Table 1_Simultaneous semen and urine biomonitoring of neonicotinoids and associations with semen quality in men.docx

Urinary 5-hydroxy-imidacloprid (5-OH-IMI) was associated with sperm concentration, total count and normal morphology. Seminal desnitro-imidacloprid (DN-IMI) and imidacloprid-urea (IMI-urea) were negatively associated with sperm concentration, total sperm count, and motility. Mixture analyses revealed a 27% reduction in sperm concentration per one-quartile increase in seminal NEO exposure (QGC: –27%, 95% CI: –43% to –7%), with DN-IMI identified as the major contributor to the observed mixture association (BKMR posterior inclusion probability (PIP) = 0.913).

Age-stratified analyses suggested age-related differences in associations between NEO exposure and semen quality.</p>Conclusions<p>Seminal NEO concentrations, which were not adequately reflected by urinary biomarkers, were associated with lower sperm concentration, highlighting semen as a potentially informative matrix for reproductive risk assessment. These findings underscore that assessments relying solely on urinary biomarkers may not fully capture reproductive-relevant NEO exposure profiles.

Longitudinal studies incorporating hormone profiling and functional sperm assessments are needed to further clarify causal pathways and inform regulatory thresholds.</p>