Table 2.
Summary of human studies on association between PBDE exposure and thyroid parameters.
| Study Design | Country | Study Sample | Sample Size (N) | Age (Years) | Main Results | Exposure Assessment Matrix/Chemical Concentration | Confounders | Reference |
|---|---|---|---|---|---|---|---|---|
| Prospective cohort | USA | Great Lakes anglers (non-Hispanic White) | 36 | 29–45 | No statistically significant associations among nine PBDE congeners or their sum, and either TSH or FT4 | Serum blood BDE-47: median 7.9 ng/g lipid Sum PBDE: median 15 ng/g lipid LOD range: 0.002–0.028 ng/g lipid |
(1), (14), physician-diagnosed goiter or thyroid condition, use of thyroid-active pharmaceuticals at the time of blood donation, having ever worked with or near plastics | [127] |
| Retrospective cohort | USA | Pregnant women. Blood samples collected at 27.3 ± 3.1 weeks’ gestation |
270 | 18–45 | None of the five PBDE congeners or their sum significantly associated with FT4 and TT4 concentrations. All PBDE congeners (BDE-28, 47, 99, 100, 153) significantly inversely associated with TSH (10.9–18.7% decrease in TSH for a 10-fold increase in serum concentration of individual congeners). |
Serum blood Sum PBDE: GM 26.5 ng/g lipid, median 25.2 ng/g lipid LOD range: 0.2–1.6 ng/g lipid |
(1), (2), (3), (4), (5), (6), (7), (8), (9) at the time of blood collection, (14), drug consumption during pregnancy, blood lead, serum PCB, organochlorine pesticide concentrations | [128] |
| Retrospective cohort | USA | Pregnant women. Blood samples collected at 27 3 ± 3 weeks’ weeks’ gestation (n = 209) and at 40 ± 2 weeks’ gestation (n=80). TSH levels measured in infants within 24 h after birth |
289 |
18–45 | No statistically significant associations between maternal total serum PBDE concentrations and neonatal TSH levels |
Serum blood Sum PBDE: GM 28,0 ng/g lipid, median 25.4 ng/g lipid LOD range: 0.2–2.6 ng/g lipid |
(1), (2), (3), (6), (7), (9), (10), (11),(12), (13) duration of residence in US, serum levels of total PCBs, HCB, DDT, and DDE | [135] |
| Cross-sectional | USA | Women with singleton deliveries. Umbilical cord blood collected at delivery | 92 | 14–43 | For infants born by spontaneous, vaginal, unassisted deliveries, BDE-47 significantly correlated with increased TSH levels in cord blood. PBDEs showed a negative association (not statically significant) with FT4 and TT4. |
Serum blood BDE-47: mean 14.4 ng/g lipid, median 13.8 ng/g lipid Median LOD: 1.3 ng/g lipid |
(1), (2), (3), (4), (8), (9), (10), (13), maternal socioeconomic status; history of STDs, hypertension, diabetes, and anemia | [129] |
| Prospective cohort | USA | Great Lakes fish consumers (adult males) | 308 | 30–59 | ΣPBDEs significantly and positively associated with TT4, FT4, urinary T4, rT3, and albumin-bound T4, and was negatively associated with TSH and TT3 Similar results for BDE-47, the dominant PBDE congener ΣPBDEs positively related to the percentage of T4 bound to albumin and inversely related to the percentage of T4 bound to TBG |
Serum blood Sum PBDE: GM 27.7 g/g lipid, median 38 ng/g lipid LOD range: 0.025-0.15 ng/g lipid |
(1), (4), (5), (14), medication use, Great Lakes sport fish meals in the past year, sport fish meals in the past year, ΣPCBs, DDE, years consuming sport fish meals, years consuming Great Lakes sport fish meals, HA1c level, levels of testosterone, SHBG, and SHBG-bound testosterone |
[121] |
| Prospective cohort | USA | Pregnant women (80% non-Hispanic black) Blood samples collected at >34 weeks’ gestation |
137 | 18–39 | TT4 positively and significantly correlated with BDE-47, 99, 100, and ΣPBDEs FT4 positively and significantly associated with BDE-47, 153, and ΣPBDEs No significant association between TSH, TT3 or FT3 and PBDEs |
Serum blood: BDE-47: GM 16.5 ng/g lipid |
(1), (2), (4), (8), (9) | [122] |
