Clean air acts
Your Technofile item states that tannin cleans air
(22 July, p 11).
Is that how pot-pourri works?
Queue for the loo
Both sexes “get the same number of loos” states your otherwise brilliant
article on the endless queue for the ladies
(29 July, p 40).
I’m told by my father, a retired council building control officer, that this isn’t
true鈥攂oth sexes get the same amount of space.
Because urinals take less space, this means that men get approximately twice
as many toilet facilities as women. This, combined with the longer time taken by
women (and, I suspect, more frequent visits) leads to the endless queues known
to all women. Blame the architects.
Letter
A major advance for women could be won by us all insisting that architects
and building owners (mostly male of course) provide facilities on the basis of
access points per expected user population, not area.
An additional factor that should be accounted for is that women are the large
majority of carers of young children, the disabled and the aged. This alone
would justify a significant increase in the number of facilities for women.
Letter
Robert Matthews dismisses the unisex option by saying that men would lose
their “natural advantage”. Does this refer to the ability to pee in a standing
position at a urinal without the need to enter a cubicle?
If this is the case, he may be interested in the website www.restrooms.org,
which gives a woman’s perspective on the problem. The radical solution is for
women to adopt the same stance and use a urinal. It seems this is not a real
problem as far as biology and dress (including jeans) is concerned.
Letter
I am sure that reducing the waiting time at ladies’ loos is in the best
interests of both sexes.
However, it must have occurred to those proposing more loos for ladies that
their best intentions could easily be thwarted if the result is reduced pressure
from waiting companions and those in the queue behind, so that the individual
time in the loo increases.
Following the argument in the article, even a small increase would have a
disproportionate effect.
Trilobite mania
In his review of Trilobite! by Richard Fortey, Michael Taylor states
that if you want true immortality, “get a trilobite named after yourself”
(22 July, p 48).
While I was studying geology at Edinburgh in the late 1970s, the whole
department jumped on this bandwagon by naming the departmental football team
“Sporting Trilobites” as a mark of the affection most of us felt for the wee
beasties. The real problem lay in trying to get opposition teams to pronounce
the name even half correctly.
Smelly washing
Good for Halifax Novia Scotia and the Mounties
(Feedback, 5 August).
As an asthma sufferer I can confirm that scented products do me no good at all.
Perfume is the least of the problem. The major culprit, these days, is
whatever they put in washing powder and fabric conditioner. I absolutely refuse
to use conditioner and it’s hard to find a brand of powder that doesn’t have
smelly stuff in it.
Unfortunately, it’s in every home (except mine), for everyone does washing or
has it done for them. Intending to enjoy coffee on the patio the other day, I
found myself about to be asphyxiated by the down draught from my neighbour’s
washing line. Had I still been working in a lab, letting out such a high
concentration of any stinky chemical would have earned me a lecture on safety
regulations and instant banishment to the remotest fume hood.
My neighbour will soon be doing even more washing鈥攕he is almost 9
months pregnant. Can anyone consider this to be the proper environment for a
newborn infant?
Alas, not true
With regard to the adage about the size of a man’s feet being related to the
size of other extremities of the body
(24 June, p 35),
I can only offer the
following observation. My own feet are rather on the large size (UK size 13). To
the disappointment of both myself and members of the opposite sex, I remain,
however, “hung like a hamster”. You will excuse me if I prefer to remain:
Name and address supplied
Odder and odder
I am intrigued by the illustration of an IQ question provided in your editorial (29 July, p 3). Was it by design that you could have legitimately chosen each one of the diagrams as an odd one out? Number 1, on the basis of the scale of the diagram, number 2 as the only one in which the figure has no curved boundaries, number 3 as the only one without a vertical axis of mirror symmetry, and (on a higher level of abstraction) number 4 on the basis that it is the only one which you would have no logical reason to choose. Are such ambiguities usual in IQ tests?
Just slow down
Ian Wright comments that the amount of attention required for drivers to look
out for speed traps must have an adverse effect on their driving abilities
(5 August, p 55).
Some of us have found a novel solution to this. We simply observe the speed
limit.
The dirt on soil
We were interested in the comments by G. Gillespie
(22 July, p 52)
that a “growing percentage of British soil is unstable due to lack of organic matter”
and that minerals and trace elements in all soils “are depleted through
cropping”.
Our organisations have been funded by the British Ministry of Agriculture,
Fisheries and Food to look at these very questions. Between 1980 and 1995, the
median topsoil concentration of organic carbon at 898 arable sites has hardly
changed (2.4 per cent and 2.3 per cent respectively), and at 771 permanent
(managed) grassland sites it has decreased from 4.2 per cent to 3.7 per cent. We
were unable to establish any relationship between these small changes in organic
carbon in the soil and soil stability.
Similarly, we have been unable to find any substantial change in trace
elements in these soils. Indeed, we would make the point that significant
amounts of trace elements are returned to the soil in the form of manures, crop
residues and so on. Although removals of major nutrients by crops have increased
between 1980 and 1995, the concentrations of phosphorous, potassium and
magnesium that are available to plants have all increased or remained the
same鈥攏o doubt due to adequate maintenance of reserves through normal
farming practices.
We do not disagree that returning organic matter to the soil can be
beneficial, but suggest that the message is better delivered on the basis of
appropriate research and not broad generalisations that are not borne out by the
evidence and are easily misread as alarmist.
Radiation doses
Your Newswire item “It’s never safe”
(10 June, p 19)
was misleading in several respects.
The Federal Court of Australia did not rule “that two soldiers died of cancer
because they were exposed to low levels of radiation while occupying Hiroshima
in 1945″. The court upheld an earlier decision of the Administrative Appeals
Tribunal (AAT) that a possible link existed between the soldiers’ cancers and
their exposure to radiation.
