Importance of information in forensic toxicology.

Information in forensic toxicology plays a very important role. The forensic pathologist usually seeks toxicologic analyses on basis of the information available at the time of the medicolegal autopsy. Such information may be obtained from different sources: hospitals, authorities, relatives, friends, or neighbors of the deceased and, obviously, macroscopic findings at the time of the autopsy. In order to evaluate the relative importance of these different sources of information, the authors have studied, retrospectively, results of 580 postmortem examinations performed at the Institute of Legal Medicine of Lisbon, wherein toxicologic analyses had been requested. These cases pertain to the years 1987 and 1988, but do not include alcohol determination in the blood in cases of traffic accidents. In 274 (47.4%) of the 580 cases, there were positive findings while in the remaining 306 (52.6%) findings were negative. In cases with positive findings, circumstances and factors, which may have influenced the pathologist's decision to request toxicologic analysis, are discussed. In more than half the cases, hospital information was the decisive factor, while in approximately 25% of the cases, autopsy findings were the justification. In contrast, it is worth mentioning that in approximately 45% of the cases with analytical negative results, requests were made, in cases of blank autopsies, for toxicologic analyses in order to exclude the possibility of poisoning. It is interesting to note that in the same proportion requests were justified on grounds of hospital information. Some of the factors that may explain this apparent discrepancy are discussed. Finally, the relevance of background information is emphasized at the level of the interpretation of analytical results, whether positive or negative.(ABSTRACT TRUNCATED AT 250 WORDS)     

Application of forensic toxicology to the problem of domestic violence.

The role of the forensic toxicologist in helping to determine causes of death or in aiding in the resolution of "driving under the influence" or similar cases is well known and clearly understood. Less clearly defined is the position of the forensic toxicologist vis-à-vis other socially significant problems. However, as the 21st century approaches, it is worth considering how forensic toxicology can help in unraveling some of these problems. The problem of violence between intimates--that is, domestic violence--is a social problem in which it has been long felt that alcohol has played a part. Until now, though, no carefully controlled toxicological studies have been conducted to substantiate this or to determine whether other drug use is associated with domestic violence. At the San Francisco Medical Examiner's Office, toxicological data from both the victim and the suspect in 20 cases of domestic violence that ended in homicide have been gathered. It was found that alcohol or other drugs or a combination of these factors was invariably present in the suspect, the victim, or both. The implications of these results and how they can be used to develop a toxicological strategy to help reduce the most serious consequences of domestic violence are presented.     

Comparing two analytical methods: minimal standards in forensic toxicology derived from information theory

Frequently, new instrumentation and techniques are being applied to casework without an adequate knowledge of how this new technology compares to acceptable analytical procedures. Information theory provides a mathematical method to estimate the identification power of various analytical procedures and predicts if the new method produces a better or poorer confidence in the analysis than an accepted method. This paper makes comparisons based on relative informational power and discusses methods to make those estimates. With the procedures outlined in this paper, an analyst can estimate if a novel technique has the opportunity of reaching the accepted analytical methodology and, if necessary, identify places where the greatest improvement can be made to reach this equilivalence. Even though relative information theory can dismiss some proposed techniques before any analysis starts, it cannot verify if a given technique is adequate for a particular task. For that purpose, a complete procedural verification must be undertaken.     

近十年法医毒物分析和法医毒理学研究热点统计分析

借助Bicomb 2.0软件及SPSS 19.0软件对近十年国内外法医毒物分析和法医毒理学的研究热点进行分析,结果表明国内研究热点可以分为5类:分类1为毒品和精神活性物质的提取方法和样品稳定性研究;分类2为镇静催眠药的代谢和死后分布研究;分类3为农药的快速检测方法开发;分类4为分析方法的完善和标准化研究;分类5为新型毒物γ-羟基丁酸和合成大麻素的检测方法研究。国际研究热点分为6类:分类1为传统精神活性物质、乙醇和样品稳定性的研究;分类2为芬太尼的分析研究;分类3为氰化物的检测和毒理学研究;分类4为新型精神活性物质的检测图库建立和分析方法开发;分类5为镇静催眠药的研究;分类6为丁烷及其引起的猝死案例的研究。同时,对近十年国际合作法医毒物学研究进行了网络可视化分析。     

A comparison of Demirjian's four dental development methods for forensic age assessment

The aim of this study was to determine the comparative accuracy of Demirjian's four dental development methods for forensic age estimation in the Western Australian population. A sample comprising 143 individuals aged 4.6 to 14.5 years were assessed using Demirjian's four methods for dental development (original 7-tooth: M(2), M(1), PM(2), PM(1), C, I(2), and I(1); revised 7-tooth: M(2), M(1), PM(2), PM(1), C, I(2), and I(1); 4-tooth: M(2), M(1), PM(2), and PM(1); and an alternate 4-tooth: M(2), PM(2), PM(1), and I(1)). When comparing all four methods, the 4-tooth method overestimated age in both males and females by 0.04 and 0.25 years, respectively. The original 7-tooth was least accurate for males, while the original 7-tooth, the revised 7-tooth, and the alternate 4-tooth were unsuitable for females. Therefore, we recommend the 4-tooth method to be used for forensic age estimation in Western Australian males and females, as it has the lowest overall mean deviation and the highest accuracy.     

