The impact and recovery of asteroid 2018 LA.

The June 2, 2018, impact of asteroid 2018 LA over Botswana is only the second asteroid detected in space prior to impacting over land. Here, we report on the successful recovery of meteorites. Additional astrometric data refine the approach orbit and define the spin period and shape of the asteroid. Video observations of the fireball constrain the asteroid's position in its orbit and were used to triangulate the location of the fireball's main flare over the Central Kalahari Game Reserve. 23 meteorites were recovered. A consortium study of eight of these classifies Motopi Pan as a HED polymict breccia derived from howardite, cumulate and basaltic eucrite, and diogenite lithologies. Before impact, 2018 LA was a solid rock of ~156 cm diameter with high bulk density ~2.85 g/cm3, a relatively low albedo pv ~ 0.25, no significant opposition effect on the asteroid brightness, and an impact kinetic energy of ~0.2 kt. The orbit of 2018 LA is consistent with an origin at Vesta (or its Vestoids) and delivery into an Earth-impacting orbit via the v6 resonance. The impact that ejected 2018 LA in an orbit towards Earth occurred 22.8 ± 3.8 Ma ago. Zircons record a concordant U-Pb age of 4563 ± 11 Ma and a consistent 207Pb/206Pb age of 4563 ± 6 Ma. A much younger Pb-Pb phosphate resetting age of 4234 ± 41 Ma was found. From this impact chronology, we discuss what is the possible source crater of Motopi Pan and the age of Vesta's Veneneia impact basin.

Detection of DNA damage in workers exposed to JP-8 jet fuel.

The genotoxicity of jet propulsion fuel 8 (JP-8) was assessed in the leukocytes of archived blood specimens from U.S. Air Force personnel using the comet assay. No differences in mean comet assay measurements were found between low, moderate, and high exposure groups before or after a 4h work shift. Before the work shift, mean tail DNA and mean tail (Olive) moment increased as the concentration of benzene measured in end-exhaled breath increased, indicating that prior environmental or work-related exposures to benzene produced DNA damage. The number of cells with highly damaged DNA decreased as the pre-shift benzene concentration in breath increased. It is not clear why the decrease is occurring. Mean tail DNA and mean tail (Olive) moment decreased as the concentrations of benzene and naphthalene measured in breath immediately after the work shift increased. These inverse relationships may reflect a slower rate of absorption or a faster rate of expiration of benzene in the lung. The number of cells with highly damaged DNA increased as the concentration of urinary (2-methoxyethoxy)acetic acid (MEAA) increased. This relationship was not seen in urinary MEAA adjusted for creatinine. MEAA is a metabolite of the deicing agent 2-(2-methoxyethoxy)ethanol contained in JP-8. MEAA or a component of JP-8 correlated with MEAA may have a toxic effect on DNA.

(2-methoxyethoxy)acetic acid: a urinary biomarker of exposure for jet fuel JP-8.

PURPOSE: To demonstrate the utility of the urinary metabolite (2-methoxyethoxy)acetic acid (MEAA) as a biomarker of exposure. 2-(2-methoxyethoxy)ethanol [diethylene glycol monomethyl ether] is an anti-icing agent used in the formulation of JP-8, and it is added at a known uniform 0.1% (v/v) concentration to each batch lot. JP-8 is a kerosene-based fuel containing different compounds that vary in the content of every batch/lot of fuel; thus, MEAA has the potential to be a more specific and a consistent quantitative biomarker for JP-8 exposure. METHODS: MEAA was used to measure exposure of jet propulsion fuel 8 (JP-8) in United States Air Force (USAF) personnel working at six airbases within the United States. Post-shift urine specimens from various personnel including high (n = 98), moderate (n = 38), and low (n = 61) exposure workgroup categories were collected and analyzed by a gas chromatographic-mass spectrometric test method. The three exposure groups were evaluated for the number per group positive for MEAA, and a statistical analysis consisted of pair-wise t-tests for unequal variances was used to test for the differences in mean MEAA concentrations between the exposure groups. RESULTS: The number of samples detected as positive for MEAA exposure, that is, those above the test method's limit of detection (LOD = 0.1 µg/ml), were 92 (93.9%), 13 (34.2%), and 2 (3.3%) for the high, moderate, and low exposure workgroup categories, respectively. The mean urinary MEAA level was significantly greater in the high exposure category (6.8 µg/ml), compared to the moderate (0.42 µg/ml) and the low (0.07 µg/ml) exposure categories. The maximum concentration of urinary MEAA was 110 µg/ml for the high exposure category, while 4.8 µg/ml and 0.2 µg/ml maximum levels were found in the moderate and low exposure categories, respectively. CONCLUSION: This study demonstrated that urinary MEAA can be used as an accurate biomarker of exposure for JP-8 workers and clearly distinguished the differences in JP-8 exposure by workgroup category.

