Marco Peli

Neurofunctional dopaminergic impairment in elderly after lifetime exposure to manganese.

BACKGROUND Manganese (Mn) is an essential element that can become neurotoxic through various exposure windows over the lifespan. While there is clear evidence of Mn neurotoxicity in pediatric and adult occupational populations, little is known about effects in the elderly who may exhibit enhanced susceptibilities due to compromised physiology compared to younger adults. In the province of Brescia, Italy, the Valcamonica area has been the site of three ferroalloy plants operating from 1902 to 2001. Metal emissions of Mn and to a lesser extent lead (Pb) have impacted the surrounding environment, where a high prevalence of Parkinsonism was previously observed. This study aimed to assess neurocognitive and motor functions in healthy elderly subjects residing for most of their lifetime in Valcamonica or in a reference area unimpacted by ferroalloy plant activity. METHODS Subjects were enrolled for extensive neurobehavioral assessment of motor, cognitive and sensory functions. Exposure was assessed with 24h personal air sampling for PM10 airborne particles, surface soil and tap water measurement at individual households, Mn levels in blood and urine and Pb in blood. Dose-response relationships between exposure indicators and biomarkers and health outcomes were analyzed with generalized (linear and logistic) additive models (GAM). RESULTS A total of 255 subjects (55% women) were examined; most (52.9%) were within the 65-70 years age class. Average airborne Mn was 26.41 ng/m(3) (median 18.42) in Valcamonica and 20.96 ng/m(3) (median 17.62) in the reference area. Average Mn in surface soil was 1026 ppm (median 923) in Valcamonica and 421 ppm (median 410) in the reference area. Manganese in drinking water was below the LDL of 1 μg/L. The GAM analysis showed significant association between airborne Mn (p=0.0237) and the motor coordination tests of the Luria Nebraska Neuropsychological Battery. The calculation of the Benchmark Dose using this dose-response relationship yielded a lower level confidence interval of 22.7 ng/m(3) (median 26.4). For the odor identification score of the Sniffin Stick test, an association was observed with soil Mn (p=0.0006) and with a significant interaction with blood Pb (p=0.0856). Significant dose-responses resulted also for the Ravens Colored Progressive Matrices with the distance from exposure point source (p=0.0025) and Mn in soil (p=0.09), and for the Trail Making test, with urinary Mn (p=0.0074). Serum prolactin (PRL) levels were associated with air (p=0.061) and urinary (p=0.003) Mn, and with blood Pb (p=0.0303). In most of these associations age played a significant role as an effect modifier. CONCLUSION Lifelong exposure to Mn was significantly associated with changes in odor discrimination, motor coordination, cognitive abilities and serum PRL levels. These effects are consistent with the hypothesis of a specific mechanism of toxicity of Mn on the dopaminergic system. Lead co-exposure, even at very low levels, can further enhance Mn toxicity.

Impact of ferromanganese alloy plants on household dust manganese levels: implications for childhood exposure.

Adolescents living in communities with ferromanganese alloy plant activity have been shown to exhibit deficits in olfactory and fine motor function. Household dust may serve as an important manganese (Mn) exposure pathway to children, though dust Mn concentrations have not previously been measured to assess household contamination from ferromanganese alloy plant emissions. Here we determined the association between dust concentrations and surface loadings of Mn and other metals (Al, Cd, Cr, Cu, Fe, Pb, and Zn) in indoor and outdoor household dust from three Italian communities that differ by history of ferromanganese alloy plant activity: Bagnolo Mella, with an active ferromanganese alloy plant (n=178 households); Valcamonica, with historically active plants (n=166); and Garda Lake, with no history of ferromanganese plant activity (n=99). We also evaluated Mn levels in other environmental (soil, airborne particulates) and candidate biomarker (blood, hair, saliva, fingernails) samples from children within the households. Household dust Mn concentrations and surface loadings were significantly different between the three sites, with levels highest in Bagnolo Mella (outdoor median Mn concentration=4620, range 487-183,000µg/g), intermediate in Valcamonica (median=876, range 407-8240µg/g), and lowest in Garda Lake (median=407, range 258-7240µg/g). Outdoor dust Mn concentrations in Bagnolo Mella, but not the other communities, were significantly inversely related with distance from the plant (R(2)=0.6630, P<0.0001). Moreover, outdoor dust Mn concentrations and loadings were highly predictive of but significantly higher than indoor dust Mn concentrations and loadings by ~2 to ~7-fold (Mn concentrations) and ~7 to ~20-fold (Mn loadings). Finally, both indoor and outdoor dust Mn concentrations and outdoor dust Mn loading values were highly significantly correlated with both soil and air Mn concentrations, and with childrens hair and fingernail Mn concentrations, but weakly or not associated with saliva or blood Mn levels. Given the evidence associating elevated Mn exposure with neurological impairments in children, these data support that dust Mn levels should be reduced in contaminated environments to protect the health of resident children.

