Madam, - I always enjoy Lorna Siggins's articles on the marine environment and her Irishwoman's Diary of December 31st was no exception.
She provided a glimpse into the life and times of Rachel Carson, whose 1962 book Silent Spring warned about the effects of the excessive use of pesticides, mainly DDT, leading to its banning in the US and restrictions on its usage elsewhere.
Her article prompted Mary Hilary to express concerns about fluoride in drinking water (January 3rd), bringing a reply from Dr Seamus O'Hickey (January 9th).
Two points are worth mentioning here. The first is that fluorine is a common element but like its cousins chlorine (in common salt) and iodine, is easily washed out of soils by rain water and ends up in the sea. The human organism needs these elements; a deficiency in iodine causes goitre (so we add iodine to common salt) and a deficiency in fluorine gives rise to unhealthy teeth. We already use too much salt in our food, so there is no chlorine deficiency in our diet.
Teeth are composed largely of calcium fluoride. We know all about eating calcium-rich foods, including dairy products, but where do we get our fluorine from? Surprisingly, some familiar substances including tea contain fluorine, but not nearly enough.
The discovery in the early part of the 20th century of "Texas teeth" - brown but amazingly healthy teeth, owing to high levels of fluoride occurring naturally in Texas and Colorado - led to the widespread fluoridation of fluorine-deficient drinking water and the corresponding improvement in public health, a policy currently under attack from the anti-fluoridation lobby.
The other point concerns the ban on DDT inspired by Rachel Carson's writings. DDT was the most cost-effective anti-malarial agent available at that time (its inventor won a Nobel Prize) and its dropping led to an immediate resurgence in the almost eradicated disease malaria, which kills mainly children and pregnant women.
It is conservatively estimated by the WHO and other agencies that the banning of DDT has led directly to the deaths of at least 20 million (some say 50 million) children in Africa, leading to the rather unfair accusation that Rachel Carson was (indirectly) responsible for more deaths than Hitler and Stalin together.
Every natural or artificial substance, unless it is completely inert, has some noxious side-effect or risk, but in many cases clear benefits too. This also applies to technologies including electricity, natural gas, GM crops, air/sea/road travel, mobile phones, high-tension power lines, nuclear power, modern medicines, surgery, anaesthetics and riding bicycles in open-toed sandals. The challenge is to balance the risks and benefits and most of us do this quite well.
Sadly, some ideologically inspired groups seem unable or unwilling to accept clear benefits and agonise over the often remote (or zero) risks. They also try to ram their well-intentioned but unbalanced views down our throats, often in the guise of public policy decisions. - Yours, etc,
GEORGE REYNOLDS, Consulting Geophysicist, Annamoe, Co Wicklow.