The initial impact of a workplace lead-poisoning prevention project

Educational interventions for preventing lead poisoning in workers

BACKGROUND

Occupational lead exposure can lead to serious health effects that range from general symptoms (depression, generalised ache, and digestive signs, such as loss of appetite, stomach ache, nausea, diarrhoea, and constipation) to chronic conditions (cerebrovascular and cardiovascular diseases, cognitive impairment, kidney disease, cancers, and infertility). Educational interventions may contribute to the prevention of lead uptake in workers exposed to lead, and it is important to assess their effectiveness.

OBJECTIVES

To assess the effect of educational interventions for preventing lead uptake in workers exposed to lead.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, and OSH UPDATE to 5 June 2020, with no language restrictions.

SELECTION CRITERIA

We sought randomised controlled trials (RCT), cluster-RCTs (cRCT), interrupted time series (ITS), controlled before-after studies (CBA) and uncontrolled before-after studies that examined the effects of an educational intervention aimed at preventing lead exposure and poisoning in workers who worked with lead, for which effectiveness was measured by lead levels in blood and urine, blood zinc protoporphyrin levels and urine aminolevulinic acid levels.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results, assessed studies for eligibility, and extracted data using standard Cochrane methods. We used the ROBINS-I tool to assess the risk of bias, and GRADE methodology to assess the certainty of the evidence.

MAIN RESULTS

We did not find any RCT, cRCT, ITS or CBA studies that met our criteria. We included four uncontrolled before-after studies studies, conducted between 1982 and 2004. Blood lead levels Educational interventions may reduce blood lead levels, but the evidence is very uncertain. In the short-term after the educational intervention, blood lead levels may decrease (mean difference (MD) 9.17 µg/dL, 95% confidence interval (CI) 4.14 to 14.20; one study with high baseline blood lead level, 18 participants; very low-certainty evidence). In the medium-term, blood lead levels may decrease (MD 3.80 µg/dL, 95% CI 1.48 to 6.12; one study with high baseline blood lead level, 34 participants; very low-certainty evidence). In the long-term, blood lead levels may decrease when the baseline blood lead levels are high (MD 8.08 µg/dL; 95% CI 3.67 to 12.49; two studies, 69 participants; very low-certainty evidence), but not when the baseline blood lead levels are low (MD 1.10 µg/dL, 95% CI -0.11 to 2.31; one study, 52 participants, very low-certainty evidence). Urine lead levels In the long-term, urinary lead levels may decrease after the educational intervention, but the evidence is very uncertain (MD 42.43 µg/L, 95% CI 29.73 to 55.13; one study, 35 participants; very low-certainty evidence). Behaviour change The evidence is very uncertain about the effect of educational intervention on behaviour change. At medium-term follow-up after the educational intervention, very low-certainty evidence from one study (89 participants) found inconclusive results for washing before eating (risk ratio (RR) 1.71, 95% CI 0.42 to 6.91), washing before drinking (RR 1.37, 95% CI 0.61 to 3.06), and not smoking in the work area (RR 1.04, 95% CI 0.74 to 1.46). Very low-certainty evidence from one study (21 participants) suggested that employers may improve the provision of fit testing for all respirator users (RR 1.87, 95% CI 1.16 to 3.01), and prohibit eating, drinking, smoking, and other tobacco use in the work area (RR 4.25, 95% CI 1.72 to 10.51), however, the results were inconclusive for the adequate provision of protective clothing (RR 1.40, 95% CI 0.82 to 2.40). At long-term follow-up, very low-certainty evidence from one study (89 participants) suggested that workers may improve washing before drinking (RR 3.24, 95% CI 1.09 to 9.61), but results were inconclusive for washing before eating (RR 11.71, 95% CI 0.66 to 208.33), and for not smoking in the work area (RR 1.56, 95% CI 0.98 to 2.50). Very low-certainty evidence from one study (21 participants) suggested that employers may improve the provision of fit testing for all respirator users (RR 1.70, 95% CI 1.09 to 2.63), may provide adequate protective clothing (RR 2.80, 95% CI 1.23 to 6.37), and may prohibit eating, drinking, smoking, and other tobacco use in the work area (RR 2.13, 95% CI 1.19 to 3.81). Improved knowledge or awareness of the adverse health effects of lead The evidence is very uncertain about the effect of educational intervention on workers' knowledge. At medium-term follow-up, questionnaires found that workers' knowledge may improve (MD 5.20, 95% CI 3.29 to 7.11; one study, 34 participants; very low-certainty evidence). At long-term follow-up, there may be an improvement in workers' knowledge (MD 5.80, 95% CI 3.89 to 7.71; one study, 34 participants; very low-certainty evidence), but results were inconclusive for employers' knowledge (RR 1.67, 95% CI 0.74 to 3.75; one study, 21 participants; very low-certainty evidence). None of the studies measured the other outcomes of interest: blood zinc protoporphyrin levels, urine aminolevulinic acid levels, air lead levels, and harms. One study provided the costs of each component of the intervention.

