Tadao Matsumoto

Relationship between chlordane and its metabolites in blood of pest control operators and spraying conditions

SummaryChlordane has been widely used to protect soil and house foundations against termite infestation. Pest control operators (PCOs) are occupationally exposed to chlordane. The relationship between chlordane and its metabolites in blood of PCOs and spraying conditions were investigated. Chlordane and its metabolites were detected in the blood of some chlordane-exposed PCOs, but not in that of the controls. Trans-nonachlor and the metabolites oxychlordane and heptachlor epoxide were detected in the blood of PCOs. Total concentration of chlordane and its metabolites in blood (trans-nonachlor + oxychlordane + heptachlor epoxide) was less than 5.6 ppb (mean: 0.89 ppb). The concentration of chlordane and its metabolites in blood of chlordane-exposed PCOs was significantly correlated with the number of spraying days and the amount of chlordane sprayed, particularly with a large correlation coefficient (r = 0.81, P < 0.001) with the spraying days in the three months prior to the medical examination. The concentration of chlordane and its metabolites in blood is considered to be a useful indicator of biological monitoring for chlordane exposed workers (PCOs).

Validity of various function tests performed in Japan as a screening test for vibration syndrome

SummaryIn Japan, various function tests on the upper extremities are widely performed for the early diagnosis of vibration syndrome. The validity of these function tests was investigated by discriminant function analysis. The correct classification rate of the 120 workers exposed to vibration and the 40 control workers was 83.1%, when including the exposure-to-cold test. Therefore, the function tests were confirmed to be of diagnostic significance as a screening test for vibration syndrome. However, the rate is not sufficient to make a diagnosis only with the function tests. When not including the exposure-to-cold test, the rate was reduced by 10% because insidious functional disorders were missed in the early stage. For the early diagnosis of vibration syndrome, the exposure-to-cold test should be included in the function tests. Furthermore, to enhance the validity of the diagnosis, the results of the function tests should be evaluated together with subjective symptoms and the findings on bones and joints, the central nervous system and the endocrine system.

Determination of 3,4-dimethylhippuric acid as a biological monitoring index for trimethylbenzene exposure in transfer printing workers

SummaryThe relationship between exposure to 1,2,4-trimethylbenzene (1,2,4-TMB) and urinary concentration of 3,4-dimethylhippuric acid (3,4-DMHA), one of its metabolites, was studied in workers involved in transfer printing. Airborne TMBs were sampled by an organic vapor monitoring badge and analyzed by capillary gas chromatography. Urinary 3,4-DMHA and creatinine were analyzed under the same conditions of high-performance liquid chromatography. The exposure concentration of 1,2,4-TMB among workers was around 25 ppm, the threshold limit value (TLV). The urinary concentration of 3,4-DMHA was low at the start of each shift and high at the end. Exposure to the TLV (25 ppm) of 1,2,4-TMB results in a urinary 3,4-DMHA concentration of 410 mg/g creatinine (r = 0.897, P < 0.001). Urinary 3,4-DMHA concentration could be used as a biological monitoring index for 1,2,4-TMB exposure.

Involvement of the central nervous system in vibration syndrome

In order to clarify the involvement of the central nervous system (CNS) in vibration syndrome (VS), patients with VS and age-matched controls were given a questionnaire and neurophysiological tests on auditory brainstem response (ABR), event-related potential (P300), short-latency somatosensory evoked potentials (SLSEP), and blink reflex (BR). Twenty-eight patients with a mean age of 56.3 (SD = 3.01, range 48–65) years from western Japan were examined. They had been on sick leave for an average of 6.13 (SD = 3.2, range 1–13) years at the time of the testing. Almost all were experiencing Raynauds phenomenon in the winter of 1990–1991. They were not suffering from diseases or injuries which might have affected the CNS function. These patients were divided into two subgroups, one with more symptoms related to the CNS, especially memory and judgment (n = 13, group A), and the other with fewer symptoms (n = 15, group B). Normal controls with an average age of 55.8 (SD = 4.8, 48–65) years were people from the same area who met similar criteria. The ABR parameters of the patients were slightly, but not significantly, delayed compared with those of the controls. The SLSEP and BR parameters of the patients were not delayed. The latencies of P300 in group A were significantly delayed compared with those in the controls. The findings suggest that VS involves the cognitive and attention functions of the cerebral higher function, but not the conduction function in the auditory and somatosensory ascending tract and facial nerve reflex tract in the brainstem.

