YOUR LAB, OUR MISSION. Founded in 1966, WSLH Proficiency Testing has been providing exceptional proficiency testing for over fifty years. WSLH PT is the national public health lab that is on a mission to provide reliable, affordable and easy-to-use proficiency testing products with rapid access to results. Our experienced staff of medical technologists are available to answer any questions you might have. Contact us today or learn more at: wslhpt.org.