AUTHORS' CONCLUSIONS

Educational interventions may prevent lead poisoning in workers with high baseline blood lead levels and urine lead levels but this is uncertain. Educational interventions may not prevent lead poisoning in workers with low baseline blood lead levels but this is uncertain.

Homeopathic Plumbum metallicum for lead poisoning: a randomized clinical trial

INTRODUCTION

Poisoning due to lead and its compounds has short and long-term effects primarily on the nervous, hematopoietic, gastrointestinal, cardiovascular, musculoskeletal, renal and reproductive systems. It can manifest in acute or chronic symptoms. Measuring serum concentration is the primary method for diagnosing and monitoring exposed workers. Presently, elevated lead levels are treated by drugs whose effectiveness is contested on various fronts. Experimental studies suggest that homeopathic preparations may be in controlling blood lead levels in laboratory animals, creating the need for controlled studies to evaluate the effectiveness and safety of these preparations in humans.

OBJECTIVE

To evaluate the effectiveness of the homeopathic preparation Plumbum metallicum in reducing the blood lead level of workers exposed to this metal.

DESIGN

Double-blind randomized trial.

SETTING

Workers' clinic in the Ajax battery plant, which employs 900 workers with varying degrees of lead exposure in Bauru, São Paulo State, Brazil.

SUBJECTS

131 workers exposed to lead.

INTERVENTION

Plumbum metallicum 15 cH or placebo, orally for 35 days.

RESULTS

The percentage of workers who demonstrated a reduction in lead counts by a percentage greater than or equal to 25% following treatment was the same for both groups: 20.3% in the homeopathic groups versus 21% in the control group [Relative Risk (RR) = 0.95, confidential interval (CI) 95%: 0.47-1.92)]. Analysis by intention-to-treat also did not show any difference between the groups: 18.2% in the treated group versus 20% in the placebo group (RR = 0.91, CI 95%: 0.45-1.84).

CONCLUSION

The homeopathic preparation Plumbum metallicum had no effect, in this study, in terms of reducing serum lead in workers exposed to lead.

Results of inspections in health hazard industries in a region of the state of Washington

Results from state of Washington Occupational Safety and Health Administration (OSHA) health inspections were reviewed to characterize the level of control that existed at the work sites, identify common problems, and assess the success of targeting programs in finding and correcting uncontrolled health hazards. Data were obtained from 170 inspections conducted by industrial hygienists in a four-county area in 12 industries, including 10 that were targeted. Inspection data were accessed through the use of electronic databases and inspection reports then summarized by the following industries: bathtub refinishing, carbide tool and saw sharpening, fibercement siding installation, furniture refinishing, health care clinics, janitorial floor waxing service, landscaping, lawn maintenance, tree service, road construction, stone countertop fabrication, truck bed lining, warehouse and cold storage, and wood floor finishing. Targeted health hazards included worker exposure to airborne contaminants, noise, and bloodborne pathogens typical of the industry. Method and effectiveness of control of health hazards were evaluated by counting work sites with violations associated with engineering control, personal protective equipment, hearing conservation, or training. Results are presented by industry for the number and percentage of work sites that failed to provide required protection. Poor control of health hazards was generally found across all inspected industries. Follow-up inspections and self-reports of abatement found that more than 85% were able to successfully control the hazards and abate the violations. The results are further discussed as they relate to methods of control and risk and identifying existing and emerging high health hazard industries. Based on employment data and the poor hazard control that was found, most if not all the industries can be described as high health hazard, small-employer industries. The results can be used for the planning of interventions in other regions and industries.

