One of the most important issue in occupational health is to estimate the exposure status or health effects of workers by hazardous chemicals through biological monitoring. The one of the most commonly used tests in biological monitoring to
assess
the internal dose of a chemical is the measurement of a metabolite or sometimes of the chemical itself in urine. Results from a 25-hour specimen is most representative of average body burden, but it is more difficult to obtain, so it is
impractical and more likely to be contaminted. Therefore the analyses are commonly performed on "spot" specimens, and it is necessary to correct the results for the dilution of the urine in order to obtain a reliable estimation by
adjustment
methods. The most commonly used methods are the specific gravity method and the creatinine method. But these adjustment methods are not reliable satisfactorily, and some other adjustment methods have been suggested by some
researchers.
This study had been done to develop more reliable adjustment methods of protein and lead measurement in spot urine, and to seek the factors which affect the variability of spot urine. the subjects were 10 workers who had been exposed to lead
above
TLV.
@ES The results were as follows:
@EN 1. The coefficients of variation of lead in urine were greater than those of protein both in 24 hour urine speicmen and in spot urine specimen. And in the results in spot urine specimens, the coefficients of variation of adjusted
concentrations were less than that of unadjusted concentrations of both the protein and lead.
2. The correlation coefficients of urinary lead(adjusted concentration and unadjusted
concentration) between in spot urine specimen and in 24-hour urine specimen were 0.6-0.8, and those of creatinine adjusted value between in spot urine specimen and in 24-hour urine specimen were lower in workers who had high level of blood
lead(<40 g/dl) than in workers who had low level of blood lead(>40 g/dl).
3. The correlation coefficients of urinary protein(adjusted concentrations and unadjusted
concentration) between in spot urine specimen in 24-hour urine specimen were 0.6-0.8, and those of creatinine adjusted value between in spot urine specimen and in 24-hour urine specimen were lower in workers who had high level of blood
lead(>40 g/dl). Than in workers who had low level-of blood lead(<40ug/dl).
4. The spot urine concentrations adjusted by log-creatinine both of protein and lead were correlated highest to 24 hour urine concentrations in all three adjustment methods such as creatinine adjustment, log-creatinine adjustment and
specific
gravity adjustment method.
5. The important factors which affect the variations of spot urine were specific gravity in urinary lead, and specific gravity and urinary volume or blood lead and specific gravity in urinary protein.
6. Urinary lead concentrations was not affected seriously by urinary creatinine and urinary volume, but urinary protein concentration was affected largely by urinary creatinine, specific gravity and urinary volume. The urinary protein
adjusted by
specific gravity was less affected than other adjustment methods.
7. The recommended adjustment method for urinary lead and protein in worker exposed to lead above TLV is log-creatinine method and specific gravity method.
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