Lead poisoning is usually caused by months or years of exposure to small amounts of lead at home, work, or day care. It can also happen very quickly with exposure to a large amount of lead. Many things can contain or be contaminated with lead: paint, air, water, soil, food, and manufactured goods.
1 American Express cards have a four-digit code printed on the front side of the card above the number.  Diners Club, Discover, JCB, MasterCard, and Visa credit and debit cards cvv no open security code have a three-digit card security code.
I'm not sure if you're asking what the card number is on a Visa debit card, or if it is different than a Visa credit card... so I will try to answer both. A Visa card # is a 16-digit number, that uses a specific format. In order to be a valid number, the 16 digits have to work within the Mod 10 algorithm. All Visa numbers start with a 4. MasterCard numbers start with a 5, Amex is 3, and then there are a few others, including Discover card, etc.