Lead exposure in radiator repair workers: a survey of Washington State radiator repair shops and review of occupational lead exposure registry data

Radiator repair workers in Washington State have the greatest number of very elevated (> or =60 microg/dL) blood lead levels of any other worker population. The goals of this study were to determine the number of radiator repair workers potentially exposed to lead; estimate the extent of blood lead data underreporting to the Occupational Lead Exposure Registry; describe current safety and health practices in radiator repair shops; and determine appropriate intervention strategies to reduce exposure and increase employer and worker awareness. Lead exposure in Washington State's radiator repair workers was assessed by reviewing Registry data and conducting a statewide survey of radiator repair businesses. This study revealed that a total of 226 workers in Washington State (including owner-operators and all employees) conduct repair activities that could potentially result in excessive exposures to lead. Approximately 26% of radiator repair workers with elevated blood lead levels (> or =25 microg/dL) were determined to report to Washington State's Registry. This study also revealed a lack of awareness of lead's health effects, appropriate industrial hygiene controls, and the requirements of the Lead Standard. Survey respondents requested information on a variety of workplace health and safety issues and waste management; 80% requested a confidential, free-of-charge consultation. Combining data derived from an occupational health surveillance system and a statewide mail survey proved effective at characterizing lead exposures and directing public health intervention in Washington State.

Lead exposure in Mexican radiator repair workers

BACKGROUND

Lead exposure was investigated among 73 Mexican radiator repair workers (RRWs), 12 members of their family (4 children and 8 wives), and 36 working controls. RRWs were employed at 4 radiator repair shops in Mexico City and 27 shops in Cuernavaca and surrounding areas.

METHODS

Exposure was assessed directly through the use of personal air sampling and hand wipe samples. In addition, industrial hygiene inspections were performed and detailed questionnaires were administered. Blood lead levels were measured by graphite furnace atomic absorption spectroscopy (AAS).

RESULTS

The mean (SD) values for blood lead of the RRWs, 35.5 (13.5) microg/dl, was significantly greater than the same values for the working controls, 13.6 (8.7) microg/dl; P < 001. After excluding a single outlier (247 microg/m(3)), air lead levels ranged from 0 to 99 microg/m(3) with a mean (SD) value of 19 (23) microg/m(3) (median = 7.9 microg/m(3)). In a final multivariate regression model of elevated blood lead levels, the strongest predictors were smoking (vs. non-smoking), the number of radiators repaired per day on average, and the use (vs. non-use) of a uniform while at work, which were associated with blood lead elevations of 11.4 microg/dl, 1.95 microg/dl/radiator/day, and 16.4 microg/dl, respectively (all P <.05). Uniform use was probably a risk factor because they were not laundered regularly and consequently served as reservoir of contamination on which RRWs frequently wiped their hands.

CONCLUSIONS

Lead exposure is a significant problem of radiator repair work, a small industry that is abundant in Mexico and other developing countries.

[Occupational lead exposure assessment: a proposal for a strategy to monitor prevention of clinical and subclinical effects]

In developing countries, lead-acid battery factories are one of the heaviest consumers of lead. Due to lead's toxicological properties and prevalent working conditions in such factories, workers are subject to high exposure and health risk. This study discusses results obtained by lead exposure assessment of workers from a Rio de Janeiro battery factory, in light of Brazilian legislation and recent scientific data. Evaluation methods used were environmental (personal air sampling) and biological (determination of lead in blood, Pb-B) monitoring, showing a high personal exposure both in air (>0.1 mg/m3) and blood (55% of Pb-B >25 microg/dl). These results confirmed the inefficiency of current control measures, with a possible 46% of workers presenting a Pb-B range of 25-60 microg/dl in risk areas. Recent data suggest that Pb-B levels above 25 microg/dl are related to subclinical alterations in human body that should be investigated during clinical examination. Finally, we propose a strategy based on environmental and biological monitoring to prevent both clinical and subclinical effects.

