Lead toxicity: does the critical level of lead resulting in adverse effects differ between adults and children?

OBJECTIVES: The Scientific Committee on Neurotoxicology and Psychophysiology and the Scientific Committee on the Toxicology of Metals of the International Commission on Occupational Health in 2006 recommended that the standard for blood lead (BPb) levels be reduced to 30 microg/dl for industrial workers and 5 microg/dl for children. To examine whether the critical level of lead producing adverse effects truly differs between workers and children, we provided an overview of studies addressing the critical level of lead in workers, together with a perspective on lead toxicity in children. DATA SOURCES AND EXTRACTION: In 25 reports published in English with keywords of "benchmark dose (BMD)," "lead" and "humans," only five studies proved to be relevant to lead toxicity. Four more studies with figures illustrating significant relationships between lead and neurotoxic outcomes were selected. DATA SYNTHESIS: Based on data from previous reports using a BMD approach, the critical organ of lead in workers was thought to be the nervous system and the critical BPb level (number-weighted mean) was between 10.7 and 17.5 microg/dl. The neurotoxic effects of lead exposure at such levels seemed reversible. The BPb level at which lead-associated intellectual deficits occurred in children was as low as the critical level of BPb (below 5 microg/dl) for inhibited heme synthesis in workers. CONCLUSIONS: The neurotoxic effects of lead in workers appear to be initiated at BPb levels below 18 microg/dl, which are somewhat higher than the critical level of lead neurotoxicity in children. Each national institute for risk management should take evidence-based preventive action against subclinical lead poisoning in workers, as well as in children.

Effects of acute alcohol ingestion on neuromotor functions.

To scrutinize the neuromotor effects of acute alcohol ingestion, postural sway, hand tremor, and reaction time were measured before and after alcohol or juice ingestion in 13 healthy volunteers at 20-22 years (mean 20.7) of age. The dose of ethanol consumed by the subjects (mean+/-S.D.) was 0.59+/-0.07 g/kg body weight, and the blood ethanol concentrations were estimated to be 0.86+/-0.23 g/l at 30 min after ethanol ingestion; 0.88+/-0.19 g/l at 70 min; 0.74+/-0.27 g/l at 130 min. The 1-h and 2-h changes in sway area, total transversal sway (Dx), and Dx at 0-1 Hz with eyes closed were significantly larger after alcohol ingestion than after juice ingestion. Similarly, the 2-h changes in sway area, total Dx, and Dx at 0-1 Hz with eyes open were significantly larger after alcohol ingestion than after juice ingestion. No significant differences were seen between alcohol and juice ingestion regarding changes in hand tremor or reaction time. These data suggest that the static balance due to acute alcohol ingestion is characterized mainly by transversal sway of low frequency (0-1 Hz) with eyes closed, which seems to differ from the characteristics of postural sway in alcoholics.

Assessment of DNA damage in Japanese nurses handling antineoplastic drugs by the comet assay.

To clarify genotoxic effects of occupational exposure to antineoplastic drugs in Japan, we examined DNA damage, assessed by the comet assay, in 121 female nurses and 46 female clerks working at three hospitals in the northeast of Japan. The comet assay is considered to be a sensitive and rapid method for DNA strand break detection in individual cells, and tail length and tail moment are used as the comet parameters. Concerning the basal characteristics, the 46 control subjects had higher rates of smoking and coffee-drinking habits and lower hemoglobin than the 121 nurses (p<0.05). The log-transformed tail length in the nurses was significantly longer than that in the control subjects after adjusting for possible covariates such as age and smoking habit (p<0.05). Also, the log-transformed tail length was significantly longer, in the 57 nurses who had handled antineoplastic drugs in the last six months, than that in the 46 control subjects (p<0.05); but, no significant difference in tail length or tail moment was seen between the two nurse groups with and without experience of handling hazardous drugs (p>0.05). These results suggest that Japanese nurses who have worked at hospitals using antineoplastic drugs may have a potential risk of DNA damage. To minimize this risk in Japan, use of biological safety cabinet and appropriate protective equipment, in addition to staff education and training, should be implemented in the healthcare environment.

