Surveillance of occupational lead exposure in New Jersey: 1986 to 1989

Chronic lead exposure effects in the cynomolgus monkey (Macaca fascicularis) testis

Although reproductive consequences of high circulating blood lead levels (> or = 60 micrograms/dL) have been reported, potential adverse effects of chronic lead exposure in males that result in low to moderate blood lead levels (10-25 and 26-60 micrograms/dL, respectively) are unknown. Effects of chronic lead exposure to testis ultrastructure were determined in the cynomolgus monkey after oral administration of lead acetate (1500 micrograms/kg BW/day) in a vehicle in the following groups: from birth to 10 years (lifetime), postnatal day 300 to 10 years (postinfancy), and postnatal day 0-400 (infancy); monkeys in the control group received only the vehicle (95% glycerol and 5% distilled water). At age 10 years, circulating lead concentrations in lifetime and postinfancy-dosed monkeys were approximately 35 micrograms/dL, and in control and infancy animals the concentrations were < 1.0 microgram/dL. Sertoli and spermatogenic cells of dosed monkeys from the infancy and lifetime groups revealed injuries. Chronic exposure to lead that results in moderate blood lead concentrations induced persistent ultrastructural alterations in the cynomolgus monkey testis. Results of this study on the primate, following extrapolation to humans, could influence further refining of the impact of environmental lead contamination concentrations vis-à-vis the health of children, adults, and aged human beings.

Elevated blood lead levels in children of construction workers

OBJECTIVES

This study examined whether children of lead-exposed construction workers had higher blood lead levels than neighborhood control children.

METHODS

Twenty-nine construction workers were identified from the New Jersey Adult Blood Lead Epidemiology and Surveillance (ABLES) registry. Eighteen control families were referred by workers. Venous blood samples were collected from 50 children (31 exposed, 19 control subjects) under age 6.

RESULTS

Twenty-six percent of workers children had blood lead levels at or over the Centers for Disease Control and Prevention action level of 0.48 mumol/L (10 micrograms/dL), compared with 5% of control children (unadjusted odds ratio = 6.1; 95% confidence interval = 0.9, 147.2).

CONCLUSIONS

Children of construction workers may be at risk for excessive lead exposure. Health care providers should assess parental occupation as a possible pathway for lead exposure of young children.

Sperm chromatin structure is altered in cynomolgus monkeys with environmentally relevant blood lead levels

Exposure to lead has been associated with a variety of adverse reproductive outcomes such as spontaneous abortion, impaired fecundity, and sterility. Although decreased sperm counts and serum testosterone levels have been found in men with occupational lead exposure, animal experiments suggest that fertility may be impaired at blood lead levels that have no apparent effect on reproductive hormone levels or sperm concentration. Consequently, this study investigated the effect of chronic lead treatment on semen quality in healthy cynomolgus monkeys aged 15-20 years with mean (+/-SD) blood lead levels of 10 +/- 3 micrograms/dL (range 6-20 micrograms/dL, n = 4) and 56 +/- 49 micrograms/dL (range 22-148 micrograms/dL, n = 7) compared to a reference group with blood lead levels < 1.0 microgram/dL (n = 8). Blood and semen samples were collected once from each monkey in five different months. Serum testosterone levels were determined by radioimmunoassay, and lead effects on chromatin structure were analyzed by flow cytometry. There were no effects of treatment on circulating levels of testosterone or parameters of semen quality such as sperm count, viability, motility, and morphology. However, significant (p < 0.03) treatment-related effects were seen on SD alpha t values in the treated vs control animals. Group comparisons also revealed that the effects of chronic lead exposure were significant (p < 0.05) for both lead-exposed groups compared to the reference group. We conclude that chronic lead exposure alters sperm chromatin structure at blood lead levels relevant to the human population and in the absence of effects on endocrine function and traditional measures of semen quality.

Unraveling the chronic toxicity of lead: an essential priority for environmental health

Although population exposure to lead has declined, chronic lead toxicity remains a major public health problem in the United States affecting millions of children and adults. Important gaps exist in knowledge of the pathophysiology of chronic lead intoxication. These gaps have impeded development of control strategies. To close current gaps in knowledge of chronic lead toxicity, we propose an integrated, multidisciplinary, marker-based research program. This program combines a) direct measurement of individual lead burden by 109Cd X-ray fluorescence analysis of lead in bone, b) determination of ALA-D phenotype, an index of individual susceptibility to lead, and c) assessments of subclinical injury produced by lead in the kidneys, nervous system and, reproductive organs. Data from this research will provide answers to questions of great public health importance: a) Are current environmental and occupational standards adequate to prevent chronic lead intoxication? b) is lead mobilized from the skeleton during pregnancy or lactation to cause fetal toxicity? c) Is lead mobilized from bone during menopause to cause neurotoxicity? d) What is the significance of genetic variation in determining susceptibility to lead? e) What is the contribution of lead to hypertension, renal disease, chronic neurodegenerative disease or declining sperm counts? f) Is chelation therapy effective in reducing body lead burden in persons with chronic overexposure to lead?

