Just how bad is pollution? A little head scratching could yield an answer.
Ad hoc and non-systematic collection of air and water samples provide some useful information and underpin a wide range of environmental pollution studies. However, scientists have been scratching their heads for years hoping to come up with a better way of monitoring pollution that could provide a long view of our exposure to heavy metals and other substances. Now, a collaboration between researchers in Russia and the USA has focused on scalp hair as a possible biomarker for a wide range of elemental pollutants.
The researchers point out that in light of growing regulatory, media and public interest in markers for human exposure to environmental pollutants there is a need to find ways to assess pollution, both qualitatively and quantitatively, something that is not generally possible with conventional environmental sampling and analysis. Ideally, continuous monitoring is needed, but is expensive, technically demanding and generally limited to highly polluted places, such as cities and industrial sites. Hair was suggested as a dose monitor back in the 1970s and has been used in environmental and occupational health research for decades. Indeed, at least 100 research papers on hair analysis are published annually. But, there is no official baseline data, so interpreting the results of hair analyses is problematic as no “normal” range data is available; moreover, the data that is available is not necessarily tied to gender, age, hair colour or other factors.
Sofia Zaichick of the Department of Microbiology and Immunology, at Northwestern University in Chicago and Vladimir Zaichick of the Department of Radionuclide Diagnostics at the Russian Academy of Medical Sciences, in Obninsk, used highly sophisticated analytical techniques to determine base line levels of a wide range of elements in hair. The researchers point out that, “Trace element concentrations in hair samples represent an integrated response over time compared with blood and urine levels, which can rapidly fluctuate in response to variations of nutritional and environmental conditions.” They have also assessed the extent to which trace element content of hair correlates with an analysis of elements present in rib bone. “The samples of hair and rib-bone were taken from cadavers of luckless persons,” Zaichick says, “Most of them died in fatal accidents and all were apparently healthy before death as the pathologists did not find any chronic diseases.”
The team used Instrumental Neutron Activation Analysis (INAA) and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) to determine levels of chemical elements in scalp hair of 80 apparently healthy 15- to 58-year-old citizens (36 females and 44 males) from a non-industrial part of Central European Russia. The list of elements found in the hair samples is long – Ag, Al, As, Au, Ba, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Eu, Fe, Gd, Hf, Hg, I, K, La, Li, Lu, Mg, Mn, Mo, Na, Nd, P, Pb, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Tm, V, Yb and Zn. Full base line data from samples obtained from fresh cadavers are reported this month in the International Journal of Environment and Health.
However, statistical analysis demonstrates that elemental content in hair does not correlate significantly with bone. “The content in bone reflects the body burden of many bone-seeking elements,” the team says, “Lack of a significant correlation between the contents of these elements in hair and those in rib-bone indicates that hair element analysis does not provide a measure of body burden, exposure to pollution, for bone-seeking elements.”
The same analytical techniques could be used to build a database of “background” element levels in hair from cadavers from across the globe, given the will and financial support. Indeed, it would also be possible to do retrospective analysis of preserved hair samples from known individuals who died across decades, or even centuries past.
Zaichick, S., & Zaichick, V. (2011). The scalp hair as a monitor for trace elements in biomonitoring of atmospheric pollution International Journal of Environment and Health, 5 (1/2) DOI: 10.1504/IJENVH.2011.039860