2.6 Collection of biological samples and determination of
biomarkers
Fasting blood, spot urine, and hair samples were collected from
participants on the morning of recruitment day. Blood samples were saved
on ice and transferred to the clinical laboratory of Shimen Central
Hospital for routine measurement. Urine samples were collected into
cleaned conical 50 ml polypropylene tubes, and packed into coolers with
frozen ice packs. Hair samples were saved in envelops and transferred to
Shimen Center for Disease Control and Prevention for measurement. Blood
arsenic and urine arsenic were analyzed in the laboratory of Tongji
School of Public Health, Huazhong University of Science and Technology
by inductively coupled plasma-mass spectrometry (Agilent 7700X, USA).
Hair arsenic concentration was determined by nondispersive atomic
fluorescence spectrometry (Ruiguang RGF-7800, China). Details could be
found in our previous paper15.
For human participants, serum levels of
pruritic biomarkers were
determined by ELISA, following the manufacturer’s instructions for
commercial kits of β-endorphin
(BSK00470, Bioss), substance P
(BSK00600, Bioss), nerve growth factor (BSK00127, Bioss), histamine
(BSK00598, Bioss), interleukin-31 (BSK00467, Bioss), IgE (BSK00568,
Bioss), endothelin-1 (BSK00345, Bioss), and 5-hydroxytryptamine
(BSK00601, Bioss). For mice, β-endorphin was measured using an ELISA kit
(0557M1, Meimian). All standards and samples were run in duplicate, and
the values were within the range of acceptable variability according to
the kit’s standards.