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APPROACHES TO HUMAN AGE DETERMINATION A BRIEF CRITIQUE OF CURRENT PRACTICE AND A PROPOSAL
Dr Richard Bassed B.D.S. PhD. Dip.For.Odont
Prof. Stephen Cordner AM, MA, MBBS, FRCPA, FRCPATH
Introduction:
Verified documentation of birth date is the only way to determine the exact age of an individual. To estimate the age of an individual where such documentation is not available, forensic practitioners must rely on population data concerning growth and development. This data enables the creation of a biological profile of the developmental status of an individual of unknown age, thus leading to an estimate of age. This profile is based on the assessment of skeletal and dental anatomical growth markers. The search for the best anatomical growth markers which will provide the most reliable age assessments has been on-going for decades. It must be stressed that biological variation in human development means that any assessment of age based on analysis of anatomical growth markers is only an estimate, and thus will contain a degree of error. The size of that error depends, in large measure, on the anatomical markers used, the statistical methods used to construct an age estimation table or formula based on these markers, and also on the developmental characteristics of the population being assessed.
Determination of an individuals age, and thus whether they are an adult or a child, is vital in terms of how that person will be treated by the law. This is so not only in criminal prosecutions (including of people smugglers), but also in civil hearings including determination of refugee status.
The difficult task for forensic practitioners assessing age for the purposes of our legal system is to accurately convey the degree of error inherent in whatever method is used, and to clarify the likelihood that an individual below 18 years of age will be wrongly classified as an adult ADDIN EN.CITE ADDIN EN.CITE.DATA [1-3].
Current practice to assess whether an individual has achieved 18 years of age Hand / Wrist X-rays:
Age assessments will use different anatomical growth or ageing markers depending on the particular age of interest to the examiner (e.g. is the person more or less than 40, 25, or 18 years). Current age assessments for individuals suspected of people smuggling in Australia, whose age status is unknown, are based on the radiological assessment of the development status of the hand/wrist, as stated in the Human Rights Commission discussion paper of December 2011. This technique (the GP method) was actually designed as a medical tool to assess the general physical development of children, especially their skeletal development, comparing this to their known age, not as a tool to determine their age ADDIN EN.CITE Greulich19591611161116116Greulich, W.W.Pyle, S.I.Radiographic Atlas of Skeletal Development of the Hand and Wrist2nd edition1959CaliforniaStanford University Press[4].
The technique relies on an anatomical atlas of standard hand/wrist x-rays taken of a group of 1000 American children aged from birth to 19 years in the 1930s and 1940s. This atlas displays standard skeletal development at 3 month intervals during the first year of life, at six month intervals from 1 year to 5 years, and at one year intervals thereafter to age 19.
Another technique that is briefly mentioned in the Human Rights Commission discussion paper is that developed by Tanner and Whitehouse, the TW2 or TW3 method [5]. This is again a system devised to assess maturity of children rather than determination of chronological age. Its use in forensic situations has been examined with varying results [6], and has been found to offer no particular advantage over the GP atlas method. Recent literature would indicate that this method is applicable to individuals only up until the age of 16, making it of little use in the assessment of legal maturity [7].
A major drawback when using the GP technique today, even for its stated purpose, is that the individuals chosen for inclusion in the atlas were growing up in another hemisphere more than 60 years ago. Economic circumstances and general health of the population are crucial determinants of the amount and rate of growth. There is no way of comparing those determinants in America in the 1930s and 40s with those in Iraq, Afghanistan or Indonesia today. The existence of genetic differences that may or may not exist, and which may contribute to differences in development and its timing, also needs to be considered. Put another way, there is no way of knowing whether an American child in the 1940s developed to the same degree or at the same rate at which an Iraqi, Afghani, Indonesian or indeed an Australian child will develop today.