Association of alcohol dehydrogenase 2 and aldehyde dehydrogenase 2 genotypes with fasting plasma glucose levels in Japanese male and female workers.

AIMS: The objective was to clarify the effect of alcohol dehydrogenase 2 (ADH2) and aldehyde dehydrogenase 2 (ALDH2) genotypes on the diabetic risk in Japanese workers. METHODS: At the time of mandatory health checkup, the ADH2 and ALDH2 genotypes, as well as fasting plasma glucose (FPG) levels, body mass index (BMI), smoking habit, and weekly alcohol intake, were examined in 492 men and 183 women working at motor vehicle dealerships. RESULTS: In using two-way analysis of variance to manipulate ADH2 and ALDH2 genotypes and alcohol intake (>70 g/week for men and >35 g/week for women), the FPG level after the adjustment for age, BMI, smoking habit, and another genotype was significantly higher in the men with ADH2*1/1 genotype than in those with the other genotypes, but there was no significant difference in the FPG level between the men with and without ALDH2*1/1 genotype. In contrast, the women with ALDH2*1/1 genotype had significantly lower FPG levels than those with the other genotypes, but there was no significant difference in the FPG level between the women with and without ADH2*1/1 genotype. Also, a significant interaction between ethanol intake and ALDH2 genotypes was seen only in the women. CONCLUSIONS: These findings suggest that genotypes of ADH2 and ALDH2 can modify the diabetic risk, irrespective of amounts of alcohol consumed. Also, there may be sex differences in the effect of these enzyme genotypes on glucose metabolism.

[Usefulness of umbilical cord mercury concentrations as biomarkers of fetal exposure to methylmercury].

In epidemiological studies on the health effect of methylmercury (MeHg) exposure, maternal-hair mercury concentration has been used as an exposure biomarker because of its ease of collection and capability to recapture the exposure history. However, artificial hair-waving reduces the mercury concentration and there is little agreement about which part of the hair strand properly represents fetal exposure. We presented an overview of the studies addressing umbilical cord and mercury in PubMed and evaluated the usefulness of umbilical cord mercury concentrations as biomarkers of fetal exposure to MeHg. The mean total mercury (T-Hg) concentration in cord blood was between 0.5 and 35.6microg/l, and the cord blood-to-maternal blood ratio of T-Hg concentrations was estimated to be approximately 1.5. MeHg concentrations in dried cord tissue did not exceed 0.4 microg/g in Japanese populations without particular exposure to MeHg. Dried cord tissue appeared to be better than wet tissue because the definition of wet weight of the umbilical cord is ambiguous. Both cord-blood and cord-tissue mercury concentrations seemed to correlate closely with maternal-hair and maternal-blood ones. Since cord mercury concentrations are a direct exposure biomarker of the fetus and the cord blood-to-maternal blood ratio of mercury differed markedly among mother-child pairs, mercury concentration in cord blood or dried cord tissue should therefore be used in assessing the possible effects of fetal exposure to MeHg on the susceptible brain. Further studies are required to clarify at which period of exposure during gestation the cord mercury concentration represents in relation to mercury concentrations in maternal segmental hair.

Assessment of intrauterine methylmercury exposure affecting child development: messages from the newborn.

