Hazmat labeling for batteries + chemicals, how is it handled?

Hazmat shipping is regulated by DOT (US), Transport Canada, and IATA (air). Auto-parts hazmat categories:

• Class 8, Corrosives: lead-acid batteries, brake fluid (DOT 3/4/5.1), engine coolant.
• Class 9, Miscellaneous: lithium-ion / lithium-polymer batteries (UN3480 / UN3481), airbag inflators (Class 9 with special permit), some lubricants.
• Class 2.2, Non-flammable gas: refrigerants (R-134a, R-1234yf), tire-inflator cans.
• Class 3, Flammable liquids: fuel additives, paint, some cleaners.

Magento implementation: hazmat product attribute with the UN number + class. At checkout, the cart inspects line items, applies the correct shipping carrier (some carriers refuse certain classes, FedEx Express won’t take lithium batteries above certain watt-hours), generates the DOT shipping paper / hazmat label, and surfaces a regulatory disclosure to the customer (e.g. “This product contains lithium batteries. Restricted to ground shipping. Not eligible for international air.”).

For lithium batteries specifically: PHMSA HMR Section 173.185 governs limits. Most aftermarket EV / hybrid battery packs need a HazMat Certified shipper and trigger a $25, $50 hazmat surcharge per shipment. Integration: Labelmaster for compliant labels, 3E HazMat for SDS sheet management, FreightCenter handles routing automatically once the hazmat flag is set.

Returns add complexity, customer can’t ship a hazmat product back via standard mail. Requires a hazmat-certified return label or in-store return only. Build it into the RMA workflow.