Dental enamel as biomarker for environmental contaminants in relevant industrialized estuary areas in São Paulo, Brazil.

Heavy metal contamination is a long-standing and very well-known public health problem, and its exposure can cause damage to several organs of human body, especially on the central nervous system of young children and teenagers. The aim of this article is to evaluate lead, cadmium, and manganese contamination in 125 children from 6 to 13 years old living in contaminated areas during the period from 2006 to 2009 (São Vicente, Cubatão Downtown, Bertioga and Cubatão Pilões/Água Fria). This estuary area is the most important example of environmental degradation by chemicals from industrial sources. This is a cross-sectional study through clinical examinations and dental enamel tests. All mothers from these children lived in the area since before the pregnancy. Lead, cadmium, and manganese levels (µg/g) were measured on dental enamel samples through graphite furnace atomic absorption spectrometry, searching for the occurrence of heavy metals. The mean lead concentrations were 139.48 µg/g in Cubatão Pilões/Água Fria, 170.45 µg/g in Cubatão Downtown, 213.52 µg/g in São Vicente, and 151.89 µg/g in Bertioga. The mean cadmium concentrations were 10.83 µg/g in Cubatão Pilões/Água Fria, 12.58 µg/g in Cubatão Downtown, 10.92 µg/g in São Vicente, and 14.57 µg/g in Bertioga. The mean manganese concentrations were 23.49 µg/g in Cubatão Pilões/Água Fria, 30.90 µg/g in Cubatão Downtown, 41.46 µg/g in São Vicente, and 42.00 µg/g in Bertioga. Dental surface enamel may be used as an efficient biomarker of past environmental exposure to lead, manganese, and cadmium which are associated to well-known sources of heavy metal contamination. The results suggest that the evaluated children were exposed to sources of lead, cadmium, and manganese since before their conceptions. Although Bertioga initially was chosen as a control area of this study, it was also was verified to have heavy metal contamination on examined children.

Lead concentrations in whole blood, serum, saliva and house dust in samples collected at two time points (12 months apart) in Santo Amaro, BA, Brazil.

UNLABELLED: Whole Blood Lead Level (BLL) is the main marker used to verify lead contamination. The present study explores how BLL is associated with lead concentrations in serum, saliva and house dust. Samples were collected twice from Santo Amaro, BA, Brazil, a region that was contaminated by a lead smelter in the past; a time interval of 12 months was allowed between the two collections. It is noteworthy that the following measures have recently been taken to diminish exposure of the population to lead: streets have been paved with asphalt, and educational campaigns have been launched to reduce exposure to contaminated dust. RESULTS: Compared with the first time point, all the samples collected at the second time point contained lower lead concentration (p<0.05), which suggested that the adopted measures effectively reduced exposure of the population to lead present in contaminated soil and dust. Statistically significant correlations only existed between lead in blood collected in the first year and lead in blood collected in the second year (Spearman's r=0.55; p<0.0001; n=62), and lead in house dust collected in the first year and lead in house dust collected in the second year (Spearman's r=0.5; p<0.0001; n=59). CONCLUSIONS: Results support the validity of lead determination in blood and in house dust to assess lead exposure over time. However, lead in blood and lead in dust did not correlate with lead in serum or lead in saliva.

Anatomical variations in primary teeth microelements with known differences in lead content by micro-Synchrotron Radiation X-Ray Fluorescence (µ-SRXRF) - A preliminary study.

Shed teeth have been proposed as trace element biomarkers. This study determined variations in the spatial distribution of Ca, K, Zn, Pb, Mn, Cu, and Sr in four anatomical locations: superficial enamel (SE, 0-10µm), subsuperficial enamel (SSE, 10-30µm), primary dentin (PD), and secondary dentin (SD). Five primary incisors were analyzed by micro Synchrotron Radiation X-Ray Fluorescence (µ-SRXRF). Two teeth had low concentrations of lead in the SE (<250µg/g), while three contained very high lead concentrations in the SE (>2000µg/g). Teeth were sliced, and five spot measurements (20µm beam diameter) were accomplished in each location. The data are shown as absolute values and as the ratio between the different elements and Ca. The distribution of K was close to that of Ca. Zn was the third most abundant element, with the highest levels being found in the SE and SD and low levels detected in the PD. Increasing Sr levels were found progressing from the enamel to the dentin, with the highest levels being found in the SD, a distribution that was unique. Pb, Mn, and Cu exhibited a similar trend, with higher signals for these elements detected in the SE. This study provides preliminary data on the heterogeneous distribution of different elements in the tooth, highlighting the importance of the first 10µm of the SE for determination of some elements, such as Zn, Pb, Mn, and Cu.