In evaluating the health effects in the offspring born to the mothers exposed to methylmercury (MeHg) during pregnancy, biomarkers obtained from maternal blood and hair, and umbilical cord have been employed for the exposure assessment. However, which biomarker is employed may affect the study conclusion. In this sense, umbilical cord mercury concentration appears to be a direct exposure biomarker of the fetus. We present an overview of the studies addressing umbilical cord and mercury and scrutinize the usefulness of umbilical cord samples for intrauterine exposure assessment of MeHg. The mean total mercury concentration in cord blood ranged from 0.5 to 35.6 microg/L among the studies reviewed. In Japanese populations, MeHg concentrations in dry cord tissue did not exceed 0.4 microg/g. Also, dry cord tissue would be preferable to wet tissue because the definition of wet weight of the umbilical cord is ambiguous. The cord blood-to-maternal blood ratio of mercury concentrations differed considerably among mother-child pairs despite the significant positive correlation between the cord and maternal mercury concentrations. Moreover, the increased cord mercury concentration was associated with some neurobehavioral and neurophysiological deficits in child. Therefore, mercury concentrations in cord blood and tissue can be accepted as more useful and valid biomarkers of fetal exposure to MeHg, for assessing a dose-response relationship in children at the developmental stage, than maternal mercury concentrations at parturition. Because umbilical cord blood has been used for cord-blood stem cell transplants, dry umbilical cord tissue should be effectively utilized for the advancement of medical sciences.

Interaction between resting pulmonary ventilation function and cardiac autonomic function assessed by heart rate variability in young adults.

An association between ambient air pollution and reduced cardiac autonomic function assessed by heart rate variability (HRV) mainly in elderly persons has been suggested by a number of epidemiological studies, but the link between the HRV and pulmonary function in humans remains unknown although such air pollution should primarily affect pulmonary function. To clarify this link, pulmonary ventilation parameters such as oxygen uptake (V(O(2))) and carbon dioxide output (V(CO(2))), as well as the HRV with spectral analysis (high- and low-frequency components of HRV, i.e., CCV(HF) and CCV(LF), reflecting cardiac parasympathetic and sympathetic activities, respectively), were measured in 66 healthy women aged 19-20 years after an overnight fast of 12 h. Significant correlations were found between the CCV(HF) of HRV and both the end-tidal carbon dioxide concentration (FET(CO(2))) and gas exchange ratio (V(CO(2))/V(O(2))) in the subjects (partial correlation coefficients r = 0.354 and 0.320, respectively), whereas there was no significant connection between the FET(CO(2)) and the V(CO(2))/V(O(2)). Similarly, the CCV(LF) correlated significantly with the resting tidal volume of lung (r = 0.364). These findings suggest that resting pulmonary ventilation function interacts with cardiac autonomic function assessed by the HRV, at least in healthy young adults, which may be useful for explaining the pathophysiology concerning the short-term effect of air pollution such as fine particulate matter on cardiovascular function.

Neurophysiological evidence of methylmercury neurotoxicity.

BACKGROUND: A variety of neurophysiological measures are useful in hospital settings for diagnostic and other clinical purposes. Previously, abnormal changes in various sensory evoked potentials (EPs), and heart rate variability (HRV) were observed in patients with acquired and fetal Minamata disease (MD; methylmercury poisoning). In recent years, some of these methods have been used for the risk assessment of low-level methylmercury exposure in asymptomatic children. The objectives of this article were to present an overview of neurophysiological findings involved in methylmercury neurotoxicity and to examine the usefulness of those measures. METHODS: The reports addressing both neurophysiological measures and methylmercury exposure in humans were identified and evaluated. RESULTS: The neurological signs and symptoms of MD included paresthesias, constriction of visual fields, impairment of hearing and speech, mental disturbances, excessive sweating, and hypersalivation. Neuropathological lesions involved visual, auditory, and post- and pre-central cortex areas. Neurophysiological changes involved in methylmercury, as assessed by EPs and HRV, were found to be in accordance with both clinical and neuropathological observations in patients with MD. CONCLUSIONS: EPs and HRV appear to be useful and objective methods for assessing methylmercury neurotoxicity. However, subtle changes due to low-level methylmercury exposure may not necessarily be of clinical relevance, and interpretation of small deviations from expectations must be cautious.

Spontaneous awakening from nocturnal sleep and cardiac autonomic function in preschool children.

