Occupational Health Expertise

Dr. Tommy Hysler, HASC Chief Medical Officer, provides medical oversight for HASC occupational health centers nationwide and leads the team of providers supporting each location. A board-certified occupational medicine physician and Fellow of the American College of Occupational and Environmental Medicine (FACOEM), Dr. Hysler brings extensive experience supporting contractor and owner organizations with occupational health, workforce readiness, and regulatory compliance needs. As Medical Director for multiple industry organizations and a recognized subject matter expert in worker health, he ensures HASC delivers consistent, high-quality occupational health services that support safe, healthy, and site-ready workforces.

Dr. Bill Christian serves as Regional Medical Director, West for HASC Occupational Health Services, bringing expertise in occupational medicine, public health, and preventive medicine. He completed specialized training at the University of Texas Health Science Center at Houston, where his work focused on high-risk industrial environments and collaboration with safety teams. With advanced training in worker health and workplace risk management, Dr. Christian is dedicated to helping employers build healthier, safer workforces through proactive health initiatives, wellness programs, health screenings, and preventive care. His combined background in occupational medicine and public health helps employers address workplace health risks while promoting employee well-being and long-term workforce health.

Dr. Todd Hamel serves as Regional Medical Director, East for HASC Occupational Health Services, providing medical oversight and leadership for HASC Occupational Health Centers throughout the region. With experience spanning family medicine, corporate health, and occupational medicine, Dr. Hamel has supported some of the nation's largest industrial employers, including leadership roles with Quanta Services and Dow. His extensive background in workforce health, emergency medical services, and occupational medicine ensures HASC delivers high-quality healthcare solutions that support employee well-being, workforce readiness, and safe operations.

Jelsa Antu is a board-certified Family Nurse Practitioner with more than 25 years of healthcare experience and a strong focus on occupational medicine and workforce health. She supports industrial employers and workers across Texas through fit-for-duty evaluations, DOT physicals, injury care, chronic disease management, and return-to-work assessments. Her extensive clinical background, multilingual communication skills, and patient-centered approach reflect a strong understanding of workforce health, regulatory compliance, and operational readiness.

Gregory Baker is a Nurse Practitioner with extensive experience in occupational medicine, practicing since 1998. He brings a unique clinical foundation that combines advanced nursing practice with chiropractic medicine, supporting a wide range of occupational health services and workforce evaluations. He is a certified DOT-NRCME Medical Examiner, licensed by the Texas Board of Chiropractic Examiners, and is board-certified through the American Academy of Nurse Practitioners. His long-standing experience in occupational health supports employers in maintaining regulatory compliance, employee safety, and operational readiness.

Michael Dow is a board-certified Family Nurse Practitioner with experience in occupational and family medicine since 2008. He holds advanced degrees in nursing as well as a background in chiropractic and human biology, providing a multidisciplinary clinical foundation for workforce health services. He is a certified DOT-NRCME Medical Examiner,  a Fellow of the International Academy of Medical Acupuncture, and board-certified by the American Academy of Nurse Practitioners. His diverse clinical expertise supports comprehensive occupational health care, injury management, and employee wellness programs.

Allissa Joseph is a Louisiana native and board-certified Family Nurse Practitioner serving as an occupational health clinician with HASC. She supports workforce health and safety for industrial clients across the Gulf Coast energy sector through occupational injury care, regulatory examinations, fitness-for-duty evaluations, and return-to-work support. Ms. Joseph earned her Bachelor of Science in Nursing from the University of Louisiana Monroe and her Master of Science in Nursing - Family Nurse Practitioner from Simmons University. Her background includes primary care, urgent care, hospital-based nursing, and rural health experience caring for pediatric, adult, and geriatric populations. She brings strong clinical judgment and a practical understanding of the unique occupational health needs of industry workforce.

Morgan Mathews is a board-certified Family Nurse Practitioner with experience across a variety of healthcare settings supporting employee health and wellness. She holds advanced training in nursing and a background in kinesiology, giving her a well-rounded clinical foundation for occupational health services. Morgan is committed to delivering high-quality care that helps organizations support workforce health, maintain compliance, and ensure operational readiness.

Brandon Myers brings more than 25 years of experience in occupational and industrial medicine, supporting workforce health across some of the nation's most demanding industries. A certified Physician Assistant and veteran of the U.S. Public Health Service Commissioned Corps, he has extensive experience serving the oil and gas, petrochemical, maritime, and offshore sectors. His deep understanding of occupational health and high-risk work environments helps employers reduce risk, maintain compliance, and support a safe, healthy, and productive workforce.

Debreka Reed is an experienced Nurse Practitioner with more than 15 years of clinical experience in occupational medicine, urgent care, corporate health, and workers’ compensation management. She has provided care across refinery, construction, and corporate environments throughout the Texas Gulf Coast and has extensive experience performing fit-for-duty evaluations, return-to-work assessments, OSHA and DOT examinations, injury management, and employee health surveillance programs. Known for her collaborative approach and dedication to quality care, Ms. Reed works closely with employees, safety teams, and employers to support workplace safety and timely return-to-work outcomes.

John E. Slaughter is a board-certified Family Nurse Practitioner, DOT-NRCME Federal Medical Examiner, and Texas Department of Insurance Workers’ Compensation Division Designated Doctor. A native Texan and Eagle Scout, John earned degrees from San Jacinto College, the University of Houston, Hardin-Simmons University Patty Hanks Shelton School of Nursing, and Samford University. He brings extensive experience supporting workforce evaluations, occupational health services, injury care, and regulatory compliance programs.