Before DDT was introduced in the 1940s, lead arsenate was widely used as a pesticide. It was originally introduced in the United States in 1892, to control gypsy moth.
Massachusetts was the first state to manufacture and begin spraying lead arsenate.
The first small outbreak of polio (26 cases) occurred the following year, in 1893 .
Also in Massachusetts.
Boston, Massachusetts actually, which happened to be downstream of where the lead arsenate was being manufactured by Merrimack Chemical Corporation (later bought by Monsanto) in Woburn.
(By the end of the century, Merrimack Chemical Corporation was the biggest manufacturer of lead arsenate in the US. It is estimated that 13 tonnes of arsenic made it’s way into the Aberjona River and Mystic Lakes, which were then public water supplies, during the decades that lead arsenate was being manufactured in Woburn) .
Arsenic still contaminates the watershed area downstream of Woburn today, and even decades after production had ceased, rates of childhood leukemia in Woburn were 4-fold higher than the national average .
The following year, 1894, an even bigger outbreak occurred just over the state border in Rutland County, Vermont – now officially recognised as America’s first polio epidemic.
Nearly all cases occurred in the Otter Creek Valley, a fertile valley nestled between two mountain ranges, and surrounded by agricultural industries. It was noted that numerous horses, dogs and fowls had also died with symptoms of paralysis, (yet polio is said to only affect humans), and some victims died suffering strange rashes and convulsions (symptoms of poisoning) .
Strangely, convulsions were often reported in relation to poliomyelitis, with many doctors confirming that the disease did not seem to be contagious, often seeming to affect only one child in the household, and put it down to “abnormal atmospheric conditions” .
There had been numerous isolated cases of ‘infantile paralysis’ for decades, and was originally blamed on teething, because of its propensity to strike suddenly when a child was teething. It may seem odd to us now, to blame teething for paralysis and convulsions, but teething used to be a dangerous business! For example, in 18th century France, one half of all infant deaths were attributed to teething. In 19th century England, 12% of all deaths under 4yrs of age were recorded as teething .
What made teething dangerous? The teething powders used to soothe fussing and fractious infants contained mercury . Unfortunately, the connection between mercury and ‘teething deaths’ wasn’t made until the 1940’s, and only after some observant doctors noted the similarities between arsenic and mercury poisoning .
It wasn’t just mercurial teething powders that made teething fraught with danger. Opiates, such as laudanum were commonly used to sedate irritable babies and dull the pain of teething, and many cases of lethal intoxication occurred .
With the advent of arsenical pesticides, however, clusters of young paralysis victims became more and more common, especially during the summer and autumn months (when the fruits sprayed with arsenic were being eaten, and children were swimming in creeks and waterholes contaminated by pesticide run-off).
As the codling and gypsy moths developed resistance, heavier applications of lead arsenate were required – up to 5 or 6 applications per season. It was not until the 1920’s that researchers realized pesticide residues were not removed by washing or rubbing – about two-thirds of the residue remained on the fruit .
By 1929, almost 30 million pounds of calcium or lead arsenate were being sprayed every year, onto the fields and orchards of America .
Arsenic was also being widely used in medicine, during the early 20th century, especially as a treatment for syphilis – some patients were given more than 100 injections of arsenic-containing Tryparsamide (which was developed by the Rockefeller Foundation, and manufactured by Merck) to ‘treat’ advanced syphilis .
There were several reports of polio following arsenical injections – one of those occurred in a children’s home in Germany in 1913, where 5 children were diagnosed with polio. All were being treated for syphilis at the time, via arsenical injections .
Arsenical injections were also employed to treat yaws – a tropical skin disease. In 1936, a campaign to eradicate yaws in Western Samoa preceded a large polio epidemic. Thirty-six thousand locals were given two or more injections in the buttock. A week after the second injection, the first cases of paralysis appeared – all were in the lower limbs, and all had received arsenical injections. In total, 138 locals suffered paralysis after receiving injections. .
When widespread vaccination campaigns began, for diptheria and pertussis, paralysis cases, diagnosed as ‘polio’, also followed . At the time, those vaccines contained mercury as a preservative.
It was not just arsenic or mercury that caused polio symptoms – phosphorus, lead, carbon monoxide and cyanide poisoning were also reported in cases of poliomyelitis.
Lead arsenate finally fell out of favour in the 1940’s and was largely replaced by another poison – DDT. Arsenic-based pesticides weren’t banned until the 1980’s, however, and some ‘modified arsenates’ are still in use today, on cotton crops. It is thought that ground contamination is the cause of elevated levels of arsenic in rice today.
The use of arsenical pesticides in China continued beyond the year 2000, and it is suspected they still continue to use them illegally, hence the presence of arsenic in apple juice imported from China 
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