Volume 149, April 2016, Pages 190–201
Highlights
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- This is the first detailed study looking at the menstrual cycle characteristic of the Cree women of James Bay, Canada.
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- Collinearity in POH and element data was reduced by principal components analysis to a few uncorrelated variables.
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- The menstrual cycle characteristics data were bootstrapped to provide a conservative less biased set of response variables.
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- After adjusting for confounders a principal component showed significant negative association with cycle length.
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- The menstrual cycle function of these women may be altered by exposure to POHs and elements from their environment.
Abstract
Persistent
organohalogens (POHs) and metals have been linked to alterations in
menstrual cycle function and fertility in humans. The Cree First Nations
people living near James Bay in Ontario and Quebec, Canada, have
elevated levels of POHs, mercury and lead compared to other Canadians.
The present study examines the interrelationships between selected POHs
and elements on menstrual cycle function in these Cree women.
Menstrual
cycle characteristics were derived from structured daily diaries and
endocrine measurements from daily urine samples collected during one
cycle for 42 women age 19–42. We measured 31 POHs in blood plasma and 18
elements in whole blood, for 31 of the participants. POHs and elements
detected in ≥70% of the participants were transformed by principal
component (PC) analysis to reduce the contaminant exposure data to
fewer, uncorrelated PCA variables.
Multiple
regression analysis revealed that, after adjusting for confounders, PC-3
values showed significant negative association with cycle length, after
adjusting for confounders (p = 0.002). PC-3 accounted for 9.2% of the
variance and shows positive loadings for cadmium, selenium, and PBDE
congeners 47 and 153, and a negative loading for copper. Sensitivity
analysis of the model to quantify likely effect sizes showed a range of
menstrual cycle length from 25.3 to 28.3 days using the lower and upper
95% confidence limits of mean measured contaminant concentrations to
predict cycle length. Our observations support the hypothesis that the
menstrual cycle function of these women may be altered by exposure to
POHs and elements from their environment.
Keywords
- Lead;
- Mercury;
- Cadmium;
- Persistent organic pollutants;
- Hormones;
- Menstrual cycle;
- Cree
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