Exclusive Expert Interview: A Forensic Toxicologist Discusses Breathalyzers & Drug Testing

 

Interviewer (I): Today, we’re speaking with Dr. Lea Camsi, a forensic toxicologist with over 15 years of experience in forensic drug and alcohol testing. She has worked with law enforcement agencies and forensic labs to improve accuracy in DUI and drug-related investigations. Dr. Camsi, thank you for joining us.

Dr. Lea Camsi(LC): Thank you for having me.

1. Understanding the Science Behind Breathalyzers

I: Breathalyzers are widely used in DUI enforcement. Can you explain how they work from a forensic perspective?

LC: Absolutely. Breathalyzers measure Blood Alcohol Concentration (BAC) using Henry’s Law, which states that the alcohol concentration in breath is proportional to that in the blood. There are three main types:

1. Fuel Cell Breathalyzers – These are electrochemical devices that react with ethanol to produce an electric current.

2. Infrared Spectroscopy Breathalyzers – Used in police stations, they identify ethanol molecules based on how they absorb infrared light.

3. Semiconductor Breathalyzers – These are cheaper and used in personal devices but are prone to false positives.

The most legally admissible results come from infrared spectroscopy or properly calibrated fuel cell devices.

2. Accuracy & Common Misconceptions

I: There have been cases where breathalyzers gave incorrect readings. What are the common reasons for false positives?

LC: Great question. Some factors that can cause false positives or inaccurate BAC readings include:

Mouth alcohol (recent drinking, mouthwash, or even certain medications).

Medical conditions like acid reflux or diabetes, which produce acetone that breathalyzers may misinterpret as alcohol.

Improper calibration – Breathalyzers require regular maintenance to ensure accuracy.

This is why officers conduct multiple tests and confirm results with blood tests if needed.

3. Drug Testing: Identifying Illicit Substances in the Body

I: Moving to drug testing—unlike alcohol, drugs affect the body differently. What are the main methods used to detect drugs?

LC: We use four primary biological samples to detect drugs:

1. Urine Testing – The most common method, detecting drug metabolites for days or weeks after use.

2. Blood Testing – More accurate for detecting recent drug use but has a short detection window.

3. Saliva Testing – Effective for detecting drugs immediately after use, making it ideal for roadside tests.

4. Hair Analysis – Can detect drug use months after consumption, often used in workplace and forensic investigations.

Each method has its strengths and limitations, so we choose based on the case.

4. Emerging Technologies in Drug Detection

I: Technology is evolving rapidly. What are some of the newest advancements in drug and alcohol testing?

LC: One of the most exciting advancements is portable mass spectrometry, which allows officers to test substances in the field with near-laboratory accuracy. Other innovations include:

AI-powered drug analysis to detect emerging synthetic drugs.

Fentanyl test strips for instant overdose prevention.

Non-invasive sweat patch testing, which continuously monitors drug use over time.

These new technologies are enhancing forensic accuracy and preventing wrongful arrests.

5. Real-World Challenges & Notable Cases

I: What are some real-world challenges in forensic drug and alcohol testing?

LC: One major challenge is the rise of synthetic drugs like designer opioids and cannabinoids, which evade traditional tests. Another issue is false positives, which can have serious legal consequences.

For example, in the State v. Chun (2008, New Jersey) case, defense attorneys challenged the accuracy of a breathalyzer, leading to stricter regulations on device calibration.

Another case involved a man falsely accused of opioid use because he had eaten a poppy seed bagel before a drug test. This case reinforced the need for confirmatory testing with mass spectrometry.

6. Ethical & Legal Considerations

I: Do you see any ethical concerns in forensic testing?

LC: Absolutely. Workplace drug tests raise privacy concerns—should an employee be penalized for cannabis use weeks before a test if they’re not impaired on the job? We need to balance public safety with personal rights.

Also, law enforcement must ensure that breathalyzers and drug tests are accurate to avoid wrongful convictions. Cases like State v. Chun prove that forensic evidence must always be scientifically validated.

7. Final Thoughts & The Future of Forensic Testing

I: What do you think the future holds for forensic toxicology?

LC: I believe we’ll see:

Faster, more portable drug tests with AI integration.

More accurate impairment tests rather than just presence tests.

Improved roadside drug detection to prevent impaired driving.

As forensic technology evolves, we must ensure it is scientifically sound, legally admissible, and ethically responsible.

8. Closing Remarks

I: Dr. Lea Camsi, this has been incredibly insightful. Thank you for sharing your expertise with us.

LC: My pleasure. Thank you for highlighting the science behind forensic drug and alcohol testing.