Jean-Claude Mas made his much-anticipated first statement on the third day of one of France's biggest trials, which sees Mas and four others face charges of aggravated fraud for using non-authorised silicone gel in implants.
An estimated 300,000 women in 65 countries are believed to have received the implants made by the firm PIP, which some health authorities say are twice as likely to rupture as other brands.
"Where risk is concerned, I maintain that I did not make (people) take risks", Mas told the courtroom, adding that the gel used in the implants was safe and could have received official approval.
As some 100 plaintiffs looked on, Mas told the judge he had obtained the gel formula from a plastic surgeon with whom he had worked in the early 1980s — his first contact with the breast implant sector.
News of the faulty implants in 2011 sparked fears worldwide, but health officials in various countries have said they are not toxic and do not increase the risk of breast cancer.
More than 5,000 women have registered as plaintiffs in the trial in the southern city of Marseille — which sees the defendants face up to five years in prison — alleging that the gel poses a health risk.
Marie-Therese Louvet, one of the plaintiffs present at the trial — due to last until May 17th — told AFP on Friday that she had had PIP implants fitted after breast cancer and had to have them hastily removed.
She said they were "seeping through" when the surgeon took them out.
Mas, a former life-insurance salesman who also dabbled in the wine industry and in diamonds, got his start in the medical business by selling pharmaceuticals and founded PIP in 1991 to take advantage of the boom in cosmetic implants.
He built the company into the third-largest global supplier but came under the spotlight when plastic surgeons began reporting an unusual number of ruptures in his products.
Health authorities later discovered he was saving millions of euros by allegedly using industrial-grade gel in 75 percent of the implants. PIP's implants were banned and the company eventually liquidated.
PIP exported more than 80 percent of its implants, with about half going to Latin America, about a third to other countries in western Europe, some 10 percent to eastern Europe and the rest to the Middle East and Asia.
Questioned after him on Friday, Mas's former right-hand man Claude Couty admitted having allowed the sale of implants that had not been officially authorised, but said he was "never aware of the danger".
He added Mas was "a know-it-all… We quite often disagreed on how to run the firm."
PIP's quality control director Hannelore Font, who started working at the firm in 1999 aged 22, said she had blocked the sale of some batches of implants in 2009.
"I'm sorry, I want to apologise. I wasn't up to the job and I apologise to the patients who had to suffer due to this," she said, breaking down into sobs, forcing the judge to suspend the session but drawing some anger.
"Her youth doesn't explain everything, it doesn't excuse the fact that she let things happen, health is too important," said Joelle Manighetti, a plaintiff.
Some of the defendants, including Mas, are also the subject of separate and ongoing manslaughter and financial fraud investigations arising from the scandal.
The manslaughter probe is related to the 2010 death from cancer of a woman who was fitted with the implants.