Carcinogenic formaldehyde in U.S. residential buildings: Mass inventories, human health impacts, and associated healthcare costs.

Formaldehyde, a human carcinogen, is formulated into building materials in the U.S. and worldwide. We used literature information and mass balances to obtain order-of-magnitude estimates of formaldehyde inventories in U.S. residential buildings as well as associated exposures, excess morbidity, and healthcare costs along with other economic ramifications. Use of formaldehyde in building materials dates to the 1940s and continues today unabated, despite its international classification in 2004 as a human carcinogen. Global production of formaldehyde was about 32 million metric tons (MMT) in 2006. In the U.S., 5.7 ± 0.05 to 7.4 ± 0.125 MMT of formaldehyde were produced annually from 2006 to 2022, with 65 ± 5 % of this mass (3.7 ± 0.03 to 4.8 ± 0.08 MMT) entering building materials. For a typical U.S. residential building constructed in 2022, we determined an average total mass of formaldehyde containing chemicals of 48.2 ± 10.1 kg, equivalent to 207 ± 40 g of neat formaldehyde per housing unit. When extrapolated to the entire U.S. housing stock, this equates to 29,800 ± 5760 metric tons of neat formaldehyde. If the health threshold in indoor air of 0.1 mg/m3 is never surpassed in a residential building, safe venting of embedded formaldehyde would take years. Using reported indoor air exceedances, up to 645 ± 33 excess cancer cases may occur U.S. nationwide annually generating up to US$65 M in cancer treatment costs alone, not counting ~16,000 ± 1000 disability adjusted life-years. Other documents showed health effects of formaldehyde exist, but could not be quantified reliably, including sick building syndrome outcomes such as headache, asthma, and various respiratory illnesses. Opportunities to improve indoor air exposure assessments are discussed with special emphasis on monitoring of building wastewater. Safer alternatives to formaldehyde in building products exist and are recommended for future use.

Field Study and Evaluation of KrCl* Far UV-C Device Capability for Inactivation of Phi6 Bacteriophage.

"Far UV-C" is an effective disinfection method that can be deployed in occupied areas. Commercially available Krypton Chloride (KrCl*) excimer lamps filtered to emit at 222 nm are effective in disinfecting pathogens and safe for human exposure up to an allowable threshold exposure, which is much longer than for conventional UV lamps emitting at 254 nm. Laboratory and controlled field testing of a filtered KrCl* excimer lamp for disinfection of a virus suspended in a thin film aqueous solution in an occupied office setting was conducted. Complete inactivation of almost 6 log (99.9999%) of Phi6 bacteriophage virus was achieved in ~20 min of exposure time in a field setting, equivalent to a dose of about 10 mJ cm-2 . The Phi6 inactivation rate constant for the field test results were not statistically different from laboratory values (P > 0.05, paired t-test). When positioned at 1 m distance from possible human exposure, this device can be used safely for almost 4.5 h of continuous direct exposure without any acute or long-term adverse health effects. This study illustrates the applicability and deployment of Far UV-C for pathogen reduction and can help in decision making for implementation of Far UV-C for disinfection in human-occupied environments.

Exome Array Analysis of Early-Onset Ischemic Stroke.

BACKGROUND AND PURPOSE: The genetic contribution to ischemic stroke may include rare- or low-frequency variants of high-penetrance and large-effect sizes. Analyses focusing on early-onset disease, an extreme-phenotype, and on the exome, the protein-coding portion of genes, may increase the likelihood of identifying such rare functional variants. To evaluate this hypothesis, we implemented a 2-stage discovery and replication design, and then addressed whether the identified variants also associated with older-onset disease. METHODS: Discovery was performed in UMD-GEOS Study (University of Maryland-Genetics of Early-Onset Stroke), a biracial population-based study of first-ever ischemic stroke cases 15 to 49 years of age (n=723) and nonstroke controls (n=726). All participants had prior GWAS (Genome Wide Association Study) and underwent Illumina exome-chip genotyping. Logistic-regression was performed to test single-variant associations with all-ischemic stroke and TOAST (Trial of ORG 10172 in Acute Stroke Treatment) subtypes in Whites and Blacks. Population level results were combined using meta-analysis. Gene-based aggregation testing and meta-analysis were performed using seqMeta. Covariates included age and gender, and principal-components for population structure. Pathway analyses were performed across all nominally associated genes for each stroke outcome. Replication was attempted through lookups in a previously reported meta-analysis of early-onset stroke and a large-scale stroke genetics study consisting of primarily older-onset cases. RESULTS: Gene burden tests identified a significant association with NAT10 in small-vessel stroke (P=3.79×10-6). Pathway analysis of the top 517 genes (P<0.05) from the gene-based analysis of small-vessel stroke identified several signaling and metabolism-related pathways related to neurotransmitter, neurodevelopmental notch-signaling, and lipid/glucose metabolism. While no individual SNPs reached chip-wide significance (P<2.05×10-7), several were near, including an intronic variant in LEXM (rs7549251; P=4.08×10-7) and an exonic variant in TRAPPC11 (rs67383011; P=5.19×10-6). CONCLUSIONS: Exome-based analysis in the setting of early-onset stroke is a promising strategy for identifying novel genetic risk variants, loci, and pathways.