Did Tea Drinking Cut Mortality Rates in England?

By Francisca Antman. She is Associate Professor in the Department of Economics at the University of Colorado Boulder. Excerpts:

"This occurred through the widespread adoption of tea drinking in England which began in the 18th century. Since brewing tea required boiling water, and boiling water is a method of water purification, the rise of tea consumption in 18th century England would have resulted in an accidental improvement in the relatively poor quality of water available during the Industrial Revolution.  To what extent can the rise of tea drinking account for a drop in mortality rates at this crucial juncture in economic history?

Descriptive Evidence of the Impact of Tea on Mortality

Aggregate statistics at the national level provide descriptive evidence in support of these claims.  The above figure links data on English tea imports from China and the English crude death rate over the 1761-1834 period, distinguished by the precipitous drop in the tea tariff in 1785, a major turning point in the widespread adoption of tea as the national beverage.  Panel A shows a dramatic increase in tea imports per person from around 1 pound per person at the beginning of this period to almost 3 pounds per person by the end.  Panel B shows that over the same period, the English crude death rate fell from around 28 to 23 deaths per 1,000 people, a decline that appears to have accelerated after 1785.  Thus, the national picture over this critical period in the development of England, prior to the documented link between water and disease, is marked by a dramatic rise in tea consumption and an impressive drop in mortality rates.

To further bolster the evidence that the mechanism behind these relationships was the improvement in water quality brought about by boiling water for tea, I use cause-specific death data from London collected in Marshall (1832) to show that higher tea imports curbed deaths from water-borne diseases such as dysentery, commonly described as flux or bloody flux (Wrigley and Schofield 1981), but did not significantly affect deaths that were not directly linked to water quality. This is shown in the above figure, where deaths from flux decline with greater tea imports in Panel A, but show no significant relationship to contemporaneous deaths from air-borne diseases such as tuberculosis (consumption) in Panel B. These patterns are consistent with the notion that the special relationship between tea and mortality ran through the consumption of water, and not some other economic explanation.  Thus, data from London provide suggestive support for the link between the rise of tea and the drop in mortality, as well as the causal mechanism through boiled water." 

[The data] "suggest a drop in mortality rates of roughly 25% in low water quality areas, while they dropped by a more modest 7% in better water quality parishes"

"in periods following larger imports of tea, parishes with high and low water quality levels both saw a reduction in mortality rates, but parishes with worse water quality saw a bigger decline."

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