A cross-sectional study was carried out to clarify the physiological features of spontaneous awakening from nocturnal sleep (i.e., whether a child can spontaneously wake up on weekday mornings). The study population comprised 116 children at ages 5 and 6 years. Heart rate variability reflecting cardiac sympathetic and parasympathetic activities was measured. Children's typical bedtimes and wake times for weekdays and the presence/absence of spontaneous awakening from nocturnal sleep were reported by parents, and information about obligatory naptimes was provided by preschool teachers. The mean total sleep duration in the children was 625+/-56 (standard deviation) min. Total and nocturnal sleep durations were significantly shorter in 52 children without spontaneous awakening than in 64 children with it. Similarly, the parasympathetic activity was significantly lower in the children without spontaneous awakening, even in using analysis of covariance. Heart rate was significantly increased in the children without spontaneous awakening, but neither total nor nocturnal sleep durations were significant covariates in the analysis of covariance. In conclusion, the absence of spontaneous awakening from nocturnal sleep in preschool children is suggested to be characterized by short sleep duration, parasympathetic hypoactivity, and elevated heart rate.

Total mercury levels in hair, toenail, and urine among women free from occupational exposure and their relations to renal tubular function.

To investigate the relations among total mercury levels in hair, toenail, and urine, together with potential effects of methylmercury intake on renal tubular function, we determined their levels, and urinary N-acetyl-beta-D-glucosaminidase activity (NAG) and alpha1-microglobulin (AMG) in 59 women free from occupational exposures, and estimated daily mercury intakes from fish and other seafood using a food frequency questionnaire. Mercury levels (mean+/-SD) in the women were 1.51+/-0.91 microg/g in hair, 0.59+/-0.32 microg/g in toenail, and 0.86+/-0.66 microg/g creatinine in urine; and, there were positive correlations among them (P<0.001). The daily mercury intake of 9.15+/-7.84 microg/day was significantly correlated with total mercury levels in hair, toenail, and urine (r=0.551, 0.537, and 0.604, P<0.001). Among the women, the NAG and AMG were positively correlated with both the daily mercury intake and mercury levels in hair, toenail, and urine (P<0.01); and, these relations were almost similar when using multiple regression analysis to adjust for possible confounders such as urinary cadmium (0.47+/-0.28 microg/g creatinine) and smoking status. In conclusion, mercury resulting from fish consumption can explain total mercury levels in hair, toenail, and urine to some degree (about 30%), partly through the degradation into the inorganic form, and it may confound the renal tubular effect of other nephrotoxic agents. Also, the following equation may be applicable to the population neither with dental amalgam fillings nor with occupational exposures: [hair mercury (microg/g)]=2.44x[toenail mercury (microg/g)].

Effects of mercury vapor exposure on neuromotor function in Chinese miners and smelters.

OBJECTIVES: Current risk assessment of elemental mercury vapor is based on the tremor toxicity. To clarify the neuromotor effects of occupational exposure to mercury vapor, hand tremor and postural sway were measured in 27 miners and smelters (i.e., exposed workers) and 52 unexposed subjects. METHODS: Urine samples were collected and total mercury and creatinine concentrations were determined. Data of the tremor and postural sway were analyzed using the fast Fourier transformation. RESULTS: The geometric means of the urinary mercury level (UHg) were 228 (range 22.6-4,577) microg/g creatinine for the exposed workers and 2.6 (1.0-17.4) microg/g creatinine for the unexposed subjects. Total tremor intensity and frequency-specific tremor intensities at 1-6 and 10-14 Hz were significantly larger in the exposed workers than in the unexposed subjects (P < 0.05), but they were not significantly related to the UHg among the exposed workers (P > 0.05). In contrast, there were no significant differences in any postural sway parameters between the above two groups (P > 0.05), but the transversal sway with eyes open was positively related to the UHg among the exposed workers in using multiple regression analysis (P < 0.05). CONCLUSIONS: These findings suggest that postural sway, as well as hand tremor, may be affected by elemental mercury vapor exposure, but the former test seems to be less sensitive to mercury than the latter one.

Long-term consequences of arsenic poisoning during infancy due to contaminated milk powder.

