Former senior City of Toronto engineer Liza Ballantyne posed an intriguing question to the city’s associate medical officer of health in December 2017: When the city has residents test their tap water for lead, why does it tell them first to run or “flush” their taps for five minutes?“By flushing for five minutes we may not get a true representation of the residents’ lead exposure,” Ballantyne wrote in an email to the medical officer, Howard Shapiro at Toronto Public Health. A more realistic testing method would “provide homeowners with a less conservative lead value to encourage them to replace their lead pipes,” she wrote in another email to colleagues.The consensus in the scientific community — from academics to the federal government —agrees with her. Flushing tap water immediately before collecting samples produces misleadingly low results that fail to alert residents and municipalities to real lead levels and the accompanying health risks. These include learning disabilities, memory loss, brain damage, high blood pressure, heart disease and renal dysfunction, as well as a greater number of miscarriages and preterm births. In children, lead levels can affect brain development and have been linked to ADHD, lower IQs and academic performance, behavioural problems and delayed puberty. Health Canada recommends that tap water sit for 30 minutes before sampling; in the U.S., the standing time for lead test samples is six hours.“It must be recognized that many provinces and territories currently assess compliance for lead based on a flushed sample, which is not representative of exposure,” reads Health Canada’s lead testing guideline released in March 2019.For mandatory lead test results submitted to the province, the City of Toronto follows the provincial requirement of testing water that has been standing for 30 minutes. But far more tests each year are conducted under the city’s ...
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