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Children’s exposures to boron and biocides from slime products in Asian regions



Chemical exposure from slime toys can cause potential health effects. Although slime toys are popular in Asia, the regulation of boron, chloromethylisothiazolinone (CMIT), and methylisothiazolinone (MIT) in these toys has been implemented only in Korea.


In this study, we investigated boron migration levels and CMIT and MIT concentrations in 127 slime products from Asian cities and estimated children’s exposure to boron and the biocides in Korea.


Slime boron migration levels were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES), according to Part 3 of the European Standard on the safety of toys (EN 71-3:2013). CMIT and MIT concentrations were analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS). Exposure doses of boron, CMIT, and MIT were calculated using the exposure pattern of children slime users in Korea.


Average boron migration levels of the slime products in Seoul, Bangkok, Hong Kong, Taipei, and Yokohama were 691.9, 851.1, 806.6, 509.0, and 956.2 mg/kg, respectively. Of the 127 slime products tested, 70.1% exceeded the EU boron migration limit of 300 mg/kg for toys made with sticky material. Boron migration levels in slime products in Korea did not differ significantly by manufacturing date, although the Korean boron regulations were enacted in January 2019. CMIT and MIT were detected from 51.2% and 36.2% of all products, respectively, and tended to be detected simultaneously. Exposure doses of boron, CMIT, and MIT were highest among infants.


Oral exposure was the most important for boron exposure. It is necessary to manage boron level in slime products and minimize exposure from hand to mouth action in infants.

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Fig. 1: Comparison of boron migration levels among slime products manufactured before December 2018 (n = 11) and after January 2019 (n = 18), when Korean boron migration regulation were established.
Fig. 2: Correlation between CMIT and MIT concentrations among slime products that contained both CMIT and MIT (n = 46).


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This study was partially supported by the Basic Science Research Program through the NRF funded by the Ministry of Education, Science and Technology (NRF-2019R1A2C1083938).

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Correspondence to Kiyoung Lee.

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Lim, M., Guak, S., Cheong, N.Y. et al. Children’s exposures to boron and biocides from slime products in Asian regions. J Expo Sci Environ Epidemiol 32, 103–111 (2022).

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  • Slime
  • Boron
  • CMIT
  • MIT
  • Hand-to-mouth
  • Children


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