The environmental burden of inhalation.

Inhalation systems, mostly metered dose inhalers (MDIs) and dry powder inhalers (DPIs), are currently submitted to a critical assessment for their carbon footprint (CF) and environmental impact. They are related to greenhouse gas (GHG) emissions and they produce waste of used devices with withheld drug residues and unused doses. However, with estimated contributions to anthropogenic GHG-emissions of 0.03 % for MDIs and 0.0012 % for DPIs globally, it may not be expected that mitigating the GHG emissions from inhalers will have a meaningful effect on the current climate change and global warming, notwithstanding that nationally these percentages may be somewhat higher, depending on the ratio of MDIs to DPIs and the total national CF. MDIs are particularly the preferred type of inhalers over DPIs in the USA and UK with ratios of 9: 1 and 7: 3 respectively. In such countries, a partial switch from MDIs to DPIs is to be recommended, providing that such a switch does not jeopardize the therapy. Using renewable energy only for the production and waste management of DPIs will make this type of inhaler almost climate neutral. A greater concern exists about inhaler waste, more particularly about the residual drug and unused doses in discarded devices. Inhalers contribute <0.02 % to global plastic waste annually and most plastic inhalers end in the domestic waste bin and not as litter polluting the environment with plastic. However, they do contain retained drug and unused doses, whereas even full inhalers are disposed. Because globally most municipal waste (70 %) ends up in dumps and landfills, leakage of the drugs into the soil and surface waters is a serious problem. It pollutes drinking water and endangers species and biodiversity. Therefore, a good collection system and an adequate waste management program for used inhalers seems to be the most meaningful measure to take for the environment, as this will stop inhalers and drugs from putting ecosystems at risk.