You must have a hazardous materials endorsement on your CDL to drive a vehicle that is placarded for hazardous materials. However, not all packages of hazardous materials require placarding your vehicle. For example, relatively small quantities of consumer-grade chemicals such as drain openers and bleaches may be exempt. Federal regulation 49 CFR 172.500 exempts certain amounts and types of hazardous materials from placarding, but states may impose more stringent requirements. Check with your state's transportation department.