The news that a Delaware family vacationing on the island of St. John, part of the US Virgin Islands, were exposed to toxic amounts of the pesticide methyl bromide in their rental villa has raised important questions as to the circumstances of this exposure and what it means from a public health standpoint. From news reports, it appears that the exposures emanated from an apartment below their villa and were significant with all 4 family members severely poisoned with symptoms such as seizures and loss of consciousness occurring; 3 of the 4 members required mechanical ventilation.
Several points to keep in mind are:
- It is primarily used as a fumigant and is odorless--making it hard to know one has been exposed
- The route of exposure in humans is usually via inhalation
- It has many toxic effects, but its most notable is on the central nervous system
- It is directly toxic to neurons via its ability to methylate certain molecules within them
- Seizures, tremors, and kidney failure can occur in toxic exposures
- There is no specific treatment
In my career in infectious disease, critical care medicine, internal medicine, and emergency medicine I have never seen an exposure--nor heard of one--to this chemical so the events in St. John appear to me to be a rare occurrence and possibly stem from excessive spraying in an area in which humans were present. That this has made headlines reflects the fact that such occurrences are rare and newsworthy. An interesting side issue is that since genetic variations in the enzyme glutathione transferase can also predispose to toxicity perhaps the family was genetically predisposed to toxicity at lower levels?
Nonetheless, given this exposure occurred, it will be important to understand how such toxic levels were achieved in a personal dwelling and whether proper safeguards are in place in other areas in which this odorless chemical are being used.
Makes me glad that time when I complained about a cockroach in my room in the US Virgin Islands they did nothing!