Lead may affect glucocorticoid signal transduction in cultured hepatoma cells through inhibition of protein kinase C

Specific cellular sites of lead action have not been completely defined. To elucidate the effects of lead exposure on glucocorticoid-mediated signal transduction in hepatic hormonal target tissues, the induction of tyrosine aminotransferase (TAT) specific activity in the H4-IIE-C3 hepatoma cell culture model system was employed. It had been found that lead acetate (3-10 microM) exposure of HTC cells significantly reduced TAT specific activity in a concentration- and time-dependent manner. Two possible molecular targets of the lead-induced effect were investigated: interference with calcium-mediated cellular processes and calcium- and phospholipid-dependent protein kinase C (PKC) activity and isoform-type interactions. Lead acetate treatment (5 microM) reduced TAT specific activity below sodium acetate treated controls by 31%. One-half of the TAT specific activity was recovered by co-treatment with 5 microM lead acetate and 10 mM calcium chloride. As the concentration of lead acetate was increased to 10 microM, interference in calcium-mediated events also increased. Potentiation of glucocorticoid induction by phorbol myristate acetate (PMA) (300 nM) in control cells was 34%, but was abolished by exposure of cells to 10 microM lead acetate (48 h). Treatment with the kinase inhibitor genistein decreased TAT specific activity by 55% and 45% in control and lead acetate exposed cells, respectively. Following treatment with dexamethasone (100 nM), significant increases in both cytosolic and particulate PKC were noted in control cells but not lead acetate exposed cells. Western blot results indicated that lead exposure may increase PKC beta and decrease PKC alpha translocation from cytosolic to particulate fractions, respectively. Taken together, these results suggest that glucocorticoid signal transduction pathways in HTC cells involve calcium-mediated cellular events and PKC isoforms. Exposure of cells to lead results in interference with calcium-mediated events and aberrant modulation of PKC activities. Within hormonal target cells, these may be toxic molecular sites of action of the heavy metal lead and may contribute to the overall toxicity of lead exposure.

The acute effect of lead acetate on glucocorticoid receptor binding in C6 glioma cells

Lead exerts significant toxic effects on the nervous system, the hematopoietic system and the kidney. Specific cellular sites of action of this environmental pollutant have not been elucidated in the central nervous system. The present investigations were conducted to test the hypothesis that lead exposure perturbs glucocorticoid-mediated events in central nervous system hormonal target tissues. Utilizing the C6 glioma cell culture model in these studies, glucocorticoid receptor binding to its cytosolic receptor was investigated. Receptor binding studies yielded a Kd= 10.5 +/- 0.5 nM and a Bmax = 486 +/- 27 fmol/mg protein in untreated cells versus a Kd = 23.1 +/- 2.6 nM and Bmax = 472 +/- 35 fmol/mg protein in cells exposed to 10 microM lead acetate for 24 h. Presence of lead in these glial cells may decrease affinity of the glucocorticoid for its receptor without affecting receptor number. Treatment with 10 microM lead acetate for 48 h, resulted in a significant reduction in glucocorticoid-regulated glycerol phosphate dehydrogenase (GPDH) specific activity. These effects were not due to cell cytotoxicity assessed as cell number growth curves, [3H]thymidine incorporation or trypan blue exclusion. In protein kinase C (PKC) activity assays, treatment of cells with sodium or lead acetate and dexamethasone indicated that both lead and dexamethasone affect the distribution of PKC. In lead-treated cells cytosolic PKC activity was reduced 48% when compared to sodium acetate treated controls. Taken together, these results suggest that acute exposure of C6 cells to lead may inhibit processes involved in glucocorticoid-mediated signal transduction events within central nervous system hormonal target cells. Lead may perturb initial glucocorticoid binding events possibly by affecting PKC-mediated phosphorylations in the glucocorticoid signal transduction system.

Blood lead levels in radiator repair workers in Colorado

A laboratory-based blood lead surveillance system in Colorado identified radiator repair workers as having the highest blood lead levels of all worker groups reported. A survey of 42 radiator repair shops in ten locales throughout Colorado was undertaken to estimate the prevalence of workers with elevated blood lead levels > 25 micrograms/dL. The survey was designed to test the sensitivity of the surveillance system and to assess working conditions and practices in the radiator repair industry in Colorado. Of 63 workers, 39 (62%) had blood lead levels > 25 micrograms/dL. The sensitivity of the surveillance system for detecting radiator repair workers with elevated blood lead levels was estimated at 11%. None of the radiator repair shops had adequate local exhaust ventilation. Work practice and engineering modifications are needed to reduce lead exposure in this industry.

