Educational interventions for preventing lead poisoning in workers New

Abstract

Abstract
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.

Author(s)

Sara Allaouat, Viraj K Reddy, Kimmo Räsänen, Sohaib Khan, Mieke EGL Lumens

Abstract

Plain language summary

 Educational programs and training to prevent lead uptake in workers exposed to lead 

 Background 

On a daily basis, workers in a wide range of industries come in contact with a harmful metal called lead. There is no known level of exposure to lead that does not cause harm to health, therefore, reducing exposure is essential. Educational programmes and training can prevent the uptake of lead in workers.

 What is the aim of this review? 

We searched five databases for randomised (RCT) and non‐randomised studies to assess the effectiveness of these educational programmes.

 Key messages 

Educational interventions may prevent lead poisoning in workers but we are very uncertain of this finding, therefore, more studies of better quality are required.

 What was studied in the review? 

We included four uncontrolled before‐after studies in this review. The studies assessed the effectiveness of educational interventions for preventing lead uptake in workers exposed to lead. We assessed a critical risk of bias in three studies and a moderate risk of bias in one.

 What are the main results of the review? 

Very low‐quality evidence from three studies with participants with high baseline blood lead levels, suggested a decrease in blood lead after education; one study with participants with low baseline blood lead found conflicting results. Very low‐quality evidence from one study suggested a decrease in urinary lead levels.

There may be an effect, but we are very uncertain if educational interventions are effective in preventing lead poisoning in workers with high baseline blood lead levels and urine lead levels. For workers with low baseline blood lead levels, the results were inconclusive.

 How up‐to‐date is this review? 

We searched for studies to 5 June 2020.

Author(s)

Sara Allaouat, Viraj K Reddy, Kimmo Räsänen, Sohaib Khan, Mieke EGL Lumens

Reviewer's Conclusions

Authors' conclusions

Implications for practice

Educational interventions may prevent lead poisoning in workers with high baseline blood lead levels (BLL) and urine lead levels (ULL) but we are very uncertain of this effect. We are also very uncertain if educational interventions may not have any effect in preventing lead poisoning in workers with low baseline BLL.

Implications for research

Future research should focus on high‐quality studies to evaluate the effectiveness of educational interventions for preventing lead poisoning in workers, and include a control group. Carrying out randomised‐controlled trials (RCTs) or cluster‐RCTs would be ideal. However, they present major challenges in occupational settings, where the education is given to groups of workers, and the educational component would likely be part of a more comprehensive intervention. Therefore, other designs should be considered. One alternative is the use of controlled before‐after studies, when it is possible to control for possible changes over time. This could be done, for example, by collecting data from factory sections where workers are not enrolled to receive the educational intervention. An interrupted time series study design could also be used, since it allows investigators to control for changes over time. Moreover, unlike the uncontrolled before‐after study design, they show that a change in outcome is clearly related to implementation of the intervention (Goodacre 2015). Other study designs, like a stepped‐wedge RCT, could also be implemented (Schelvis 2015).

These trials should be conducted especially in low‐income countries, where there is a higher incidence of occupational lead poisoning. Other studies, which have focused on educational and behavioural interventions to reduce chemical exposure have shown positive results (Bradman 2008). Future trials should also include women, who constitute a more lead sensitive population than men.

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