Shakhriiarkhon Karimova

The Impact of New York City Water Quality on Dental Enamel

Started May 30, 2025

Abstract or project description

The average quality of water consumed varies tremendously across sources, even water within the same city, and the quality of water can affect dental enamel over time. Key factors such as water hardness, pH, copper, chlorine, and fluoride levels have been shown to impact enamel, either contributing to its erosion or providing protective effects. Since eggshells share a similar mineral composition to dental enamel, this study used them as a proxy to assess how New York City tap water affects enamel. 

Water samples were collected from six NYC playground fountains and one bottled water source. Identical eggs were submerged in these samples for two weeks, while one control egg was placed in Coca-Cola. Each egg’s initial and final weight and shell thickness were measured after seven days. Water quality was measured for pH, hardness, total chlorine, fluoride, copper, iron, and nitrate levels—all of which have been associated in previous literature with changes in enamel integrity. 

The eggs used in this experiment had initial weights ranging from 0.16 to 0.19 lbs and thicknesses between 0.27 mm and 0.37 mm. After 7 days of submersion, most eggs placed in NYC park water showed minimal weight loss of 0.01 lb. These same eggs exhibited no measurable change in shell thickness (0.00 mm difference). The egg placed in bottled water showed no change in weight or thickness. The egg submerged in Coca-Cola experienced a much more dramatic reaction. It lost 0.03 lb in weight, and underwent significant physical changes: the egg turned dark brown, and the outer layer of the shell began peeling off, indicating extensive surface damage not seen in any of the water samples. Among the variables analyzed, lower water hardness and higher copper levels were most correlated with greater egg weight loss, suggesting a potential erosive effect. These findings suggest that water quality—particularly mineral composition—may play a protective or damaging role in enamel health. While the differences in NYC tap water caused only mild erosion, the Coca-Cola sample produced extreme damage, reinforcing concerns about acidic beverages. These results support the importance of monitoring drinking water quality, and highlight the need for further research into the long-term effects of everyday water exposure on human enamel. 

These findings suggest that water quality, particularly hardness, plays a significant role in protecting enamel. While the differences in NYC tap water caused mild erosion, Coca-Cola resulted in extreme enamel damage, supporting public health concerns around acidic drinks. Government agencies could work to monitor and improve aspects of water quality that correlate with enamel erosion, and future research could investigate long-term effects on human enamel.