Herbalife shares closed down 4.2 percent at $40.17 on Monday on the New York Stock Exchange.
Grell said in an interview Monday that individual tablets may not exceed California's 0.5 microgram limit on lead in dietary supplements, but he said the daily recommended dosage would result in lead exposure large enough to warrant a warning label.
A document purported to be an invoice from Analytical Laboratories in Anaheim Inc, based in Brea, California, for $5,820 for testing the six products was posted on Fraud Discovery's Web site. Analytical Laboratories did not reply to calls and an e-mail to discuss any tests.
Minkow previously uncovered a discrepancy in the biography of Gregory Probert, who was then Herbalife's president and chief operating officer, that led to Probert's resignation in April.
Probert had said he had earned an MBA degree at California State University. The company said he had been enrolled at the university during the 1980's but never obtained a degree.
Herbalife's market value, after Monday's stock decline, was $2.61 billion. It had sales of $2.15 billion in 2007.
Last month, Herbalife said that Spain had issued an alert cautioning on the consumption of Herbalife products due to suspicious cases of liver damage. Herbalife said it was in discussions with the ministry.
"For more than 28 years, tens of millions of Herbalife consumers worldwide have been safely using Herbalife products with an extremely low incidence of serious adverse event reports citing liver function abnormalities," the company said at the time.
