Dimethyl sulfide

DMS originates primarily from DMSP, a major secondary metabolite in some marine algae.^[5] DMS is the most abundant biological sulfur compound emitted to the atmosphere.^[6][7] Emission occurs over the oceans by phytoplankton.

DMS is also produced naturally by bacterial transformation of dimethyl sulfoxide (DMSO).^[8]

Marine phytoplankton also produce dimethyl sulfide,^[9] and DMS is also produced by bacterial cleavage of extracellular DMSP.^[10] This may be an adaptive trait, as the algae can use the resulting clouds to disperse themselves around the world.^[11] DMS has been characterized as the "smell of the sea",^[12] though it would be more accurate to say that DMS is a component of the smell of the sea, others being chemical derivatives of DMS, such as oxides, and yet others being algal pheromones such as dictyopterenes.^[13]

Dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide have been found among the volatiles given off by the fly-attracting plant known as dead-horse arum (Helicodiceros muscivorus). Those compounds are components of an odor like rotting meat, which attracts various pollinators that feed on carrion, such as many species of flies.^[14]

Dimethyl sulfide has a characteristic odor commonly described as cabbage-like. It becomes highly disagreeable at even quite low concentrations. Some reports claim that DMS has a low olfactory threshold that varies from 0.02 to 0.1 ppm^{[clarification needed]} between persons, but it has been suggested that the odor attributed to dimethyl sulfide may in fact be due to disulfides, polysulfides and thiol impurities, since the odor of dimethyl sulfide is much less disagreeable after it is freshly washed with saturated aqueous mercuric chloride.^[21] Dimethyl sulfide is also available as a food additive to impart a savory flavor; in such use, its concentration is low. Beetroot,^[22] asparagus,^[23] cabbage, maize and seafoods produce dimethyl sulfide when cooked.

Dimethyl sulfide is also produced by marine planktonic microorganisms such as the coccolithophores. It contributes to the characteristic odor of sea air. In the Victorian era, before DMS was discovered, the origin of sea air's 'bracing' aroma was misattributed to ozone.^[24]

Dimethyl sulfide is the main volatile product various of truffles. It is the compound that animals trained to uncover the fungus (such as pigs and detection dogs) sniff out when searching for them.^[25]

Dimethyl sulfide is highly flammable;^[33] its flash point is −38 °C (−36 °F)^[34] or −49 °C (−56 °F).^[35] Its self-ignition temperature is 205 °C (401 °F).^[35] It is an eye and skin irritant and is harmful if swallowed. It has an unpleasant odor at even extremely low concentrations.^[36]

Dimethyl sulfide is normally present at very low levels in healthy people, namely less than 7 nM in blood, less than 3 nM in urine and 0.13 to 0.65 nM on expired breath.^[37][38]

At pathologically dangerous concentrations, this is known as dimethylsulfidemia. This condition is associated with blood borne halitosis and dimethylsulfiduria.^[39][40][41]

• Coccolithophore, a marine unicellular planktonic photosynthetic algae, producer of DMS
• Dimethylsulfoniopropionate, a parent molecule of DMS and methanethiol in the oceans
• Emiliania huxleyi, a coccolithophorid producing DMS
• Gaia hypothesis
• Geosmin, the substance responsible for the odour of earth
• Petrichor, the earthy scent produced when rain falls on dry soil