Silent Spring by Rachel Carson

Another Britis h experi mente r who applied DDT in acetone s olution to his s kin reported
heavines s and aching of limbs , mus cular weaknes s , and ‘s pas ms of extreme nervous tens ion’.
He took a holiday and improved, but on return to work his conditi on de teriorated. He then
s pent three weeks in bed, made mis erable by cons tant aching in limbs , ins omnia, nerv ous
tens ion, and feelings of acute anxiety. On occas ion tremors s hook his whole body—tre mors of
the sort now made all too fa miliar by the s ight of birds pois oned by DDT. The experime nte r los t
10 weeks from his work, and at the end of a year, when his case was reporte d in a Britis h
medical journal, recovery was not complete. (Despite this evidence, several American
inves tigators conducting an experiment with DDT on volunteer s ubjects dis miss ed the
complaint of headache and ‘pain in every bone’ as ‘obvious ly of ps ychoneurotic origin’.)
There are now many cas es on record in which both the s ymptoms and the whole cours e of the
illness point to ins ecticides as the caus e. Typically, s uch a victim has had a known expos ure to
one of the ins ecticides , his s ymptoms have s ubs ided under treatme nt which included the
exclus ion of all insecticides from his environment, and most significantly have returned with
each renewed contact with the offending chemicals. This s ort of evidence—and no mo re—
forms the bas is of a vas t amount of medical therapy in many othe r dis orde rs. There is no
reas on why it s hould not serve as a warning that it is no longer sensible to take the ‘calculated
risk’ of saturating our environment with pes ticides. Why does not everyone handling and using
insecticides develop the same symptoms? Here the matter of individual sensitivity enters in.
There is s ome evidence that women a re more s us ceptible than me n, the very young more than
adults , those who lead sedentary, indoor lives more than those leading a rugged life of work or
exercise in the open. Beyond these differences are others that are no less real because they are
intangible. What makes one person allergic to dust or pollen, sensitive to a poison, or
susceptible to an infection whereas another is not is a medical mystery for which there is a t
pres ent no explanation. The problem nevertheles s exis ts and it affects significant numbers of
the population. Some phys icians es timate that a thi rd or more of their patients s how s igns of
s ome form of s ensitivity, and that the number is growing. And unfortunately, s ens itivity ma y
s uddenly devel op in a pe rs on previous ly ins ensitive. In fact, s ome me dical men believe that
intermitte nt expos ures to che micals may produce jus t s uch s ens itivity. If this is true, it may
explain why s ome s tudies on men s ubjected to continuous occupational exposure find little
evidence of toxic effects. By their constant contact with the chemicals thes e men keep
themselves desensitized—as an allergist keeps his patients desensitized by repeated small
injections of the allergen. The whole problem of pesticide poisoning is enormously complicated
by the fact that a human being, unlike a laboratory animal living under rigidly controlled
conditions , is never expos ed to one chemical alone. Between the major groups of ins ecticides ,
and between them and othe r chemicals, there are interactions that have serious potentials.
Whethe r released into soil or water or a man’s blood, these unrelated chemicals do not remain
segregated; there are mysterious and uns een changes by which one alters the power of
anothe r fo r ha r m. There is interaction eve n between the two major groups of ins ecticides
us ually thought to be completely dis tinct in their action. The power of the organic phos phates ,
thos e pois oners of the ne rve-protective enzyme cholinesterase, may become greater if the
body has firs t been expos ed to a chlorinated hydrocarbon which injures the liver. This is
becaus e, when liver function is dis turbed, the cholines teras e level drops below normal. The
added de pres s ive effect of the organic phos phate may then be enough to precipitate acute