Why there’s no safe amount of lead in tap water in Hong Kong, or anywhere

James Nickum says the WHO standard is outdated, and we need to work to avoid a recurrence of the contamination at Hong Kong housing estates

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Why you can trust SCMP

James Nickum

Published: 5:15pm, 19 May 2016Updated: 5:15pm, 19 May 2016

When lead is detected at any level in water, the cause should be determined and, to the extent possible, fixed.

It has been nearly a year since four out of 30 samples of drinking water in the Kai Ching Estate were found to have levels of lead in excess of the World Health Organisation standard of 10 parts per billion (ppb). The highest was 23ppb.

This revelation set off a circular firing squad of accusations and investigations centring on how lead solder, which has long been banned, found its way into the estate’s water pipes. Terms such as “scare”, “scandal”, “dangerous”, “crisis” and “toxic” filled the media and the speeches of politicians.

The government set up three task forces and the Water Services Department took thousands of samples at both “affected” estates and “unaffected” ones. On May 11, one of those task forces, the Commission of Inquiry into Excess Lead Found in Drinking Water, submitted its report to the chief executive. The government is now mulling over the results.

Members of the Democratic Party and Labour Party protest while Chief Secretary Carrie Lam attends a special meeting on the water scandal. Photo: K. Y. Cheng

Findings and recommendations of lead-in-water inquiry must be released in full

What tends to get ignored in all this hullabaloo is the magic number of 10ppb. Where did the WHO get this figure? What does it mean? Is 11ppb a scandalous figure? Is 9ppb safe? The answer in both cases would seem to be “no”.