Use of pets as indicators of heavy metal exposure across Sydney

Intense urbanization, industrial development and population growth is responsible for reducing environmental quality and in particular increasing the concentrations of contaminants in soils. Exposure to toxic metals and other contaminants in urban soils may be affecting not only the environment, but also the health of humans and other animals. This may especially be the case for those in cities such as Sydney who are living in residential developments that are in close proximity to past and present industrial centres. This research investigates the utility of domestic dog hair as a surrogate method to determine levels of contamination that may present risks to human health. Because domestic dogs live in the same environment as their owners, the presence of metals in dog hair may indicate a potential risk to human health through soil, dust and atmospheric emissions. Positive linear correlations were found between all metal(loid)s analysed (Cr, Cu, Zn, As, Pb and Hg) and domestic dog hair and soil (p < 0.05). The strongest correlation between soil and hair concentrations was found for Cr (Pearson correlation coefficient (PCC) 0.355), while there was a weak to negligible relationship for Cu, Zn, As, Hg and Pb (PCCs 0.090, 0.084, 0.137, 0.089 and 0.022, respectively). Linear regression analyses showed that correlations were significantly positive for Cr, Cu, Hg and Pb concentrations in dog hair and residential soil, very weakly positive for Zn concentrations and negative for As concentrations. The result also indicated that physiological, ecological and environmental parameters such as age, hair colour, gender and type of diet affected uptake of metals, although this the effect was less for Zn, which is present in most dry dog foods. While there are no national or international standards or guidelines for metal concentrations in hair, the use of hair as a biological matrix offers significant advantages in terms of ease of collection and ethics approval compared with blood and other body tissues. While the correlation between soil and hair concentrations for Pb, As and Hg was weak, any concentration of these metal(loids) in body tissue represents a health risk, and accordingly further research to develop guidelines for contamination exposure using hair has utility, as does the use of domestic dogs as a sentinel for potential human health risks.