When the family's toddler was tested for lead at a preschool, the child's blood contained 27 micrograms of lead per deciliter, or more than five times the level considered dangerous by the Centers for Disease Control and Prevention.
The toddler's younger brother, a 4-month-old baby, had even higher amounts of lead in his blood.
Staff at the New Mexico Department of Health immediately suspected the eye makeup as the metal source. Scientists have known for decades that kajal can contain lead. And the metal can easily seep into a child's blood through the skin or eyes.
The parents said they were using the kajal to promote eye health.
When health workers tested the kajal in the family's home, the eyeliner turned out to be 54 percent lead. That's 540,000 parts per million, or 27,000 times the cap set by the Food and Drug Administration for color additives in makeup.
Lead is a neurotoxin. And it's especially harmful to babies and young children. Even small amounts can damage developing brains and cause permanent problems.
The two children in Albuquerque haven't shown any adverse symptoms. And their blood lead levels started to decline a month after the parents stopped using the makeup, the authors said in the report.
Kajal, which is also known as kohl and surma, is illegal in the U.S. because of its very high concentration of lead. But cosmetics generally aren't regulated for metals.
A study published in June found that 24 of 36 American lipsticks tested had traces of lead them. Still though, the largest concentration was about only about 1.3 parts per million — or 0.00013 percent.