There were no significant differences (Two-Way ANOSIM; depth nested within sampling year) between sampling years.
Although differences in PCB-153 concentrations among birth cohort quartiles across sampling years were not significant for some sampling years, the most recently born cohort (1941 1950) appeared to have the lowest concentrations, and the earliest cohort (1925 1934) had the highest.
Of 60 randomly selected men, 53 had sufficient sample volumes in ≥ 3 sampling years (11 missing samples were randomly distributed across sampling years).
Unadjusted cortisol levels across repeated sampling years in high-risk and control offspring can be found in Fig. 2.
The median and range of sample times across repeated sampling years can be found in Additional file 1: Table S1.
In controls, logT3 cortisol significantly increased over repeated sampling years (p = 0.0077), while all other measurements of cortisol were stable over time (CAR: p = 0.25, logAUC: p = 0.86).
b 3-day mean saliva cortisol levels at awakening (T0), 30 min later (T1), 60 min later (T2) and at 8 00 p.m. (T3) across repeated sampling years in control offspring.
Additionally, linear mixed-effects models were also used to assess the effect of 'Location', 'Season', and an interactive effect of 'Location' and 'Season' on soil moisture and soil nutrients across multiple sampling years.
Using adjusted mixed models, in high-risk offspring, there was no significant difference in cortisol levels across repeated sampling years (CAR: p = 0.45, logAUC: p = 0.40, logT3: p = 0.66).
Salivary cortisol was quite stable over the repeated sampling years in high-risk and control offspring with the exception of evening 8 00 p.m. cortisol increasing in control offspring over time.