The use of buffered celite columns in drug extraction techniques and their proposed application in forensic toxicology

The recoveries of acidic, basic, and neutral drugs through buffered celite columns are reported. The methods are rapid, simple, clean, and efficient, especially with compounds having a high volatility.     

Sensitive and specific multiresidue methods for the determination of pesticides of various classes in clinical and forensic toxicology

Original and sensitive multiresidue methods are presented for the detection and quantitation, in human biological matrices, of 61 pesticides of toxicological significance in human. These methods involved rapid solid-phase extraction using new polymeric support (HLB and MCX) OASIS cartridges. Gas chromatography-mass spectrometry (GC-MS) was used for volatile (organophosphate, organochlorine, phtalimide, uracil) pesticides and liquid chromatography-ionspray-mass spectrometry (LC-MS) for thermolabile and polar pesticides (carbamates, benzimidazoles). Acquisition was performed in the selected ion monitoring (SIM) mode. Extraction recovery varied owing to the nature of pesticides, but was satisfactory for all. Limits of detection (LODs) and limits of quantitation (LOQs) ranged, respectively, from 2.5 to 20 and from 5 to 50ng/ml. An excellent linearity was observed from LOQs up to 1000ng/ml for all the pesticides studied. The proposed procedures yielded reproducible results with good inter-assay accuracy and precision. A few cases of intoxication are presented to demonstrate the diagnostic interest of these methods: in two cases were determined lethal concentrations of endosulfan and carbofuran; in four other cases, the procedures helped diagnose intoxication with, respectively, parathion-ethyl, the association of bromacil and strychnine, bifenthrin and aldicarb.     

Estimating the uncertainty associated with Widmark's equation as commonly applied in forensic toxicology

No computation is performed more frequently by forensic toxicologists than that involving Widmark's equation. The equation is employed to estimate either the number of drinks consumed or the corresponding blood or breath alcohol concentration. Despite the wide use of Widmark's equation, rarely is an uncertainty estimate also provided. Estimates from Widmark's equation involve at least seven uncertain random variables. Uncertainty estimates are presented that rely on methods of general error propagation compared to a method developed by Widmark. Assuming reasonable variable and uncertainty estimates, the error propagation method yielded for N=10.4 drinks, a combined uncertainty (standard deviation) of 1.3 drinks (CV=12.3%). Similarly, estimating the blood alcohol concentration yielded for 0.120 g/100 ml, an uncertainty of 0.0255 g/100 ml (CV=21.2%). Widmark's uncertainty method yielded 1.6 drinks (CV=15.4%). The derivation of Widmark's uncertainty estimate is also presented, showing that he considered only rho and beta to be uncertain. Widmark estimates for the number of drinks should include a 2CV estimate of approximately 25% while the blood alcohol concentration estimate should include a 2CV estimate of approximately 42%. Including valid estimates of uncertainty should enhance the legal admissibility and confidence for Widmark estimations.     

Likelihood ratio methods for forensic comparison of evaporated gasoline residues

In the investigation of arson, evidence connecting a suspect to the fire scene may be obtained by comparing the composition of ignitable liquid residues found at the crime scene to ignitable liquids found in possession of the suspect. Interpreting the result of such a comparison is hampered by processes at the crime scene that result in evaporation, matrix interference, and microbial degradation of the ignitable liquid.Most commonly, gasoline is used as a fire accelerant in arson. In the current scientific literature on gasoline comparison, classification studies are reported for unevaporated and evaporated gasoline residues. In these studies the goal is to discriminate between samples of several sources of gasoline, based on a chemical analysis. While in classification studies the focus is on discrimination of gasolines, for forensic purposes a likelihood ratio approach is more relevant.In this work, a first step is made towards the ultimate goal of obtaining numerical values for the strength of evidence for the inference of identity of source in gasoline comparisons. Three likelihood ratio methods are presented for the comparison of evaporated gasoline residues (up to 75% weight loss under laboratory conditions). Two methods based on distance functions and one multivariate method were developed. The performance of the three methods is characterized by rates of misleading evidence, an analysis of the calibration and an information theoretical analysis.The three methods show strong improvement of discrimination as compared with a completely uninformative method. The two distance functions perform better than the multivariate method, in terms of discrimination and rates of misleading evidence.     

Extraction procedures for some common drugs in clinical and forensic toxicology.

The results of four extraction systems for 86 drugs are reported. These systems were investigated with the view to obtaining a rapid, reliable, and efficient extraction technique in clinical and forensic toxicology.     

