In drug and alcohol testing, precision is everything. The results we deliver can influence crucial decisions, which is why every result must be accurate, fair and scientifically sound. One of the most important factors in interpreting those results is the cut-off level. This is the point at which a result changes from not detected to detected, helping us determine whether a substance is present at a meaningful level.
How do we ensure accuracy?
At Cansford Labs, we work to three key thresholds that keep testing consistent and reliable:
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Limit of detection (LOD): the smallest amount of a substance our instruments can reliably identify.
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Limit of quantification (LOQ): the lowest concentration we can measure accurately and confidently.
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Cut-offs: the threshold we use for reporting, ensuring results are clear and meaningful.
These checks mean we don’t just detect substances — we measure them precisely, and only report what can be scientifically trusted. Our instruments can identify incredibly small amounts of drugs, often at levels other laboratories cannot. Cut-offs help create a shared standard, making sure that results are based on agreed scientific limits, not equipment sensitivity.
Why do cut-offs matter?
Cut-offs exist to ensure fairness, consistency and accuracy in testing. A single positive result doesn’t always mean regular or recent use. Patterns of use and patterns of behaviour are what really matter.
A one-off use months ago might not appear above the cut-off, while frequent or heavy use likely will. But everyone is different: age, metabolism, hair type, gender, and even lifestyle can all affect how drugs bind to hair and are detected in the body.
Cut-offs help account for these differences. They ensure results are interpreted correctly, so that mistakes don’t cost people their reputation or livelihood.
How are cut-offs decided?
Cut-offs aren’t arbitrary. They’re based on scientific research and regularly reviewed by the Society of Hair Testing to ensure fairness across laboratories. Extremely low levels — such as those from environmental exposure — often have no clinical or behavioural significance. Cut-offs filter these out, ensuring that results reflect genuine use rather than background exposure.
What influences a cut-off value?
The values can vary depending on:
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The substance tested – for instance, cocaine and THC have different thresholds.
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The sample type – hair, blood and urine each have their own parameters.
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The testing method – initial screening and confirmation testing use different limits.
The takeaway
Cut-offs are an essential part of reliable drug and alcohol testing. They bring balance to a process that must be both precise and fair, ensuring that results are interpreted in context and that people are judged on patterns of behaviour, not isolated traces.
At Cansford Labs, we combine scientific rigour with transparency to deliver results you can trust. Every result aims to give clarity, confidence, and a true reflection of reality.
