A few days ago there was a story in the local news about a man who strangled his wife. Both the prosecution and defence in the case jointly submitted that the man should not be held criminally responsible for his actions because he was affected by metal poisoning. The metal poisoning theory was proposed by a psychiatrist and supported by lab tests showing high levels of metals, including lead, cadmium and manganese, in the man’s blood. Could the metal poisoning have caused the murder?
Lead, cadmium and manganese are all known to have neurotoxic properties. Lead poisoning has been associated with cognitive dysfunction, distraction, inattentiveness, impulsive behaviour and other symptoms, although primarily in children. Occupational exposures to manganese have been shown to cause Parkinson-like symptoms. Cadmium has been shown to affect reaction time and concentration. So all of these metals can certainly affect the brain, although it is a big leap from the typical occupational effects to committing murder.
However, the exposure in this case was fairly unique. The man worked at a scrap yard in a position where he was regularly exposed to metal fumes – certainly a high occupational exposure scenario. To make matters worse, he didn’t wear the mask meant to provide protection from the fumes due to discomfort (which was probably illegal – compliance with occupational health and safety regulations is mandatory here). Then this was compounded further by some “magic metal belts” made of silver, zinc and lead that he and his wife had been wearing while attempting to get pregnant. On the day of the killing, he melted the belts, resulting in a high acute exposure on top of the chronic occupational exposure.
I don’t have access to the court records or toxicology reports. However, it is apparent that this man had an extremely abnormal exposure to multiple neurotoxic metals. Could it have caused this man to kill his wife? I can’t rule it out, and for both prosecution and defence to agree the case must be reasonably strong. But I have to stress this is not even remotely a normal situation – a combination of high occupational exposure, failure to comply with occupational health and safety regulations, additional exposure from superstitious beliefs, and a final extremely high acute exposure. These metals are all naturally occurring substances that we are all exposed to on a daily basis, but even more “normal” occupational exposures wouldn’t be expected to produce effects of this magnitude.