Risky alcohol use, age at onset of drinking, and adverse childhood experiences in young men entering the US Marine Corps.

OBJECTIVE: To examine how childhood experiences relate to risky underage drinking. DESIGN: A survey study of men starting military training between June 11, 2002, and April 5, 2006. Multivariate logistic regression models compared risky drinkers with "all others" or with nonrisky drinkers; excluding nondrinkers. SETTING: Marine Corps Recruit Depot, San Diego, Calif. PARTICIPANTS: Forty-one thousand four hundred eighty-two men aged 18 to 20 years. Main Exposures Age at drinking onset; childhood emotional, physical, and sexual abuse; childhood emotional and physical neglect; and household alcohol abuse, mental illness, domestic violence, or divorce. MAIN OUTCOME MEASURES: Risky drinking identified by scoring responses to 3 questions about alcohol consumption. RESULTS: Of 41,482 young men, 6128 (14.8%) were identified as risky drinkers, 18,693 (45.1%) as nonrisky drinkers, and 16 661 (40.2%) as nondrinkers. Among drinkers, early initiation of alcohol use was strongly associated with risky drinking, with a 5.5-fold risk if age at onset of drinking was 13 years or younger. Other associated factors included tobacco use, rural or small hometown, higher education, motivation to join the military for travel or adventure or to leave problems at home, numerous close friends and relatives, household alcohol abuse or mental illness, and childhood sexual or emotional abuse. When the comparison group included nondrinkers, additional associated factors included childhood physical abuse and domestic violence. CONCLUSIONS: These analyses confirm previous findings on risks for alcohol misuse in young adults and quantify these risks in new, large, multivariable models, adding unique perspective from a population of young Marines. Public health efforts to decrease alcohol misuse may be effectively targeted by prevention of underage alcohol use, tobacco use, and childhood abuse.

Myopericarditis following smallpox vaccination among vaccinia-naive US military personnel.

CONTEXT: In the United States, the annual incidence of myocarditis is estimated at 1 to 10 per 100,000 population. As many as 1% to 5% of patients with acute viral infections involve the myocardium. Although many viruses have been reported to cause myopericarditis, it has been a rare or unrecognized event after vaccination with the currently used strain of vaccinia virus (New York City Board of Health). OBJECTIVE: To describe a series of probable cases of myopericarditis following smallpox vaccination among US military service members reported since the reintroduction of vaccinia vaccine. DESIGN, SETTING, PARTICIPANTS: Surveillance case definitions are presented. The cases were identified either through sentinel reporting to US military headquarters surveillance using the Defense Medical Surveillance System or reports to the Vaccine Adverse Event Reporting System using International Classification of Diseases, Ninth Revision. The cases occurred among individuals vaccinated from mid-December 2002 to March 14, 2003. MAIN OUTCOME MEASURE: Elevated serum levels of creatine kinase (MB isoenzyme), troponin I, and troponin T, usually in the presence of ST-segment elevation on electrocardiogram and wall motion abnormalities on echocardiogram. RESULTS: Among 230,734 primary vaccinees, 18 cases of probable myopericarditis after smallpox vaccination were reported (an incidence of 7.8 per 100,000 over 30 days). No cases of myopericarditis following smallpox vaccination were reported among 95,622 vaccinees who were previously vaccinated. All cases were white men aged 21 years to 33 years (mean age, 26.5 years), who presented with acute myopericarditis 7 to 19 days following vaccination. A causal relationship is supported by the close temporal clustering (7-19 days; mean, 10.5 days following vaccination), wide geographic and temporal distribution, occurrence in only primary vaccinees, and lack of evidence for alternative etiologies or other diseases associated with myopericarditis. Additional supporting evidence is the observation that the observed rate of myopericarditis among primary vaccinees is 3.6-fold (95% confidence interval, 3.33-4.11) higher than the expected rate among personnel who were not vaccinated. The background incidence of myopericarditis did not show statistical significance when stratified by age (20-34 years: 2.18 expected cases per 100,000; 95% confidence interval [CI], 1.90-2.34), race (whites: 1.82 per 100,000; 95% CI, 1.50-2.01), and sex (males: 2.28 per 100,000; 95% CI, 2.04-2.54). CONCLUSION: Among US military personnel vaccinated against smallpox, myopericarditis occurred at a rate of 1 per 12 819 primary vaccinees. Myopericarditis should be considered an expected adverse event associated with smallpox vaccination. Clinicians should consider myopericarditis in the differential diagnosis of patients presenting with chest pain 4 to 30 days following smallpox vaccination and be aware of the implications as well as the need to report this potential adverse advent.

