TRANSOCEANIC SOIL DUST TRANSPORT AND MEDICAL IMPLICATIONS

Increasing transoceanic dust flux may affect public health, especially among chemically sensitive and medically compromised individuals. Indigenous dust in the western U.S. is known to transport the valley fever pathogen Coccidioides immitis, but effects of African dust, which transports bacteria, viruses, and spores of fungi including numerous species of Aspergillus, have not been investigated until recently.

Estimates of annual African dust flux to the Amazon basin, Caribbean, and southeast U.S. range into the hundreds of millions of tons. Flux of African dust to the Caribbean and U.S. has increased dramatically since 1970 because of the ongoing drought in North Africa. The drought is a result of fluctuations in the North Atlantic Oscillation (NAO), and long-term dust monitoring in Barbados and Miami shows a direct correlation with the NAO. The incidence of asthma on Barbados and nearby Trinidad, documented by the Caribbean Allergy and Respiratory Association (CARA), is among the highest in the world and has increased 17-fold since 1973. The dust contains mercury and aluminum and arsenic is present in the ppm range. Arsenic, commonly used as a wood preservative, has well known health effects and has recently been implicated in endocrine disruption and lung cancer.

Of 65 microbial species cultured from transoceanic dust, 25% were plant pathogens and 10% were opportunistic human pathogens. Because soil dusts can serve as carriers for 1) pesticides, 2) heavy metals, 3) naturally occurring radioactive isotopes (Be-7 and Pb-210), 4) viable bacteria, fungi, viruses, 5) organic debris, and 6) insects, further evaluation, monitoring and prediction of transatlantic soil dust events may be warranted.