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Comment on: metals in bones of the middle-aged inhabitants of Sardinia island (Italy) to assess nutrition and environmental exposure [Bocca et al. (2018), Environ Sci Pollut Res]
No full textThis comment addresses several inferences made by Bocca et al. (2018) to assess the nutrition of middle-aged inhabitants from four Sardinian localities (Alghero, Bisarcio, Geridu, and Sassari). Bocca et al. analyzed 72 human bone specimens dating from the twelfth to the eighteenth century for metal contents (Ba, Ca, Cd, Cu, Hg, Pb, Sr, and Zn) by SC-ICP-MS and applied a univariate and multivariate approach, using element-Ca ratios, to examine the eating habits and environmental exposure of the individuals. While we agree with their interpretation of the Hg/Ca and Pb/Ca ratios, attributable to various forms of environmental exposure, we disagree with some of their paleodiet claims
Commentary on “Analyses of human dentine and tooth enamel by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to study the diet of medieval Muslim individuals from Tauste (Spain)” by Guede et al. 2017, Microchemical Journal 130, 287–294
No full textThe study of trace element (TE) distribution within human and animal teeth is crucial to decrypt information about their diet, ecology and behaviours in the past. Thanks to several efforts TE applications have spread also to the study of modern environments, with repercussions in medicine and forensic contexts. However, the use of TE analysis to infer eating habits of our ancestors has been used for decades without the proper theoretical basis. After the paper of Ezzo Ezzo (1994) that demonstrated the non-validity in the use of bioessential TE elements in bones and teeth as palaeodiet markers this trend has decreased. However, still some recent papers continue to ignore that portion of the literature that strongly contrasts the use of TE analysis for palaeodiet. With this commentary, we would like to share our remarks on the paper of Guede et al. Guede et al. (2017), where, in our opinion, there is a lack of literature review and thus a misinterpretation of the TE dataset
In situ trace element analysis of human hard tissues by Laser Ablation ICP–MS
No full textAfter the advent of the laser ablation system (LA), the analysis of micro-samples of hard materials has spread to many scientific fields (i.e. geology, engineering, archaeometry, anthropology). The Laser Ablation Coupled with a Mass Spectrometer (as in the LA–ICP–MS) allows to investigate any hard material at the scale of a few μms, for example, defining the elemental compositional profile of bone, teeth and nephroliths, measuring any element with an atomic mass between 2 and 255 amu (i.e. heavy metals as Pb, Cr, Cd, As, etc.). Moreover, one of the main advantages offered by LA, compared to more traditional techniques, is the drastic reduction of analytical time, because the sample is analysed as it is without chemical dissolution or separation of elements. In this work, we have tested and developed a routine to measure all trace elements in human bones and teeth with the LA–ICPMS housed at the University of Modena and Reggio Emilia. We analyse all trace element but we have focused here our attention on Zn and Pb, given their importance and significance in dentistry, human health and forensic pathology studies. We have then analyzed two human teeth, measuring their trace elements compositional profile and drawing conclusions on the health history of these two individuals. Materials and Methods. We analysed two human teeth (molar 1HT–R and premolar 2HT–R) sampled from two post-medieval mummies (Roccapelago, Modena, 16th – 18th cent.). The concentrations of Pb and Zn were measured in situ through a 213 nm Nd:YAG Laser Ablation system coupled to a quadrupole ICP–MS system (Thermo Fisher Scientific® X SeriesII). Before analysis, each sample was cut in half with a diamond low-speed wheel saw, to expose the inner parts of the tooth. Eighteen LA–spots (diameter 100 μm) were analysed along two profiles (n=10 sample 1HT–R; n=8 sample 2HT–R), exploring enamel and dentine. The elemental concentrations of our samples have been corrected through a calibration with NIST 1486 Bone Meal as a multi-element standard. To correct any matrix-related effect, the calcium concentration, measured with an ESEM Quanta 200, has been used as the internal standard. To ensure the accuracy of the method, a two-tailed t-test was performed on two certified elements of the standard. Statistical analysis shows no significant difference between expected and measured values (p<0.05; mean of 3 analyses). Results. The first tooth (1HT–R) shows a Zn concentration ranging from 230 in the outer enamel to 110 ppm in the inner primary dentine (x = 150 ± 38 ppm, 1σ) and, respectively, a Pb concentration ranging from 3 to 1 ppm (x = 2 ± 1 ppm, 1σ). From the outer enamel to the inner dentine, the second tooth (2HT–R) shows a Zn concentration ranging from 301 to 123 ppm (x = 177 ± 66 ppm, 1σ) and a Pb concentration ranging from 6 to 2 ppm (x = 3 ± 1 ppm, 1σ). Conclusions. Our results are in agreement