Lindane “Worst-Case Scenario” Water Supply Calculation

What would have happened if a population-proportional amount of lindane shampoo and lotion sold in the state of NY had been poured directly into the municipal water supply of Albany, NY in 2004?

Unrealistic, worst-case assumption

This example assumes that no removal, filtering, or chemical breakdown of lindane took place during sewage treatment after it was washed down the drain
Instead, it assumes that 100% of lindane shampoo and lotion was poured directly into the Albany tap water supply

Relevant figures used for calculation

2004 annual water use for Albany, NY = 7,435,559,466 gallons ( = 7.4 billion gallons)
2004 population of city of Albany = 101,000
2004 population of state of NY = 19,227,088
Population-based proportional use factor for city of Albany = 0.525%
2004 lindane shampoo sales in state of NY = 14,793 units
2004 lindane lotion sales in state of NY = 10,404 units
Volume of each medication unit sold = 2 fluid oz.
Concentration of lindane contained in shampoo and lotion = 1%

Calculation

(25,197 total units) × (2 oz. per unit) × (1% lindane concentration) × (0.525% Albany proportional use factor) = 2.65 oz. of pure lindane in Albany water during 2004
(2.65 oz. of pure lindane) ÷ (128 oz. per gallon) = 0.021 gallons of pure lindane
(0.021 gallons of lindane) ÷ (7,435,559,466 gallons of water) = 2.8 parts per trillion (ppt)
2.8 parts per trillion (ppt) is equivalent to approximately 0.003 parts per billion (ppb)

Conclusion

A 0.003 ppb level of lindane is 67-times lower than conservative level of 0.2 ppb considered safe by the EPA in 1991, and 333-times lower than <1.0 ppb level considered safe by the EPA in 2003.