Manganese concentrations in soil and settled dust in an area with historic ferroalloy production

Ferroalloy production can release a number of metals into the environment, of which manganese (Mn) is of major concern. Other elements include lead, iron, zinc, copper, chromium, and cadmium. Mn exposure derived from settled dust and suspended aerosols can cause a variety of adverse neurological effects to chronically exposed individuals. To better estimate the current levels of exposure, this study quantified the metal levels in dust collected inside homes (n=85), outside homes (n=81), in attics (n=6), and in surface soil (n=252) in an area with historic ferroalloy production. Metals contained in indoor and outdoor dust samples were quantified using inductively coupled plasma optical emission spectroscopy, whereas attic and soil measurements were made with a X-ray fluorescence instrument. Mean Mn concentrations in soil (4600 μg/g) and indoor dust (870 μg/g) collected within 0.5 km of a plant exceeded levels previously found in suburban and urban areas, but did decrease outside 1.0 km to the upper end of background concentrations. Mn concentrations in attic dust were ~120 times larger than other indoor dust levels, consistent with historical emissions that yielded high airborne concentrations in the region. Considering the potential health effects that are associated with chronic Mn inhalation and ingestion exposure, remediation of soil near the plants and frequent, on-going hygiene indoors may decrease residential exposure and the likelihood of adverse health effects.

Manganese and Developmental Neurotoxicity

Manganese (Mn) is an essential metal that plays a fundamental role for brain development and functioning. Environmental exposure to Mn may lead to accumulation in the basal ganglia and development of Parkinson-like disorders. The most recent research is focusing on early-life overexposure to Mn and the potential vulnerability of younger individuals to Mn toxicity also in regard to cognitive and executive functions through the involvement of the frontal cortex.Neurodevelopmental disturbances are increasing in the society, and understanding the potential role of environmental determinants is a key for prevention. Therefore, assessing the environmental sources of Mn exposure and the mechanisms of developmental neurotoxicity and defining appropriate biomarkers of exposure and early functional alterations represent key issues to improve and address preventive strategies. These themes will be reviewed in this chapter.

Back-Analysis of an Artificially Triggered Landslide: A Case Study in Northern Italy

Open image in new window The paper presents a case study of a landslide event, artificially triggered by an exceptional infiltration in an otherwise stable slope. The work aims at investigating the slope failure mechanism within a simplified two-dimensional conceptual framework based on the formation of a perched water table. The landslide occurred in Northern Italy in April 2010, on a hillside with average slope angle 36°–37°; the event affected an area of about 200 m2, the slip surface was located approximately 1 m below the slope profile, in the uppermost layers of a predominantly coarse, well graded soil. A series of numerical simulations were performed to back-analyze the event, using a commercial computer program. The artificial water infiltration and water content evolution were simulated with a two-dimensional finite element (FE) model of the unsaturated-saturated domain with appropriate infiltration boundary conditions. The slope stability analyses were conducted with classic limit equilibrium (LE) methods and were performed at different time instants during the infiltration process. The soil-water retention curves and conductivity functions were defined according to the van Genuchten-Mualem model, with parameters estimated by means of the software Rosetta (United States Department of Agriculture). The combined FE and LE simulations showed the gradual formation of a perched water table, whose associated localized pore pressure distribution results in the loss of the suction stabilizing effect and thus in the reduction of the safety factor. Although supported by basic soil mechanical and hydraulic characterization, the numerical simulations allowed to perform a back-analysis which effectively captured the timing of the event, the location and depth of the slip surface along the slope.