I did not actually tell the federal court anything and I did not participate
in its proceedings. In 1997, I provided evidence to the AAT, some of which was
quoted in the court’s decision in 2000. Your Newswire item misrepresented my
evidence by quoting my words “Even extremely low doses have an associated risk”
out of context. The court’s decision quoted me correctly, saying: “The
estimation of risks at low levels of radiation involves an assumption that all
doses of radiation, even extremely low doses, have an associated risk which
increases with increase in dose.”
I believe that the above assumption leads to substantial overestimation of
risks from low doses. Nevertheless, on the basis of this assumption, I provided
the AAT with an estimate that the presumed exposures to about 1 millisievert of
radiation at Hiroshima would have caused a fatal cancer risk of about 1 chance
in 20 000 for each of the soldiers.
I also told the AAT that another possible effect of a low dose of radiation
is to stimulate the immune system and thus provide protection against cancers,
including cancers not caused by radiation. Like the possible carcinogenic
effect, this may vary from person to person. The net effect of radiation on the
incidence of cancer in an exposed group depends on the balance between the
damaging effects on DNA and the protective effects of stimulating cellular DNA
repair.
However, for an individual who is not suffering from cancer, it is clear that
far and away the most likely health effect of exposure to low radiation doses
(up to at least 200 millisieverts) is no effect at all.
Iron facts
I feel I must reply to the letter from Sheila Walsh
(29 July, p 66).
She argues that because iron deficiency anaemia is common in pregnancy, it follows
that this must be physiological rather than pathological.
On the contrary, the total circulating iron increases during pregnancy due to
the increased number of red blood cells carrying iron. The oxygen-carrying
capacity of the blood is therefore increased, rather than decreased, as Walsh
suggests. However, the concentration of haemaglobin (Hb), which contains the
iron, is low because the blood volume increases, thus diluting the blood
cells.
Walsh expresses concern about iron therapy in pregnancy. However, routine
iron therapy has not been used for many years, since the reduced Hb
concentration has been recognised as physiological. Even so, it must be
remembered that pregnancy increases the demand for iron, protein, folic acid and
vitamin B12, in order to supply the fetus and growing maternal tissues. This is
especially true of the last 12 weeks of pregnancy, when the fetus increases its
absorption of iron.
So as Hb levels are not a clear indicator of iron deficiency in pregnancy,
many midwives and doctors use the mean cell volume, which declines rapidly in
cases of iron deficiency.
A healthy woman with a good dietary intake will not require iron supplements.
However, it must be remembered that some women have inadequate iron intake or
absorption for a number of reasons, such as poverty or eating disorders. Such
women will need iron supplements, as iron deficiency anaemia is associated with
poor fetal growth, intrauterine hypoxia, pre-term birth, and increase perinatal
mortality. Moreover, these women are at higher risk of infection following
childbirth, not to mention exhaustion and poor healing.
Iron supplements cannot increase the oxygen consumption by the fetus to the
degree that concerns Walsh. The aim of iron therapy is not to increase Hb
levels, but to prevent or correct iron deficiency. Iron absorption by the gut is
limited and the excess is excreted. The iron absorbed is used to make new red
blood cells and to supply the fetus.
Frozen traffic
In Mark Buchanan’s feature “It’s flaming freezing!”, Dirk Helbing is quoted
as believing that “traffic measures that promote the frozen state could save lives”
(15 July, p 28).
Equally, the piece mentions that this frozen traffic
state “also has the highest overall throughput of vehicles”.
In Belgium such traffic measures already exist. Every year a large number of
people there rush to the seaside. Lots of day tourists pile into their cars and
clog the Brussels to Ostend motorway. In order to keep traffic flowing at
optimal speed, drivers are forced into so-called “block” driving.
Motorised policemen stop the traffic until a large block of vehicles has
formed. This block is then guided at a steady pace of 60 kilometres an hour to
the seaside as a big “crystalline” formation. Traffic is thus chopped up into a
string of guided blocks. No one is allowed to pass.
I’m not sure when this measure was introduced for the first time, but I
believe that it has been in existence from the early 1980s.
Theory beached
The article on research by Brian Lapointe and his team concerning beach
erosion at Negril in Jamaica
(29 July, p 5)
makes certain claims about the problem of beach erosion on tropical carbonate
beaches and suggests a possible mechanism.
A team from the University of the West Indies, comprising Edward Robinson,
Ravidya Maharaj, Shakira Khan and myself, have been studying this problem for
the past year and have data that questions the facts and interpretations of
Lapointe’s model.
Lapointe’s main contention is that the calcareous green alga
Halimeda was the most important sand-producing organism at Negril,
producing some 80 per cent of the beach sand, and that Halimeda
production has seriously declined due to “overrunning” by fleshy green algae
over the last 10 years. We have analysed beach samples from Negril that we
collected in 1999 and compared them with beach samples collected by Malcomb
Hendry in 1980. We studied both sets of samples to eliminate errors from
different counting techniques.
Our results show that in fact, there has been a slight increase in the
proportion of Halimeda (from 13.2 per cent to 13.9 per cent of skeletal
grains, or from 6.2 per cent to 7.7 per cent of all sand grains) in beach sand
from 1980 to 1999. Clearly, Halimeda was never an important carbonate
sand producer at Negril, and beach erosion cannot be blamed on its displacement
by fleshy green algae.
While Lapointe’s team has demonstrated that increased nutrient levels may
have caused severe damage to the coral reef at Negril, where there has been a
great increase in fleshy green algae, their hypothesis linking a decline in
Halimeda production to beach erosion is untenable.