MDMA心肌毒性的法医毒理学研究进展

3,4-亚甲基二氧基甲基苯丙胺(MDMA)是近年来在全世界,特别是亚洲地区公共娱乐场所流行性滥用的"摇头丸"的主要药物成分。MDMA主要作用于人体神经系统从而表现出各种神经系统症状。目前的实验研究发现,MDMA对人体多个系统具有毒性作用,其中对心血管系统的毒性损害作用较为显著。本文就近年来针对MDMA心肌毒性机制的法医毒理学研究进展进行综述,为进一步深入研究提供理论信息。     

Alcohol screening with the Alcoscan test strip in forensic praxis

The Alcoscan test strip was applied as an assay for the screening of alcohol in vitreous humor and urine samples in autopsy cases and in saliva from drunken drivers. The method gives instant and reliable semi-quantitative information on the presence of alcohol and is valuable when considering the necessity of chemical sampling especially during autopsy.     

Difficulties of sex determination from forensic bone degraded DNA: A comparison of three methods

Sex determination is of paramount importance in forensic anthropology. Numerous anthropological methods have been described, including visual assessments and various measurements of bones. Nevertheless, whatever the method used, the percentage of correct classification of a single bone usually varies between 80% and 95%, due to significant intra- and inter-population variations, and sometimes variations coming from secular trends. DNA is increasingly used in a forensic context. But forensic DNA extraction from bone raises several issues, because the samples are very often badly altered and/or in very small quantity. Nuclear DNA is difficult to get from degraded samples, according to low copy number, at least in comparison with mitochondrial DNA. In a forensic context (as in a paeleoanthropological context) DNA sex determination is usually complicated by the weak amount of DNA, the degraded nature of nucleic acids, the presence of enzymatic inhibitors in DNA extracts, the possible faint amplification of Y band and the risk of contamination during either excavation or manipulation of samples.The aim of this work was to compare three methods of DNA sex determination from bones: procedure #1 using a single PCR amplification, procedure #2 using a double PCR amplification, and procedure #3 adding bleaching for decontamination of the bone, instead of simply rubbing the bone. These processes were applied to samples of bones (49 samples coming from 39 individuals) that were in various states of post mortem alteration.The main results are the following. (i) No DNA could be extracted from three skulls (parietal bones, mastoid process), the compact bone of one rib, and the diaphysis of one femur; (ii) there was a contamination in three skulls; and (iii) the Y band did not appear in two male cases, with one of the three procedures (male tibia, procedure #2) and with procedures #2 and #3 (male femur).This study emphasises the main issue while working with altered bones: the impossibility to extract DNA in some cases, and, worth of all, the contamination of the sample or the faint amplification of Y band which leads to a wrong sex answer. Multiple and significant precautions have to be taken to avoid such difficulties.     

人骨骼及牙齿DNA提取方法的比较和优化

目的人骨骼和牙齿DNA提取方法的比较和优化。方法收集18份不同个体的长骨、30颗磨牙和同一个体2根股骨、8颗磨牙。利用TissueLyser-Ⅱ组织破碎仪和PreFiler Express BTA^TM法医DNA提取试剂盒（BTA法）,应用Automate Express^TM自动化法医DNA提取系统提取DNA,进行STR分型,与脱钙法进行比较,并进行实验条件优化。结果用TissueLyser-Ⅱ结合BTA法,约2.5h即可完成骨骼和牙齿的DNA提取,分型成功率分别为94.4%和96.7%。与脱钙法比较,两种方法获得DNA质量浓度和检出率比较接近（P〈0.05）,但BTA法在操作过程方面更具优势。最佳样本量为100mg,消化时间为2h。结论采用TissueLyser-Ⅱ组织破碎仪结合BTA法对骨骼和牙齿进行DNA提取和分型检验,能满足实际检案的要求,可在法医学实践中选择使用。     

Novel technique for the combined recovery, extraction and clean-up of forensic organic and inorganic trace explosives samples.

This paper describes a simple processing and analysis scheme for explosives trace swab samples which deals both with organic and inorganic materials. Swabs, wetted with ethanol or ethanol/water mixture, were extracted with ethanol/water mixture. The extract was passed directly through a simple column containing an acrylonitrile/styrene copolymer adsorbent. The adsorbent retained common organic explosives, which were recovered with an efficiency of 30-50% as a relatively clean ethyl acetate solution. The concentrated ethyl acetate eluate was analysed using gas chromatography with chemiluminescence or mass spectrometric detection. The unretained inorganic ions and sugars, which were recovered with generally high efficiency as an ethanol/water solution, could be directly analysed using ion chromatography and/or capillary electrophoresis. Minor difficulties encountered in the analysis of sugars, fluoride and phosphate were examined.     

A comparison of extraction and adsorption methods for the recovery of accelerants from arson debris

Two different methods of recovering arson accelerants from fire debris are compared: distillation with addition of n-hexane and adsorption onto activated charcoal. Both procedures involve the use of the gas chromatography/mass spectrometry (GC/MS) utilizing specific mass ion programs. Some casework examples have been analyzed and the results show that, in spite of the advantages of short application times in the adsorption method, the distillation technique presented a higher degree of efficiency.     

分子印迹技术在法庭毒物分析中的研究进展

分子印迹聚合物具有预识别性、高度选择性、实用性,已广泛应用在样本前处理中,可以选择性的识别复杂基质中低浓度目标物,提高检测灵敏度。本文旨在综述和探讨分子印迹技术的原理和在法庭科学领域毒物分析应用中的研究进展。