United States house dust Pb concentrations are influenced by soil, paint, and house age: insights from a national survey

Lead systemic toxicity: A persistent problem for health

Lead (Pb) has been used by humans since prehistoric times to make tools due to its malleability and durability. The Roman Empire, the Industrial Revolution, and the introduction of Pb in gasoline during the 1920s contributed to increased environmental concentrations. Pb toxicity led to its removal from gasoline after several decades. However, Pb continues to be emitted from various anthropogenic sources, including but not limited to batteries, mining, foundries, smelting, e-waste recycling, and painting. Pb remains an environmental concern, as no established safe concentration for human health has been identified. Children are more susceptible to the absorption and poisoning of Pb. Occupational exposure to Pb poses a significant risk to workers and individuals living near lead industries. The primary routes of exposure are inhalation and ingestion, and bioaccumulation and biomagnification through the food chain are major sources of human exposure. This review aims to provide an overview of Pb and its systemic toxicity of Pb, including its effects on the lungs, blood, liver, kidneys, and nervous, cardiovascular, and reproductive systems. Since Pb is classified as a probable carcinogen for humans, the article also addresses genotoxicity and cancer risk. Furthermore, it reviews the most researched mechanisms of toxicity, including calcium mimicry, oxidative stress, and inflammation, along with other less-studied mechanisms. Nevertheless, the authors emphasize the importance of exploring less examined cells, tissues, and mechanisms to deepen the understanding of Pb toxicity at various concentrations, particularly in cases of chronic low-level Pb exposure, to develop better prevention and treatment strategies for lead poisoning.

Lead source apportionment and climatic impacts in rural environmental justice mining communities

After a sequence of natural disasters in Gila County, Arizona, USA environmental justice (EJ), mining areas, community members raised concerns about metal(loid)s exposure and origin. To address these concerns, non-residential sediments (0-2 cm, 2-15 cm, and 15-30 cm), household soil (0-2 cm), and indoor and outdoor dust samples were analyzed for metal(loid)s concentration and Pb isotopes via inductively coupled plasma mass spectrometry. To identify the potential sources of Pb, 37 studies were considered, and 21 different Pb isotopic ratios were documented and compared. Spearman's correlation and principal component analysis were used to investigate the co-occurrence of metal(loid)s associated with Pb. The results demonstrated a clear association (p < 0.05) between Pb and mining activity in households and non-residential locations as well as a co-occurrence with As, Cd, Cu, Mo, Sb, and Zn at 0-2 cm and in non-residential with As, Cd, and Zn at 2-15 cm and 15-30 cm. The outdoor household dust was impacted by a mixture of Pb sources and was associated with metal(loid)s coming from mining, wildfire, lead based-paint and landfill, whereas indoor Pb dust was associated mainly with metal(loid)s coming from geogenic sources. Further, 66% of town/city sediment samples across depth and 53.8% of outdoor dust samples were aligned with mining fingerprint and 30.1% of outdoor dust and 25% of household soil samples were aligned with the wildfire Pb isotopic ratio/fingerprint. The Positive Matrix Factorization model illustrates flood's ability to remobilize metal(loid)s from neighboring mine sites to the households' locations. Currently there is no established Pb isotopic ratio composition for wildfires in Arizona; this study lays the foundation for understanding the complex relationship between the myriads of lead sources in our environment, wildfires, and flooding.

Lead Speciation, Bioaccessibility, and Sources for a Contaminated Subset of House Dust and Soils Collected from Similar United States Residences

Residential lead (Pb) exposure is of critical concern to families globally as Pb promotes severe neurological effects in children, especially those less than 5 years old, and no blood lead level is deemed safe by the US Center for Disease Control. House dust and soils are commonly thought to be important sources of Pb exposure. Probing the relationship between house dust and soil Pb is critical to understanding residential exposure, as Pb bioavailability is highly influenced by Pb sources and/or species. We investigated paired house dust and soil collected from homes built before 1978 to determine Pb speciation, source, and bioaccessibility with the primary goal of assessing chemical factors driving Pb exposure in residential media. House dust was predominately found to contain (hydro)cerussite (i.e., Pb (hydroxy)carbonate) phases commonly used in Pb-based paint that, in-turn, promoted elevated bioaccessibility (>60%). Pb X-ray absorption spectroscopy, μ-XRF mapping, and Pb isotope ratio analysis for house dust and soils support house dust Pb as chemically unique compared to exterior soils, although paint Pb is expected to be a major source for both. Soil pedogenesis and increased protection from environmental conditions (e.g., weathering) in households is expected to greatly impact Pb phase differences between house dust and soils, subsequently dictating differences in Pb exposure.