Biological effects of inhaled hydraulic fracturing sand dust. VIII. Immunotoxicity

Abstract

Hydraulic fracturing ("fracking") is a process used to enhance retrieval of gas from subterranean natural gasladen rock by fracturing it under pressure. Sand used to stabilize fissures and facilitate gas flow creates a potential occupational hazard from respirable fracking sand dust (FSD). As studies of the immunotoxicity of FSD are lacking, the effects of whole-body inhalation (6 h/d for 4 d) of a FSD, i.e., FSD 8, was investigated at 1, 7, and 27 d post-exposure in rats. Exposure to 10 mg/m 3 FSD 8 resulted in decreased lung-associated lymph node (LLN) cellularity, total B-cells, CD4+ T-cells, CD8+ T-cells and total natural killer (NK) cells at 7-d post exposure. The frequency of CD4+ T-cells decreased while the frequency of B-cells increased (7 and 27 d) in the LLN. In contrast, increases in LLN cellularity and increases in total CD4+ and CD8+ T-cells were observed in rats following 30 mg/m 3 FSD 8 at 1 d post-exposure. Increases in the frequency and number of CD4+ T-cells and NK cells were observed in bronchial alveolar lavage fluid at 7-d post-exposure (10 mg/m 3 ) along with an increase in total CD4+ T-cells, CD11b + cells, and NK cells at 1-day post-exposure (30 mg/m 3 ). Increases in the numbers of B-cells and CD8+ T-cells were observed in the spleen at 1-day post 30 mg/m 3 FSD 8 exposure. In addition, NK cell activity was suppressed at 1 d (30 mg/m 3 ) and 27 d post-exposure (10 mg/m 3 ). No change in the IgM response to sheep red blood cells was observed. The findings indicate that FSD 8 caused alterations in cellularity, phenotypic subsets, and impairment of immune function.

Role of metabolic reprogramming in pro-inflammatory cytokine secretion from LPS or silica-activated macrophages

“…Airborne crystalline silica, also known as silicon dioxide (SiO 2 ), is one of the most abundant minerals on Earth. More than 2 million workers in the United States and more than 230 million workers worldwide are exposed to crystalline silica annually, predominantly due to activities, such as mining and construction (127,128). The health effects of silica inhalation are mainly characterized by chronic lung inflammation and progressive fibrosis.…”

Profiling of metabolites, proteins, and protein phosphorylation in silica-exposed BEAS-2B epithelial cells

“…Workers in contemporary practices such as denim sandblasting and the stone industry have experienced increases in silicosis in addition to workers in miners [2]. More than 230 million individuals were exposed to silica, including 2 million in the United States and 23 million in China [3][4][5][6]. Although protective measures such as dust control and respirators have been used [1,7,8], the prevalence of the disease remains high worldwide, especially in developing countries.…”