Improving the design and conduct of aquatic toxicity studies with oils based on 20 years of CROSERF experience

Laboratory toxicity testing is a key tool used in oil spill science, spill effects assessment, and mitigation strategy decisions to minimize environmental impacts. A major consideration in oil toxicity testing is how to replicate real-world spill conditions, oil types, weathering states, receptor organisms, and modifying environmental factors under laboratory conditions. Oils and petroleum-derived products are comprised of thousands of compounds with different physicochemical and toxicological properties, and this leads to challenges in conducting and interpreting oil toxicity studies. Experimental methods used to mix oils with aqueous test media have been shown to influence the aqueous-phase hydrocarbon composition and concentrations, hydrocarbon phase distribution (i.e., dissolved phase versus in oil droplets), and the stability of oil:water solutions which, in turn, influence the bioavailability and toxicity of the oil containing media. Studies have shown that differences in experimental methods can lead to divergent test results. Therefore, it is imperative to standardize the methods used to prepare oil:water solutions in order to improve the realism and comparability of laboratory tests. The CROSERF methodology, originally published in 2005, was developed as a standardized method to prepare oil:water solutions for testing and evaluating dispersants and dispersed oil. However, it was found equally applicable for use in testing oil-derived petroleum substances. The goals of the current effort were to: (1) build upon two decades of experience to update existing CROSERF guidance for conducting aquatic toxicity tests and (2) to improve the design of laboratory toxicity studies for use in hazard evaluation and development of quantitative effects models that can then be applied in spill assessment. Key experimental design considerations discussed include species selection (standard vs field collected), test substance (single compound vs whole oil), exposure regime (static vs flow-through) and duration, exposure metrics, toxicity endpoints, and quality assurance and control.

"Heal Thyself."—An Argument for Granting Asylum to Healthcare Workers Persecuted During the 2014 West African Ebola Crisis

This article argues for a change in United States asylum policy at a time when change is needed most. Those seeking asylum must prove that they fear persecution in their home country based on one of five protected categories and that their government is the persecutor or is unable to control the actions of the persecutors. Multiple articles have recognized that the "particular social group" is the most difficult category of asylum seeker to analyze. Not only do the standards for particular social groups (PSGs) vary among circuit courts, but judicial consistency is lacking. This article focuses on a particular PSG, healthcare workers from recently Ebola-stricken West Africa. During the 2014 Ebola crisis, these healthcare workers faced discrimination and violence due to their association with western medicine. Hospitals were frequently threatened and ransacked. Multiple accounts of violence against local and international healthcare workers were recorded by Doctors Against Borders, the Centers for Disease Control, and the international media. However, because of the inconsistencies in asylum law and the ever-present political influence in what originates as a humanitarian process, it is unlikely for these PSGs to be found asylum-eligible. This highlights the need for a more consistent and humanitarian-based asylum policy with less political influence.

Chronic Toxicity of Unweathered and Weathered Macondo Oils to Mysid Shrimp (Americamysis bahia) and Inland Silversides (Menidia beryllina)

Chronic, 21-28-day toxicity tests of Macondo source (Massachusetts, or MASS) and weathered Slick A (CTC) and Slick B (Juniper) oils field collected during the 2010 Deepwater Horizon (DWH) Incident in the Gulf of Mexico (GOM) were conducted using standardized procedures. Standard species, Americamysis bahia and Menidia beryllina, were evaluated for changes in survival and growth during daily static-renewal tests. Both species demonstrated an increased sensitivity to low-energy water accommodated fractions (WAFs) of un-weathered MASS oil, with growth and survival decreasing as oil loading rate increased from 0.01 to 1.0 g/L. Survival and growth of mysid shrimp exposed to weathered oil (Slick A and Slick B) did not differ from that of test controls. In contrast, survival and growth of inland silversides declined relative to that of test controls at loading rates of 1 g/L for both weathered oils. Based on the concentration of total polycyclic aromatic hydrocarbons (TPAH42), no observed effect concentrations were lower for inland silverside survival (5.00-7.61 µg/L) and growth (<2.02 to <7.61 µg/L) in chronic exposures to Slick B and Slick A weathered oils compared with mysids (4.75-17.9 µg/L). Average TPAH concentrations in full strength WAFs followed the weathering trend, with 165 ± 17.2, 17.9 ± 0.480, and 4.75 ± 0.521 µg/L for MASS, Slick A, and Slick B oils, respectively. The effect (LOEC, IC25) and no-effect exposure concentrations (in TPAHs) from the standardized laboratory toxicity studies with un-weathered and weathered oils are discussed relative to the actual exposure concentrations in the GOM in 2010. The exposures evaluated in the laboratory toxicity tests represent the highest concentrations of total PAHs that were rarely observed in water column samples collected in the GOM during the release and post release periods of the DWH incident.