Metabolism of hexachlorobenzene in humans: association between serum levels and urinary metabolites in a highly exposed population.

Abstract

Serum and urine from 100 subjects of a general population highly exposed to airborne hexachlorobenzene (HCB) were analyzed to obtain new insights into the metabolism of this ubiquitous compound. HCB was detected in all serum samples with concentrations ranging between 1.1 and 953 ng/ml. The major known metabolites of HCB were investigated in urine collected over 24 hr. Pentachlorophenol (PCP) was detected in all urines with values ranging between 0.58 and 13.9 micrograms excreted in 24 hr [mean +/- standard deviation (SD), 2.52 +/- 2.05; geometric mean, 2.05]. A sulfur derivative that, after hydrolysis, yielded pentachlorobenzenethiol (PCBT) could also be identified and quantified in all the urines with values ranging between 0.18 and 84.0 micrograms of PCBT excreted in 24 hr (mean +/- SD, 3.47 +/- 10.8; geometric mean, 1.39). The sulfur derivative assessed as PCBT appeared to be the main metabolite, with urinary concentrations surpassing those of PCP in the subjects with higher HCB accumulation (HCB in serum > 32 ng/ml). PCBT concentration in urine collected over 24 hr showed a very strong association with HCB concentration in serum; the association was stronger in males than in females. An increase of 1 ng/ml of HCB in serum led to an increase of 2.12 micrograms of PCBT excreted in urine collected over 24 hr in males (95% CI, 1.82-2.44) and to an increase of 0.67 microgram of PCBT in females (CI, 0.33-1.09). A weaker association was found between PCP in urine and HCB in serum, which was only statistically significant in males (an increase of 1 ng/ml of HCB in serum led to an increase of 0.63 microgram of PCP excreted in urine collected over 24 hr; (CI, 0.34-0.95). These results show that the formation of the cysteine conjugate is a quantitatively more important metabolic pathway in humans than the formation of PCP. Moreover, the association found suggests that PCBT is a good urinary marker of HCB internal dose and glutathione-mediated metabolism.ImagesFigure 1.Figure 2. AFigure 2. BFigure 3. AFigure 3. B

Urinary Porphyrin Excretion in a Human Population Highly Exposed to Hexachlorobenzene

“…10 Negative ion chemical ionization gas chromatography coupled to mass spectrometry was used to confirm the presence of these compounds in the samples.…”

Evaluation of urinary porphyrin excretion in neonates born to mothers exposed to airborne hexachlorobenzene.

“…The porphyrin profile of the highly exposed subjects was normal (17). Analysis of HCB metabolism and excretion in urine and feces revealed a strong correlation between HCB serum concentrations and pentachlorobenzenetiol (PCBT) in urine (18) and unmetabolized HCB (19).…”

An Update on the Safety of Foods of Animal Origin and Feeds

“…Furthermore, beta-HCH was detected at trace levels in blood sera when its levels in milk fell below the analytical limits. As pointed out by other authors (Gupta et al, 1978, To-Figueras et al, 1997, Waliszewski et al, 2004, the results of the study reported by Ronchi and Danieli (2008) suggest a high sensibility of blood as an early indicator of OCP exposure, thus making cattle blood sampling an useful technique in biomonitoring plans to prevent animal exposure to agro-environmental pollution. The pollution by polychlorodibenzodioxins and -furans (PCDDs and PCDFs) and dioxin-like polychlorobiphenyls (DL-PCBs) of food of animal origin can give an useful indication in determining the link between livestock and the territory contamination, especially for extensive and outdoor farming systems.…”