The acute effect of lead acetate on glucocorticoid regulation of tyrosine aminotransferase in hepatoma cells

Specific cellular sites of action of the environmental pollutant, lead, have not been completely defined. The present investigations were conducted to test the hypothesis that lead exposure perturbs glucocorticoid-mediated effects in hormonal target tissues. The cell culture model chosen for these investigations was the effects of lead on glucocorticoid-regulated tyrosine aminotransferase (TAT) specific activity in the H4-II-C3 hepatoma cells. Cells were treated with 300 nM-10 microM lead acetate for 24 or 48 h in absence or presence of the inducing agent, dexamethasone. Lead dose-dependently inhibited TAT specific activity up to 52% and 61% following 24 and 48 h lead treatments, respectively. These treatment times and concentrations of lead acetate did not significantly alter total cell numbers, [3H]thymidine incorporation or trypan blue exclusion. Glucocorticoid receptor-binding studies yielded a Kd = 8.3 nM and a Bmax = 290 fmol/mg protein in untreated cells versus a Kd = 9.2 nM and Bmax = 262 fmol/mg protein in cells exposed to 10 microM lead acetate for 48 h. Treatment with lead did not significantly perturb uptake of the inducing glucocorticoids or initial cytosolic receptor-binding events. To sustain induced levels of TAT, glucocorticoid must be continuously present. Following steroid withdrawal, enzyme de-induction was significantly altered in lead-treated cells. At 6 h following dexamethasone withdrawal, TAT levels had decreased to 51% of maximum in sodium acetate-treated cells. This was significantly reduced to 33% of maximum in lead acetate-treated cells. Lead treatment of HTC cells was also shown to ameliorate PMA amplification of dexamethasone-induced TAT activity. Taken together, these results suggest that acute exposure of cells to lead may inhibit processes involved in glucocorticoid-mediated enzyme induction within the hormonal target cell. Results suggest that lead may be acting to increase the turnover of TAT by actions at the transcription, translation and/or posttranslational level. Lead may also be affecting PKC-mediated phosphorylations in the glucocorticoid-TAT signal transduction system.

Occupational lead poisoning: can it be eliminated?

The continued occurrence of occupational lead poisoning and overexposure in the United States represents a serious challenge to the occupational health community. We outline a proposed action strategy which integrates case-based surveillance, hazard surveillance, increased requirements for biological monitoring, and targeted educational activities, with a goal of eliminating occupational lead poisoning. The system provides a simple mechanism for monitoring compliance in lead-using employers, in order to identify employers for enforcement action. Lead poisoning should be viewed as an eradicable condition; successfully solving the persistent lead overexposure problem can serve as a model for approaching other occupational diseases.

California adults with elevated blood lead levels, 1987 through 1990

OBJECTIVES

Follow-up of California blood lead registry reports, 95% of which are of occupationally exposed adults, can guide interventions at specific high-risk work sites and measure the impact of targeted, industry-specific interventions.

METHODS

A protocol was implemented to follow up the most severe case reports (> or = 2.90 mumol/L) and establish a statistical database for descriptive analysis.

RESULTS

From 1987 through 1990, the California Department of Health Services received 17,951 reports for 4069 civilian, noninstitutionalized adults employed by at least 328 companies. Of 232 incident case subjects with severe lead toxicity (> or = 2.90 mumol/L), 182 were successfully traced and interviewed. Index case subjects were mostly male (95%) and disproportionately Hispanic (46%); 35% lived with children aged 7 or younger, and 10% had been hospitalized. Ninety-four percent involved overexposures at work sites that lacked medical removal (50%), ventilation (36%), appropriate respirators (62%), training (64%), clothing changes (45%), or showering (60%).

CONCLUSIONS

Well-known risk factors for occupational lead poisoning clustered at the work sites of index case subjects. Despite standards of the Occupational Safety and Health Administration, lead overexposure in California adults remains a significant public and occupational health concern.