Final answer:
A hair follicle test can typically detect drug use within a 90-day window based on the average rate of hair growth, but it can provide a record of drug use for up to six months or longer depending on various factors.
Step-by-step explanation:
The statement that hair follicle testing can provide a history of drug use for six months prior to testing is mostly true, although the exact time frame can vary based on several factors. Hair follicle testing involves analyzing a small sample of hair for the presence of drug metabolites. Since hair grows at an average rate of approximately 0.5 inches (1.27 cm) per month, and the standard length of hair tested is usually 1.5 inches (3.8 cm), this test typically covers a 90-day detection window. However, drugs can be detectable in hair for up to six months, and even longer in some cases, depending on factors such as hair growth rate, the amount of drug taken, and the frequency of use.