Drugs and their metabolites are deposited into nail tissue – keratin – via blood vessels underneath the nail. As the nail grows longer and thicker, its layers provide a history of substance use.
In cases where head hair is unavailable or regularly chemically treated, nail clippings (2-3mm minimum) may be used. Nail clippings can have a longer window of detection in comparison to head hair and are tested as a ‘whole’ sample, i.e. nails cannot be sectioned like head hair.
A toenail sample will tell us whether the substance has been used in the last 12 (twelve) months. With the faster growth rate of fingernails, this timeline is narrowed down to the last 6 (six) months.
Nail samples are sent to Cansford Laboratories in the UK. Cansford have over seven years’ experience with nail testing and can analyse for more than 130 drugs/substances in nail samples, including illicit drugs and prescription medications, alcohol, steroids and New Psychoactive Substances.
In front of a trained ToxLogic collector, the client will use nail clippers or scissors (provided by ToxLogic) to cut their own nail samples, clipping down as far as the top of the fingertip. Nail samples must have a normal appearance as well as be clean and not painted with nail varnish etc.
In general, fingernail (or toenail) testing should only be used when there is no head or body hair to test, or when a donor has very short head or body hair. While this is the “last resort” in a list of testing options, it provides a reliable yes/no view of whether the donor has used drugs in the last six months (or twelve months in the case of toenails).
Occasionally, nail testing can be used in conjunction with hair testing – generally in cases where a client is regularly bleaching/dyeing their hair or their hair is shorter than the time period required. In these cases, hair testing may be requested to cover a timeframe of a month or two and nail testing will cover the last six or twelve months.
Please note: nail tests are not appropriate for detecting one-off substance use. Toenail samples from donors with diabetes or peripheral artery disease are unsuitable, as these illnesses can affect the results.