Window renovation and exposure to lead--an observational study

BACKGROUND: Renovation of windows in old houses has recently established itself as an industry. A recognizable occupational lead exposure exists, which has not been studied previously. AIM: To compare lead exposure amongst window renovators with other groups of lead-exposed workers. METHODS: Using blood lead results measured at the Health and Safety Laboratory (HSL), Sheffield, comparisons were made between three cohorts: window renovation workers, all male workers monitored by HSL during the period 1999-2001 and 63 male subjects involved in chemical paint-stripping of wood. RESULTS: Both the window renovation and the wood-stripping cohorts show significantly higher blood lead distributions than the 'all workers' cohort (P < 0.001). A similar pattern was also found for comparison of the prevalence of subjects above the UK suspension level of 60 microg/dl (2.89 microM) (window renovation, P < 0.001; wood-stripping, P < 0.0001). Blood lead results at or above the suspension level in wood-strippers were significantly higher compared to window renovators (P = 0.034). CONCLUSION: Window renovation is shown to present a potential for significant lead exposure, and suspension from work under The Control of Lead at Work Regulations 2002. Two groups of risk factors predominate: the well-documented potential for release of lead from old paint, and the peripatetic nature of the work.     

Lead exposure in scaffolders during refurbishment construction activity--an observational study

The toxic effects of lead have been known for centuries. Occupational exposure to this chemical hazard has also been well documented in relation to various industry groups, including construction, where workers are recognized as being significantly exposed during refurbishment work, in particular through inhalation and ingestion of lead fumes and dust. It is easy to see how so-called 'burners', 'cutters' and 'blasters'--workers directly involved in removing old lead paint--may become exposed; the influence of personal hygiene, smoking, eating/drinking and nail biting has also been documented in the literature. We now report on one group, the scaffolders, not previously considered to be at risk. Although not directly involved in the paint removal, anecdotal and personal experience of the authors indicate that these workers, who erect and later dismantle access structures during the renovation of previously lead-painted surfaces, may take up significant amounts of lead, mainly by ingestion, to raise their personal blood lead levels (and body burden) in line with recognized 'lead workers'. Exposures of this magnitude would also bring the scaffolders involved in such refurbishment work under the Control of Lead at Work Regulations 1998. The authors make various recommendations on measures to minimize and control exposure of scaffolders to lead.     

Lead exposure in the lead-acid storage battery manufacturing and PVC compounding industries

This study was conducted as part of the Human Exposure Assessment Location (HEAL) Project which comes under the United Nations Environment Programme/World Health Organisation (UNEP/WHO) Global environmental Monitoring System (GEMS). The objective of the study was to evaluate workers' exposure to lead in industries with the highest exposure. All subjects were interviewed about their occupational and smoking histories, the use of personal protective equipment and personal hygiene. The contribution of a dietary source of lead intake from specified foods known to contain lead locally and personal air sampling for lead were assessed. A total of 61 workers from two PVC compounding and 50 workers from two lead acid battery manufacturing plants were studied together with 111 matched controls. In the PVC compounding plants the mean lead-in-air level was 0.0357 mg/m3, with the highest levels occurring during the pouring and mixing operations. This was lower than the mean lead-in-air level of 0.0886 mg/m3 in the lead battery manufacturing plants where the highest exposure was in the loading of lead ingots into milling machines. Workers in lead battery manufacturing had significantly higher mean blood lead than the PVC workers (means, 32.51 and 23.91 mcg/100 ml respectively), but there was poor correlation with lead-in-air levels. Among the lead workers, the Malays had significantly higher blood lead levels than the Chinese (mean blood levels were 33.03 and 25.35 mcg/100 ml respectively) although there was no significant difference between the two ethnic groups in the control group. There were no significant differences between the exposed and control group in terms of dietary intake of specified local foods known to contain lead. However, Malays consumed significantly more fish than the Chinese did. There were no ethnic differences in the hours of overtime work, number of years of exposure, usage of gloves and respirators and smoking habits. Among the Malays, 94.3% eat with their hands compared with 9.2% of the Chinese. Workers who ate with bare hands at least once a week had higher blood lead levels after adjusting for lead-in-air levels (mean blood lead was 30.2 and 26.4 mcg/100 ml respectively). The study indicated that the higher blood lead levels observed in the Malay workers might have been due to their higher exposure and eating with bare hands.     

