Agreement ℜ of Four Analytical Methods Applied to Pb in Soils from the Small City of St. John’s, Newfoundland, Canada

Abstract

In the small city of St. John’s, NL (2020 population ~114,000), 100% of the soils of the pre-1926 properties exceeded the Canadian soil Pb standard, 140 mg/kg. The Pb was traced to high-Pb coal ash used for heating and disposed on the soils outside. Analytical instruments became available in the late 1960s and 1970s and were first used for blood Pb and clinical studies and repurposed for measuring environmental Pb. The environmental research part of this study compared four common soil Pb analysis methods on the same set (N = 96) of St. John’s soil samples. The methods: The US EPA method 3050B, portable X-ray fluorescence spectrometry (pXRF), The Chaney–Mielke leachate extraction (1 M nitric acid), and the relative bioaccessibility leaching procedure (US EPA method 1340). Correlation is not the same as agreement. There is strong agreement (Berry–Mielke’s Universal R) among the four soil Pb analytical methods. Accordingly, precaution is normally advisable to protect children from the high-Pb garden soils and play areas. A public health reality check by Health Canada surveillance of St. John’s children (N = 257) noted remarkably low blood Pb. The low blood Pb of St. John’s’ children is contrary to the soil Pb results. Known urban processes causing the rise of environmental Pb and children’s Pb exposure includes particle size, aerosol emission by traffic congestion, and quantities of leaded petrol during the 20th century. Smaller cities had minor traffic congestion and limited combustion particles from leaded petrol. From the perspective of the 20th century era of urban Pb pollution, St. John’s, NL, children have blood Pb characteristics of a small city.

Lead in Air, Soil, and Blood: Pb Poisoning in a Changing World

“…The focus on measuring blood Pb and ascribing the exposure to lead-based paint missed obvious environmental signals such as atmospheric Pb and settled Pb dust concentrations [ 10 ]. Eventually, the same analytical instruments were adopted to measure air Pb and soil Pb [ 11 ], but the findings were often ignored [ 12 ]. The purpose of this article is to conduct an integrative review to (1) demonstrate the links between air Pb, soil Pb, and blood Pb, and (2) identify mitigation strategies that limit multiple Pb dust sources and decrease human Pb exposure.…”

Novel Policies are Required to Reduce Pediatric Lead Exposure from Legacy Lead (Pb) in Soil and Air

“…Studies of indoor Pb dust and hand Pb within inner city and outer city communities of Rochester, NY indicated an unknown alternative source of Pb dust that was responsible for pediatric exposure 16 . Recent advances in soil Pb analysis has been boosted with the development during the 1990s and 2000s of the portable (specifically, handheld) X-Ray Fluorescence analytical instrument (pXRF) 19 . Soil analysis with pXRF requires minimal preparation.…”

“…Soil analysis with pXRF requires minimal preparation. Four soil Pb extraction methods were compared on the same sample set and the agreement R between them were excellent 19 . This means that soil analysis can be conducted on-site as a point-of-care soil testing activity.…”

“…In the 2017 survey, the median SPb is 54 mg/kg and the median BPb is 1.3 μg/dL. The objectives of this article are 1) to demonstrate the practical application of an advanced handheld Pb analysis instrument (X-Ray Fluorescence or pXRF) for mapping soil Pb 19 , and 2) to apply the information toward prevent pediatric Pb dust exposure. This article builds on previous studies of the spatiotemporal dynamics of pediatric Pb exposure 18 .…”