Funding for this research was provided by:
Narodowym Centrum Nauki (2014/13/B/NZ5/03166, OPUS 7)
Text and Data Mining valid from 2020-02-25
Received: 16 July 2019
Accepted: 11 February 2020
First Online: 25 February 2020
Ethics approval and consent to participate
: The study was conducted following the Declaration of Helsinki and good clinical practice. The study protocol has been approved by the Ethics Committee at Institute of Occupational Medicine and Environmental Health, Sosnowiec and Medical University of Silesia. Informed written consent was obtained from all subjects enrolled to the study.
: Not applicable.
: The authors declare that they have no competing interests. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.