Occupational lead poisoning: can it be eliminated?

Bone manganese is a sensitive biomarker of ongoing elevated manganese exposure, but does not accumulate across the lifespan

Studies have established associations between environmental and occupational manganese (Mn) exposure and executive and motor function deficits in children, adolescents, and adults. These health risks from elevated Mn exposure underscore the need for effective exposure biomarkers to improve exposure classification and help detect/diagnose Mn-related impairments. Here, neonate rats were orally exposed to 0, 25, or 50 mg Mn/kg/day during early life (PND 1-21) or lifelong through ∼ PND 500 to determine the relationship between oral Mn exposure and blood, brain, and bone Mn levels over the lifespan, whether Mn accumulates in bone, and whether elevated bone Mn altered the local atomic and mineral structure of bone, or its biomechanical properties. Additionally, we assessed levels of bone Mn compared to bone lead (Pb) in aged humans (age 41-91) living in regions impacted by historic industrial ferromanganese activity. The animal studies show that blood, brain, and bone Mn levels naturally decrease across the lifespan without elevated Mn exposure. With elevated exposure, bone Mn levels were strongly associated with blood Mn levels, bone Mn was more sensitive to elevated exposures than blood or brain Mn, and Mn did not accumulate with lifelong elevated exposure. Elevated early life Mn exposure caused some changes in bone mineral properties, including altered local atomic structure of hydroxyapatite, along with some biomechanical changes in bone stiffness in weanlings or young adult animals. In aged humans, blood Mn ranged from 5.4 to 23.5 ng/mL; bone Mn was universally low, and decreased with age, but did not vary based on sex or female parity history. Unlike Pb, bone Mn showed no evidence of accumulation over the lifespan, and may not be a biomarker of cumulative long-term exposure. Thus, bone may be a useful biomarker of recent ongoing Mn exposure in humans, and may be a relatively minor target of elevated exposure.

Increased reporting of occupational hearing loss: workers' compensation in Washington State, 1984-1998

BACKGROUND

Workers' compensation claims for hearing loss increased two-fold during 1984-1991 in Washington State.

METHODS

This population-based descriptive study examined 27,019 claims filed during 1984-1998 and accepted for hearing loss, in the workers' compensation jurisdiction that covers nearly all non-federal workers in Washington State.

RESULTS

The number of claims increased 12-fold during 1984-1998. The annual incidence reached 2.6/1,000 workers statewide, and 70/1,000 in the most impacted industry. The increase involved all ages over 35 years, especially claimants over 65 years. Only 4% of providers accounted for 66% of claims. Most claimants (90%) received permanent partial disability compensation. In 1998, identifiable costs exceeded $57 million dollars.

CONCLUSIONS

The striking increase in claims is probably largely due to reporting phenomena unrelated to current work circumstances. However, occupational hearing loss is probably much more common than usually recognized, and contemporary workers may still face substantial risk for hearing loss.

Airborne exposure and soil levels associated with lead abatement of a steel tank

This study reports on airborne exposure levels and soil concentrations of lead in regard to abatement of a steel structure (water tank). The tank was de-leaded by abrasive sand blasting. The ball of the tank had a lead surface level that exceeded the Environmental Protection Agency (EPA) definition of lead-based paint (LBP) (0.5% lead), but paint on stem and base was below this criterion. Personal and area airborne samples were collected during different activities of lead abatement of the tank. Summary results suggest during abrasive blasting of ball and stem/base personal exposure levels, as reported with arithmetic and geometric means, exceed the Occupational Safety and Health Administration (OSHA) permissible exposure limit (50 microg/m3). Highest personal exposure (occupational exposure) was associated with blasting of ball. Distribution of airborne and soil samples suggest non-normality and is best represented by a logarithmic form. Geometric standard deviations for air and soil lead support a non-normal distribution. Outlying values were found for personal and area air samples. Exposure levels associated with blasting stem/base section of tank support OSHA's policy requiring air monitoring of work at levels below the criterion established by EPA in identifying LBP. Area samples were statistically lower than personal samples associated with blasting ball and stem/base of tank. Exposure data suggest that workers performing abatement on steel structures have elevated lead exposure from surface lead. Respirator protection requirements are discussed. Soil lead concentration was suggested to decrease as distance increased from tank. Soil lead is suggested to be a result of deposition from LBP on tank surface. Minimal efforts were required to reduce average lead soil levels below EPA's upper acceptable criterion (1200 ppm Pb).

Lead intoxication epidemic caused by ingestion of contaminated ground paprika

OBJECTIVE

Report of a lead intoxication epidemic caused by ingestion of contaminated ground paprika.

DESIGN

Retrospective study of case histories.

SETTING

Institutional, toxicological and medical referral center for ambulatory and hospitalized care.

PATIENTS

One hundred forty-one adults consumed paprika contaminated with lead tetroxide (red lead).

INTERVENTIONS

Intravenous calcium disodium versenate (edetic acid).

MAIN OUTCOME MEASURES

Measurement of zinc protoporphyrin:heme ratio of whole blood and the blood lead level. EDTA mobilization test.

RESULTS

Fifty-three patients had symptoms and signs of lead poisoning. The most common clinical signs were colic and/or anemia. Twenty-six persons showed increased lead absorption without clinical symptoms and signs. Chelation therapy with calcium disodium versenate resulted in complete clinical recovery.

CONCLUSION

Lead-contaminated ground paprika, not previously described as a cause of alimentary lead intoxication, may cause symptomatic poisoning.

Occupational lead poisoning: who should conduct surveillance and training?

This commentary challenges the current employer-controlled model for delivering occupational health services. Problems emanating from traditional employer-based medical surveillance and worker education programs for occupational lead poisoning are identified. A new public health model for delivering these services is proposed. This model utilizes a case-based and hazard-based method for bringing workplaces and employers into the program and features direct delivery of surveillance and training services by public health agencies.