Deadlifts do not cause injury, deadlifting with improper form causes injury. Make sure you are performing hip-hinge movements (deadlifting, good mornings, Romanian deadlifts, straight-leg deadlifts, etc.) with a neutral spine. Deadlifting with a rounded back compresses your spinal discs and can lead to a herniated disc. This occurs when the lower back muscles are too weak to pull the attempted weight off the ground. So, next time you deadlift, make sure your back is straight and if you feel your back deviate from this position, lower the bar and lower the weight. Remember, lifting with poor form does not make you stronger, lifting correctly makes you stronger.