Uses for weedkiller: poisoned underwear and exploding trousers

It was a headline no toxicologist could not ignore: “Underwear ‘soaked in poison rots man’s genitals”.

The story goes that a woman in China soaked her husband’s pants in a solution of paraquat weedkiller which then poisoned him after being absorbed through the skin.  His immediate symptoms were shrunken genitals and difficulty breathing, although he seemed to have noticed the former before the latter.

Having conducted some research with paraquat many years ago, my skeptical senses started to tingle - is this really feasible?

Paraquat is a weedkiller first manufactured by ICI in the UK (where I did my limited amount of work back in early 1990s). In the far East, there is an alarmingly high suicide rate with paraquat although it is through oral ingestion, not through skin absorption.

For a chemist, the striking thing about paraquat is that it has two positively-charged nitrogen atoms, which form a chloride salt of high water solubility. It is therefore perfectly possible to make a concentrated solution of paraquat in which to soak clothing thus providing a high dose to the skin. The same electrical charges however, make the dermal absorption of paraquat very poor and tests have shown that concentrations of up to 9 grams per litre did not pass through the skin to any significant extent. Paraquat-laced pants therefore seem feasible but the poisoning still looks a little unlikely (no pun around lace pants intended).

The story went on to explain that the paraquat caused skin damage to the man's genital area over a period of 2-weeks.  I assume that the man’s wife must have soaked several pairs of pants in paraquat over this period and it wasn’t the same pair for all of this time! High concentrations of paraquat will certainly cause skin-irritation and damaged skin will absorb more paraquat than healthy skin. On the other hand, if it was a single pair of pants worn for 2-weeks, then it might be more than just paraquat that was causing skin-irritation. Either way, the story starts to look feasible again. 

The unfortunate husband recovered and so the symptoms do not appear to have become life-threatening, although shrivelled genitals is not something any man is likely to ignore. Nevertheless, systemic blood concentrations were probably not overtly high.  Someone at the hospital must have joined the dots between symptoms, perhaps blood tests (not unlikely in China where paraquat poisoning is relatively common) and perhaps even analysis of the man’s underwear. I’ll give that doctor ten out of ten for their detective skills. 

This story is a little reminiscent of the 1930s exploding trousers incident in New Zealand. Farmers were using high quantities of sodium chlorate herbicide to kill off an invasion of ragweed.  Their trousers became contaminated with the herbicide and the composite of sodium chlorate and cotton resulted in a potentially explosive combination. In fact, several deaths were reported. There was an episode of the TV show Myth Busters that actually demonstrated the feasibility of exploding trousers (Season-4, Episode-14). 

I don’t think I need to worry about poised pants or exploding trousers. Firstly paraquat is now banned across Europe and sodium chlorate is rather hard to come by. Secondly, I do the household laundry. Thirdly, my wife is a smart woman and I am confident she’d come up with a better plan if she wanted to cash in the life insurance.