|bot=InternetArchiveBot |fix-attempted=yes }}</ref> It was not until the second half of the 20th century that subclinical lead exposure became understood to be a problem. During the end of the 20th century, the blood lead levels deemed acceptable steadily declined. Blood lead levels once considered safe are now considered hazardous, with no known safe threshold.In the late 1950s through the 1970s Herbert Needleman and Clair Cameron Patterson did research trying to prove leads toxicity to humans. In the 1980s Needleman was falsely accused of scientific misconduct by the lead industry associates.In 2002 Tommy Thompson, secretary of Health and Human Services appointed at least two persons with conflicts of interest to the CDCs Lead Advisory Committee. In 2014 a case by the state of California against a number of companies decided against Sherwin-Williams, NL Industries and ConAgra and ordered them to pay $1.15 billion. The disposition of The People v. ConAgra Grocery Products Company et al. in the California 6th Appellate District Court on 14 November 2017 is that:... the judgment is reversed, and the matter is remanded to the trial court with directions to (1) recalculate the amount of the abatement fund to limit it to the amount necessary to cover the cost of remediating pre-1951 homes, and (2) hold an evidentiary hearing regarding the appointment of a suitable receiver. The Plaintiff shall recover its costs on appeal.
Esophageal webs are seen associated in 50% of patients with this condition. Rarer forms of cervical esophageal diverticula are the Killians diverticulum and the Laimers diverticulum. Killians diverticulum is formed in the Killian-Jamiseon triangle (located inferior to the cricopharyngeus on both sides of this muscles insertion into the cricoid cartilage). Laimers diverticulum is formed in Laimers triangle (located inferior to the cricopharyngeus in the posterior midline above the confluence of the longitudinal layer of esophageal muscle). Laimers triangle is covered only by the circular layer of esophageal muscle. Diagnosis
A combination of the simple barium swallow and a  thorough endoscopy will normally confirm the diverticulum. Treatment
If small and asymptomatic, no treatment is necessary. Larger, symptomatic cases of Zenkers diverticulum have been traditionally treated by neck surgery to resect the diverticulum and incise the cricopharyngeus muscle. However, in recent times non-surgical endoscopic techniques have gained more importance (as they allow for much faster recovery), and the currently preferred treatment is endoscopic stapling (i.e. diverticulotomy with staples ). This may be performed through a diverticuloscope. Other methods include fibreoptic diverticular repair.Other non-surgical treatment modalities also exist, such as endoscopic laser, which recent evidence suggests is less effective than stapling. Epidemiology
Zenkers diverticulum mainly affects older adults. It has an incidence of 2 per 100,000 per year in the UK, but there is significant geographical variation around the world. References
External links

Zenkers diverticulum at eMedicine