Split Testing: A Built-in Safeguard for Employees

DOT requires split sample testing as a safeguard to ensure fairness and accuracy.

After collecting the urine, 30 mL goes into the primary test bottle and 15 mL into the secondary sample.

If an employee believes their test result is incorrect, they have 72 hours to request the secondary sample (the "split") be sent to a different certified laboratory for testing.

Unlike the initial test, split sample testing does not check for drug concentration levels. It only confirms the presence of metabolites.

Is it possible for a split sample to overturn a positive test?

Highly unlikely — studies show that almost no split sample tests overturn the initial positive result. Some employees request a split sample analysis to delay the process, but it's very rare for the result to change.

DOT Drug Testing: Split Samples, Payment Rules & Shy Bladder Process Explained

Drug testing for safety-sensitive employees under the Department of Transportation (DOT) follows strict procedures to ensure fairness and accuracy. One major safeguard built into DOT drug testing is the split sample test, which allows employees to challenge a test result. But what happens when an employee can’t afford a split test? Or what if they struggle to provide a urine sample?

This section breaks down the split sample process, payment rules, and the shy bladder protocol in easy-to-understand language.

What Is a Split Sample Test?

DOT testing follows a built-in safeguard that Congress considered essential when it passed the Omnibus Testing Act. That safeguard is the split sample test, which means that every urine specimen is divided into two separate bottles at the time of collection:

1. 30 mL in the primary bottle (used for initial testing)
2. 15 mL in the secondary bottle (saved for split testing upon request)

If an employee disputes their test result, they must request a split sample analysis within 72 hours of speaking with the Medical Review Officer (MRO).

Key Fact: The split sample is not tested at the same laboratory — it is sent to a completely different certified lab to check for errors in the original result.

What Does a Split Test Analyze?

Unlike regular urine drug tests, split sample testing does not check for drug concentration levels. Instead, it only looks for the presence of drug metabolites.

Why is this important?
Standard drug tests require a cutoff level — meaning the amount of a drug metabolite must reach a certain concentration before the test result is positive. But a split sample test only checks whether metabolites exist, not the amount.

Can a split test overturn a positive result?
It is extremely rare for a split sample analysis to overturn an original positive result. Most employees request a split test to delay the process, but they should not expect the result to change.

How Long Are Samples Stored?

1. Non-negative samples (potential positives) must be stored for 90 days in case the employee requests a split sample test.
2. Negative samples can be discarded.

The testing process now requires validity testing on every single sample to check for adulteration or tampering.

Who Pays for a Split Sample Test?

1. Employers can require employees to pay for the split sample test, but DOT regulations do not allow employers to deny a split test if an employee cannot afford it.
2. If an employee cannot pay upfront, the employer must cover the cost and then deduct the expense from the employee’s paycheck or separation pay.
   
   

DOT does not regulate testing costs. Fees for split testing are determined by employers, laboratories, or collection sites.

Final Thoughts: Staying Informed & Compliant

DOT drug testing is designed to be fair but strict, ensuring employees adhere to safety-sensitive requirements.

1. Employees have the right to request a split sample test — but positive results are rarely overturned.
2. Employers cannot deny a split test due to cost, but they can require employees to pay for it later.
3. Observed collections require direct monitoring, and situational anxiety is not an acceptable medical excuse for shy bladder cases.

Staying informed about DOT drug testing rules can help employees navigate testing procedures with confidence. Whether dealing with split sample requests or shy bladder concerns, understanding the process helps avoid surprises and ensures compliance.