X-ray fluorescence with synchrotron radiation to elemental analysis of lead and calcium content of primary teeth.

Primary teeth were analyzed by micro-SRXRF. The aim of this study was to determine the elemental distribution of lead and calcium in different regions of primary incisor of children living in a notoriously contaminated area (Santo Amaro da Purificação, Bahia State, Brazil). The measurements were performed in standard geometry of 45 degrees incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil).

Histological and histochemical effects after occlusion alteration in suprahyoid muscles.

This study verified the effect of unilateral teeth extraction on the suprahyoid muscles in gerbils (Meriones unguiculatus). Ten adult male gerbils weighing about 50g had induced occlusal alterations by upper molar teeth extraction on the left side while the other ten animals were only subjected to surgical stress, control group. After 60 days, animals of both groups, experimental and control had the suprahyoid muscles removed and processed for histological and histochemical (adenosine triphosphatase (ATPase), nicotine adenine dinucleotide tetrazolium reductase (NADH-TR) and succinate dehydrogenase (SDH)) purposes. The fiber type area was estimated in % according to Weibel method (point-counting method) using a test-system. The myosinic ATPase pH 4.7 activity in the control group of the digastric, milohyoid and geniohyoid muscles presented a small area of type I fiber and a larger area of type IIa fibers; in the experimental group, significant contractile capacity alteration was not observed. Samples of the digastric, milohyoid and geniohyoid muscles, after SDH activity, showed a small area with high metabolic activity fibers, and a large area with intermediary and low metabolic activity fibers in the control group. The milohyoid muscle of the experimental group presented low metabolic fibers in a reduced area, in both sides, however without significant difference. In the experimental group, high metabolic fibers were observed on the left side in a reduced area in the geniohyoid muscle, but without statistical significance. Thus, the geniohyoid muscle did not change the metabolic activity after occlusal alteration. In conclusion, 60 days of unilateral malocclusion induced was able to alter the fibers oxidative activity of the suprahyoid muscles, however, it does not affect the contractile property of the fibers. The digastric muscle has adequate fibers to produce fast contraction and able to resist to fatigue in intermediate degrees, but became more fatigable after unilateral exodontia.

A plateau detected in lead accumulation in subsurface deciduous enamel from individuals exposed to lead may be useful to identify children and regions exposed to higher levels of lead.

In a previous study, we showed 4 times more lead in surface deciduous enamel (1.9-5.9 microm) of a notoriously contaminated area (Bauru, São Paulo State, Brazil) in comparison to samples from a region with no lead contamination described (Ribeirão Preto, São Paulo State, Brazil). The samples from the more superficial enamel (1.9-3.18 microm) showed higher amounts of lead and the highest variability, while in the subsurface enamel (3.18-5.9 microm) a plateau in lead content was detected in children living in the contaminated environment (around 600 microg/g). Here we expand our previous study, and use only samples obtained from subsurface enamel (Ribeirão Preto, n=186; Bauru, n=20). We tried to distinguish regions with more children with lead above the threshold of 600 microg/g of lead in enamel. We tested whether differences in the percentage of children with ''high" lead (600 microg/g) could be observed among the different Kindergartens studied in Ribeirão Preto. We also tested whether these results were different from the ones provided by conventional comparison of the data. Ribeirão Preto showed almost 4 times less lead than Bauru (p<0.0001), and a statistically significant difference was found only in Ribeirão Preto between Kindergarten 2 and 5 (p<0.01). Twelve percent of the children from Ribeirão Preto had "high" lead, while 55% of the children from Bauru did so. However, when we looked at the percentages of children with "high" lead in each Kindergarten, and compared them, a whole new picture emerged, in which we could see children with "high" lead concentrated mainly in 3 Kindergartens from Ribeirão Preto, with Kindergarten 5 with 33% of the children with "high" lead, being statistically different from all Kindergartens, except 4 and 6. The threshold of 600 microg/g of lead in subsurface enamel was tentatively settled here after the plateau seen in exposed children, and enabled us to identify locations with more children exposed to a higher amount of lead.