[High exposure to polycyclic aromatic hydrocarbons may contribute to high risk of esophageal cancer in northeastern Iran]

The northeastern region of Iran has some of the highest rates of esophageal squamous cell carcinoma [ESCC] in the world. To investigate the role of polycyclic aromatic hydrocarbons [PAHs] in the etiology of ESCC in northeastern Iran, we measured urine 1-hydroxypyrene glucuronide [1-OHPG], a stable PAH metabolite, in 99 inhabitants of this area. Results: The median urine 1-OHPG in participants of this study was 4.2 pmol/ml. Forty-two subjects [42%] had levels ranging from 1 to 5 pmol/ml, indicative of moderate PAH exposure, and 41 [41%] had levels above 5 pmol/ml, indicative of very high exposure. Further analysis showed that 1-OHPG levels were high in all subgroups of our study subjects, including both sexes; rural and urban dwellers; and smokers and non-smokers. Only 15% of the variance in 1-OHPG was explained by age, sex, residence, smoking, nass, or opium consumption. This pattern of PAH exposure parallels with the ESCC incidence pattern seen in this area. We conclude that people in northeastern Iran are exposed to widespread and very high levels of PAH, largely from unknown sources, and this may contribute to the high rates of ESCC observed in this area

[Ecologic study of serum selenium and upper gastrointestinal cancers in Iran]

Both observational and experimental studies have shown that higher selenium status reduces the risk of upper gastrointestinal cancers in selenium deficient populations. Recent cancer registry data have shown very different rates of esophageal cancer [EC] and gastric cancer [GC] in four provinces of Iran, namely Ardabil, Mazandaran, Golestan, and Kerman. The aim of this study was to have a preliminary assessment of the hypothesis that high rates of EC in Golestan and high rates of GC in Ardabil may be partly attributable to selenium deficiency. We measured serum selenium in 300 healthy adults from Ardabil [n=100], Mazandaran [n=50], Golestan [n=100], and Kerman [n=50], using inductively coupled plasma, with dynamic reaction cell, mass spectrometry [ICP-DRC-MS] at the US Centers for Disease Control [Atlanta, Georgia]. The median serum selenium concentrations were very different in the four provinces. The medians [IQR] for selenium in Ardabil, Mazandaran, Golestan, and Kerman were 82 [75-94], 123 [111-132], 155 [141-173], and 119 [110 -128] micro g/L, respectively [p<0.001]. The results of linear regression showed that the province variable, by itself, explained 76% of the variance in log selenium [r2=0.76]. The proportion of the populations with a serum selenium more than 90 micro g/L [the concentration at which serum selenoproteins are saturated] was 100% in Golestan, Kerman, and Mazandaran but only 29% in Ardabil. Our findings suggest that selenium deficiency is not a major contributor to the high incidence of EC seen in northeastern Iran, but it may play a role in the high incidence of GC in Ardabil province