Lead toxicity on the accessory reproductive organs in humans

The prostatic function of 50 males was studied. Thirty of the males were exposed to lead and 20 males were not exposed. The exposed individuals included workers at a battery manufacturing plant. The analysed variables were both acid and prostatic phosphatases. The level of exposure was estimated by means of lead concentration in blood. The total acid phosphatase activity was significantly higher in exposed subjects, when compared to control subjects. This was not the case with the acid prostatic phosphatase. These findings suggest that an extensive exposure to lead initially causes a direct prostatic toxicity likely to be reflected in alteration of seminal characteristics.     

Organophosphate toxicity and occupational exposure

The ubiquitous organophosphates present a continuing health hazard in agriculture, public health eradication programmes and as chemical warfare agents. Despite significant progress in understanding the potential mechanisms of toxicity far beyond the commonly accepted mechanism of cholinesterase inhibition in intentional exposures, the precise health effects following occupational exposures are yet to be completely defined. A much greater understanding exists of the clinical features of organophosphate poisoning. These are characterized by a triphasic response involving an initial acute cholinergic phase, an intermediate syndrome (both associated with high mortality) and a disabling but non-lethal delayed polyneuropathy. The delayed polyneuropathy may occur in the absence of the cholinergic or intermediate phases. However, progress is still required in order to improve the quantification and assessment of occupational exposures and the implementation of appropriate preventive measures. Finally, evidence-based guidelines for appropriate or optimal therapeutic interventions following poisoning are required urgently and collaborative work with colleagues in developing countries, where the occurrence of organophosphate exposures is more frequent, may provide the answers.     

The decay of blood lead levels in workers suspended under the control of lead at work regulations

AIMS: To study the rate of decline in blood lead levels post-suspension under Control of Lead at Work Regulations (CLAW) and thereby suggest sampling frequencies for follow-up blood lead measurements. METHODS: A retrospective cohort of lead workers with blood lead levels over the current suspension level were identified from blood lead records. Data on their suspension and follow-up blood lead measurements were obtained. RESULTS: Sixteen per cent of the identified cohort did not appear to return to lead work under CLAW. Twenty-seven suspension cases with an initial mean blood lead of 79 microg/dl (3.82 micromol/l) formed the dataset for analysis of decline in blood lead levels. The mean length of time between the blood sample indicating suspension and the first follow-up blood sample was 32 days. The mean length of suspension under CLAW was 61 days. The mean initial rate of blood lead decay was 0.659 microg/dl per day (0.032 micromol/l per day), although with a wide range. The rate of decline in blood lead after suspension was increased by the blood lead level at suspension, but was decreased by increasing past cumulative exposure. CONCLUSIONS: A follow-up blood lead sample 1 month after suspension should show a mean decrease between 13 and 26 microg/dl (0.63-1.25 micromol/l), which is substantially greater than that due to analytical 'noise' associated with two sequential measurements (approximately 5 microg/dl). Therefore, a follow-up blood sample taken around 3-4 weeks after suspension would seem practical. A decrease in blood lead of 7-8 mug/dl (0.36 micromol/l) or less in the month after suspension may suggest continuing lead exposure.     

Mercury toxicity due to the smelting of placer gold recovered by mercury amalgam

A 19-year-old man developed tremor in both hands and fatigue after starting work at a placer gold mine where he was exposed to mercury-gold amalgam. Examination revealed an intention tremor, dysdiadochokinesis and mild rigidity. The 24-h urinary mercury concentration reached a peak of 715 nmol/l (143 ug/l) shortly before the clinical examination, after which he was removed from working in the gold room [Mercury No. Adverse Effect Level: 250 nmol/l (50 ug/l)]. On review 7 weeks later his tremor had almost resolved and the dysdiadochokinesis and rigidity had gone. The 24-h urinary mercury concentration had fallen to 160 nmol/l (32 ug/l). The principal exposure to mercury was considered to be the smelting of retorted gold with previously unrecognized residual mercury in it. The peak air concentration of mercury vapour during gold smelting was 0.533 mg/m3 (Mercury Vapour ACGIH TLV: 0.05 mg/m3 TWA). Several engineering and procedural controls were instituted. This episode occurred at another mine site, unrelated to Mount Isa Mines Limited.     

