Association of phthalate exposure with thyroid function during pregnancy

• Background: The extent of thyroid disruptive effects of phthalates during pregnancy remains unclear. Aim: To investigate the association of maternal urinary phthalates with markers of the thyroid system during early pregnancy. Methods: Urinary concentrations of phthalate metabolites and serum concentrations of thyroid stimulating hormone (TSH), free and total thyroxine (FT4 and TT4) and free and total triiodothyronine (FT3 and TT3) were measured in pregnant women in early pregnancy in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy study (2007-ongoing), a population-based prospective cohort. Results: In the 1,996 included women, higher di-ethyl-hexyl phthalate (DEHP) metabolites were associated with a lower FT4 (β [SE] for the molar sum: −0.13 [0.06], P = 0.03) and a higher TSH/FT4 ratio (0.003 [0.001], P = 0.03). Higher concentrations of di-iso-nonyl phthalate (DINP) metabolites were associated with a lower TT4 (β [SE] for the molar sum: 0.93 [0.44], P = 0.03) as well as with lower TT4/FT4 and TT4/TT3 ratios. Higher metabolites of both dibutyl and butyl-benzyl phthalate (DBP and BBzP) were associated with lower T4/T3 ratio (free and total) and higher FT4/TT4 and FT3/TT3 ratios. A higher diisononyl cyclohexane dicarboxylate (DINCH) metabolite concentration was associated with a higher TT3. Conclusions: These results translate results from experimental studies suggesting that exposure to phthalates may interfere with the thyroid system during pregnancy. This is also true for compounds that have been introduced to replace known disruptive phthalates. Further experimental studies should take into account the human evidence to better investigate the potential underlying mechanisms of thyroid disruption by phthalates.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Folkhälsovetenskap, global hälsa, socialmedicin och epidemiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Public Health, Global Health, Social Medicine and Epidemiology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Arbetsmedicin och miljömedicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Occupational Health and Environmental Health (hsv//eng)

Keyword

Endocrine disrupting chemicals

Phthalates

Pregnancy

Thyroid

Biomolecules

Endocrine disrupters

Esters

Metabolites

Molar concentration

Molar ratio

Early pregnancy

Metabolite concentrations

Phthalate exposures

Phthalate metabolites

Thyroid function

Thyroid stimulating hormones

Thyroid systems

Obstetrics

Public Health Science

Folkhälsovetenskap

Endocrine disrupting chemicals

Phthalates

Pregnancy

Thyroid

Publication and Content Type

ref (subject category)

art (subject category)