Even if the atlas accurately reflected current growth trends, it would still be of limited use in predicting chronological age. The stated variability in the model is that for a boy predicted to be 17 years old, there is a standard deviation of 15.4 months (see p 55 of the GP atlas for a complete list of standard deviations across all ages). In other words, assuming a confidence interval of 95%, (i.e. there is a 95% probability that the individuals age falls within the range) this person would have a possible age range of 17 +/- 2.5 years. He could therefore, be aged anywhere from 14.5 to 19.5 years. Plainly, if the question being asked is whether or not this person is an adult or still a minor, this method cannot provide a reliable answer. It would be interesting to know, and it is beyond the scope of this paper, precisely how the atlas has been used in proceedings to date. There is nothing in the literature that we can find to describe how the atlas has been used in this context.
Other anatomical growth markers available and in current use:
Forensic practitioners have a variety of age determination methods available to them. These include physical examination by a suitably qualified medical practitioner, assessment of the degree of dental development, and assessment of other skeletal elements such as the clavicle, which has a longer development time than does the wrist, and can be used to assess age well into the 20s. Depending on the question to be answered, these methods may be more or less reliable.
These age determination methods are used on a regular basis in forensic practice in areas such as: disaster victim identification where children of various ages who have died in a single incident may only be separated on the basis of their ages, in assessment of school age entry level for immigrant children who do not know their exact age, or for the assessment of suspected child pornography images to assess the ages of the individuals involved.
Many of these methods were developed from research conducted decades ago and on populations which geographically, environmentally, and nutritionally do not accurately reflect current population demographics ADDIN EN.CITE ADDIN EN.CITE.DATA [8]. For the very young, that is those individuals under the age of 15 years, these systems, especially those describing dental development, have proven to be quite adequate for the various purposes required. Recent research, however, would suggest that these older methods can be improved upon for these young individuals ADDIN EN.CITE Graham201022932293229317Graham, J. P.O'Donnell, C. J.Craig, P. J.Walker, G. L.Hill, A. J.Cirillo, G. N.Clark, R. M.Gledhill, S. R.Schneider-Kolsky, M. E.Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Victoria, Australia. gramach@bigpond.net.auThe application of computerized tomography (CT) to the dental ageing of children and adolescentsForensic Sci IntForensic Sci Int58-621951-32009/12/222010Feb 251872-6283 (Electronic)
0379-0738 (Linking)20022437http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=20022437S0379-0738(09)00468-X [pii]
10.1016/j.forsciint.2009.11.011eng[9], and it is suspected that major improvements can be achieved for those individuals older than 15 years of age.
In recent years, partially as a result of the production of the National Academy of Science report into the state of forensic science in the USA ADDIN EN.CITE NRC20092706270627066NRCStrengthening Forensic Science in the United States: A path forward2009Washington D.C.The national Academies Press[10], there have been increasing calls to improve the evidence basis on which forensic science conclusions rest. In relation to forensic anthropologists and odontologists the report emphasises the importance of improving the evidence base for age estimation methods, especially with regards to developing new reference standards for particular populations, and devising a more scientifically robust definition of the error and range in age estimations.
New research is now focusing on the development of multifactorial methods for age estimation, whereby a combination of methods (or anatomical growth markers) can provide the most accurate age estimate with the smallest possible error ADDIN EN.CITE ADDIN EN.CITE.DATA [11]. New techniques have been developed for older teenage individuals which are able to provide age estimates with substantially narrower age ranges at the 95% confidence level ADDIN EN.CITE Bassed201135043504350417Bassed, R.B.Briggs, C.Drummer, O. H.Age estimation using the third molar tooth, the medial clavicular epiphysis, and the spheno-occipital synchondrosis: A multifactorial approach.forensic Sci IntForensic Sci IntIn Press201110.1016/j.for-sciint.2011.06.007[12]. The development of the third molar (wisdom tooth) probably provides the best single method to discriminate between individuals above and below the age of 18 years, and should be part of any age assessment procedure for late teenage individuals ADDIN EN.CITE ADDIN EN.CITE.DATA [13, 14]. It must be noted that the formulae used to construct age ranges in the latest research has been developed using an Australian population, and therefore may not reflect developmental differences with other populations. Work is underway to expand our knowledge to the South East Asian population. To the extent this has been researched, there appears to be some robustness in the development of the third molar between different populations [15], thus giving a measure of confidence in recent Australian research and its applicability to populations of interest.
