Findings

Sampling Sites
Sampling station in Bamako, Mali. Sal Island, Cabo Verde.		Galera Point, Trinidad.

Chemical contaminants: To date, banned and current-use pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCB congeners) have been identified in dust event air samples collected from the African Sahara/Sahel (Mali), offshore from the African continent (Cape Verde), and from the Caribbean (Trinidad-Tobago and the U.S. Virgin Islands). Air samples from Mali contained significantly higher concentrations of the same suite of contaminants than USVI, Trinidad, Tobago, and Cape Verde air samples. Mixtures of multiple persistent organic contaminants and bioactive metals are typically found. Dioxins and furans were detected only in air samples from the source region. These contaminants are known to persist in the environment, bioaccumulate, and be toxic to organisms, including humans. All are known to affect one or more of the following: endocrine, immune, hepatic, neurological, and reproductive systems. Some act as carcinogens, mutagens, and/or teratogens. Only a few metals were enriched over mean upper crustal concentrations, primarily lead in Mali. Petrol contained lead in Mali until February 2008 and in Trinidad until 2006.

Bioaccessibility of some metals with known or suspected human/ecosystem health risks generally increased along the transect from the dust-source region (Mali) to the Caribbean. Inhalation and ingestion exposure pathways were explored by extraction of the samples using simulated lung and gastric fluids. Some sample metal concentrations exceeded EPA residential soil screening levels (SSls) and ecological (ECO) SSLs and are under further investigation.

Air samples collected during dust events in the USVI and Trinidad contained approximately 2-8 times as many cultureable microorganisms per volume as did air samples collected during non-dust conditions. Air in Mali contained orders of magnitude more cultureable microorganisms per volume than air sampled in the downwind areas (USVI, Trinidad, and Cape Verde) and more taxa.

The pathogenic strain of the fungus known to cause sea-fan disease and mortality of sea fans throughout the Caribbean region was isolated from:

• air samples collected in the USVI during African dust conditions but not from non-dust periods.
• soil from the Sahel (Mali).