Arsenic toxicity is a global health problem affecting many millions of people. The main source of exposure is drinking water contaminated by natural geological sources. Current risk assessment is based on the recognized carcinogenicity of arsenic, but neurotoxic risks have been overlooked. In 1955, an outbreak of arsenic poisoning occurred among Japanese infants, with more than 100 deaths. The source was contaminated milk powder produced by the Morinaga company. Detailed accounts of the Morinaga dried milk poisoning were published in Japanese only, and an overview of this poisoning incident and its long-term consequences is therefore presented. From analyses available, the arsenic concentration in milk made from the Morinaga milk powder is calculated to be about 4-7 mg/L, corresponding to daily doses slightly above 500 microg/kg body weight. Lower exposures would result from using diluted milk. Clinical poisoning cases occurred after a few weeks of exposure, with a total dose of about 60 mg. This experience provides clear-cut evidence for hazard assessment of the developmental neurotoxicity. At the present time, more than 600 surviving victims, now in their 50s, have been reported to suffer from severe sequelae, such as mental retardation, neurological diseases, and other disabilities. Along with more recent epidemiological studies of children with environmental arsenic exposures, the data amply demonstrate the need to consider neurotoxicity as a key concern in risk assessment of inorganic arsenic exposure.

Impact of total sleep duration on blood pressure in preschool children.

The onset of some adult diseases, e.g., cardiovascular disease, is known to be associated with lifestyles in childhood. The objective of this study was to clarify the relationship between total sleep duration (TSD) and systolic and diastolic blood pressure (SBP and DBP) among 117 children at ages 5-6 years. Parents reported their children's typical bedtimes and wake times for weekdays, and questions about mandatory nap times were answered by the preschool teachers. In the children, the mean TSD, SBP, and DBP were 624 +/- 57 (standard deviation) min, 99 +/- 10 mmHg, and 62 +/- 9 mmHg, respectively. When the children were divided into quartile groups based on TSD, the SBP was significantly higher in the highest group (TSD > 660 min) than in the lowest group (TSD < or = 585 min). The TSD was significantly correlated with SBP (r = 0.265) but not with DBP (r = 0.105), these relationships were similar when TSD and possible confounders such as age and body mass index were set as independent variables of multiple regression analysis. These findings suggest that sleep duration in preschool children is associated with SBP, and extremely short or long sleep may invite subclinical health problems.

Cardiac autonomic hypofunction in preschool children with short nocturnal sleep.

Preschool children with sleep deficit may suffer from autonomic symptoms or hypotension. Heart rate variability, reflecting cardiac parasympathetic and sympathetic activities, and blood pressure were assessed to clarify the effects of nocturnal sleep duration on cardiac autonomic function in 134 preschool children aged 5 and 6 years. Parents reported their children's typical bedtimes and wake times for weekdays. In the children, the mean nocturnal sleep duration (+/- standard deviation) was 575 +/- 42 min. The parasympathetic and sympathetic activities and systolic blood pressure (SBP) were significantly lower in the 80 children with short sleep (nocturnal sleep duration < 10 hrs) than in the 54 children with long sleep (> or = 10 hrs). Only the SBP was positively correlated with nocturnal sleep duration in the children (p < 0.001); also, short nocturnal sleep duration was significantly related to hypotension (SBP < 100 mmHg), as judged by multiple logistic regression analysis. Among the children, inverse correlations were seen between the parasympathetic activity and SBP and between the sympathetic activity and diastolic blood pressure (p < 0.05). These findings indicate that shortening of nocturnal sleep is associated with cardiac autonomic hypofunction and low SBP in preschool children. We suggest that sleep duration is an important predictor for autonomic development in childhood.

Relation between benchmark dose and no-observed-adverse-effect level in clinical research: effects of daily alcohol intake on blood pressure in Japanese salesmen.

