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Liquid crystal monomers in human, dog and cat feces from the United States

npj Emerging Contaminants 2024 12 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Yuan Liu, Kurunthachalam Kannan

Summary

Chemicals used in digital screens (called liquid crystal monomers, found in TVs, phones, and computers) are showing up in the feces of humans, dogs, and cats, meaning we're all being exposed to them somehow, likely through household dust or everyday contact with electronics. Humans had notably higher levels than pets, and while scientists don't yet know if these chemicals harm our health, this study is one of the first to show that exposure is real and widespread, making it a good candidate for future research, much like the ongoing concerns about microplastics in our bodies.

Little is known about exposure of humans and companion animals to liquid crystal monomers (LCMs), which are extensively used in digital displays. We determined the concentrations of 52 LCMs in feces of humans, pet dogs and cats from New York State, USA, using gas chromatography-high resolution mass spectrometry (GC-HRMS). Twenty-four, eight, and six LCMs, that were mainly fluorinated, were detected in human, dog, and cat feces, respectively. ∑LCMs concentrations in the feces of humans (mean: 8.01 ng/g dry weight [dw]) were significantly higher (p < 0.05) than those of dogs (mean: 1.82 ng/g dw) and cats (mean: 1.24 ng/g dw) and with concentrations measured as high as 39.8 ng/g dw. Rel-4'-((1r,1'r,4 R,4'R)-4'-ethyl-[1,1'-bi(cyclohexan)]-4-yl)-3,4-difluoro-1,1'-biphenyl (RELEEBCH or 2bcHdFB) was found at the highest detection frequency (DF) among LCMs analyzed in human (DF: 89 %), dog (DF: 28 %), and cat (DF: 50 %) feces, although this compound accounted only < 4 % of ∑LCM concentrations. The mean cumulative daily intakes of ∑LCMs, calculated through a reverse dosimetry approach, were 71.7, 87.5, and 10.7 ng/kg body weight (bw)/day for humans, dogs, and cats, respectively. This study provides evidence of exposure of both humans and pets to LCMs, highlighting the importance of assessing sources of exposure and associated health risks.

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