A study by European researchers has found that ship emissions from the combustion of heavy fuel oil (HFO) and diesel fuel (DF) have adverse effects on pulmonary macrophages, from increased cell death to altered metabolic profile, depending upon the aerosol component. Their open access paper is published in the journal PLOS ONE.
Macrophages are white blood cells and are part of the immune system. Often referred to as scavenger cells, they absorb and engulf microorganisms. In addition, the cells destroy tumor cells, remove cell debris, present antigens and promote wound healing. There are four types of pulmonary macrophages: alveolar; interstitial; intravascular; and the dendritic. The alveolar macrophages are the only macrophages in the body which are exposed to air. Located at the interphase between air and lung tissue, they represent the first line of defense against inhaled airborne elements.
Since macrophages also play a key role in lung diseases such as COPD (chronic obstructive pulmonary disease), the new study is important for understanding the health risks of ship exhausts.
In work reported in 2015, the researchers showed that exposure to particle emissions from HFO and diesel adversely affects human lung cells and is responsible for strong biological responses of the cells. For example, inflammatory processes are triggered that may influence the development of interstitial lung diseases.
Now, the team led by Professor Ralf Zimmermann has found in further studies that macrophages are also influenced by the exhaust gases. These are much more sensitive than lung epithelial cells and therefore react more strongly to exposure.
Zimmermann is speaker of the international consortium Helmholtz Virtual Institute of Complex Molecular Systems in Environmental Health (HICE), head of the cooperation group Comprehensive Molecular Analytics (CMA) at Helmholtz Zentrum München and head of the Department of Analytical Chemistry at the University of Rostock.
Macrophages respond more sensitively to particulate matter in the lungs than lung epithelial cells, since they are the ‘first line of response’ against foreign invaders in the lungs such as germs or even fine dust particles. We found that the ship emissions of heavy fuel oil and diesel fuel had different effects on triggering pro-inflammatory reactions.—Sean Sapcariu, first author of the study and doctoral student at the University of Luxembourg
Fine particles from heavy fuel oil emissions have a stronger effect on the development of pro-inflammatory reactions than particles emitted from diesel ship engines, but the latter more strongly influence other fundamental biological processes such as DNA-, RNA- and protein-synthesis.
The team found that the emitted particles both from the heavy fuel oil and from the diesel exhaust had similarly high toxic effects on the macrophages, said Zimmerman.
Surprisingly, the toxic effects leading to cell death are even slightly lower in the heavy fuel oil emissions, although the concentrations of known toxic pollutants in the heavy oil emissions are much higher.
Foregoing the ban of the heavy fuel oil use in coastal shipping, as is currently propagated and partially already implemented via the current fuel-sulfur content regulations, is therefore probably less beneficial than expected for protecting the health of people in coastal areas. The simplest and safest way to mitigate these adverse health effects from ship engine emissions would be to introduce efficient particle reducing measures such as exhaust gas scrubbers and particle filters. These would precipitate the harmful fine particles from the emissions and thus reduce the adverse health effects, irrespective of the fuel used. Since such measures are generally not implemented on a voluntary basis, in our view there is an urgent need for action by policy makers in government and by national and European regulatory authorities.—Professor Zimmerman
Sapcariu SC, Kanashova T, Dilger M, Diabaté S, Oeder S, Passig J et al. (2016) “Metabolic Profiling as well as Stable Isotope Assisted Metabolic and Proteomic Analysis of RAW 264.7 Macrophages Exposed to Ship Engine Aerosol Emissions: Different Effects of Heavy Fuel Oil and Refined Diesel Fuel,” PLOS ONE, Volume 10, doi: 10.1371/journal.pone.0157964
M-L. Lohmann-Matthes, C. Steinmüller, G. Franke-Ullmann (1994) “Pulmonary macrophages” Eur Respir J 7, 1678–1689 doi: 10.1183/09031936.94.07091678