Chronic lead poisoning in an adult battery worker

BACKGROUND: Lead poisoning is a common environmental health hazard in developing countries. Incidences of lead poisoning are seen in all age groups, especially in adults working in lead-based industries, where many still remain unaware of the adverse effects of exposure to unusually high levels of lead. METHODS: We report the case of an adult battery worker, who initially received symptomatic treatment because of clinical misdiagnosis. Later, he was treated with appropriate chelators, which helped to decrease blood lead levels drastically. However, being unable to change his occupation, he continues to be exposed to potentially lethal doses of lead. CONCLUSIONS: A key role for health agencies, besides providing opportunities for diagnosis and therapy, should be to increase public awareness about this widespread environmental hazard through education, documentation and communication.     

Lead exposure in ironworkers

In adults, lead toxicity is most commonly caused by occupation in a lead industry. Whereas lead toxicity has been described in workers who are involved in bridge rehabilitation, as of this date there has been no systematic evaluation published regarding the conditions responsible for lead toxicity in ironworkers. This is a report of a study designed to identify risk factors for elevated blood-lead levels in ironworkers. One hundred fifty members of a 2,400-member local ironworkers union volunteered to have their blood drawn for lead and zinc protoporphyrin analysis and to complete a questionnaire regarding demographics, health, and occupation. The relationships between these variables and blood-lead level were analyzed using student's t-test, chi-square, and logistic regression. Current work on a lead job, rivet busting as the predominant job task, and cigarette smoking were all found to be significantly associated with elevated blood-lead level. Whereas cigarette smoking and current work with lead have been previously identified as risk factors for toxicity, interventions to prevent lead toxicity in ironworkers should also focus on work practices during rivet busting. Am. J. Ind. Med. 32:540–543, 1997. © 1997 Wiley-Liss, Inc.     

氧化损伤与铅毒性研究进展

铅是一种对全身组织有广泛亲和力的毒物,作用的基点是体内一些生物大分子(蛋白质、脂类、核酸),进而使大分子受损,影响到细胞功能.     

硒对铅毒性的拮抗作用

近年来,随着对硒研究的不断深入,人们发现硒有拮抗铅毒性的作用:一方面硒是体内抗氧化系统的重要组成成分,能明显改善铅中毒诱发的脂质过氧化反应,减轻铅的危害;另一方面硒与金属有很强的亲和力,可在体内与铅结合形成金属硒蛋白复合物,从而可降低铅的毒性作用。本文从硒拮抗铅毒性作用的机理、硒对铅毒性的拮抗作用以及不同形式的硒对铅毒性作用的影响三个方面综述了硒与铅毒性之间的关系。     

Occupational health in the European Union

Despite extensive legislation in the European Union, employees remain exposed to occupational risks and there is still a significant burden of work-related ill-health. The trend for more people to work in service industries rather than manufacturing has resulted in a change in the nature of risk and pattern of occupational illness. Worker access to occupational health services ranges from 15 to 96% and depends on the country in which employees live and the type of operation in which they work. The increasing number of small enterprises provides a particular challenge when trying to provide occupational health support to the European Union's 158.4 million workers. European law alone is not sufficient to improve the health of those at work and further action is needed at state, employer and professional level. New initiatives seek to improve the health of the Union's workforce, including a drive for better compliance with new law by every member state. Governments are working with key stakeholders through partnering strategies to develop innovative approaches for better access to quality occupational health services. Furthermore, targets for reduction in occupational ill-health have been identified. Where country laws do not mandate the provision of occupational health services, employers need to see the benefit of providing occupational health support. Finally, the medical profession is making procedures for self-regulation more rigorous and professional bodies are actively engaged in issuing professional standards and guidelines. Ultimately, the individual practitioner is responsible for ensuring that he or she develops and maintains the necessary knowledge and skills to provide competent services.     

