Table 6: Some cross-sectional epidemiological studies on metabolic syndrome.

ExposureStudy populationRelative risk or odds ratio (95% confidence interval)Main strengthsMain limitationsReference

Polybromobiphenyl-153367 Adults participating in NHANES 2003-2004OR for highest quartile of serum concentration compared to “non detectable”: 3.1 (1.4–6.9) 𝑃 t r e n d < 0 . 0 1 Precise measurement of personal internal exposure. Adequate control of confounding. 237 casesOnly 18 cases in referent category [199]
PBDE-153OR for second quartilea of serum concentration compared to “non detectable”: 2.5 (1.1–5.6). 𝑃 t r e n d = 0 . 0 2 a 4 other PBDEs did not show a significant association

Cumulative measureb of PCDDsOR for highest quartile of serum concentration compared to lowest quartile: 1.3 (0.7–2.5) 𝑃 t r e n d = 0 . 3 5
Cumulative measureb of PCDFsOR for highest quartile of serum concentration compared to lowest quartile: 1.6 (0.9–2.8). 𝑃 t r e n d = 0 . 1 1
Cumulative measureb of Dioxin-like PCBs721 Nondiabetic participants in the National Health and Nutrition Examination Survey 1999–2002 aged   20 yearsOR for highest quartile of serum concentration compared to lowest quartile: 2.1 (1.0–4.3). 𝑃 t r e n d = 0 . 0 1 Precise measurement of personal internal exposure. Adequate control of confoundingc. 175 casesPositive pairwise correlations between the different classes of pops[224]
Cumulative measureb of non-dioxin-like PCBsOR for third quartilea of serum concentration compared to lowest quartile: 1.8 (1.0–3.4) 𝑃 t r e n d < 0 . 0 1 a
Cumulative measureb of organoclorine pesticidesOR for highest quartile of serum concentration compared to lowest quartile: 5.3 (2.5–11.3). 𝑃 t r e n d < 0 . 0 1

PCDDs1,374 subjects not occupationally exposed to these pollutants, living throughout Japan during 2002–2006OR for highest quartile of serum concentration compared to lowest quartile: 3.2 (1.6–6.7). 𝑃 t r e n d < 0 . 0 1 Precise measurement of personal internal exposure Adequate control of confoundingUse of BMI instead of waist circumference and of glycated haemoglobin instead of serum glucose[225]
PCDfsOR for highest quartile of serum concentration compared to lowest quartile: 4.4 (2.0–11). 𝑃 t r e n d = 0 . 0 4
Dioxin-like PCBsOR for highest quartile of serum concentration compared to lowest quartile: 4.8 (2.2–11). 𝑃 t r e n d < 0 . 0 1

aAn inverted U-shaped association was observed, and the 𝑃 value for quadratic term is shown.
bTo yield a cumulative measure of pops belonging to a specific class, such as PCDDs or organochlorine pesticides, the ranks of the individual pops were summed. The summary values were categorised by cut-off points of 25th, 50th, and 75th percentile values.
cAdjusted for age, sex, race, poverty income ratio, cigarette smoking, serum cotinine, alcohol consumption, and exercise.