Seasonal patterns in trace elements assessed in toenails.

BACKGROUND: Seasonal patterns in measured exposure biomarkers can cause measurement error in epidemiological studies. There is little research about the seasonality of metals and trace elements when assessed in toenail samples. Adjusting for such patterns in models for estimating associations between long-term exposures and health outcomes can potentially improve precision and reduce bias. OBJECTIVES: Assess and describe seasonal patterns in toenail measurements of trace elements. METHODS: The Sister Study enrolled women residing in the US, including Puerto Rico, whose sister had been diagnosed with breast cancer. At the time of enrollment, participants removed nail polish and collected their toenail clippings, which were cleaned before analysis. We considered the following elements: iron, vanadium, aluminum, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, molybdenum, cadmium, tin, antimony, mercury, and lead. For two subsamples of the cohort, we fit trigonometric regression models with toenail element measures as the outcome, using sine and cosine functions of the collection day (transformed to an angle) to capture seasonal patterns. These models can estimate the amplitude and timing of the peaks in measures. We evaluated the evidence for a seasonal effect by comparing for each measured element the trigonometric model to a model that was constant across time. RESULTS: There was a seasonal trend in toenail element concentration for iron, aluminum, vanadium, chromium, manganese, cobalt, arsenic, molybdenum, cadmium, tin, and lead, all of which peaked near mid-August. Seasonal patterns were concordant across two non-overlapping samples of women, analyzed in different labs. DISCUSSION: Given the evidence supporting seasonal patterns for 11 of the 17 elements measured in toenails, correcting for seasonality of toenail levels of those trace elements in models estimating the association between those exposures and health outcomes is important. The basis for higher concentrations in toenails collected during the summer remains unknown.

Seasonal patterns in trace elements assessed in toenails.

Seasonal patterns in measured exposure biomarkers can cause measurement error in epidemiological studies. There is little known about the seasonality of trace elements when measured in toenails. Adjusting for such patterns when estimating associations between long-term exposures and health outcomes could be needed to improve precision and reduce bias. Our goal was to assess seasonal patterns in toenail measurements of trace elements. At enrollment, Sister Study participants, who were US residents, removed polish and collected toenail clippings, which were cleaned before analysis. We measured: iron, vanadium, aluminum, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, molybdenum, cadmium, tin, antimony, mercury, and lead. For a sample of the cohort we fit trigonometric regression models with toenail element measures as the outcome, using sine and cosine functions of the collection day of the year (transformed to an angle) to assess seasonality. Results were replicated in a second sample of women, with measurements done in a separate lab. There was a seasonal association between day of collection and toenail measures for iron, aluminum, vanadium, chromium, manganese, cobalt, arsenic, molybdenum, cadmium, tin, and lead, all of which peaked near mid-August. Seasonal patterns were concordant across the two samples of women. Given the evidence supporting seasonal patterns for 11 of the 17 elements measured in toenails, correcting for seasonality of toenail levels of those trace elements in models estimating the association between those exposures and health outcomes is important. The basis for higher concentrations in toenails collected during the summer remains unknown.

Eating disorders and trauma history in women with perinatal depression.

OBJECTIVE: Although the prevalence of perinatal depression (depression occurring during pregnancy and postpartum) is 10%, little is known about psychiatric comorbidity in these women. We examined the prevalence of comorbid eating disorders (ED) and trauma history in women with perinatal depression. METHODS: A research questionnaire was administered to 158 consecutive patients seen in a perinatal psychiatry clinic during pregnancy (n=99) or postpartum (n=59). Measures included Structured Clinical Interview for DSM (SCID) IV-based questions for lifetime eating psychopathology and assessments of comorbid psychiatric illness including the State/Trait Anxiety Inventory (STAI), Patient Health Questionnaire (PHQ-9), Edinburgh Postnatal Depression Scale (EPDS), and Trauma Inventory. RESULTS: In this cohort, 37.1% reported a putative lifetime ED history; 10.1% reported anorexia nervosa (AN), 10.1% reported bulimia nervosa (BN), 10.1% reported ED not otherwise specified-purging subtype (EDNOS-P), and 7.0% reported binge eating disorder (BED). Women with BN reported more severe depression (EPDS score, 19.1, standard deviation [SD 4.3], p=0.02; PHQ-severity 14.5, SD 7.4, p=0.02) than the referent group of women with perinatal depression and no ED history (EPDS 13.3, SD=6.1; PHQ 9.0, SD=6.2). Women with AN were more likely to report sexual trauma history than the referent group (62.5% vs. 29.3%, p<0.05), and those with BN were more likely report physical (50.0%, p<0.05) and sexual (66.7%, p<0.05) trauma histories. CONCLUSIONS: ED histories were present in over one third of admissions to a perinatal psychiatry clinic. Women with BN reported more severe depression and histories of physical and sexual trauma. Screening for histories of eating psychopathology is important in women with perinatal depression.

Maternal eating disorders influence sex ratio at birth.

We explored sex ratio at birth, defined as the proportion of male live births, in women with anorexia nervosa, bulimia nervosa, binge eating disorder, and eating disorders not otherwise specified-purging type (EDNOS-P) relative to a referent group in a large population-based sample of 38,340 pregnant women in Norway. Poisson regressions were adjusted for mother's age, pre-pregnancy BMI, lifetime smoking status, maternal education, income, marital status, gestational age, and parity. Lower proportions of male live births were observed in the anorexia and bulimia groups, while binge eating disorder and EDNOS-P were associated with a higher proportion of male births. These data suggest that maternal eating disorders may influence offspring sex and that the direction of effect may vary by eating disorder subtype. If confirmed, this finding could provide evidence in formulating hypotheses regarding the consequences of eating disorders and determinants of sex ratio at birth.