Fatal Bromethalin Poisoning ?

1. Fatal Bromethalin Poisoning ? “In 2004, 643 bromethalin exposures were reported to 62 major poison control centers across the United States . . . to our knowledge, a fatal human poisoning has never been previously reported.” Kassandra Luening and Neil Rybak

2. The Case Report • 21 year old male brought to emergency room after discovery with “multiple open packages of rat poison”, self reportedly ate “8 packs” • Symptoms: repetitive speech, labile emotions, diminished responsiveness to direct questions, normal vital signs, one episode of emesis • Treated with promethazine, thiamine, folic acid, and diphenhydramine • “medically cleared” and sent to psychiatric hospital • The last 2 days of 3 in psychiatric hospital, was “obtunded and catatonic”, sent to hospital for further study • Stable vital signs, no fever, anisocori pupils, unresponsive to verbal or painful stimuli. Flaccid extremities • Intubated and placed on a ventilator • Developed distended bladder, and decreased rectal tone • Declared brain dead 7 days after ingestion of “No Pest”

3. Overview • Chemistry of MS SIM • Quantification problems • Lethal Dosage • Process of determination of cause of death • Alternate hypothesis for cause of death

4. Mass Spectrometry Selected Ion Monitoring • Allows for scanning of specific mass fragments, as opposed to a full scan • Faster than a full scan as only a section of the spectrum is being scanned • Less matrix interference • The atomic mass units of the fragments of interest must be known

6. Demethylated form of bromethalin found in brain and liver samples • Positive control resulted in a peak • Negative control resulted in no peak

7. Problem: • Knowing that there is bromethalin in the tissues does not necessarily indicate a lethal dosage, only that it was there.

8. The Quantification Problem • “Because of a lack of analytical standard, no attempt was made to quantitate this analyte.”1 • The presence of bromethalin was shown, but not the quantity.

9. “accurate quantification of bromethalin in tissues is limited by the rapid photodegredation of bromethalin in sample extracts”2 • Would quantification even be accurate?

10. Lethal Dosages • The lethal dosage (LD50) is the amount of a substance that would kill a certain percent of a population • Based on the ‘standard person’ concept and may not be suitable to all sub-populations Determining Lethal Dosage • Extrapolating from human cultures • Extrapolating from LD50 of other animals

11. Bromethalin Lethal Dosages • Cat: 0.54 mg/kg1, 1.8 mg/kg2 • Dog: 4.7 mg/kg2 • Rabbit: 13 mg/kg2 • Guinea Pig: >1,000 mg/kg2 • Case Study Patient: 0.33 mg/kg • Not quantified experimentally • Based on self report of the patient who had shown diminished cognitive function, as well had a chronicled history of strange behaviour • unreliable source of information

12. “the ischemic neuronal changes seen on microscopic examination are likely related to his terminal diagnosis and do not necessarily reflect bromethalin toxicity”1 • “the sensitivity of humans to bromethalin has not been previously studied, and the LD50 in people is unknown”1

13. Determination of Cause of Death in Case Study • History of exposure to potentially toxic dose • Clinical signs • Physiological indicators • Histologic presence of white matter vacuolization • Detection of drug in the body • Bromethalin found in brain and liver samples • It’s possible to use this same methodology to identify barbiturates as a possible cause of death

14. Barbiturates • Central Nervous System depressants • Resulting in mild sedation, to total anesthesia • Possible side effects include; hypotensia, ataxia, mortality, sedation (coma), areflexia, apnoea, hypotension, hypothermia • Widely prescribed and frequently used for intentional self poisoning4 • 15th most common medication class associated with fatal poisoning in the US4 • “the collective experience (and comfort) of clinicians for managing patients with severe barbiturate toxicity is fading”4

15. History of Exposure to Toxic Dose • A urine drug screen was positive for barbiturates • Lethal dosage ranges from 30 µg/ml to 80 µg/ml depending on which barbiturate5 • Combined with other CNS depressants, toxicity can increase5 • Patient was treated with promethazine, and phenhydramine; both are strong sedatives

16. Clinical Signs of Barbiturate Overdose • Changes in alertness, decreased interpersonal function, severe confusion, areflexia, ataxia, pupil effects, decreased urine production, ventilation required, possible complications such as pneumonia, coma, brain death, mortality • These signs were apparent in the case study patient • Patient exhibited; repetitive speech, labile motions, diminished response to direct questioning, aniscoric pupils, flaccid extremities (ataxia), and was placed on a ventilator, coma, brain death, declared dead

17. Physiological Indicators • Barbiturate overdose can lead to global ischemia, a complete stoppage of blood flow to the brain • EEG performed on patient a day before death indicated low amplitude voltage, which is a non specific finding consistent with global ischemia and impending brain death • Other possible explanations for white matter vacuolization • Can be caused by PCP and ketamines • Carbon tetrachloride exposure from cleaning agents can cause white matter vacuolization6 • It has been shown that bromethalin exposure at an anticipated lethal dosage does not necessarily lead to death7

18. Detection of Barbiturate in the Body • An initial urine screening was positive for barbiturates • No further testing was done • “The initial positive urine barbiturate screen was never accounted for in the medical records reviewed.”

19. Barbiturate Poisoning Diagnosis • Urine screening show barbiturates • Indicated a history of drug use • Clinical signs of barbiturate overdose were seen • Global ischemia, a result of barbiturate overdose was observed in the patient • MS SIM analysis was only done for expected demethylated bromethalin, no follow up was done on the positive screening in the urine analysis

20. Summary • The bromethalin found in the patient was not quantified • The LD50 of bromethalin in humans is not known • The method used to determine bromethalin poisoning as cause of death could also be used to determine barbiturate poisoning as cause of death

21. Conclusion • It cannot be positively determined that Bromothalin poisoning was the only possible cause of death in this case study.

22. References • Pasquale-Style, M., Sochaski, M., Dorman, D., Krell, W., Shah, A., Schmidt, C., Fatal Bromethalin Poisoning Journal of Forensic Science2006 vol 51, pp. 1154 – 1157 • Dorman, D., Simon, J., Harlin, K., Buck, W., Diagnosis of Bromethalin Toxicosis in the Dog J Vet Diagn Invest 1990 pp 123 – 128 • Cooks, R., Soltero-Rigau, E., Kruger, T., Identification of Barbiturates by Chemical Ionization and Mass Analyzed Ion Kinetic Energy Spectrometry Analytical Chemistry1977 vol 49 pp. 435 – 442 • Roberts, D., Buckley, N., Enhanced Elimination in Acute Barbiturate Poisoning – A Systematic Review Clinical Toxicology2011 vol 49 pp. 2 – 12 • American Society of Health System Pharmacists; AHFS Drug Information 2009. Bethesda, MD. (2009), p. 2578 • USP Convention. USPDI - Drug Information for the Health Care Professional. 17th ed. Volume I. Rockville, MD: Convention, Inc., 1997. (Plus Updates)., p. 505 • Odabasi, M., Halogenated Volatile Organic Compounds from the Use of Chlorine – Bleach – Containing Household Products Environmental Science and Technology2008 vol 42 pp. 1445 – 1451 • Dorman, D., Zachary, J., Buck, W., Neuropathological Findings of Bromethalin Toxicosis in the Cat Veterinary Pathology Online1992 vol 29 pp. 139 – 144

23. “the sensitivity of humans to bromethalin has not been previously studied and the LD50 in people is unknown”1 • “no attempt was made to quantitate this analyte”1 • “the ischemic neuronal changes seen on microscopic examination are likely related to his terminal diagnosis and do not necessarily reflect bromethalin toxicity”1