Thiocyanate levels of mainly dietary origin in serum and urine from a human population sample in Port Harcourt, Nigeria

Abstract

Thiocyanate levels were determined in serum and urine samples obtained from a human population sample of healthy non-smoking volunteers (aged between 14 and 30 years) of both sexes known to eat gari-based meals at least once a day. The samples were collected before and 3-4 hours after a gari- or rice-based meal. The values obtained before the test meals showed a wide variation, ranging between 39.20 +/- 1.95 to 160.95 +/- 8.06 mumol/l of serum, and 81.92 +/- 9.78 to 294.01 +/- 14.70 mumol/l of urine. For each volunteer, the serum and urine thiocyanate were affected by the test meals. Average increases of 18 and 20% were observed for serum and urine thiocyanate, respectively, following a gari-based meal. A rice-based meal produced, on the average, 10% decrease in both serum and urine thiocyanate. No significant effect of sex or age on the thiocyanate levels was observed. The gari samples used in the study, as well as random samples from the locality of study, had no detectable thiocyanate but contained between 0.013 and 0.015 mg cyanide per kg of gari. These findings indicate that conversion to thiocyanate is a significant pathway in the metabolism of HCN and contributes significantly to thiocyanate found in body fluids and tissues of man. In addition, support is provided for the possible involvement of the sulphur-transferases in the process of cyanide detoxication.

Intake of Iodine and Perchlorate and Excretion in Human Milk

“…Urinary excretion may not reflect circulating levels because in part thiocyanate is formed in vivo from cyanide (10), present in certain foods (11), and formed during protein metabolism (10). In smokers, cigarette smoke is an important source of HCN (12).…”

Quantitative analysis of nitrate and nitrite contents in vegetables commonly consumed in Delta State, Nigeria

“…These observations might increase the risk of a cassava-eating population to the carcinogenic activities of nitrates and nitrite in vegetables that they consume. A previous report (Eminedoki et al 1994) has demonstrated that daily consumption of a cassavabased diet by human subjects increases the level of thiocyanate in their serum and urine. Therefore, the control of nitrate and nitrite intake may be important in Delta State, Nigeria, where plasma thiocyanate content is generally high because of the consumption of cassava-based diets, and especially now that the nitrate levels in V. amygdalina (bitter leaf), and Telfaria occidentalis (pumpkin) grown in the industrialised regions of the state are within the reference levels reported to be associated with an increased incidence of gastric cancer (Armijo et al 1981;Dutt et al 1987).…”

Derivatization Method of Free Cyanide Including Cyanogen Chloride for the Sensitive Analysis of Cyanide in Chlorinated Drinking Water by Liquid Chromatography-Tandem Mass Spectrometry

“…In order to study optimal derivatization conditions, the reaction was performed for various amounts of D-cysteine and sodium hypochlorite (0.25, 0.5, 1.0, 1.25, 1.5, and 1.75 mM) and reaction times (2,5,8,10,20,30, and 40 min) at room temperature in water. Derivatization efficiencies were calculated at various pH levels (3.0, 4.0, 4.5, 5.0, 5.5, 6.0, 7.0, 8.0, and 9.0) at room temperature.…”