Nail drug testing provides an alternative sample when hair is not available or too short for the time period required.
Nail testing works by detecting drugs and their metabolites that are deposited into nail tissue. Blood vessels underneath the nail deposit these metabolites into the keratin, the part that makes your nail hard. 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. A section of nail can have longer window of detection in comparison to head hair. This is because they are tested as a whole sample, that is nails cannot be sectioned like head hair.
A toenail sample will tell us whether the substance has been used in the last 12 months. With the faster growth rate of fingernails this is narrowed down to the last six months.
Nail samples are sent for analysis 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. This includes illicit drugs and prescription medications, alcohol, steroids and new psychoactive substances.
In front of a trained ToxLogic collector, the individual will wash and dry their nails. They will then be given sanitised nail clippers or scissors (provided by ToxLogic) and then, in front of the collector, the individual will cut their own nail samples. The nail is then clipped down as far as the top of the fingertip.
Nail samples must have a normal appearance, be clean and free of false nails or nail varnish etc.
In general, nail drug 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. Nail testing is not the preferred method if hair is available. However, that does not diminish its accuracy. Nail drug testing can provide a yes/no answer to whether a specific substance has been used. For fingernails it is in the last six months, or twelve months if toenails are sampled.
Occasionally, nail testing can be used in conjunction with hair testing – generally in cases where an individual is regularly bleaching/dyeing their hair. It is also useful if 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.
Nail testing has its limitations, especially when compared to hair testing. Nails are much slower growing than hair meaning the most recent time period assessed will be around three months in the past. Hair testing on the other hand can detect use as recently as two weeks.
Nail testing is also non-specific in its timeframes. While hair drug testing can section out month by month, enabling the indication of increasing or decreasing use, nail testing will only provide an overall result. The results timeframe, depending on the sample, will be six months for fingernails and twelve months for toenails.
Please note: nail tests are not appropriate for detecting one-off substance use. Toenail samples from individuals with diabetes or peripheral artery disease are unsuitable, as these conditions can affect the results.