Yoko Morita

δ-Aminolevulinic acid in plasma or whole blood as a sensitive indicator of lead effects, and its relation to the other home-related parameters

To evaluate the subclinical effect of lead exposure, we determined δ-aminolevulinic acid (ALA) levels in plasma (ALA-P), blood (ALA-B), and urine (ALA-U) and the activity of δ-aminolevulinic acid dehydratase (ALAD) in lead workers. Almost all of the ALA molecules in blood were present in plasma and not in blood cells, irrespective of the blood lead concentration (Pb-B). ALA-P or ALA-B levels increased slowly at Pb-B levels below 40 μg/dl (slow phase) and rapidly at levels above 40 μg/dl (rapid phase). In both phases, ALA-P and ALA-B were well correlated with Pb-B and ALAD activity. The threshold value (no-effect level) of Pb-B for elevation of the ALA-P or ALA-B level was coincident with that for ALAD inhibition; the value was around 5 μg/dl. In the rapid phase, ALA-P increased continuously up to 100 μg/dl of Pb-B, while ALAD activity reached a plateau. Receiver operative characteristic (ROC) plot analyses indicated that ALA-P and ALAD activity [ALAD(u)] had a similar diagnostic value at Pb-B levels between 10 and 40 μg/dl, although ALAD(%), the remaining ALAD activity as a percentage of the whole activity restored by zinc and dithiothreitol, had the most powerful diagnostic efficiency at these Pb-B levels. By contrast, ALA-U and zinc protoporphyrin were less effective for the diagnosis of lead exposure than ALAD and ALA-P. These findings indicate that ALA-P is the best discriminators of lead exposure form baseline to high levels of exposure.

Assessment of Urinary Cotinine as a Marker of Nicotine Absorption from Tobacco Leaves: A Study on Tobacco Farmers in Malaysia

Assessment of Urinary Cotinine as a Marker of Nicotine Absorption from Tobacco Leaves: A Study on Tobacco Farmers in Malaysia: Mayumi Onuki, et al. Department of Public Health, Graduate School of Medicine, The University of Tokyo—To assess dermal absorption of nicotine from tobacco leaves in relation to Green Tobacco Sickness (GTS), urinary cotinine concentrations were measured in 80 male tobacco‐growing farmers and in 40 healthy males (controls) who did not handle wet tobacco leaves in Kelantan, Malaysia. Among non‐smokers, urinary cotinine levels in farmers were significantly higher than those of controls; farmers with urinary cotinine of 50 ng/ml/m2 or above showed eye symptoms more frequently than those below this level (p<0.05). Farmers who did not wear protective equipment had subjective symptoms more frequently than those who used the equipment (p<0.05); some of these symptoms were seen more frequently in organophosphate (Tamaron) users than in non‐users. As tobacco farmers evidence a risk of nicotine poisoning from tobacco leaves, assessment including GTS together with effects of pesticides will be necessary.

Relationship between delta‐aminolevulinic acid dehydratase genotypes and heme precursors in lead workers

BACKGROUND The objective of this study was to investigate the relationships between genotypes of delta-aminolevulinic acid (ALA) dehydratase (ALAD) and disturbances in the heme biosynthetic pathway by lead exposure. METHODS The subjects were 192 male lead workers and 125 control subjects. Blood lead concentrations (Pb-B), plasma ALA concentrations (ALA-P), and ALAD genotypes were determined for all subjects. In lead workers, ALAD activity, ALA in urine (ALA-U), and erythrocyte zinc protoporphyrin (ZP) were also determined. RESULTS The frequency of ALAD2 (minor type of ALAD allele) was calculated to be 0.087 in all subjects. No significant relationship was found between ALAD2 frequency and Pb-B levels in lead workers. ALAD1 homozygotes showed significantly higher levels of ZP and ALA-P in comparison with those of ALAD2 carriers at Pb-B levels more than 20 microg/dL and 40 microg/dL, respectively. CONCLUSIONS ALAD1 homozygotes might be more susceptible than ALAD2 carriers to disturbances in heme metabolism caused by lead exposure.

