Nov. 20, 2013 -- Toxicology experts today challenged the data and the research method of a private report that concluded "Clueless" star Brittany Murphy died from poisoning.

The report compiled by The Carlson Company, a lab in Colorado, used faulty methods and cited non-existent standards for heavy metal poisoning, the critics said.

Murphy died nearly four years ago of an apparent heart attack when she was 32 years old. The Los Angeles County Coroner's Office later ruled that she died of a combination of pneumonia, anemia and prescription drug intoxication.

Angelo Bertolotti, Murphy's father, commissioned the Carlson Company to conduct new tests.

The Carlson lab also advertises "infidelity DNA testing by mail." Its web site states, "We test suspicious stains related to infidelity for the presence of the other woman or man, e.g. blood, vaginal fluid, hair, DNA, semen, sperm, seminal fluid, saliva, condoms, cosmetics."

The lab concluded that Murphy had high levels of heavy metals in her hair samples, citing World Health Organization Standards.

"Ten (10) of the heavy metals evaluated were detected at levels higher that [sic] the WHO high levels," the report reads and displays the WHO logo.

WHO, a U.N. agency that provides leadership in global health issues, responded today and dismissed Carlson's methods and objected to its logo being included in the report.

"WHO does not establish reference ranges for chemicals in hair, therefore, the 'high values' for the chemicals listed in the Carlson Company report are from some other source, and not from WHO, and the laboratory should provide accurate citation for the source or sources of these values," said WHO scientist Joanna Tempowski, who works in the organization's International Programme on Chemical Safety.

WHO publishes guidelines for chemicals in food additives and drinking water, but these chemicals are more often measured in blood and urine, said Tempowski.

"Hair is not, however, a reliable material for the determination of exposure to many chemicals because it is prone to contamination from the external environment," she said.

Tempowski also said the Carlson Company does not have permission to use WHO's logo.

When the Carlson Company was asked to clarify the WHO standards it was citing, the Carlson Company manager Denny Seilheimer left ABCNews.com a voice message saying they were referring to "the recommended high value established by the national World Health Organization. I hope I've answered your question. Have a good day."

Seilheimer could not be reached to clarifiy his reference to the national World Health Organization or the criticism that the use of hair samples was improper.

Toxicologists also dismissed Carlson's method of using hair samples after ABCNews.com asked them to review the report. They said there are additional reasons that it's unlikely Murphy was poisoned.

Bruce Goldberger, a toxicologist who directs UF Health Forensic Medicine at the University of Florida, said Murphy lacked the telltale sign of heavy metal poisoning when she died: lines across her fingernails.

These lines, called Mees' lines or leukonychia striata, are a key tool for diagnosing heavy metals poisoning, Goldberger said. Without them, it's unlikely heavy metals played a role in Murphy's death.

Fatal heavy metal poisoning symptoms can manifest in many different ways, but commonly includes gastrointestinal distress, said Marcel Casavant, the chief of toxicology at Nationwide Children's Hospital in Ohio.

Goldberger said this was not noted in the coroner's report.

"The bottom line is these hair test results cannot be used to support any allegation of poisoning, and cannot be used to establish a cause and manner of death," Goldberger told ABCNews.com.

Read more about Brittany Murphy on our topic page.