The mortality rate for people who develop cerebral involvement is about 25%, and of those who survive who had lead encephalopathy symptoms by the time chelation therapy was begun, about 40% have permanent neurological problems such as cerebral palsy. Long-term
Exposure to lead may also decrease lifespan and have health effects in the long term. Death rates from a variety of causes have been found to be higher in people with elevated blood lead levels; these include cancer, stroke, and heart disease, and general death rates from all causes. Lead is considered a possible human carcinogen based on evidence from animal studies. Evidence also suggests that age-related mental decline and psychiatric symptoms are correlated with lead exposure. Cumulative exposure over a prolonged period may have a more important effect on some aspects of health than recent exposure. Some health effects, such as high blood pressure, are only significant risks when lead exposure is prolonged (over about one year). Furthermore, the neurological effects of lead exposure have been shown to be exacerbated and long lasting in low income children in comparison to those of higher economic standing. This does not imply that being wealthy can prevent lead from causing long-term mental health issues. Violence
Lead poisoning in children has been linked to changes in brain function that can result in low IQ, and increased impulsivity and aggression. These traits of childhood lead exposure are associated with crimes of passion, such as aggravated assault in young adults.
Clinical significance
Disease
Spina bifida is a congenital disorder in which there is a defective closure of the vertebral arch. Sometimes the spinal meninges and also the spinal cord can protrude through this, and this is called spina bifida cystica. Where the condition does not involve this protrusion it is known as spina bifida occulta. Sometimes all of the vertebral arches may remain incomplete.Another, though rare, congenital disease is Klippel–Feil syndrome, which is the fusion of any two of the cervical vertebrae. Spondylolisthesis is the forward displacement of a vertebra and retrolisthesis is a posterior displacement of one vertebral body with respect to the adjacent vertebra to a degree less than a dislocation. Spondylolysis, also known as a pars defect, is a defect or fracture at the pars interarticularis of the vertebral arch. Spinal disc herniation, more commonly called a "slipped disc", is the result of a tear in the outer ring (anulus fibrosus) of the intervertebral disc, which lets some of the soft gel-like material, the nucleus pulposus, bulge out in a hernia. Spinal stenosis is  a narrowing of the spinal canal which can occur in any region of the spine though less commonly in the thoracic region. The stenosis can constrict the spinal canal giving rise to a neurological deficit. Pain at the coccyx (tailbone) is known as coccydynia.Spinal cord injury is damage to the spinal cord that causes changes in its function, either temporary or permanent.