These new methods still have inherent within them a degree of error, due to the aforementioned human variability, but they are at least
based on data from a contemporary population which displays some cultural and genetic heterogeneity,
significantly more accurate and precise for assessing unknown age in the population from which the data is derived than the out-dated GP hand/wrist method.
There may still be judgements to be made when the data from one population is applied to individuals from another.
X-Ray Exposure Ethical Issues and Medical Risk
Comprehensive age assessment of living individuals necessarily involves the use of ionising radiation (x-rays), with unavoidable radiation exposure to various tissues. This exposure is not at a level sufficient to cause immediate harm, but does raise the total lifetime dose of radiation experienced by the individual concerned. Medical imaging is continually advancing, and development of methods such as ultrasound, MRI, and more focused low-dose CT technology may resolve some of these issues. As an example of radiation dosage, an x-ray of the jaws, required for examination of developing wisdom teeth, will result in radiation exposure equivalent to 3-5 days of normal background radiation. The medical risk of such an exposure has been categorised as negligible [16].
There are medical ethical and legal considerations involved in conducting radiological procedures on living people, with no defined medical need, that are yet to be properly addressed. It can be said, however, that to achieve the most accurate assessment of a persons age requires examination of internal skeletal and dental structures. This currently cannot be done without x-rays. If age estimation is limited, as some have suggested, to an external physical examination only, then the potential for gross error in either over- or under-estimation of age is considerable.
Conclusions:
The current age estimation method apparently utilised in immigration and people smuggling proceedings relies heavily on the assessment of hand/wrist x-rays. It has been shown that this technique is one which:
was developed from a population that may bear little resemblance in a developmental sense to current populations,
was developed from a population that probably bears little resemblance to the populations from which individuals of interest to Australian courts related to people smuggling come,
was not designed specifically for age estimation,
has been shown to have a degree of error which is large, even if applied to the population upon which the method was based, let alone a different, unrelated population from another era.
There are other more accurate methods available which would involve no significantly greater radiation exposure, are based on modern population data, have a smaller error margin, and are just as simple to apply in practice. Specifically, it is our recommendation that radiological assessment of the development of the third molar tooth be a mandatory component of any age assessment for a late teenage individual. This, conducted in conjunction with a radiological examination of the developing clavicle will, according to the latest scientific research [12], provide the best available means to establish the adult/child status of any unknown age individual. These procedures should follow a physical examination conducted by a physician who can properly assess the fitness of the individual to agree to a radiographic procedure, and record the actual consent, as part of the overall medical assessment. Once all relevant information concerning the age of the individual of interest has been gathered, we recommend that consideration be given to having this assessed by a small panel of recognised experts in the field of age estimation. Such a panel may include a forensic odontologist, forensic anthropologist, forensic physician, and a person with experience in the analysis of biostatistics.
Lastly, there needs to be considered debate regarding the risks and ethics associated with the use of x-rays for non-medical purposes, versus the benefits of more accurate age assessments in the interests of justice.
Appendix 1. Suggested procedure for scientific age assessment.
The protocol outlined below is to be used when no definitive evidence of age can be found through normal investigative means, if the veracity of such evidence is doubted, or as a prelude to further investigation.
Medical assessment by a medical practitioner, including an assessment of fitness to consent and assessment of willingness or otherwise to undergo an age assessment procedure. Forensic physicians have experience in conducting such medical assessments, including for the purposes of estimating age.
