Gregory A. Hobbs, PhD

Lab Director
Dr. Hobbs is a Diplomate of the American Board of Clinical Chemistry and a Fellow of the National Academy of Clinical Biochemistry. He received his Doctor of Philosophy in Biochemistry from Oklahoma State University in May 1988.

Prior to joining Truetox as Laboratory Director, he held the position of Scientific Director, Toxicology with Quest Diagnostics. Dr. Hobbs has also held various Laboratory Director positions with Sciteck Laboratories, Inc, Microbac Laboratories, Inc., and THE LAB, INC.,

Dr. Hobbs has also published over 15 papers in toxicology, medicinal chemistry and successful laboratory workflows.

William Closson, PhD

Assistant Lab Director
Dr. Closson received his PhD in Clinical Chemistry from St. John’s University in 1983 and has spent the last 32 years as a nationally recognized leader in forensic toxicology. Prior to joining Truetox he held the position of Lab Director with Bendiner-Schlesinger, a full-service toxicology laboratory in which more than 9000 specimens were processed daily. He developed legally defensible analytical methods involving immunoassay, gas and liquid chromatography/mass spectrometry and was responsible for assuring compliance with regulatory agencies and maintaining professional licensing.

Dr. Closson consulted with law enforcement and medical clients involving issues relating to drug testing and drug abuse and provided expert testimony in the field of toxicology, drug abuse, pharmacokinetics and product liability.

Nan Hoo

Lab Manager
Ms. Hoo holds an M.S. in Clinical Immunology from Long Island University and a B.S in Biology from State University of New York, Old Westbury. Prior to joining Truetox she held the position of Toxicology Supervisor at AFTS labs and has held Laboratory Technologist positions at ICON, Mercy Medical Center and the Neuroscience Research Foundation at SUNY.

Steven Silverman, MD

Dr. Silverman received his medical degree from New York Medical College. He completed a medical residency at St. Lukes Hospital, Case Western Reserve, Cleveland, Ohio. Dr. Silverman is board certified by the American Board of Addiction Medicine, one of approximately 3000 other physicians. He is certified by the Substance Abuse and Mental Health Services Administration (SAMHSA) for medically assisted treatment of opiate abuse.

Dr. Silverman has a full-time practice in addiction medicine, seeing patients with a wide range of addiction problems.