Tattoo exposure and biomarkers of male fecundity: A cross-sectional study among young Danish males.

BACKGROUND

Tattoo inks are mixtures of organic and inorganic color pigments and having a tattoo may be adversely associated with biomarkers of male fecundity.

OBJECTIVE

To examine the association between tattoo exposure and biomarkers of male fecundity.

METHODS

Participants were young adult Danish males (aged 18-21 years) sampled from the Danish National Birth Cohort. Upon recruitment in 2017-2019, participants answered a comprehensive questionnaire including information on tattoo exposure and provided a semen and blood sample. We applied a negative binomial regression model to estimate percentage differences (95 % confidence intervals [CI]) in semen characteristics, testicular volume, and reproductive hormone levels between tattooed and non-tattooed participants.

RESULTS

Among the 1045 participants included in this study, 174 (17 %) had at least one tattoo and most tattooed participants (84 %) had tattoo(s) in only black color. About half (53 %) had one tattoo, 21 % had two tattoos, and 26 % had three or more tattoos. We observed no association between either number or color scheme of tattoo(s) relative to semen characteristics or reproductive hormone levels. Having a tattoo was associated with 6 % (95 % CI: 0, 12) larger testicular volume, but since testicular volume was measured by the participants themselves, this finding may be due to differential misclassification bias. Across all outcomes the crude and adjusted models were comparable.

CONCLUSION

Overall, we found no support for adverse associations between tattoo exposure and biomarkers of male fecundity, but studies with more details on tattoo exposure and longer follow-up of participants are needed before firm conclusions can be drawn.