The benchmark dose (BMD) is defined as the dose that corresponds to a specific change in an adverse response compared to the response in unexposed subjects, and the lower 95% confidence limit is termed the benchmark dose level (BMDL). In this study, the threshold of daily ethanol intake affecting blood pressure was calculated by both the BMD approach and multiple logistic regression analysis to clarify the relation between the BMDL and no-observed-adverse-effect level (NOAEL). Systolic and diastolic blood pressures (SBP and DBP) and daily ethanol intake were explored in 1,100 Japanese salesmen. The SBP and DBP were positively related to daily ethanol intake (p < 0.001) when adjusting for possible confounders such as age, body mass index, and smoking status. The adjusted risk for hypertension (SBP >or= 140 mmHg or DBP >or= 90 mmHg) increased significantly when daily ethanol intake exceeded 60 g/day, and the categorical dose of interest was 60.1-90 g/day. The BMDL and BMD of ethanol intake for increased SBP and DBP were estimated to be approximately 60 and 75 g/day, respectively. These findings suggest that the BMDL and BMD correspond to the NOAEL and lowest-observed-adverse-effect level, respectively, if the sample number of clinical data is large enough to confirm the dose-response association.

Subclinical effects of prenatal methylmercury exposure on cardiac autonomic function in Japanese children.

OBJECTIVES: The subclinical effects of prenatal exposure to methylmercury from fish consumption on the cardiac autonomic function were assessed in 136 Japanese 7-year-old children recruited for this study. METHODS: Samples of child's hair and dry umbilical cord preserved were collected, and hair mercury and cord tissue methylmercury concentrations were determined as current and prenatal exposure biomarkers, respectively. Cardiac autonomic indicators of parasympathetic and sympathetic activities were calculated from the electrocardiographic RR intervals measured. RESULTS: In the children, the cord tissue methylmercury (0.017-0.367, median 0.089 microg/g) was not significantly correlated with the hair mercury (0.43-6.32, median 1.66 microg/g). The cord tissue methylmercury was related negatively to parasympathetic components of cardiac autonomic indicators (P < 0.05) and positively to sympathovagal indices (P < 0.05), even after correction for possible confounders such as age and sex, although the hair mercury was not significantly correlated with any cardiac autonomic indicators. CONCLUSIONS: Despite the potential limitations involved in the retrospective study, these findings suggest that prenatal methylmercury exposure (median of estimated maternal hair mercury at parturition, 2.24 microg/g) may be associated with reduced parasympathetic activity and/or sympathovagal shift.

Factors affecting hand tremor and postural sway in children.

OBJECTIVES: It is crucial to consider covariates relevant for outcome variables in developing dose-effect relations of environmental hazardous toxins. The aim of this study was to clarify the covariates affecting hand tremor and postural sway in children. METHODS: Hand tremor and postural sway, as well as hair mercury concentrations, were measured in 155 boys and 148 girls at age 7 years. RESULTS: Current mercury concentrations in child hair ranged from 0.35 to 6.32 µg/g (geometric mean, 1.71 µg/g for boys and 1.58 µg/g for girls), and were not significantly correlated with the neuromotor parameters. All hand tremor and postural sway parameters, except for tremor intensity at 1-6 Hz with non-dominant hand, were significantly larger in the boys than in the girls. Using multiple regression analysis, some postural sway parameters were related negatively to age in the boys and girls (p<0.05), and positively to height (p<0.05). Similarly, hand tremor parameters were positively related to age, height and heart rate either in the boys or in the girls (p<0.05). Also, there were positive relationships between tremor intensity at 1-6 Hz and transversal and sagittal sways at 1-2 Hz and 2-4 Hz (p<0.05). CONCLUSIONS: Heart rate and postural sway, together with age, sex, and height, should be considered in interpreting hand tremor in children. Hand tremor or postural sway may not be so sensitive or specific to methylmercury exposures at levels of less than 7 µg/g in hair.

Benchmark dose of lead inducing anemia at the workplace.

