patterns varied between participants and seasons. Future work using time activity patterns, gender and age of the population who participated in this study will provide us the opportunity to investigate the implications in human health.

REFERENCES

Anderson, K. A., G. L. Points, 3rd, C. E. Donald, H. M. Dixon, R. P. Scott, G. Wilson, L. G. Tidwell, P. D. Hoffman, J. B. Herbstman and S. G. O'Connell (2017). "Preparation and performance features of wristband samplers and considerations for chemical exposure assessment." J Expo Sci Environ Epidemiol 27(6): 551-559.

Huckins, J., J. Petty and K. Booij (2006). Monitors of Organic Chemicals in the Environment. New York, Springer Science+Business Media.

Kile, M. L., R. P. Scott, S. G. O'Connell, S. Lipscomb, M. MacDonald, M. McClelland and K. A. Anderson (2016). "Using silicone wristbands to evaluate preschool children's exposure to flame retardants." Environ Res 147: 365-372.

O’Connell, S. G., L. D. Kincl and K. A. Anderson (2014). "Silicone Wristbands as Personal Passive Samplers." Environmental Science & Technology 48(6): 3327-3335.