For some reason, a lot of the dyes used in clothing, particularly jeans, have a less than pleasant odour. When we purchase these jeans, we may not even notice the smell until we get home. New black-wash jeans are prime candidates for this chemical smell, as a lot of dye is used to make them black. Repeated washing of these jeans will do no good and cause them to fade. Special care needs to be taken with these persistently unpleasant trousers.
Wash the jeans as you normally would.
During the final rinse cycle, add a fabric softener sheet. Fleecy has been known to work quite well.
Allow the fabric softener sheet to dissolve in the water and allow the jeans to finish washing.
Turn the jeans inside out, and put them in the dryer with another fabric softener sheet.
Hang the jeans outside in the sunshine if the jeans need a little more help shaking the odour. Sunshine is great for getting rid of bad smells.
Some jeans will always have this smell, but it will lessen in time. Save your receipt, and return the jeans if the smell is too strong and will not go away.