A Christian holiday with origins in Europe， Mardi Gras， meaning \"Fat Tuesday\" in French， is recognized as a day of indulgence before the beginning of the penitential season of Lent on Ash Wednesday. But there is a dark underside to the Mardi Gras festivities.

Every year， an estimated 25 million pounds of plastic beads make their way to New Orleans.

The beads are central to the ritualized gift exchanges of Mardi Gras season， a multi-day series of parties and parades that brings an estimated million revelers to the streets for what is sometimes called \"the Greatest Free Show on Earth.\"

Members of Mardi Gras \"krewes，\" the private social organizations that stage the parades， spend thousands to purchase the shiny baubles before flinging them to crowds who beg for them with the exclamation， \"Throw me something， mister!\"

These beads are made from toxic waste， and are likely to end up in the bodies， landfills and water supply of the citizens of New Orleans.

\"There isn't a system in the body that isn't affected by lead，\" said Dr. Howard Mielke， a Tulane toxicologist who has been studying lead levels in the city for many years.

Dr. Mielke， along with the Ann Arbor， Michigan-based non-profit group HealthyStuff.org and Dr. Holly Groh， a founder of VerdiGras in New Orleans， studied beads used during Mardi Gras. They found lead and an array of toxic and cancer-causing metals and chemicals， including bromine， chlorine， cadmium， arsenic， tin， phthalates and mercury.