Serum hormone levels in humans with low serum concentrations of 2,3,7,8-TCDD

Abstract

We measured current serum hormone and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentrations in 37 men who sprayed 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in the State of Victoria, Australia. TCDD levels were consistently significantly inversely related to prolactin levels in all analyses. In correlation analyses, TCDD levels were also inversely related to triiodothyronine (T3), thyroid-stimulating hormone (TSH), and testosterone levels, and positively associated with glucagon levels. The mean serum TCDD concentration in these sprayers was between 2.6 and 8.1 parts per trillion (ppt). Since such TCDD levels are commonly found in the general population in countries such as the US, the results could suggest that background levels of TCDD in the general population could have an effect on hormone levels. The findings are preliminary and need to be replicated in order to evaluate their full public health significance.

Serum Dioxin, Testosterone, and Subsequent Risk of Benign Prostatic Hyperplasia: A Prospective Cohort Study of Air Force Veterans

“…Other investigators have also reported similar results (Egeland et al 1994; Johnson et al 2001). Egeland et al (1994) studied 231 controls and 248 chemical production workers who were occupationally exposed to TCDD and found an inverse association between TCDD and serum testosterone.…”

Dioxin effects on neonatal and infant thyroid function: routes of perinatal exposure, mechanisms of action and evidence from epidemiology studies

“…The largest study, conducted on 1,009 Vietnam Air Force Veterans and 1,429 unexposed subjects, showed, in agreement with animal data, elevated TSH levels in individuals with higher TCDD body burden (Pavuk et al 2003). The other investigations were based on a much smaller number of subjects and produced inconsistent results (Table 2) (Calvert et al 1999;Johnson et al 2001;Nagayama et al 2001;Ott et al 1994;Pavuk et al 2003;Zober et al 1994).…”

“…Further understanding of toxicological mechanisms, including the relationship between AhR pathway activation and thyroid function, will be critical to the definition of dioxin individual responsiveness and perinatal toxicity. (n=15) TCDD None of the subjects had biochemical evidence of thyroid dysfunction Ott et al (1994) BASF autoclave accident (n=131 exposed subjects, n=141 unexposed referents) TCDD Positive associations of serum TCDD with TBG and total T 4 Zober et al (1994) Exposed (n=158), unexposed (n=161) chemical workers TCDD Clinical thyroid disease more frequent in the exposure group Calvert et al (1999) 2,4,5-TCP production workers (n=281) and unexposed referents (n=260) TCDD Higher mean free thyroxin index among highly exposed workers Johnson et al (2001) 2,4,5-TPA sprayers (n=37) TCDD Serum TCDD levels inversely associated with T 3 and TSH Nagayama et al (2001) Yusho accident exposed subjects (n=16) PCBs, PCDDs, PCDFs No association with T 3 , T 4 , TSH Pavuk et al (2003) Vietnam Air Force Veterans (n=1,009 exposed, n=1,429 unexposed subjects) TCDD Positive correlation between TSH and serum TCDD levels…”

Endocrine disrupting polyhalogenated organic pollutants interfere with thyroid hormone signalling in the developing brain

“…The AhR is, just as the steroid and TH receptors, a ligand-activated trancription factor that will bind to dioxin-response elements (DREs) in target genes, including many members of the CYP enzyme family. It is known that this system will influence the metabolism of steroids and THs, and dioxins can indeed change TH availability (110)(111)(112) and eventually also estradiol and testosterone secretion (112)(113)(114). This disturbance in hormone homeostasis may indirectly cause changes in gene expression in developing cerebellum as observed for several PCBs, but there also seem to be more direct effects involved.…”