Measurement of Soil Lead Levels Adjacent to Lead-Sheathed Communications Cables

Abstract

Lead exposure reduction has been one of the most successful environmental health campaigns ever undertaken. However, for the target goal of "zero" micrograms of lead in blood to be met, it will be necessary to go beyond controlling lead-based paint, lead water lines, and consumer products and to seek out and reduce other overlooked exposures. This paper explores one such source--lead exposure from aerial terrestrial and submarine lead sheathed communications cables (LSCCs). LSCCs were widely used from the late 1800s to the 1960s and ultimately replaced by plastics and other synthetic coverings. The cables were suspended on utility poles and when going under water bodies, bundled together as submarine cables. In both aerial and submarine LSCCs, the metallic sheen of new cables quickly oxidizes to a dull lead oxide coating that prevents further corrosion. This coating may be friable and released as cables sway and may be subject to various weather conditions. The objective of this investigation was to conduct a preliminary assessment of the extent of soil contamination from submarine and aerial LSCCs and to assess potential risks to children's health.

Introduction

Lead exposure reduction has been one of the most successful environmental health campaigns ever undertaken.1 However, for the target goal of "zero" micrograms of lead in blood to be met, it will be necessary to go beyond controlling lead-based paint, lead water lines, and consumer products and to seek out and reduce other overlooked exposures.2 This paper explores one such source-lead exposure from aerial terrestrial and submarine lead sheathed communications cables (LSCCs).

LSCCs were widely used from the late 1800s to the 1960s3 and ultimately replaced by plastics and other synthetic coverings. The cables were suspended on utility poles (i.e., aerial cables) and when going under water bodies, bundled together as submarine cables. In both aerial and submarine LSCCs, the metallic sheen of new cables quickly oxidizes to a dull lead oxide coating that pre-vents further corrosion. This coating may be friable and released as cables sway and may be subject to various weather conditions (i.e., wind, rain, snow, and ice). The objective of this investigation was to conduct a preliminary assessment of the extent of soil contami-nation from submarine and aerial LSCCs and to assess potential risks to children's health.

Methods

Sampling sites of aerial and submarine cables were chosen at loca-tions identified by a Wall Street Journal investigative report.4,5 The three submarine sites were in Southeast Louisiana. The aerial sites were in suburban communities in New Jersey (cable length 825 ft long), New York (650 ft), and Pennsylvania (550 ft).

On-site lead in soil analysis directly below and adjacent [ - 6 ft ( - 1:83 m)] to LSCCs were taken as well as background readings. Sampling was performed using a direct reading handheld Niton XL3t X-ray Fluorescence Analyzer (XRF). All XRF readings were taken in soil mode at surface level, with grass and debris pushed aside. Appropriate calibration checks instituted prior to each sampling period. For submarine sites, testing was conducted on dry land at the point where the cable exited the ground. Samples were taken in concentric circles radiating out from the cable until background levels were approached. Results from paired in situ and dried/sieved samples were used to calculate an in situ correction factor.6 On average, raw XRF measurements were adjusted 25%-46% upward. Approximately 10% of collected samples were sent to an accredited lead labora-tory for quality control. The cutoff for natural vs. anthropogenic lead concentration was chosen based on US Environmental Protection Agency (EPA)/US Geological Survey (USGS) Lead in Soil Background levels.7 Readings below the 95% upper confi-dence limit of background soil lead for the location were excluded from the analysis.

To ascertain the source of lead in soil individual Pb isotopes were measured-namely 204lead (204Pb), 206Pb, 207Pb and 208Pb at select sites. The ratio of these isotopes to one another is commonly used to fingerprint a particular source.8 Samples of lead sheathing were collected using a precleaned handheld wire cutter. Comparison cable lead and soil Pb isotopes were analyzed at the University of Washington's Isotope Geochemistry Laboratory in Seattle, Washington, for four sites, Pennsylvania, Louisiana, New York, and New Jersey. Detailed analytical procedures are available at Bidwelletal.9

Results and Discussion

A total of 315, 209, and 52 XRF readings were taken at the New Jersey, New York, and Pennsylvania sites, respectively (Table 1). In each case, lead concentrations in soil from areas immediately below aerial LSCCs were substantially higher than background levels. A frequency distribution of aerial soil leads is presented in Figure 1.

The three exposed submarine cables assessed at the Louisiana sites all showed elevated lead in and around the cable. Elevated levels of lead in soil tended to be localized within a radius of a few feet from the LSCC (Table 1).