To estimate the critical dose of lead inducing anemia in humans, the effects of lead on hemoglobin (Hb) and hematocrit (Hct) levels and red blood cell (RBC) count were examined in 388 male lead-exposed workers with blood lead (BPb) levels of 0.05-5.5 (mean 1.3) micromol/L by using the benchmark dose (BMD) approach. The BPb level was significantly related to Hb (regression coefficient beta=-0.276), RBC (beta=-11.35), and Hct (beta=-0.563) among the workers (p < 0.001) when controlling for age and working status. The average BPb levels were significantly higher in the workers with anemia (1.85 micromol/L), based on the WHO criteria, than in those without anemia (1.26 micromol/L). The benchmark dose levels of BPb (i.e., lower 95% confidence limits of BMD), calculated from the K-power model set at an abnormal probability of 5% in unexposed workers and an excess risk of 5% in exposed workers were estimated to be 0.94 micromol/L (19.5 microg/dl) for Hb, 0.94 micromol/L (19.4 microg/dl) for RBC, and 1.43 micromol/L (29.6 microg/dl) for Hct. These findings suggest that reduction in hematopoietic indicators may be initiated at BPbs below the level currently considered without effect.

Critical dose of lead affecting postural balance in workers.

BACKGROUND: The threshold blood lead (BPb) level for nervous system dysfunction in adults has been estimated to be 30-40 microg/dl. This study was carried out to estimate the critical dose of lead affecting the neuromotor function in workers by introducing the benchmark dose (BMD) approach, as well as to identify the specific postural sway to lead exposure. METHODS: Postural sway parameters with spectral analysis were compared between 121 lead workers with BPb levels of 6-89 (mean 40) microg/dl and 60 unexposed controls. RESULTS: All sway parameters, except for sagittal sways with eyes open, were significantly larger in the lead workers than in the controls; also, the Romberg quotient for sagittal sway was significantly higher in the lead workers. The BPb level in the lead workers was significantly related to sagittal sways at 1-2 Hz and 2-4 Hz with eyes open, and sagittal and transversal sways at 1-2 Hz and 2-4 Hz with eyes closed. The BMD levels of BPb (i.e., lower 95% confidence limits of BMD) were estimated to be 12.1-17.3 (mean 14.4) microg/dl for postural sway. CONCLUSIONS: Neuromotor dysfunction in lead workers may be initiated at BPbs below the level previously accepted as effectless, and be characterized mainly by an increased sway of high frequency (1-4 Hz) in the sagittal direction with eyes closed (high Romberg quotient).

[Safety awareness of anticancer drug handling among Japanese nurses].

OBJECTIVES: The purpose of this study was to investigate Japanese nurses' awareness of the adverse effects of occupational exposure to anticancer drugs and safe handling, as well as their associations. METHODS: A self-rating questionnaire was mailed to 939 nurses in 107 university hospitals, 13 cancer-special hospitals, and 193 general hospitals with over 300 beds and at least five or more clinics in Japan. A total of 571 female nurses responded to the questionnaire. RESULTS: About 40% of the nurses were not at all aware of the potential adverse effects of occupational exposure to anticancer drugs. Eighty-eight percent of the nurses prepared anticancer drugs in the hospital wards; in most cases, nurses, not doctors or pharmacists, transported and administered such drugs to cancer patients. Regarding safety, 39% of the nurses took protective countermeasures against anticancer drugs; 15% paid special attention to the handling environment; 10% had guidelines for the handling of anticancer drugs; and, only 7% took countermeasures with body fluids or linen handling of cancer patients. Although 82% of the nurses were concerned about the potential health effects of occupational exposure, 75% or over did not know whether the exposure might affect their future health or progeny. Awareness of adverse effects was significantly related with precaution in anticancer drug handling, for which 95% of the nurses stated a desire for special education and training. CONCLUSIONS: Approximately 60% of Japanese nurses are aware of the risk of occupational exposure to anticancer drugs, but this might be an overestimate because of the sampling bias. Since only small numbers of nurses take sufficient safety precaution, programs for education and training for safe handling of anticancer drugs are crucial.