LOS ANGELES — The Honest Co. built its reputation as an environmentally minded alternative to everyday consumer products such as soaps, lotions and cleaning products , winning over fans and media attention with its celebrity co-founder, actress Jessica Alba.

But the Los Angeles-area company’s image as a safer brand is being called into question by the Wall Street Journal, which commissioned lab tests that showed Honest laundry detergent contained a harsh chemical the company swore it never used.

The ingredient, sodium lauryl sulfate, or SLS, is listed as forbidden in the company’s Honestly Free Guarantee, which is posted on its website. The chemical is widely used in toothpaste, shampoo and detergent and blamed for causing skin irritation.

The Wall Street Journal conducted two lab tests that found the company’s liquid laundry detergent contained SLS, according to a story published Thursday.

Honest, which has raised $222 million in private funding, disputes the Wall Street Journal’s findings and called the story “reckless.”

“We stand behind our laundry detergent and take very seriously the responsibility we have to our consumers to create safe and effective products,” the company said in an emailed statement.