An analysis of the lateral distribution of soil lead levels directly under the New York LSCC site was taken at the New York site. Eight of the 13 transect sites showed a clear decrease in soil Pb level within a few feet off the aerial cable centerline. The average drop-off in Pb levels was ~ 35%. This seems to confirm the pri-mary contamination point was directly below the suspended cable.

The results of isotopic analysis show that the 206Pb=204Pb ratios for the soil sample approach that of LSCC for two of the four sites tested-namely site 5 and 6 (Table 1). The data from the two other sites (seven in New Jersey and eight in New York) were inconclu-sive. Similar isotopic ratios indicate a common source of elemental lead.

The main finding of this study was that lead from existing LSCCs can be transported from the cables and contaminate sur-rounding soil and dust. This contamination, in residential areas, has high potential to result in childhood lead exposure. According to the US EPA's Integrated Exposure Update and Biokinetic Lead Exposure Model, children exposed to a residential level of ~ 325 ppm in soil would yield a blood lead level of 35 lg=L, equal to the current Centers for Disease Control and Prevention (CDC) reference level (3:5 lg=dL). The US EPA has recently lowered its guideline regarding levels of lead in soil for residential properties from400 to 200 mg=kg (orppm).10

Lead contamination from LSCCs is a previously overlooked source of lead exposure in the United States.4 Although the expo-sure pathway may not equal that of lead-based paint or lead-contaminated foods, its impact has yet to be thoroughly explored, and in cases of high exposure sites in residential areas, remedia-tion may be warranted.

References

References

1. Ruckart PZ, Jones RL, Courtney JG, LeBlanc TT, Jackson W, Karwowski MP, et al. 2021. Update of the blood lead reference value-United States, 2021. Mmwr Morb Mortal Wkly Rep 70(43):1509 1512, PMID: 34710078, https://doi.org/10. 15585/mmwr.mm7043a4.

2. Landrigan PJ, Bellinger D. 2021. It's time to end lead poisoning in the United States. JAMA Pediatr 175(12):1216 1217, PMID: 34570192, https://doi.org/10. 1001/jamapediatrics.2021.3525.

3. Tharby R. 1990. The use of lead sheathed cables by British Telecom. In: IEE Colloquium on Stray Current Effects of DC Railways and Tramways. 11 October 1990. London, UK: IET, 1/3/1-1/3/3.

4. Pulliam S, Ramachandran S, West J, Jones C, GrytaT. 2023. America is wrapped in miles of toxic lead cables. Wall Street Journal. 9 July 2023. https://www.wsj. com/articles/lead-cables-telecoms-att-toxic-5b34408b?st=50yvzgj30j8d0es&reflink= desktopwebshare_permalink[accessed 22 November 2023].

5. West J, Champelli P, Gomez J, Pulliam S, Ramachandran S. 2023. Epicenter of America's lead cableproblem. Wall Street Journal. 10 July 10 2023. https://www. wsj.com/articles/lead-cables-louisiana-telecoms-59f36ffe?st=geqfxdkj62o52fg& reflink=desktopwebshare_permalink[accessed 22 November 2023].

6. Ge L, LaiW, Lin Y. 2005. Influence of and correctionformoisturein rocks, soilsand sediments on in situXRF analysis. Xray Spectrom 34(1)28-34, https://doi.org/10. 1002/xrs.782.

7. US EPA (US Environmental Protection Agency). 2007-2010. Background Soil Lead Survey State Data. https://www.epa.gov/superfund/usgs-background-soil-lead-survey-state-data [accessed 22 November 2023].

8. KomárekM,EttlerV, ChrastnýV, Mihaljevic M.2008. Lead isotopes in environmental sciences: a review. Environ Int 34(4):562-577, PMID: 18055013, https://doi.org/ 10.1016/j.envint.2007.10.005.

9. Bidwell AL, Callahan ST, Tobin PC, Nelson BK, DeLuca TH. 2019. Quantifying the elemental composition of mosses in Western Washington USA. Sci Total Environ 693:133404, PMID: 31377372, https://doi.org/10.1016/j.scitotenv.2019.07.210.

10. US EPA. 2022. Biden-Harris Administration Strengthens Safeguards to Protect Families and Children from Lead. https://www.epa.gov/newsreleases/biden-harris-administration-strengthens-safeguards-protect-families-and-children-lead [accessed 22 November 2023].