Isotope analysis
A recent development in forensic science is the isotopic analysis of hair strands. Hair has a recognisable growth rate of 9-11mm per month or 15 cm per year. Human hair growth is primarily a function of diet, especially drinking water intake. The stable isotopic ratios of drinking water are a function of location, and the geology that the water percolates through. Sr, Sr and oxygen isotope variations are different all over the world. These differences in isotopic ratio are then biologically 'set' in our hair as it grows and it has therefore become possible to identify recent geographic histories by the analysis of hair strands. For example, it could be possible to identify whether a terrorist suspect had recently been to a particular location from hair analysis. This hair analysis is a non-invasive method which is becoming very popular in cases that DNA or other traditional means are bringing no answers.
Hair care
During pregnancy and breast feeding, the normal and natural shedding process is typically suspended (starting around month three because it takes a while for the body to recognize and reset for the hormonal shifts the body goes through) for the period of gestation and extended longer if one breast feeds (this includes pumping for breast milk). Upon cessation of either of these, it typically takes around two months for the hormones to shift again to the normal hormonal settings, and hair shedding can increase exponentially, for approximately 3–6 months until hair returns to its normal volume. It is commonly noticed that hair seems thicker and shinier, even, during pregnancy and breast feeding in response to the influx of shifting hormones. It is not unusual also for hair color to change, or hair structure to change (e.g., straighter hair, curlier hair). These changes can occur more often than people may realize yet isn't often reported.