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Lead exposure, through the contamination of drinking water, can have major health implications.
Lead is a neurotoxin which can put unborn babies and young children at particular risk, as they absorb more lead than adults. In young children, lead exposure can cause developmental delay and learning difficulties, abdominal pain, vomiting, constipation and hearing loss, among other symptoms.
In adults, the symptoms of lead exposure can include miscarriage, fatigue, headaches, memory loss and joint and muscle pain.
It is therefore vital that municipal authorities can employ accurate testing methods to identify sources of lead contamination: these sources can include lead plumbing materials in homes and other buildings, and lead service lines (LSLs).
LSLs have been banned in the US since 1986, but many ageing lead water pipes are still in operation.
And according to a report released in 2021 by the Natural Resources Defense Council (NRDC), between 9.7 million to 12.8 million lead pipes carry water to homes in the US. The NRDC also noted that 40 states did not know where their lead pipes were located.
Inductively coupled plasma mass spectrometry (ICP/MS) is one of the most common methods of measuring lead concentrations in water.
This technique uses an inductively coupled plasma to ionize the sample, which creates atomic and small polyatomic ions – which are then detected. It is a highly accurate testing method.
Water samples taken in the field are shipped to a laboratory, where the testing using ICP/MS is carried out by a professional chemist.
Anodic stripping voltammetry (ASV) is an electrochemical technique which is also used to detect the level of lead in water.
ASV involves the reduction of metals on mercury electrodes by a current, followed by using a doped electrode as a conductor to determine the amount of metals plated on the electrode and therefore, the concentration of metal in the water.
This technique can be used to generate accurate results in the field, if used with a portable testing system. In this case, samples don’t need to be sent to a laboratory for testing.
In 2006, the City of Montreal launched a program to eliminate the estimated 69,000 LSLs in its territory within 20 years.
However, Montreal faced a major challenge: except for some rehabilitated areas, there were no reliable records that could be used to locate many of these LSLs.
The systematic profiling of probable LSL sites was considered too costly, intrusive and impractical by city authorities.
Therefore, a reliable and cost-effective field method was needed to locate properties with an LSL. A project was then launched to develop and test a protocol for use in the field by the City of Montreal’s teams: this would measure lead concentrations at the tap to detect an LSL.
The study was funded by The Canadian Water Network within a larger research effort carried out by the Natural Sciences and Engineering Research Council of Canada Industrial Chair on Drinking Water.
Three key criteria were used in the development of the protocol:
It was identified that ICP/MS did not meet the protocol criteria, as it required the use of laboratory facilities, is time-consuming and should be carried out by a professional chemist. Shipping samples to a laboratory would have stretched testing timeframes even further.
A portable solution using ASV to detect lead in drinking water was instead used by the City of Montreal in the development of the protocol.
The accuracy of this method was validated by ICP/MS and two types of lead samples were tested, including 107 tap water samples from households in Montreal, and 27 laboratory-prepared samples.
Following the sampling exercise, it was found that the portable system using ASV provided highly satisfactory accuracy for the tap water samples and there was a good correlation with the ICP/MS measurements. This indicated that a portable ASV could be used to detect LSLs.
The efficiency, cost effectiveness and suitability for field work of this method were all acknowledged.
On-site measurement allows authorities to quickly inform the occupants of a building that lead is present in tap water, as well as indicating the presence of an LSL.
The use of a portable ASV solution was instrumental in the development of the ‘Montreal Protocol’, as it’s now widely known. This is the analysis approach, using portable ASV, to predict with a high degree of certainty that an LSL is present at a home or building.
Palintest has developed Kemio™, a simple method of testing for lead in water using a portable device. Kemio™, uses ASV to test for heavy metals and it is the only portable US Environmental Protection Agency (EPA) approved method for lead testing.
The test doesn’t require any specialist training, can be performed on-site within three minutes and gives accurate results even with low concentrations of lead. It allows water utility professionals to carry out testing at consumers’ taps and efficiently and quickly identify corroded LSLs, which can cause lead contamination in drinking water.
