[Environmental exposure to inorganic lead and neurobehavioural tests among adolescents living in the Sulcis-Iglesiente, Sardinia]

In several recent studies blood lead levels below 100 microg/L have been associated with reduced neurocognitive capacities and neurobehavioural performances in children, with no clear evidence of the lowest "safe" level not associated to adverse effects on the CNS. We analyzed blood lead concentration and the results of 5 neurocognitive tests, two derived from the Swedish Performance Evaluating System (SPES) and three from the Wechsler Intelligence Scale for Children-Revised (WISC-R), in 139 Sardinian adolescents living in Portoscuso, a town 2 Km far from a lead smelter, and in 72 age-matched students living in S. Antioco, a town about 15 Km far from the same smelter. The blood lead concentrations were lower than 100 microg/l in almost subjects, but, in average, significantly higher particularly among males, in the Portoscuso group compared to controls. The regression coefficients derived from the multivariate stepwise analysis, adjusted for the student's age and gender and for the educational and socio-economic level of parents, showed that reduced performances in neurocognitive test were significantly associated to increasing blood lead concentrations. According to previous our surveys in the same area and to the recent scientific literature on this topic, the present study suggests the need to further low the blood lead levels, considered by the U.S. CDC in 1991 as potentially "safe" for the children's CNS, to a threshold possibly < 50 microg/L.

[Intellectual quotient and environmental exposure to low doses of lead]

The effects of low-level lead exposure on children's intelligence quotient (IQ) were investigated in 64 Sardinian adolescents (13-16 years old). To estimate potential early adverse effects on the Central Nervous System (CNS) due to very low-level lead, the Intelligence Quotient (IQ) of adolescents with present blood lead concentrations (PbB) generally below 10 microg/dl was measured. We analyzed blood lead concentration and individual IQ of 32 Sardinian children living in Portoscuso, a town 2 Km far from a lead smelter, and of other 32 controls living in S. Antioco, a town about 15 Km far from the same smelter. The Wechsler Intelligence Scale for Children Revised (WISC-R) was administered. The relation between IQ and blood lead concentration was estimated by linear multivariate models adjusting for several potential confounders, such as the educational and socio-economic level of the parents. The blood lead concentration was in average significantly higher in the Portoscuso group compared to controls. The linear model applied to the total population studied (n 64) showed that the blood lead concentration was inversely and significantly associated with IQ, with an extrapolated decline of 1.29 points in total IQ for each microg/dl increase of lead blood concentration. According to the recent scientific literature on this topic, results of our pilot study suggest the need to further lower the blood lead concentration for children to a threshold significantly below 10 microg/dl, value till now considered "safe" for the children's CNS.

[Study on mortality by specific cause among workers at a lead and zinc foundry in Sardinia]

The mortality of 918 Sardinian lead-smelter workers followed between 1972 and 2001 is reported. The assessment of individual exposure to inorganic lead was based on several environmental and blood lead measurements available, for each department and task, between 1985 and 2001. The mortality for all cancers was within the expected numbers (SMR 1.01, n 108). Even if not statistically significant, the mortality for gastric cancer (SMR 1.22, n 4), for lung cancer (SMR 1.21, n 18) and for lymphomas and leukaemias (SMR 1.82, n 6) was higher than that expected from the regional rates during the follow-up. Only for the lung cancer mortality a statistically significant upward trend with increasing categories of lead exposure was observed (SMR 1.96, 95% CI 1.02-3.68 for the highest exposure group). Our study, even if of small size, suggests an association between occupational exposure to inorganic lead and lung cancer risk.

[Shift-work and cardiovascular diseases among chemical industry workers]

In order to assess the prevalence of cardiovascular abnormalities among shift workers, who were free from such abnormalities at the time of hiring, compared to day workers and ex-shift workers, we studied the QTc interval and several cardiovascular risk factors in 61 chemical workers, including 40 shift workers, 11 day workers, and 10 ex-shift workers. We found a high prevalence rate of ischemic heart disease and conduction abnormalities among ex-shift workers (5/10, 50%). We did not observe variations in the QTc interval among the three groups. The occurrence of cardiovascular disease is a reason for moving workers to day work. Therefore, the shift workers group in our study might have been selected among subjects with a healthier lifestyle preventing side effects on their cardiovascular system.

[Mortality from lung cancer among workers of a Sardinian lead smelter [Follow-up: 1972-2001]]

The mortality of 918 Sardinian lead-smelter workers followed between 1972 and 2001 is reported. The assessment of individual exposure to inorganic lead was based on several environmental and blood lead measurements available, for each department and task, between 1985 and 2001. The mortality for all cancers was within the expected numbers (SMR 1.01, n 108). Even if not statistically significant, the mortality for gastric cancer (SMR 1.22, n 4), for lung cancer (SMR 1.21, n 18) and for lymphomas and leukaemias (SMR 1.82, n 6) was higher than that expected from the regional rates during the follow-up. Only for the lung cancer mortality a statistically significant upward trend with increasing categories of lead exposure was observed (SMR 1.96, 95% CI 1.02-3.68 for the highest exposure group). Our study, even if of small size, suggests an association between occupational exposure to inorganic lead and lung cancer risk.