with Pb and Zn profiles described in literature for human teeth (Humphrey et al. 2008). The concentrations of both elements tend to increase from the enamel-dentine junction (EDJ) to the enamel external surface and tend to decrease from the EDJ to the inner dentine. The Pb concentration of both samples is on average lower than the threshold of poisoning reported for human bones (5 ppm; Hess et al. 2013). The Zn concentrations are low, in particular in the outer enamel. As reported by Lynch (2011), this could be related to tooth wear or to the old age of the two individuals (~ 40 yr). The LA–ICP–MS is a non-destructive in–situ analytical technique, fundamental in forensic pathology and human health studies to measure the elemental composition of human hard tissue and in particular, in outlining the history of the tooth by trace element compositional profile from the inner to the outer portions of the tooth
In situ high spatial resolution 87Sr/86Sr ratio determination of two Middle Pleistocene (c.a. 580 ka) Stephanorhinus hundsheimensis teeth by LA–MC–ICP–MS
Full text linkBone and tooth tissues are important biological archives to study eating habits and provenance of ancient humans and animals. By taking advantage of the high spatial resolution offered by the Laser Ablation Multi Collector Inductively Coupled Plasma Mass Spectrometry (LA–MC–ICPMS) technique, we investigated the 87Sr/86Sr intra-tooth variability of two Stephanorhinus hundsheimensis tooth fragments from the Middle Pleistocene site of Isernia La Pineta. We detected significant Sr isotopes variability within the rhinos tooth enamel (enamel average ±2 sigma: sample RH–IS30 0.70951 ± 0.00014; sample RH–IS260.70976 ± 0.00015) with values higher than the “local”87Sr/86Sr ratio (dentine average ±2 sigma: sample RH–IS30 0.70918 ± 0.00013; sample RH–IS26 0.70934 ± 0.00009). This is likely linked to a different water and food intake with a Sr isotopic signature similar to volcanic soils nearby (Roccamonfina: from 0.7093 to 0.7100; Colli Albani: >0.7100) and supports the idea that the Stephanorhinus hundsheimensis species moved around seasonally. The improvement of non-destructive, accurate and precise analytical methods to decrypt the information hidden within bone and tooth hard tissues of archeological material is crucial to unravel critical questions about evolution, migration and ecology of human and animals. We have successfully took upon this challenge using three matrix-matched reference materials, with variable Sr concentration (c.a. 100–1000 ppm), to correct unresolved interferences arising from LA analyses
In situ strontium isotope analysis on biogenic apatite: the use of Laser Ablation and Multi Collector Inductively Coupled Plasma Mass Spectrometer (LA–MC–ICPMS) in anthropological research
No full textThe use of LA–MC–ICPMS in anthropological research is an innovative approach for measuring strontium isotopic ratios of human enamel. This technique, due to its micro-destructivity, allows to exam 87Sr/86Sr on precious human remains, without the drawbacks of the dissolution method. Despite this advantage, the laser ablation technique (LA) is not without flaws, principally related to unavoidable analytical interferences. For these reasons, data obtained with the laser are usually less precise and accurate than data obtained with the classical dissolution method. In particular, problematic interferences are represented by 86Kr formed in the gas, by double-charged REE (Rare Earth Element), by 87Rb, and by other polyatomic isobaric interferences (i.e. 44Ca40Ar, 40Ca44Ca, 40Ca13P16O). In this work, we measured the Sr isotopic ratio of a shark tooth with both dissolution and LA method, to test the precision of the LA method. A shark tooth is a bio-apatite formed in a marine environment, thus its 87Sr/86Sr ratio reflects the modern marine ratio of ~0.7092. Our preliminary laser analyses show that we are able to reproduce the isotopic ratio of our shark tooth obtained by Sr chromatographic separation and HR–MC–ICPMS with a precision to the fourth decimal place and that this ratio reflects the modern sea water value. If confirmed by further studies, our preliminary results suggest that the LA technique is a reliable method to explore hominin movement and migrations
Strontium Isotope MC-ICP-MS Analysis of Hair Strands from Human Mummies: Transhumance Pastoralism of Early-Modern Individuals between Northern and Central Italy
No full textMammal hair is formed by a scleroprotein, namely
keratin, composed by some major elements (C, N, H, O, S),
but including also trace elements such as Sr, Pb, Fe, K, Na
and Ca. The latter are fixed through diet and exposure to
exogenous sources, mainly water and air. Given that the
average human scalp hair growth is ~1 cm/month, timeresolved
hair sampling yields information about a specific
period, reflecting the elemental and isotopic composition of
the diet and environment at that time. The 87Sr/86Sr ratio of
mammal tissues is generally directly correlated to the local
bioavailable strontium, providing the chance to reconstruct
the individual movements in a given time interval.