Orthopantomograph (OPG) radiograph taken of the jaws to assess dental development, specifically the root development of the third molar tooth. At the conclusion of this examination it may be determined in a certain number of cases that the individual is either definitely a child or definitely an adult. For some individuals, however, their status will still be in doubt. From a practical procedural point of view, a decision will need to be made about an assessment of the OPG being completed prior to proceeding to further x-rays, or further x-rays being taken at the same time as the OPG.
In the event that the dental examination alone is unable to provide a definitive answer to the question of legal maturity, a CT scan is required to be taken of the medial clavicles to ascertain the developmental stage of this age marker. When combined with the third molar stage, and with the application of the correct formula, it will be possible to provide an age range [12]. This range may place an individual as either above or below the age of 18 years at the 95% confidence level, or it may not. There will inevitably be instances where the calculated age range will include the age of 18, and in these instances it will not be possible to make any statements regarding the adult or child status of the individual at the level of 95% confidence, although it may be possible in such cases on the dental-skeletal assessment to give an estimated probability of the individual being an adult or not.
References
ADDIN EN.REFLIST 1. Schmeling, A., et al., Criteria for age estimation in living individuals. Int J Legal Med, 2008. 122(6): p. 457-60.
2. Olze, A., et al., Age estimation of unaccompanied minors. Part II. Dental aspects. Forensic Sci Int, 2006. 159 Suppl 1: p. S65-7.
3. Schmeling, A., et al., Age estimation of unaccompanied minors. Part I. General considerations. Forensic Sci Int, 2006. 159 Suppl 1: p. S61-4.
4. Greulich, W.W. and S.I. Pyle, Radiographic Atlas of Skeletal Development of the Hand and Wrist. 2nd edition ed. 1959, California: Stanford University Press.
5. JM Tanner, RH Whitehouse, N Cameron, Assessment of skeletal maturity and prediction of adult height (TW3 method), 2001.
6. Schmidt S, Nitz I, et al, Applicability of the skeltal age determination of Tanner and Whitehouse for forensic age diagnostics. Int J Legal Med 2008. 122(4): p 309-314.
7. Buken B, Safak A, et al, Is the Tanner-Whitehouse (TW3) method sufficiently reliable for forensic age determination of Turkish children. Turk J Med Sci 2010. 40(5): p797-805
8. Cunha, E., et al., The problem of aging human remains and living individuals: a review. Forensic Sci Int, 2009. 193(1-3): p. 1-13.
9. Graham, J.P., et al., The application of computerized tomography (CT) to the dental ageing of children and adolescents. Forensic Sci Int, 2010. 195(1-3): p. 58-62.
10. NRC, Strengthening Forensic Science in the United States: A path forward. 2009, Washington D.C.: The national Academies Press.
11. Garamendi, P.M., et al., Reliability of the methods applied to assess age minority in living subjects around 18 years old. A survey on a Moroccan origin population. Forensic Sci Int, 2005. 154(1): p. 3-12.
12. Bassed, R.B., C. Briggs, and O.H. Drummer, Age estimation using the third molar tooth, the medial clavicular epiphysis, and the spheno-occipital synchondrosis: A multifactorial approach. forensic Sci Int, 2011. 212(1-3): p 271-275.
13. Bassed, R.B., C. Briggs, and O.H. Drummer, Age Estimation and the Developing Third Molar Tooth: An Analysis of an Australian Population Using Computed Tomography. J Forensic Sci, 2010. 56(5): p 1185-1191.
14. Mincer, H.H., E.F. Harris, and H.E. Berryman, The A.B.F.O. study of third molar development and its use as an estimator of chronological age. J Forensic Sci, 1993. 38(2): p. 379-90.
15. Thevissen P.W. Fieuws G. Willems G. Human third molars development: Comparison of 9 country specific populations. ForSciInt doi:10.1016/jforsciint.2010.04.054.
16. Web ref: http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_xray.
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