[Cognitive and performance capacity among adolescents living near a lead and zinc smelter]

To estimate potential early adverse effects on the Central Nervous System (CNS) due to very low exposure to inorganic lead, the Intelligence Quotient (IQ) of adolescents with present blood lead concentrations (PhB) generally below 10 micrograms/dl was measured. We analyzed blood lead concentration and individual IQ of 32 Sardinian adolescents living in Portoscuso, a town 2 Km far from a lead smelter, and of other 32 controls living in S. Antioco, a town about 15 Km far from the same smelter. The Wechsler Intelligence Scale for Children Revised (WISC-R) was administered. The relation between IQ and blood lead concentration was estimated by linear multivariate models adjusting for several potential confounders, such as the educational and socio-economic level of the parents. The blood lead concentration was in average significantly higher in the Portoscuso group compared to controls. The linear model applied to the total population studied (n 64) showed that the blood lead concentration was inversely and significantly associated with IQ, with an extrapolated decline of 1.29 points in total IQ for each microgram/dl increase of blood concentration. According to the recent scientific literature on this topic, results of our pilot study suggest the need to further lower the definition of an elevated blood lead concentration for children to a threshold significantly below 10 micrograms/dl, value till now considered "safe" for the children's CNS.

Neurotoxic effect of lead at low concentrations

The effects of lead exposure at low concentrations were evaluated by studying the post-rotatory nystagmus (PRN) in two groups of rats exposed for 3 months to 50 parts per million (ppm) of sodium acetate and 50 ppm of lead acetate, respectively, in the drinking water. Only animals treated with lead acetate showed changes of the PRN parameters which were significantly related to the concentration of lead in the blood and in brain structures. The patterns of PRN responses were characterized and classified into four types: progressively inhibitory (40%), prematurely inhibitory (25%), late inhibitory (25%), and excitatory-inhibitory (10%). No alterations of the PRN parameters were observed in the animals treated with sodium acetate. The results show that exposure to lead, even at low concentrations, impairs both sensory and motor functions. The findings also point out that the vestibular system and brain stem structures which generate and control the PRN represent targets of the action of this heavy metal. Finally, the results indicate that the evaluation of the vestibulo-ocular-reflex can provide a test suited for the screening of the neurotoxic effects of lead even in the absence of clinical signs typical of lead intoxication.

[The energy cost and the use of individual protective devices in firefighters]

Firefighters are required to wear fire-protection devices when involved in hazardous work situations. To determine whether fire protective clothing and self-contained breathing apparatus (SCBA) affect maximal physical work performance and to assess their additional energy requirement, we studied a cohort of Italian firemen while performing a rapid air-stair climbing (Mt. 29). Heart rate (HR) and maximal speed (time/distance) were measured in 23 firemen during the exercises, performed either wearing fire protection clothing and SCBA (p2) and service dress (p1). We also measured maximal oxygen consumption (VO2 max, indirect determination), WBGT and the speed/HR ratio (iR) as an arbitrary index of physical work performance. The participant reached the sub-maximal HR in both exercises (p1 87.01%; p2 88.84%). Fire protection devices significantly reduced the exercise maximal speed (p < 0.001) and increased the maximal HR (p < 0.01). IR index was significantly (p < 0.001) lower for p2, indicating a reduction of physical work performance (-26.9%); VO2 max was inversely related with mean and maximal HR (p < 0.001). These results suggest that only well trained firefighters should be employed in emergency actions requiring fire protection devices and SCBA.

Pulmonary function in Sardinian fire fighters

Our study examined the respiratory function of 92 firemen whose main activity is fire fighting in forests and open country. Such fire fighting activities are to be considered a risk to the respiratory tract, taking into account studies already in the literature that have evaluated the nature and quantity of inhalable toxins present in activities of this kind. The control group was composed of 51 Carabinieri (policemen), who were asked to fill in a questionnaire about their work activities. Forced expiratory volume and flow, total lung capacity, respiratory volume, and the permeability of the alveolar-capillary barrier were measured. Firemen and Carabinieri (policemen) showed FVC rates higher than the European Community for Coal and Steel standards. The firemen showed a significant reduction in forced expiratory volume in 1 second (FEV1)[3.90 (0.50) vs. 4.04 (0.44); p < 0.05] and forced expiratory flow at 75% of forced vital capacity (FVC) (FEF75) [8.37 (4.11) vs. 8.38 (1.67) p < 0.05] and more markedly in the FEV 1/FVC relationship [80.07 (5.89) vs. 83.89 (1.67) p < 0.001] and in FEF50 [4.73 (1.34) vs. 5.54 (1.44) p < 0.01] and FEF25[1.58 (.47) vs. 1.99 (.69) p < 0.001]. There were no marked differences in air-blood exchanges. No correlation was found between respiratory function data and years of service or the number of fires extinguished during work experience.