“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

• 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”

The Case Report

• Chemistry of MS SIM

• Quantification problems

• Lethal Dosage

• Process of determination of cause of death

• Alternate hypothesis for cause of death

Overview

• 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

Mass Spectrometry Selected Ion Monitoring

• Demethylated form of bromethalin found in brain and liver samples

•Positive control resulted in a peak

•Negative control resulted in no peak

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

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.

The Quantification Problem

“accurate quantification of bromethalin in tissues is limited

by the rapid photodegredation of bromethalin in sample extracts”2

Would quantification even be accurate?

• 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

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

Bromethalin Lethal Dosages

“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

1. History of exposure to potentially toxic dose

2. Clinical signs

3. Physiological indicators• Histologic presence of white matter

vacuolization

4. 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

Determination of Cause of Death in Case Study

• 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

Barbiturates

• 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

1. History of Exposure to Toxic Dose

•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

2. Clinical Signs of Barbiturate Overdose

Barbiturate Overdose Patient symptoms

Changes in alertnessDecreased interpersonal functionSevere confusionAtaxia, areflexiaPupil effectsVentilation requiredPossible complications- pneumoniaComaPossible brain deathmortality

Repetitive speechDiminished response to questionsLabile emotionsFlaccid extremitiesAniscorcic pupilsPlaced on ventilatorAcute bronchoalveolar pneumoniaComaBrain death Death

• 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

3. Physiological Indicators

•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.”

4. Detection of Barbiturate in the Body

• 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

Barbiturate Poisoning Diagnosis

• 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

Summary

It cannot be positively determined that Bromothalin poisoning was the only possible cause of death in this

case study.

Conclusion

 

1.Pasquale-Style, M., Sochaski, M., Dorman, D., Krell, W., Shah, A., Schmidt, C., Fatal Bromethalin Poisoning Journal of Forensic Science 2006 vol 51, pp. 1154 – 1157

2.Dorman, D., Simon, J., Harlin, K., Buck, W., Diagnosis of Bromethalin Toxicosis in the Dog J Vet Diagn Invest 1990 pp 123 – 128

3.Cooks, R., Soltero-Rigau, E., Kruger, T., Identification of Barbiturates by Chemical Ionization and Mass Analyzed Ion Kinetic Energy Spectrometry Analytical Chemistry 1977 vol 49 pp. 435 – 442

4.Roberts, D., Buckley, N., Enhanced Elimination in Acute Barbiturate Poisoning – A Systematic Review Clinical Toxicology 2011 vol 49 pp. 2 – 12

5.American Society of Health System Pharmacists; AHFS Drug Information 2009. Bethesda, MD. (2009), p. 2578

6.USP Convention. USPDI - Drug Information for the Health Care Professional. 17th ed. Volume I. Rockville, MD: Convention, Inc., 1997. (Plus Updates)., p. 505

7.Odabasi, M., Halogenated Volatile Organic Compounds from the Use of Chlorine – Bleach – Containing Household Products Environmental Science and Technology 2008 vol 42 pp. 1445 – 1451

8.Dorman, D., Zachary, J., Buck, W., Neuropathological Findings of Bromethalin Toxicosis in the Cat Veterinary Pathology Online 1992 vol 29 pp. 139 – 144

References

• “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