Abstract
In Japan “the Regulation on the Prevention of Lead Poisoning” and “the Regulation on the Prevention of Organic Solvent Poisoning” were partially amended in 1989 to introduce biological monitoring in the special medical examinations of workers exposed to lead and 8 organic solvents (toluene, xylene, styrene, N, N-dimethylformamide, n-hexane, tetrachloroethylene, 1, 1, 1-trichloroethane, trichloroethylene).
Since many companies entrust these medical examinations to the Occupational Health Organizations (OHOs), a survey of OHOs which collect blood and urine samples for biological monitoring was made in August 1992, to ascertain the actual status of their activities from April of 1991 to March of 1992.
The following findings were obtained through this survey.
1) One hundred and eighty-six OHOs collected 129, 996 blood samples to measure the concentration of lead, and the median number of samples collected per organization was 356.
2) Thirty-nine OHOs (21.0%; Group A) measured all samples in their own laboratories. The number of samples measured was 55, 462 (42.7%). However, 133 OHOs (71.5%; Group B) entrusted the measurement of all samples to registered laboratories.
3) The median number of samples collected by OHOs in Group A was 1, 121, and the median number of Group B was 211.
4) One hundred and eighty-three OHOs collected 126, 915 urine samples to measure the concentration of δ-aminolevulinic acid and the median number of samples collected per organization was 358.
5) The blood samples as well as the urine samples were divided into three groups according to the levels of lead or δ-aminolevulinic acid concentration. The concentration is relatively low in Group 1 and relatively high in Group 3. The cut-off values for this classification are legally set in the Regulation on the Prevention of Lead Poisoning. The frequency of each group was as follows: lead (Group 1; 93.8%, Group 2; 4.9%, Group 3; 1.3%), δ-aminolevulinic acid (Group 1; 96.8%, Group 2; 3.1%, Group 3; 0.2%).
6) Two hundred and six OHOs collected 615, 148 urine samples to measure the concentration of metabolites of organic solvents. The number of samples collected for measurement of metabolites of toluene was 274, 265, which was largest in number and the number of samples was smallest for N, N-dimethylformamide (10, 353).
7) The number of OHOs which collected the urine samples for measurement of metabolites of toluene was 199 (96.6%), which was largest among 8 organic solvents. In the case of N, N-dimethylformamide, which was smallest in number, 117 OHOs (56.8%) collected the urine samples.
8) Seventeen OHOs (8.3%) measured all the urine samples of organic solvents in their own laboratories, but 169 (82.0%) OHOs entrusted the measurement of all samples to registered loboratories.
9) The urine samples were also divided into three groups according to the levels of the metabolites. The cut-off values for this classification are legally established by the Regulation on the Prevention of Organic Solvent Poisoning. The frequency of Group 1 was high in n-hexane (98.3%) and xylene (98.2%), and the lowest in styrene (87.3%). The frequency of Group 3 was the highest in styrene (3.0%) and the lowest in xylene and n-hexane (0.2%).