Dimensionless Numerical Approach to Perched Waters in 2D Gradually Layered Soils

Aiming at better understanding the processes involved in perched water tables onset and in their development, the case of a soil slope characterised by gradually decreasing hydraulic conductivity at saturation with depth was numerically investigated. Different anisotropy factors and steepness values were accounted for. The problem was led to a dimensionless form on the basis of the Buckingham π-theorem. Coherently with a theoretical solution of the 2D sloping case, the simulations evidenced (a) non-monotonic transverse profiles of the pressure head within the perched water, (b) slightly lower infiltration thresholds for perched water onset and for soil waterlogging, with respect to the 1D case. If the slope is long enough, an almost uniform flux can be observed in a branch of its central part.

Non Monotonic Imbibition Profiles and Transition to a Perched Water Table in a Gradually Layered Soil

An imbibition process at low infiltration rate into a soil, whose hydraulic conductivity at saturation K s decreaseswith depth, can lead to non monotonic water– content profiles and to the onset of a perched water table. By means of a numerical simulation of an infiltration process into a 1D, exponentially K s –decreasing soil, four different behaviors of the tensiometer–pressure profiles were observed at increasing the infiltration rate: either the solution remains monotonic, or a peak of water content onsets and vanishes and the solution recovers its monotonicity, or the peak vanishes but a perched water table onsets at the bottom and rises, or the peak itself reaches the water content at soil saturation at one point and there a perched water table onsets. This latter pattern was found in qualitative agreement with previously performed experimental results.

Assessing the contributions of metals in environmental media to exposure biomarkers in a region of ferroalloy industry

Residential proximity to ferroalloy production has been associated with increased manganese exposure, which can adversely affect health, particularly among children. Little is known, however, about which environmental samples contribute most to internal levels of manganese and other ferroalloy metals. We aimed to characterize sources of exposure to metals and evaluate the ability of internal biomarkers to reflect exposures from environmental media. In 717 Italian adolescents residing near ferromanganese industry, we examined associations between manganese, lead, chromium, and copper in environmental samples (airborne particles, surface soil, indoor/outdoor house dust) and biological samples (blood, hair, nails, saliva, urine). In multivariable regression analyses adjusted for child age and sex, a 10% increase in soil Mn was associated with increases of 3.0% (95% CI: 1.1%, 4.9%) in nail Mn and 1.6% (95% CI: −0.2%, 3.4%) in saliva Mn. Weighted-quantile-sum (WQS) regression estimated that higher soil and outdoor dust Mn accounted for most of the effect on nail Mn (WQS weights: 0.61 and 0.22, respectively, out of a total of 1.0). Higher air and soil Mn accounted for most of the effect on saliva Mn (WQS weights: 0.65 and 0.29, respectively). These findings can help inform biomarker selection in future epidemiologic studies and guide intervention strategies in exposed populations.

Lake Garda lemon houses (Italy): Opportunities of a sensitive, marginal area in urban planning

Abstract The lemon houses of Lake Garda provide Ecosystem Services, due to their history and their deep rooting in the landscape. Unfortunately, Urban Planning hasn’t ever taken into account these possible benefits. In fact, it has always allowed their reuse as residences and it has sustained the conservation of the buildings only. The lack of interest in reintroducing lemon growing or other agricultural activities has produced a noticeable impoverishment of the local landscape. To overcome these limits, Urban Planning should be oriented to implement practices, which take root in and bring out the variety of local landscapes. In order to reach this result, Urban Planning may help to bring some lemon houses, especially the abandoned or the most vulnerable ones, back to their original agricultural vocation, reintroducing autopoietic agricultural techniques, which are in balance with the environment. An interdisciplinary approach may be adopted in a profitable way, to strengthen the efficiency of the Urban Planning. Aiming at this interdisciplinary approach the paper reports our first investigations concerning the contribution of different disciplines, which will help Urban Planning to consider, in case of the reuse of Lake Garda lemon houses, immaterial benefits and to reintroduce activities linked to their original vocation.