A pilot study of take-home lead exposure in New Jersey

Studies in various industries have found an association between worker exposure to lead and elevated blood lead levels in workers' children, but the magnitude of this problem is unknown. In an effort to characterize this problem further, a pilot study was undertaken to obtain blood lead levels of children of lead-exposed workers with elevated blood lead levels who had been reported by laboratories to the New Jersey Department of Health. Fifteen workers' families participated in this study, including 28 children. Thirty-two percent of the children were found to have blood lead levels > or = 10 micrograms/dl, the level of concern set by the Centers for Disease Control and Prevention for medical monitoring. This finding is in contrast to population-based data collected from the Third National Health and Nutrition Survey, where the overall prevalence of blood lead levels > or = 10 micrograms/dl was only 4.5%.

Elevated blood lead levels among construction workers in the Massachusetts Occupational Lead Registry

Although the construction industry until recently was exempt from the Occupational Health and Safety Administration General Industry Lead Standard, including its medical monitoring provisions, periodic blood lead tests have been required for residential "deleaders" and structural painters in Massachusetts. Sixty-three percent of the 381 registrants in the Massachusetts Occupational Lead Registry with blood lead levels of 1.93 mumol/L or higher are construction workers. This proportion is much higher than that reported by registries of several states selected for comparison. These data highlight the need for better protection from lead exposure and the effectiveness of mandatory medical surveillance in identifying elevated blood lead levels among construction workers.

Job tasks, potential exposures, and health risks of laborers employed in the construction industry

Construction laborers have some of the highest death rates of any occupation in the United States. There has been very little systematic research focused exclusively on "laborers" as opposed to other workers in the construction industry. We reviewed the English language literature and various data bases describing the occupational tasks, exposures, and work-related health risks of construction laborers. The sources of information included 1) occupational mortality surveillance data collected by the states of California and Washington and the National Institute for Occupational Safety and Health (NIOSH); 2) National Occupational Exposure Survey; 3) national fatality data; 4) cancer registry data; and 5) case reports of specific causes of morbidity. While the literature reported that construction laborers have increased risk for mesothelioma, on-the-job trauma, acute lead poisoning, musculoskeletal injury, and dermatitis, the work relatedness of excess risks for all-cause mortality, cirrhosis, cerebrovascular disease, chronic obstructive pulmonary disease, ischemic heart disease, and leukemia is less clear. Furthermore, while laborers are known to be potentially exposed to asbestos, noise, and lead, and the NIOSH Job Exposure Matrix describes other potential hazardous exposures, little research has characterized other possible exposures and no research has been found that describes the exposures associated with specific job tasks. More advanced study designs are needed that include a better understanding of the job tasks and exposures to construction laborers, in order to evaluate specific exposure-disease relationships and to develop intervention programs aimed at reducing the rate of work-related diseases.

The development of registries for surveillance of adult lead exposure, 1981 to 1992

OBJECTIVES

Since 1981, 15 states have established registries for surveillance of adult lead absorption, primarily based on reports of elevated blood lead levels from clinical laboratories. I review the status of the registries and recommend steps for further development.

METHODS

Companies reported to the New York registry are compared with those cited by the Occupational Safety and Health Administration (OSHA). I present data on US workers and plants with potential lead exposures and blood tests, as well as review registries' reporting requirements.

RESULTS

Registries identify many companies not cited by the Occupational Safety and Health Administration, but underreporting occurs because (1) reporting is usually not required from laboratories outside the state, (2) most registries use a blood lead reporting level of 1.21 mumol/L, which excludes many exposed workers, and (3) many companies with potential exposures do not have routine monitoring programs.

CONCLUSIONS

Registries' reporting requirements and procedures should be standardized, including a blood lead reporting level of 0.72 mumol/L. Elevated blood lead levels should be a reportable condition nationwide, and a comprehensive national surveillance system should be established: clinical laboratories should be required to report cases to those states with lead registries or directly to the national adult lead registry.