ToxWatch Cite This: Chem. Res. Toxicol. XXXX, XXX, XXX−XXX
pubs.acs.org/crt
Wood and Biomass Smoke: Addressing Human Health Risks and Exposures Abigail F. Scott and Christopher A. Reilly*
Downloaded via TULANE UNIV on February 13, 2019 at 05:54:40 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.
Department of Pharmacology and Toxicology, Center for Human Toxicology, University of Utah, 30 South 2000 East, Salt Lake City, Utah 84112, United States ABSTRACT: Air pollutants from burning wood and biomass pose serious human health risks. Recent discoveries link the chemistry of smoke emissions with biochemical sensors and biological effect mediators. Strategic thinking of complex underlying factors is needed to protect people from harm.
≤5 μm. These PM spread in the environment and efficiently deposit in the respiratory tract. As such, these PM are believed to be the greatest risk to human health. Respirable WBSPM are chemically distinct from many other common forms of combustion-generated environmental PM.1−3 Chemical analysis has illustrated that WBSPM contain chemicals derived from thermal decomposition of cellulose, lignin, lipids, waxes, and plant resins. These products can be summarized as aromatic phenol derivatives, ketones, alcohols, aldehydes, fatty acids, and carboxylic acids. However, the absolute and relative abundances of specific chemicals in a sample of PM vary based on the material being burned, how it was burned, aging, and PM size. For example, larger WBSPM tend to have higher order polycyclic aromatic hydrocarbons (PAHs) and oxygenated hydrocarbons that are also typical of other combustion-derived PM such as engine emissions, and smaller PM have more semi-volatile and often inherently reactive chemicals. Biological Recognition of WBSPM and Toxicology. Inhaled WBSPM trigger pulmonary inflammation and injury. However, there is a paucity of knowledge for how WBSPM adversely affect the lungs and human health. Common mechanisms of lung toxicity for WBSPM and other forms of PM include the ability of the PM to (1) elicit oxidative stress through the production of reactive oxygen species, both directly and indirectly via enzymatic activation of chemicals present in/on the PM; (2) deplete antioxidants; (3) modify critical macromolecules such as lipids, proteins, and DNA through oxidative and nonoxidative processes as well as by covalent modification by electrophilic chemicals in/on the PM; and (4) activating regulatory molecules such as the aryl
E
pidemiological studies demonstrate that particulate materials (PM) contained within smoke emissions from burning wood and biomass pose considerable risk to respiratory and other aspects of human health. Exposure to wood/biomass smoke PM (WBSPM) can exacerbate preexisting respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD) as well as increase rates of respiratory infections and hospitalization due to respiratory complications.1 It is also estimated that 3−4 million deaths per year are attributable to exposure to the toxic combustion byproducts from wood and biomass burning, with countless other minor effects occurring without recognition. Chronic exposure to high levels of WBSPM (1−10 mg/m3) frequently occurs in under-developed locations where people rely on primitive cooking and heating techniques. Here, wood, dung, and other forms of biomass are burned in open, poorly ventilated fireplaces and stoves often within people’s homes. Such exposures are a likely cause of COPD and emphysema even in non-smokers.1 Episodic exposure to WBSPM also occurs worldwide with seasonal crop burning and forest or range fires. While the doses of WBSPM associated with episodic exposures tend to be lower (