The application of Ontario human rights legislation to the practice of occupational medicine

Although human rights legislation has important implications for occupational physicians, these implications may be overlooked in the practice of occupational medicine in other countries where human rights legislation may be different. The potential for significant oversights becomes greater as organizations continue to centralize international business support functions, such as occupational health services, operating from a single site. Human rights legislation has important implications with respect to policy decisions upon which an occupational physician has influence. This includes decisions about whether to conduct drug and alcohol testing; the performance of medical examinations; evaluating issues related to health and safety concerns of pregnant employees; and the need to work accommodate those with handicaps as defined by human rights legislation. This article examines the application of the Ontario human rights legislation in these areas.     

Clinical and electromyographic examinations of patients with tremor after chronic occupational lead exposure

Tremor is considered to be a clinical sign of patients with chronic lead exposure. However, the type of tremor and its pathophysiological mechanisms are controversial. The aim of this study was to examine the clinical and electromyographic characteristics of tremor in patients with chronic lead exposure. Twenty-three men, 27-49 years old, participated in the study. The tremor activity was detected using surface electrodes from a pair of antagonistic hand muscles. Serum lead concentrations were measured on the day of examination. Our results revealed 12 Hz postural and kinetic tremor, with characteristics of enhanced physiological tremor. Different pathophysiological mechanisms might be responsible for the enhanced physiological tremor of patients with chronic lead exposure. In conclusion, the tremor of patients with chronic lead exposure is an enhanced physiological one. It is probable that this tremor could be influenced by beta-blockers, known to influence the enhanced physiological tremor in anxiety. This will be of benefit for patients disturbed by persistent tremor.     

Toxicity and Bioaccumulation of Lead in Marine Protozoa Communities

The toxicity and bioaccumulation of lead has been studied using marine protozoa communities developed in laboratory microecosystems. The concentrations tested were 500 and 1000 μg · L⁻¹of lead as lead acetate. The protozoan was able to bioaccumulate 27.02–504 μg Pb · g⁻¹dry weight. Bacteria also bioaccumulated lead, but always to a lesser degree than protozoa. Lead caused a significant reduction in the density of protozoa, which could be an indirect response to the cellular increase of lead. On the other hand, the toxicant did not determine a decrease in the number of bacterial cells; this could be due to their capacity to bioaccumulate a lesser amount of lead, the increase in the number of dead cells, and the elimination of their predators by the toxicant. After 120 h, a recovery of the community was observed.     

The interpretation of zinc protoporphyrin changes in lead intoxication: a case report and review of the literature

BACKGROUND: Zinc protoporphyrin (ZPP) has been used both as a screening and diagnostic test for overexposure to lead for nearly 30 years, although limitations for both purposes are recognized. METHODS: We present longitudinal findings for ZPP and whole-blood lead in a man with two episodes of acute lead intoxication and review the literature on the use of ZPP. RESULTS AND CONCLUSIONS: ZPP elevations in both chronic and acute exposure settings lag behind elevations in whole-blood lead by approximately 8-12 weeks. Therefore, ZPP measurement, in conjunction with whole-blood lead determination, has clinical utility in cases of substantial overexposure by providing information on how long an individual may have been overexposed to lead. A guide to the interpretation of various combinations of whole-blood lead and ZPP results is provided. However, while ZPP levels do correlate with whole-blood lead measurements in aggregate, the considerable individual variability of ZPP measurements, poor sensitivity at lower ranges of lead exposure, poor specificity and delayed changes in unstable exposure conditions indicate that this test contributes little to screening programs. Finally, our results confirm that basophilic stippling is seen in acute as well as chronic lead intoxication, and may provide the first indication of lead intoxication.     

Workers' right-to-know legislation: does it work?

Workers' right-to-know (WRTK) laws and regulations were established to empower workers to protect their health by providing them with information about the hazards to which they are exposed while at work. The present study was conducted to examine the implementation of WRTK regulations in Israel. We interviewed 552 workers and 33 safety officers from a random sample employed at 50 industrial plants. The workers' questionnaire included items on awareness and self-management of workplace hazards, and the safety officers answered questions about job experience and hazards communications to workers. In 36% of cases workers and their safety officers disagreed about the existence of hazards in the workplace (p < 0.001). Most (78%) of the workers' knowledge about work hazards was based on informal sources, i.e., not those stipulated by the regulations. There were also discrepancies between worker and safety officer reports regarding the provision of safety training upon employment (p < 0.001), recent instructions about special risks and distribution of relevant printed material. We found that more than 5% of workers were unable to read the language in which the hazards material was written and 22% had levels of education below that required to comprehend the technical terms used. There are serious problems in the implementation of WRTK regulations in Israel. We recommend that employers be made aware of the importance of these laws and of their proactive duty to comply with them and that the material distributed to workers be written in simpler terms and/or explained orally in a language they understand. These findings have important implications for all countries with similar legislation and should form the basis for further and more comprehensive studies world-wide.     