Changes in Cholinesterase Activity, Nerve Conduction Velocity, and Clinical Signs and Symptoms in Termite Control Operators Exposed to Chlorpyrifos

Changes in Cholinesterase Activity, Nerve Conduction Velocity, and Clinical Signs and Symptoms in Termite Control Operators Exposed to Chlorpyrifos: Masahiro Gotoh, etal. Asahi Rosai Hospital—We have surveyed periodical medical examinations for pest and termite control operators (n=64) exposed to chlorpyrifos and other organophosphate pesticides. Distribution of serum butyrylcholinesterase (BuChE) activities of all workers ranged 0.01‐1.18 (ApH). Serum BuChE activities in 6 workers in one termite control company were severely depressed and ranged from 0.01 to 0.21 ΔpH. Erythrocyte acetylcholinesterase (AChE) activities in 3 workers were lower than the normal range. Erythrocyte AChE activities and serum BuChE acitivities in chlorpyrifos sprayers were significantly correlated (r=0.720). In other clinical signs, blood urine nitrogen (BUN) in 4 workers and white blood cell (WBC) counts in 4 workers were abnormal. Sensory nerve conduction velocities in the sural nerve of all 6 workers were significantly reduced to 18.8‐26.6 m/s in the left leg and 19.2‐27.2 m/s in the right leg. In the results of ophthalmic examinations, accommodation time (both eyes) in 4 workers extended over the normal range and electroretinography (ERG) in 2 workers showed abnormal ERG including disappearance of oscillatory potential. Chlorpyrifos residue in blood in 4 operators whose serum BuChE activities ranged from 0.01 to 0.03 ApH were detected in the range 2‐8 ng/m 1. They had sprayed chlorpyrifos daily for 5 d before every blood sampling. It is suggested that serum BuChE activity and sensory nerve conduction velocity are sensitive indicators to evaluate the effects of chlorpyrifos exposure, and may be used effectively to monitor exposure and the effects of chlorpyrifos on health.

A study of various function tests on the upper extremities for vibration syndrome

For early diagnosis of vibration syndrome, it is necessary to detect the insidious functional disorders which appear without organic changes in its early stage. In Japan, peripheral circulation and sensory tests, including tests after cold water immersion, and functional capacity motor tests are performed widely on the upper extremities. We have examined workers exposed to three kinds of vibration, and control workers, using these function tests, and analyzed the data with the use of principal component analysis. As a result, these function tests were considered to be of diagnostic significance as a screening test for vibration syndrome. It is also suspected that peripheral circulation disturbance, sensory disturbance and motor disturbance found in vibration syndrome advance independently of each other. Disparities in the findings of vibration syndrome were recognized and were attributed to differences of work conditions.

Relations between Lead Exposure and Peripheral Neuromuscular Functions of Lead-Exposed Workers—Results of Tapping Test1

In this study, four experiments using the tapping test were conducted to evaluate the possible subclinical effects of lead exposure on the neuromuscular systems of lead workers at some transfer printing factories in Japan. Decreases in the tapping ability appeared co-incidentally with higher blood lead levels. The recovery of the tapping ability after 30 sec rest in the groups of 30–45 (μg/dl and above 45 (μg/dl PbB was worse than that in the group with less than 29 μg/dl PbB. The recovery of the decreased tapping ability after 60 sec rest was better even in the group with 30–45 μg/dl PbB. The tapping ability for 0–10 sec at the first tapping test was sustained after 30 or 60 sec rest in the group with the PbB below 29 μg/dl; however, the tapping ability at the second and third tapping test decreased in the two groups with the PbB level above 30 μg/dl. The decreased finger tapping speed may be functional evidence of low-grade motor neuropathy among the workers with higher levels of lead absorption.

Serum succinyltrialanine p-nitroamlide-hydrolytic activity in workers occupationally exposed to lead

The relationship between blood lead concentration and serum succinyltrialanine p-nitroanilide-hydrolytic (STN) activity was investigated in 74 workers occupationally exposed to lead and in 28 non-exposed workers. Exposure to lead was observed during transfer-printing processes in which paints or paint powders containing 20-50% lead were used. The mean lead concentration was 0.49 mg/m3 (0.12-1.43 mg/m3) in the working environment and 1.42 mg/m3 (0.21-4.34 mg/m3) in workers involved in printing processes. Serum STN activity became lower with increasing concentrations of blood lead (PbB) in non-exposed workers (controls). In lead-exposed workers, the activity decreased with increasing concentrations of PbB of 2.0 mumol/l and more, but increased when less than 1.9 mumol/l. Among lead-exposed workers with high PbB concentrations and/or with hepatic dysfunction, the STN/PbB ratio was distributed above the regression line obtained from the controls. The present investigation suggests that serum STN activity decreases in those highly exposed to lead. Enzymes such as elastase, which hydrolyzes succinyltrialanine p-nitroanilide and additionally is not inhibited by lead, may possibly be induced among lead workers when liver function is impaired.