Q: Hello, I am in the midst of getting my ex to take a hair follicle drug test, but he claims it’s impossible because he is practically bald. Can body hair be tested instead? If so, will it affect the reliability of the test results? Thanks.

– Jess, Boston, MA

A: Body hair can definitely be tested. With a regular hair follicle test the collectors prefer to take the specimen from the scalp. Generally, they would like the sample to be 2.5-3 inches in length. The average person’s head hair grows at a rate of .5 inches per month. When the lab receives the hair for testing, it is cut to 1.5 inches in length. This length of hair roughly generates a three month window of detection.

If someone lacks hair on their head, such as your husband, most labs are willing to use a body hair collection. Sometimes it can be hard to get a significant enough quantity of body hair for analysis, but if they can it will provide a great test result. Some people have argued that because body hair grows at a different rate than head hair, the window of detection is expanded to as much as 12 months.

Find a lab that is willing to do a body hair collection, then propose the idea to your ex. If he still has an issue with it or refuses to take the test, you may consider legal action to get him to take it. Good luck.