Ta1_P01

Radiocarbon dating of forensic human bone to estimate the postmortem interval (PMI)

Indra L¹, Hamann C², Szidat S³, Kanz F⁴, Lösch S¹, Lehn C⁵

¹Department of Physical Anthropology, Institute of Forensic Medicine, University of Bern, Bern, Switzerland, ²Leibniz-Laboratory for Radiometric Dating and Stable Isotope Research, Christian-Albrechts-Universität zu Kiel, Kiel, Germany, ³Department of Chemistry, Biochemistry and Pharmaceutical Sciences & Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland, ⁴Center for Forensic Medicine, Medical University of Vienna, Vienna, Austria, ⁵Institute of Legal Medicine, Ludwig-Maximilians-University of Munich, Munich, Germany

Estimating the postmortem interval (PMI) of human remains is important in forensic anthropology, e.g. to aid the identification process. For this, a frequently employed method is radiocarbon dating, using the bomb-peak-model after 1950. Because of the bone remodeling, there is a lag time between the calibrated skeletal radiocarbon data and the actual year of death of an individual. The remodeling rate depends on the physiological state of the bone and may be different for each skeletal element. Quantifying these factors is challenging. By adding more data to this research field, our study aims to enhance the accuracy of radiocarbon-based PMI estimations of skeletal remains.

We radiocarbon-dated bone collagen from 25 forensic cases in Switzerland, Germany and Austria, of individuals that had died between 19 and 98 years of age. We sampled skull (occipital, parietal and temporal bone) and femur and combined the calibrated F¹⁴C values with the known individual data of the deceased to calculate collagen remodeling rates.

Our results show that petrous bone remodeling rates are low and lag times increasing roughly proportionate with age-at-death. The petrous bone is therefore less suitable for PMI estimation because its radiocarbon value refers to the period of the (early) childhood. Femur and skull remodeling rates are comparable. However, the inter-individual variability is pronounced, especially in the elderly. To create a universal model for year-of-death estimation based on the radiocarbon data, we need to better understand factors such as physiological status of the individual and its influence on skeletal turnover rates.

Ta1_P02

Chronological records in animal tissues

Pachnerova Brabcova K¹, Kufnerova J¹, Valasek V¹, John D^1,2, Petrova M¹, Brychova V¹, Svetlik I¹

¹Nuclear Physics Institute of the CAS, Praha, Czech Republic, ²Czech Technical University in Prague, Praha, Czech Republic

Radiocarbon dating of recent and near-future samples faces an inability to distinguish these from the pre-bomb peak ones. It is caused by radiocarbon levels decline to pre-bomb activities.

If the samples in question are of the animal tissues, such as protected species being dated for legal purposes, possible mitigation of this unfavourable trend lies in exploitation of the tissue chronological record. In the best case, the known chronology can anchor the sequence on radiocarbon calibration curve, and thus reduce the ambiguity of the dating results.

Our research aims on tissues of several endangered species, such as ivory of elephants (Loxodonta africana), scales of pangolins (Smutsia gigantea, Manis tricuspis), or tortoise shells (Testuda hermanni, Testudo graeca, Testudo marginata). Radiocarbon dating of incremental lines was accompanied with other analysis, optical and scanning electron microscopy and X-ray fluorescence. 

Ta1_P03

Absorption and Distribution of Ultra-Trace Exogenous ¹⁴C Urea in Rats

Wang L, Tang J^1,2, Zhang G¹, Shi S¹, Chen D¹, Qi L¹, Yang P³, Zhang X³, Xia C³, Shen H^1,2

¹Guangxi Normal University, Guilin, China, ²Guangxi key laboratory of nuclear physics and nuclear technology, Guilin, China, ³Guilin Medical University, Guilin, China

A study on absorption and distribution of radiocarbon labeled urea in rats was carried out at the ultra-trace level with AMS. The drug concentrations in plasma and tissues of rats after an oral administration of an ultra-trace dose of [¹⁴C]urea were measured. The drug concentration vs time curves in plasma and tissues were obtained. The results show that the drug distribution of ultra-trace dose is different from that of conventional-dose, and the [¹⁴C]urea is excreted mainly through urine and respiratory. This study provides information on the pharmacokinetics and tissue distribution of exogenous urea in rats at the ultra-trace level and verifies the feasibility of using AMS for ultra-trace dose drug research beyond the traditional measurement range.

Keywords: AMS, ultra-trace dose, [¹⁴C]urea, pharmacokinetics, distribution

Ta1_P04

Bomb pulse dating of human calculi

Wang ^1,2,3, Ding P^1,2,3, Shen C^1,2, Zhu S^2,4

¹State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, , Guangzhou, China, ²CAS Center for Excellence in Deep Earth Science, Guangzhou Institute of Geochemistry, Chinese Academy of  Sciences, Guangzho, China, ³Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou), Guangzhou, China, ⁴State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China

The onset ages of various human calculus diseases are usually later than the emergence ages of calculi in the body because the patients seek medical attention after the symptoms and complications are perceptible. Knowing the emergence ages of calculi will help doctors figure out the causes and benefit public health. In this study, we collected three kinds of calculi, including sialoliths (S), gallstone (GS), and bladder stones (BS) from 8 donors in Guizhou, Southwest China. Five of these samples are big and have multiple layers. We separated them into the inner core and outer crust parts and studied their ¹⁴C ages and ¹³C signatures. The results show the bomb pulse dating ages of BS and GS (c. 0 - 6 yrs) are much younger than those of sialoliths (c. 9 - 44 yrs). The difference between the ages of the outer crusts and inner cores indicates the growth period of calculi, ranging from 0.4 to 6.9 yrs. The growth rates of GS and BS are between 2.8 to 4.1 mm/yr. The δ¹³C values of sialoliths, GS, and BS range from -23.9 to -21.5 ‰, -22.6 to -22.2 ‰, and -20.5 to -19.5 ‰, respectively. Distinguish ages and stable isotope distribution patterns likely exist among different kinds of calculi, but further studies are needed to give a statistical conclusion.