In this work, we developed our protocol to analyse low-Sr
concentration mammal hairs for their 87Sr/86Sr ratio by
Neptune MC-ICP-MS. We tested the method on a modern
individual who traveled cyclically between Italy and Brazil.
Hair strands were sampled with a time resolution of 1 to 2
months, yielding time resolved isotopic variations from the
highest radiogenic ratios of the São Paulo area to the lower
ones of Modena waters. Thus, the Sr analysis of hair has been
applied to human mummies (Roccapelago, Modena, 16th-18th
cent.). Hair strands were cut in several sub-samples with
different length (time-resolution) in relation to the amount of
available material. The best achieved time-resolution was of 3
months in a 12-cm-long strand. These samples revealed
cyclical human movements from Roccapelago to the high
radiogenic area of the Tuscan Magmatic Province. Historical
documents attest a high frequency of human seasonal travels
to Tuscany, up to the Grosseto area, likely linked to the
exploitation of transhumance pastoralism
Stable isotope and in situ trace element analyses on human bone tissue (Roccapelago, 16th-18th cent.): preliminary inferences on diachronic change in eating habits and trace element reliability
No full textWe measured trace elements and stable isotopes (C and N on collagen) on 19 samples, taken from different anatomical area of 7 individuals from the medieval site of Roccapelago (Modena): our attempt is to reconstruct the diet of these individuals and discuss the role of trace elements in palaeodiet. The good preservation of these bodies represents a unique chance to work on likely diagenesis-free archaeological human remains, to test the trustworthiness of trace element analyses. In fact, in the last decades, trace element reliability was questioned several times. We particularly focus our attention on magnesium, strontium and zinc. Our data set shows different eating habits for the studied individuals. While collagen of the samples dated at 16th century yields typical values of a C3-plant based diet, collagen of samples dated at 18th cent yields higher values of both δ13C and δ15N, probably linked to an higher trophic level and to a shift toward a C4-environment. Similarly, Sr and Mg show the same increment in individuals of 18th cent, while Zn does not show any significant variation. The latter is quite discussed in the scientific literature and has been commonly used as a marker for a protein-rich diet. Our lack of correlation between Zn and stable isotopes (especially N) confirms the uselessness of this element in palaeodiet reconstruction. Geochemical data are also corroborated by the botanical evidence of maize presence (C4 plant) and by historical sources that attest the presence of maize in Emilia-Romagna during 18th century
C4-plant foraging in Northern Italy: stable isotopes, Sr/Ca and Ba/Ca data of human osteological samples from Roccapelago (16th–18th century AD)
Full text linkHuman osteological samples (n = 23) taken from different anatomical parts of 11 individuals from the early modern (16th–18th century AD) site of Roccapelago (Modena, Italy) were systematically analysed for δ13C, δ15N and trace elements to investigate their diet. δ13C and δ15N correlate and show a high variability between individuals, attesting to the dietary contribution of C4 plants. This is supported by pollen analysis of the burial site samples, which revealed the presence of maize. δ15N correlates with Sr/Ca, suggesting that the main protein source could have been milk and dairy. We therefore interpret the strong correlation between δ13C and δ15N as evidence for C4-plant foraging practice and the exploitation of livestock for meat and milk, combined with possible direct intake of C4 plants. The Roccapelago site represents an important case study to track the evolution of the post-medieval diet and the introduction of maize cultivation in southern Europe, as also attested by historical sources
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