Comparison of two sources of U.S. Air Force injury mortality data.

Is the military's casualty (mortality) reporting system a reliable surrogate for International Classification of Diseases-coded death certificate information? To answer this question, the investigators compare official casualty data to the Air Force Mortality Registry for injury-related deaths occurring in 1991-1997. The investigators first derived International Classification of Diseases, Ninth Revision and Supplementary Classification of External Causes of Injury and Poisoning (E) codes for each death from casualty data and then compared the precision of those codes with the registry's E codes derived and medically coded from death certificates and autopsy reports. Sixty-five percent of registry E codes were "precise" vs. 35% from casualty data. The registry listed nonspecific E codes for 1% (12 deaths) vs. 6% (81 deaths) for casualty data. Unlike casualty data, the registry included expectant deaths that occurred within 120 days after medical retirement. The study concludes that casualty information compares poorly with that of the registry. Air Force Mortality Registry data should be used instead of casualty data for epidemiological research.

Trends in positive drug tests, United States Air Force, fiscal years 1997-1999.

We investigated the relationship between various demographic factors and the risk of testing positive for marijuana or cocaine use in the U.S. Air Force in fiscal years 1997 through 1999. Overall test positive rates for marijuana and cocaine were very low, at 0.24 and 0.07% of all tests, respectively. However, monthly test positive rates increased significantly during the study period while the number of tests conducted decreased by more than 50%. Gender, race/ethnicity, service component, military rank, education level, and assignment location each predicted the likelihood of testing positive for marijuana or cocaine use. These findings were consistent with annual surveys of self-reported drug use conducted in military and civilian populations in the United States. We conclude that overall testing percentages should be re-evaluated in light of these findings, but we do not recommend oversampling from population subgroups that demonstrated a higher likelihood of testing positive.

Viruses and vitamin D in the etiology of type 1 diabetes mellitus and multiple sclerosis.

Although specific viruses have been associated with autoimmune diseases, none fulfill Koch's criteria of causation. The etiologies of such diseases appear to be complex and multifactorial. For example, one might propose that the etiology of type 1 diabetes mellitus results from a toxic metabolite of nitrosamines during an enteroviral infection. Multiple sclerosis might result from a cascade of events involving several herpes virus infections activated during periods of vitamin D deficiency. We encourage investigators to consider Rotman's sufficient-component causal model when developing hypotheses for testing for the etiology of chronic diseases. Delineating the web of causation may lead to additional strategies for prevention and treatment of several autoimmune diseases.

Dermal exposure to jet fuel (JP-8) in US Air Force personnel.

Limited research has been conducted on dermal exposure and risk assessment, owing to the lack of reliable measurement techniques and data for quantitative risk assessment. We investigated the magnitude of dermal exposure to jet propulsion fuel 8 (JP-8), using naphthalene as a surrogate, on the US Air Force fuel-cell maintenance workers. Dermal exposure of 124 workers routinely working with JP-8 was measured using a non-invasive tape-strip technique coupled with gas chromatography-mass spectrometry analysis. The contribution of job-related factors to dermal exposure was determined using multiple linear regression analyses. Average whole body dermal exposure to naphthalene (as a marker for JP-8) was 7.61 +/- 2.27 ln(ng m(-2)). Significant difference (P < 0.0001) between the high-exposure group [8.34 +/- 2.23 ln(ng m(-2))] and medium- and low-exposure groups [6.18 +/- 1.35 ln(ng m(-2)) and 5.84 +/- 1.34 ln(ng m(-2)), respectively] was observed reflecting the actual exposure scenarios. Skin irritation, use of booties, working inside the fuel tank and the duration of JP-8 exposure were significant factors explaining the whole body dermal exposure. This study clearly demonstrates the efficiency and suitability of the tape-strip technique for the assessment of dermal exposure to JP-8 and that naphthalene can serve as a useful marker of exposure and uptake of JP-8 and its components. It also showed that the skin provides a significant route for JP-8 exposure and that actions to reduce exposure are required. Studies to investigate the relative contribution of dermal uptake of JP-8 on total body dose and the toxicokinetics of dermal exposure to JP-8 are underway.