Effects of job strain on helper-inducer (CD4+CD29+) and suppressor-inducer (CD4+CD45RA+) T cells in Japanese blue-collar workers

BACKGROUND The effects of job strain on helper-inducer (CD4+CD29+) T cells and suppressor-inducer (CD4+CD45RA+) T cells are not clear. METHODS The subjects were 65 male blue-collar workers in a chemical plant in Japan. Perceived job stressors were assessed using the Japanese version of Job Content Questionnaire, i.e., job demands, job control, supervisor support and coworker support. Blood samples were taken from these subjects, and number and percentage of total lymphocytes were calculated for total T cells, helper (CD4+) T cells, suppressor/cytotoxic (CD8+) T cells, helper-inducer (CD4+CD29+) T cells and suppressor-inducer (CD4+CD45RA+) T cells using the double-staining fluorescence. RESULTS Job control significantly and positively correlated with number and percentage of helper-inducer (CD4+CD29+) T cells, after controlling for age, number of cigarettes per day and blood lead concentration (Spearmans partial correlation, p < 0.05), while job demands, supervisor support or coworker support did not (p > 0.05). The job strain index, i.e., the ratio of job demands to job control, significantly and negatively correlated with the percentage of helper-inducer (CD4+CD29+) T cells (p < 0.05). None of the job stress scales significantly correlated with number or percentage of suppressor-inducer (CD4+CD45RA+) T cells (p > 0.05). CONCLUSIONS It is suggested that higher job strain or lower job control is associated with a decrease in helper-inducer (CD4+CD29+) T cells in Japanese blue-collar workers.

Critical Dose of Lead Affecting δ-Aminolevulinic Acid Levels

Critical Dose of Lead Affecting δ‐Aminolevulinic Acid Levels: Katsuyuki Murata, et al. Akita University School of Medicine—To estimate the critical dose of the association between the blood lead concentration (BPb) and δ‐aminolevulinic acid (ALA) levels, ALA levels in plasma (ALA‐P), blood (ALA‐B), and urine (ALA‐U), and the activity of δaminolevulinic acid dehydratase (ALAD) were determined in 186 Japanese lead workers, aged 18– 62 yr, with BPb levels of 2.1–62.9 µg/dl. For this purpose, the benchmark dose (BMD) method, recently used in the environmental health field in place of the no‐observed‐adverse‐effect level, was introduced into this study. The BMD was defined as the BPb level that resulted in an increased probability of abnormal change in ALA‐related parameters by an excess risk (BMR) of 5% in exposed workers i.e., from P0 (abnormal probability of 5% in unexposed workers) to P0+BMR for exposed workers at the BMD. ALA‐related parameters were significantly correlated with BPb. The BMDs computed from the 186 workers, after controlling for age, were 15.3–20.9 µg/dl for ALA levels, and 2.9 µg/dl for ALAD; likewise, the BMDs from the 154 workers with BPb levels of less than 40 µg/dl were 3.3– 8.8 µg/dl for ALA levels, and 2.7 µg/dl for ALAD. Since the cutoff value of ALA‐P, computed from the latter workers, seems to be closer to the upper normal limit in unexposed adults than does that from the former workers, it is suggested that the critical dose of BPb causing the increased levels of ALA is below 10 µg/dl. Such critical doses are necessary to promote preventive activities of adverse effects of lead.

Relationship between Increased Blood Lead and Pregnancy Hypertension in Women without Occupational Lead Exposure in Tehran, Iran

This study was conducted to assess the relationship between blood lead levels and pregnancy-induced hypertension. Participants were 110 pregnant women, of whom 55 were hypertensive, 27 ± 5.6 yr of age (mean ± standard deviation) (range = 17-40 yr); the other 55 women were age- and gravidity-matched normotensive controls. Participants were selected on the basis of their medical history and the results of a questionnaire-based interview. Subjects were at gestational ages 37 ± 2.5 wk (range = 30-41 wk) and were not occupationally exposed to lead. Blood samples were collected within 24 hr after delivery, and blood lead levels were measured. For the hypertensive cases, blood lead levels were 5.7 ± 2 μg/dl (range = 2.2-12.6 μg/dl [0.27 ± 0.10 μmol/l; range = 0.11-0.60 μmol/I), which were significantly higher than those of the control group (i.e., 4.8 ± 1.9 μg/dl; range = 1.9-10.6 μg/dl [0.23 ± 0.09 μmol/I; range = 0.09-0.51 μmol/I]). There were no significant differences in blood lead concentrations among hypertensive subjects with proteinuria (n = 30) and those without proteinuria (n = 25). Results of this study indicated that low-level lead exposure may be a risk factor for pregnancy hypertension.

