Since you throw away the liner, I think these bottles are just more sanitary and do not worry about contaminents. (babycenter.com)
Soil contaminents and environmental toxins have changed over time. (nutritionfacts.org)
mercury PCB's and other heavy metal contaminents cause arthritis so severe in my left arm any movement backwards or above my head caused excruciating pain,. (naturalhealth365.com)