| Cross-sectional | USA | Pregnant women. Blood samples collected prior to second trimester pregnancy termination |
25 | 16–45 | Positive significant association between ΣPBDE5 and TSH levels Slightly negative association between BDE-28 and FT4 Individual OH-PBDEs and their sum positively associated with TSH Relationships between OH-PBDEs and TT4 and FT4 null except for 6-OH-BDE-47 (not significant inverse association) |
Serum blood: Sum PBDE: GM 85.8 ng/g lipids; BDE-47: GM 47.1 ng/g lipid |
(1), (2), (8), type of health insurance | [124] |
| Prospective cohort | USA | Men from an infertility clinic. Blood and house dust samples |
24 | 18–54 | Positive association of PBDEs with FT4. | House dust: BDE-47: GM 577 ng/g BDE-99: GM 809 ng/g BDE-100:GM 220 ng/g LOD: 83 ng/g |
(1), (14) | [123] |
| Prospective cohort | Canada | Pregnant women. Blood samples collected at <20 weeks’ gestation for analysis of PBDEs and THs. Maternal blood and umbilical cord blood collected at delivery for TH analyses |
387 | 17–40 | At <20 weeks’ gestation TT4 and TT3 were negatively related to BDE-47, BDE-99, and ΣPBDE. Serum TSH was not related to PBDEs. A positive relationship was observed between FT4 and PBDE-47, PBDE-99, and ΣPBDE and between FT3 and PBDE-99 and ΣPBDE At delivery, maternal TT4 decreased in relation to BDE-99. A negative association was observed between FT3 and BDE-47. No relationships were observed between TT3, TSH and PBDE congeners. In umbilical-cord blood, TT4 and FT4 levels decreased in relation to BDE-47, BDE-99, and ΣPBDE |
Serum blood Sum PBDE: median 30.92 ng/g lipid BDE-47: median 21.47 ng/g lipid |
(1), (4), (5), (9), (13), (14), (15), (16), blood selenium, blood mercury, medication use, familial history of hypothyroidism, and occupational and recreational exposures to chemicals | (130] |
| Prospective cohort | USA | 26 male and 25 female adult office workers Serum samples at approximately six-month intervals from January 2010 to May 2011. Urinary samples |
51 | 20–≥60 | Significant, inverse associations between PBDEs (BDE-28, 47, 99, 100, 153) and serum TT4. Associations of PBDEs with TSH positive but small and not statistically significant. Any important associations between PBDEs and FT4 or TT3. |
Serum blood Sum PBDE: Sample 1 GM 22 ng/g lipid; sample 2 GM 23 ng/g lipid; sample 3 GM 19 ng/g lipid LOD range: 0.2–0.8 ng/g lipid |
(1), (14), (15), (16), sex, oral contraceptives, urinary perchlorate, urinary thiocyanate, urinary specific gravity | (131] |
| Prospective cohort | China | Pregnant women. Cord blood samples collected immediately post-delivery |
123 | ≤25–≥35 | BDE-99 and Σ4PBDEs (the sum of BDE-47, 99, 100, and 153) were associated with increased TT4 levels. | Cord blood (n = 106): BDE-47: GM 4.34 ng/g lipid, median 3.96 ng/g lipid BDE-99: GM 9.90 ng/g lipid, median 15.85 ng/g lipid |
(1), (4), (8), (9) (10), (14) | (132] |
BMI: body mass index, PBDEs: polybrominated diphenyl ethers, OH-PBDEs: hyrdroxylated polybrominated diphenyl ethers, FT4: free thyroxine, TT4: total thyroxine, T4: thyroxin, TSH: thyroid-stimulating hormone, rT3: reverse triiodothyronine, FT3: free triiodothyronine, LOD: limit of detection, GM: geometric mean, PCB: polychlorinated biphenyls, HbA1: Hemoglobin A1c; HCB: hexachlorobenezene, DDT: dichlorodiphenyl trichloroethane, DDE: dichlorodiphenyl dichloroethane, SHBG: sex hormone-binding globulin; STDs: sexually transmitted diseases, TBG: thyroid binding globulin, LOD: limit of detection, GM: geometric mean. (1): age, (2): maternal race/ethnicity, (3): maternal education, (4): smoking, (5): alcohol consumption, (6): family income, (7): country of birth, (8): parity, (9): gestational age, (10): infant sex, (11): birth weight, (12): marital status, (13): mode of delivery, (14): BMI, (15): thyroid peroxidase antibodies, (16): urinary iodine concentration.