Gaschromatographic determination of butoxyacetic acid after hydrolysis of conjugated metabolites in urine from workers exposed to 2-butoxyethanol

For the gaschromatographic determination of total butoxyacetic acid (BAA), i.e., free plus conjugated BAA in urine, we studied the acid hydrolysis condition to cleave the conjugate. The optimum condition for hydrolysis was chosen to be 60 min boiling of the mixture of 1 ml twofold diluted urine and 1.2 ml hydrochloric acid. For the biological monitoring of workers exposed to 2-butoxyethanol (BE), we applied our acid hydrolysis method to the urine from 6 workers exposed to the solvent for 7 days and determined total BAA as well as free BAA and conjugated BAA, which was calculated as the difference between the concentrations of free and conjugated BAA. The percentages of conjugated BAA vs. total BAA varied from 44.4% to 92.2% (mean value 71.1 %) among 6 individual workers over 7 days and decreased gradually over the consecutive work days. In the latter half of the work week, free BAA comparatively accounted for the larger portion of urinary BAA. Significant correlations were found between urinary BAA concentrations and BE levels in the breathing-zone air (TWA). The correlation coefficients of urinary concentrations of total or conjugated BAA vs. BE levels was higher than that of free BAA concentrations vs. BE levels. Hence, the determination of total BAA in urine is a suitable test for the biological monitoring of BE exposure, because of the simplicity in procedures and the good agreement with BE exposure levels.

LC-MS determination of urinary toluenediamine in workers exposed to toluenediisocyanate.

To improve the biological monitoring method for 2,6- and 2,4-toluenediisocyanate (TDI) exposure, we developed a simple and rapid method for analysis of the corresponding urinary metabolites, 2,6- and 2,4-toluenediamine (TDA) using liquid chromatograph-mass spectrometry (LC-MS). One ml of urine was hydrolyzed at 100 degrees C for 1.5 h with H(2)SO(4). Alkalinized hydrolysate was extracted with dichloromethane (DCM) and analyzed by atmospheric pressure chemical ionization (APCI) LC-MS, in positive-ion mode. The mass spectra of TDA isomers showed the protonated molecule [M+H](+), at m/z 123 as the base peak. Calibration curves of 2,6-TDA were linear up to 400 microg/l. TDA isomers in urine of exposed workers as determined by LC-MS correlated well with those obtained by gas chromatography-mass spectrometry. 2,6- and 2,4-TDA were not detected in non-exposed subjects, whereas exposed workers showed urinary levels up to 250 and 63 microg/l, respectively.

Biological monitoring of workers exposed to dichloromethane, using head-space gas chromatography.

A biological monitoring method for urinary dichloromethane (DCM) has been developed by using head-space gas chromatography with FID detection. The calibration curve is linear in a wide range of DCM levels between 0.01 and 2 mg/l. The recovery rate is almost 100% and within-run coefficients of variation are 2.9-3.7%. A highly significant correlation is found between exposure levels and urinary concentrations of DCM. Determination of urine DCM by this method has many advantages such as sample storage, no need for correction of urine concentration, absence of gender difference and also no confounding effect of glutathione S-transferase T1 polymorphism.

Simple and rapid method for determining nicotinamide adenine dinucleotide synthetase activity by high-performance liquid chromatography

A method is described for the determination of nicotinamide adenine dinucleotide synthetase (NADS) activity in human blood. Using high-performance liquid chromatography (HPLC), the formed NAD is separated from the substrates and the other blood components in less than 13 min. The activity of NADS determined by HPLC is closely correlated with that determined by the conventional spectrophotometric method, which requires two steps of enzyme reaction. The present method is simple and reliable and facilitates the routine analysis of NADS activity.