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The exposure to airborne particulate matter (PM) and its constituents is an important factor to be considered when evaluating their potential health risk. Transition metals found in PM are known to contribute significantly to the exacerbation of respiratory ailments. Exposure to these constituents results in the induction of oxidative stress in the bronchial epithelium, thus promoting the secretion of inflammatory mediators. Therefore, it is important to know the contributions of PM 2.5 constituents to further investigate their relationship with toxic responses and associated health risks. PM 2.5 samples from three rural (Humacao, Guayama, and Guayanilla) and two urban (more populated) sites (Bayamón and Ponce) from Puerto Rico were analyzed for various inorganic constituents. A total of 59 trace elements were analyzed, of which eight were considered with the greatest toxic potential. The highest annual average concentration of PM 2.5 was reported at the urban site of Ponce (5.82 ± 1.40 μg m -3 ), while Bayamón's average concentration was not as high (4.69 ± 1.30 μg m -3 ) compared to concentrations at the rural sites Humacao, Guayama, and Guayanilla (4.33 ± 1.20 μg m -3 , 4.93 ± 1.50 μg m -3 , and 4.88 ± 1.20 μg m -3 respectively. The concentration at the Ponce site exhibited the highest summer value (7.57 μg m -3 ) compared to that of all the rural sites (~ 6.40 μg m -3 ). The lowest summer PM 2.5 values were obtained at the Humacao site with an average of 5.76 μg m -3 . Average Cu and Zn concentrations were 3- and 2-fold higher at the urban sites (0.68 ng m -3 and 6.74 ng m -3 respectively) compared to the rural sites (0.17 ng m -3 and 4.11 ng m -3 ). Relative toxicity of inorganic PM extract indicates Bayamón (urban) and Guayama with similar low LC 50 followed by Humacao, Guayanilla, and finally Ponce (urban) with the highest LC 50 . Of the eight potential toxic metals considered, only Fe was found to be higher at the rural sites. To our understanding, there are different sources of emission for these metals which potentially indicate main anthropogenic sources, together with the trade winds adding periodically volcanic and African Dust Storm particulates that affect Puerto Rico. These results are the first of their kind to be reported in Puerto Rico.

The health impact of the global African dust event (ADE) phenomenon in the Caribbean has been vaguely investigated. Heavy metals in ADE and non-ADE extracts were evaluated for the formation of reactive oxygen species (ROS) and antioxidant capacity by cells using, deferoxamine mesylate (DF) and N-acetyl-l-cysteine (NAC). Results show that ADE particulate matter 2.5 (PM2.5) induces ROS and stimulates oxidative stress. Pre-treatment with DF reduces ROS in ADE and Non-ADE extracts and in lung cells demonstrating that heavy metals are of utmost importance. Glutathione-S-transferase and Heme Oxygenase 1 mRNA levels are induced with ADE PM and reduced by DF and NAC. ADE extracts induced Nrf2 activity and IL-8 mRNA levels significantly more than Non-ADE. NF-κB activity was not detected in any sample. Trace elements and organic constituents in ADE PM2.5 enrich the local environment load, inducing ROS formation and activating antioxidant-signaling pathways increasing pro-inflammatory mediator expressions in lung cells., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Particle pollution from urban and industrialized regions in Rio de Janeiro (RJ), Brazil was analyzed for toxic and pro-inflammatory (cytokines: IL-6, IL-8, IL-10) responses in human bronchial epithelial cells. Trace elements contribution was studied. Airborne particulate matter was collected at: three industrial sites Ind-1 (PM10) and Ind-2a and 2b (PM2.5); Centro urban area (PM10) and two rural sites (PM2.5, PM10). PM10 acetone extracts were toxic and did not elicit cytokine release; aqueous extracts were less toxic and stimulated the release of IL-6 and IL-8. PM2.5 aqueous extracts from Ind-2 decreased the release of IL-6 and IL-8. Zinc concentration was higher at the industrial and rural reference sites (Ref-1-2) although metals were not associated to cytokines changes. These results demonstrate that PM from RJ can either increase or decrease cytokine secretion in vitro while being site specific and time dependent., (Copyright © 2014 Elsevier Ltd. All rights reserved.)