Predictors of lead absorption in children of lead workers

OBJECTIVES: This study was conducted to determine whether children of lead workers are at a higher risk of lead absorption and if so, to identify risk factors for absorption, including lifestyle, household, environmental and parental work practices with lead. METHODS: This cross-sectional study recruited 17 'lead worker' and 13 comparison 'non-lead worker' households. Companies and eligible employees were contacted using mail-out packs. Children were aged between 12 and 72 months. Data collection involved administration of a questionnaire and collection of dust, soil, water, paint-scraping samples, and blood from the children for the determination of lead and ferritin levels. Statistical analysis was performed using SPSS. RESULTS: Participants included seven of 29 eligible employees from 14 'scheduled' lead workplaces and 12 of 19 eligible employees from 19 'leadlighter' workplaces identified. The average lead level for workers was 13.9 micrograms/dl, children of lead workers 6.93 micrograms/dl (n = 22) and comparison group 3.93 micrograms/dl (n = 16). Water lead levels were all < 2.5 ppm. The lead content of three soil samples and nine dust samples was above suggested guideline levels. Lead levels were significantly higher in children of lead workers but all were within recommended levels. Inadequate practice of lead work hygiene measures, such as inadequate use of protective equipment and taking work clothes home, was a common factor in lead worker households that were found to have elevated soil and dust lead levels. The differences in lead levels between groups did not change significantly when adjustment was made for the clustering effect of more than one child per household. CONCLUSIONS: Children of lead workers are at higher risk of lead absorption. Poor work hygiene practices of lead workers suggest an association with elevated lead levels in their children. A number of other predictors were suggested by this study but the small numbers of participants made it difficult to detect statistically significant differences between subgroups.     

A Meta-analysis of Mortality among Workers Exposed to Organic Solvents

It has been suggested that organic solvent exposure may contributeto an increased risk of blood disorders, neurological, liverand renal disease, and cancer. A meta-analysis has been performedof 55 published mortality studies which involved solvent exposureand provided standardised mortality ratios (SMR) or relativerisk (RR). The combined results showed the overall SMR to be86.7 (95% confidence interval [CI] = 83.7–89.9), whilethat for all sites of cancer was 92.3 (CI = 87.5–97.4).Risk of death from leukaemia was increased (SMR = 112.2, CI= 101.6–146.9) as was that from cancer of liver and biliarypassages (SMR = 119.7, CI = 104.4–137.2), even thoughthe risk of death from cirrhosis was reduced (SMR = 81.5, CI= 68.1–97.4). No excess risk of death from other diseaseshas been found. The favourable mortality might be from a ‘healthyworker effect’, but the increase in death from liver cancerin the absence of excess deaths from cirrhosis is biologicallyplausible and justifies further investigation. The increasein mortality from leukaemia is likely to have been associatedwith exposure to benzene.     

Screening for lead toxicity among autobody repair workers

Fifty-one workers in 10 small, neighborhood autobody repair shops were screened for lead toxicity using blood zinc protoporphyrin (ZPP) levels and work history questionnaires. Those with high ZPP levels (greater than 50 μg/dl) had further studies, including blood lead determinations. The shops were dusty with ground putty dust (lead-free) and paint spray (lead content range 0–40%). Thirteen (26%) workers had mildly elevated ZPP levels (all were full-time sander/sprayers) though few had symptoms and none had elevated blood lead levels. Eighteen controls, workers in other occupations, had normal ZPP levels. Air monitoring during inactive periods failed to reveal high lead levels (range 0–28 μg/m²). These data suggest that workers in autobody repair shops are at risk of lead toxicity but the exposure and biologic effects are less than in many other industries that utilize lead.