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Exposure related observations in humans: other data

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Administrative data

Endpoint:
exposure-related observations in humans: other data
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
no data
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: No guideline followed and not performed under GLP but this study was performed to investigate the levels of thiocyanate in serum and urine after consumption of different types of meals.

Data source

Reference
Reference Type:
publication
Title:
Thiocyanate levels of mainly dietary origin in serum and urine from a human population sample in Port Harcourt, Nigeria
Author:
Eminedoki, D.G. Monanu, M.O. Anosike, E.O.
Year:
1994
Bibliographic source:
Plant Foods Hum Nutr 1994 Dec 46:4 277-85

Materials and methods

Type of study / information:
This study was performed to investigate the levels of thiocyanate in serum and urine after consumption of different types of meals.
Endpoint addressed:
not applicable
Test guideline
Qualifier:
no guideline followed
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Details on study design:
Blood and urine samples were collected form healthy non-smoking volunteers (23 males and 22 females, 14-30 years old). Samples were collected 3-4 hours before and after the test meal. Thiocyanate levels were determined in serum and urine. Statistics: Wilcoxon-Mann-Whitney test.

Results and discussion

Results:
The concentrations of serum and urine thiocyanate measured before the intake of test-meals ranged from 39.20 ± 1.95 to 160.95 ± 8.06 µmol/l of serum, and 81.92 ± 9.78 to 294.01 ± 14.70 µmol/l of urine. In the control group, the ranges were from 42.20 ± 2.30 to 149.60 ± 11.97 µmol/l of serum, and 92.31 ± 4.62 to 250.71 ± 20.06 µmol/l of urine, showing a similar pattern. This wide variation may be caused by differences in exposure to dietary cyanide and/or thiocyanate and in the metabolism/excretion of these compounds in the volunteers.

Significant increases (p < 0.05) for most of the subjects) of serum thiocyanate were observed following a gari-based meal. In contrast, intake of rice-based meal produced decreases in serum thiocyanate. The urine thiocyanate levels showed similar patterns.

Applicant's summary and conclusion

Conclusions:
ignificant increases (p < 0.05) for most of the subjects) of serum thiocyanate were observed following a gari-based meal. In contrast, intake of rice-based meal produced decreases in serum thiocyanate. The urine thiocyanate levels showed similar patterns. There is a wide variation between individuals in serum and urine levels.
Executive summary:

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 (processed cassave product)-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 µmol/l of serum, and 81.92 ± 9.78 to 294.01 ± 14.70 µmol/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 sulphurtransferases in the process of cyanide detoxication.