"Bottled water sales are higher amongst African-American, Asians and Hispanic groups, which typically have lower incomes than whites." Some hypothesize that these differences are due to the geographic distribution of ethnic groups. It was theorized that ethnic differences in bottled water usage "mirror the variability of water system quality between urban, suburban and rural areas (Abrahams et al. 2000) and it was also pointed out that they might reflect the memory of past problems caused by deficient tap-water systems in deprived areas (Olson 1999)." In France, a similar geographic study in the early 1970s found that bottled water consumption was found to be much higher in urban areas (Ferrier 2001). This finding was "also explained in terms of the poor quality of urban tap water and of the bad condition of the old lead pipes in French cities. Nonetheless, while poor tap water quality may motivate the public to search for alternative sources, it alone does not necessarily lead to higher consumption of bottled water."