Urinary levels of phthalate esters and heavy metals in adolescents with thyroid colloid cysts

Associations between exposure to phthalates and subclinical hypothyroidism in pregnant women during early pregnancy: A pilot case-control study in China

Phthalates are environmental endocrine disruptors with thyroid-disrupting properties; however, the association between phthalate exposure and subclinical hypothyroidism (SCH) during pregnancy is unknown. We recruited a study population from a cohort of pregnant women in Beijing, China, and conducted the present pilot case-control study of 42 SCH cases and 84 non-SCH controls matched with age and body mass index (BMI). Serum levels of thyroid peroxidase antibody, free thyroxine (FT₄), thyroid-stimulating hormone (TSH), and urinary levels of ten phthalate metabolites during early pregnancy were measured. Urinary monoethyl phthalate (MEP) levels in SCH cases were observably higher than those in controls (p = 0.01). Conditional logistic regression analysis revealed that mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), MEP, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and di-(2-ethylhexyl) phthalate (ΣDEHP) were significantly associated with a higher risk of SCH during early pregnancy (adjusted odds ratios = 1.89, 1.42, 1.81, and 1.92, respectively). Concomitantly, multiple linear regression analysis showed that MECPP, MEOHP, and ΣDEHP were positively associated with TSH and FT₄ × TSH in the entire study population. Bayesian kernel machine regression analysis and stratified analysis by BMI revealed upward tendencies in the serum levels of TSH and FT₄ × TSH. In summary, exposure to phthalates, especially DEHP, may be associated with a higher risk of SCH during early pregnancy, and a possible mechanism is the disruption of the hypothalamus-pituitary-thyroid axis.

Association of urine phthalate metabolites, bisphenol A levels and serum electrolytes with 24-h blood pressure profile in adolescents

Background

Among the possible causes of hypertension in adolescence, electrolyte imbalances and environmental pollutants are drawing increasing attention. We aimed to examine the relationship between bisphenol A (BPA), phthalate metabolites, and serum electrolytes and blood pressure.

Methods

Eighty-six participants aged 12–15 years were included in the study. Body mass index (BMI), office blood pressure and 24-h ambulatory blood pressure measurements (ABPM), and carotid intima-media thickness were determined. Blood samples were taken for hemogram, renal function tests, and serum electrolytes. Free- and total-BPA and phthalate metabolites were analyzed from urine samples.

Results

Of the participants, 34 were evaluated as normal blood pressure profile, 33 as white-coat hypertension (WCHT), and 19 as ABPM-hypertension. Adolescents in ABPM- hypertension groups had higher BMI-standard deviation score (SDS), leucocyte, platelet count; but lower serum chloride, compared to the normal blood pressure profile group. The percentage of adolescents with detectable urinary mono-benzyl phthalate (MBzP) was higher in ABPM-hypertension (42.1%) and WCHT groups (33.3%), compared to the normal blood pressure profile group (5.9%, p = 0.004). Associations between MBzP and ABPM- hypertension and WCHT were remained after confounding factor adjustment. Adolescents with detectable MBzP levels had also higher “albumin-corrected calcium” and lower serum phosphate and “albumin-corrected calcium x phosphate product” compared to others. Adolescents with detectable urinary MBzP levels had higher blood pressure profiles in some 24-h (mean arterial pressure-SDS, systolic blood pressure-SDS), daytime (systolic blood pressure-SDS), and night-time (mean arterial pressure-SDS, systolic blood pressure-SDS, and diastolic blood pressure-SDS) measurements, compared to others. WCHT was found to be associated negatively with monomethyl phthalate and the sum of dibutyl phthalate metabolites and ABPM-HT with MCPP. There was no significant association between blood pressure profiles and free- and total-BPA status.

Conclusion

MBzP was associated with adverse blood pressure profiles in adolescence. Additive follow-up studies are necessary for cause-effect relations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02774-y.

Testicular dysgenesis syndrome and phthalate exposure: A review of literature

Endocrine disruptors are chemicals that interfere with the body's endocrine system and cause adverse effects in biological systems. Phthalates are a group of man-made chemicals which are mainly used as plasticizers and classified as endocrine disruptors. They are also used in cosmetic and personal care products as color or smell fixators. Moreover, phthalates are present in inks, adhesives, sealants, automobile parts, tools, toys, carpets, medical tubing and blood storage bags, and food packages. Pathological condition known as "testicular dysgenesis syndrome" (TDS) or "phthalate syndrome" is usually linked to phthalate exposure and is coined to describe the rise in alterations in reproductive health in men, such as reduced semen quality (decrease in sperm counts, sperm motility and increase in abnormal sperms), hypospadias, cryptorchidism, reduced anogenital distance and early-life testicular cancer. Phthalates are suggested to cause direct effect on gonadal and non-gonadal tissues, impair the differentiation and morphogenesis of seminiferous tubules and accessory sex organs and testicular cells (both Sertoli and Leydig cells), alter estradiol and/or testosterone levels, decrease insulin-like 3 (INSL3) peptide production, impair spermatogenesis and lead to epigenetic alterations, all of which may lead to TDS. This review will mainly focus on phthalates as causes of TDS and their mechanisms of action.