Uncorrected and SG-corrected mycoestrogen values are shown in . In subsequent analyses we used SG-corrected values. Detectable mycoestrogen levels were found in 78% of the samples, with the highest levels found for ZEA, which was detected in 55% of the samples (). Zeranol was detected in over 20% of the samples, but levels were low. Levels of mycoestrogens according to selected study characteristics () tended to suggest some individual differences by geographical area and race (e.g., they tended to be higher in African American girls). However, these analyses were based on small numbers and need to be replicated. Mycoestrogen levels by recruitment season were similar (data not shown).
Urinary levels of zearalenone, zeranol, and related mycoestrogens among 163 participants with detectable levels in the Jersey Girl Study.
Specific gravity corrected values for zearalenone (ZEA), zeranol, and total ZEA mycoestrogens (ng/ml) according to selected characteristics among the Jersey Girl Study participants included in these analyses (n=163).
We evaluated food sources by examining mycoestrogen levels according to consumption of the major food sources of ZEA and zeranol, including corn and grains, as well as animal products (i.e., beef, pork, poultry, veal, milk, eggs, and dairy) in the subset of girls for which we had a dietary recall the day before urine was collected. When we compared levels and food consumption on the previous day, only beef and popcorn consumption seemed to be related to urinary ZEA and total mycoestrogens (). While analyses were only based on six girls who reported popcorn consumption the day before urine collection, all were mycoestrogen positive and both ZEA and total mycoestrogen levels were significantly higher among them. We also evaluated levels of mycoestrogens according to the combined exposure to beef and popcorn (data not shown). The geometric means (95% CI) of total mycoestrogens were 7.11 ng/ml (1.51–33.41) for girls consuming beef and popcorn the day before urine sample collection, and 0.07 ng/ml (0.02–0.20) for girls not consuming these two foods. When we used the three-day average intake, representing “usual intake”, the association between total mycoestrogens and beef intake persisted (data not shown). However, there was no association with any other foods, including popcorn.
Urinary mycoestrogens (95% confidence interval) according to intake of main food sources (day before sample, n=58)
We also evaluated anthropometric characteristics according to urinary mycoestrogen status (). Mycoestrogen-negative girls tended to be significantly taller and to have higher adiposity, compared to mycoestrogen-positive girls. They were also more likely to have reached the onset of breast development. These findings were not explained by differences in food consumption or age. These analyses again indicated a relationship with beef, as consumption was significantly lower in mycoestrogen negative girls, compared to girls with the highest level of urinary mycoestrogens. Stratified analyses by puberty status (having reached the onset of puberty yes/no) yielded similar results (data not shown).
Participant characteristics and food consumption according to mycoestrogen status in the Jersey Girl Study (n=163).
Girls with mycoestrogen-positive urine were less likely to have reached the onset of breast development (PR: 0.79; 95% CI: 0.60–1.04) after adjusting for age, BMI, isoflavone intake, and recruitment year (). Adding beef consumption as a covariate did not change PR estimates. We also computed ORs and 95% CI (data not shown), and as expected, point estimates were of stronger magnitude, as logistic regression tends to overestimate the association for outcomes that are not rare. Overall, the results were similar. Compared to mycoestrogen-negative, mycoestrogen-positive girls had an OR of 0.53 (95% CI: 0.21–1.34) for onset of breast development, after adjusting for age, BMI, recruitment year, and isoflavone intake. Analyses were repeated excluding overweight and obese girls, who may be more likely to be misclassified according to breast development status, with similar results (adjusted PR: 0.80; 95% CI: 0.55–1.18) (data not shown). Notably, the association for the group of overweight and obese girls was stronger and statistically significant (adjusted PR: 0.72; 95% CI: 0.53–0.99). We also repeated analyses excluding the 16 girls for which breast development status was based on mother’s Tanner assessment, rather than physician assessment, with similar results (adjusted PR: 0.81; 95% CI: 0.62–1.07).
Prevalence ratios (PR) and 95% confidence intervals (CI) for onset of breast development (B2+) according to mycoestrogen status at baseline.