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Reply To Telephone Query
Risks to School Kids?
Parents and Citizens Association An Inner-Sydney
Primary School
27 Aug 93
Dear Sir,
Further to your query seeking advice on the best
plan of action for ascertaining whether 5-7 year old children at your
child's school are at risk of high blood lead levels due to possible
lead contamination, provide the following.
The available evidence is that:-
-
the school is situated on the corner of two
busy roads;
-
there may be paint which needs attending to and
that it may be leaded paint;
-
one child's blood lead level doubled after they
attended the school whilst "all other lead exposure risk
factors in the child's life remained unchanged". (I understand
that the higher of the two blood lead results for this child was
approximately 12 months after the first blood lead result and was
below the new Australian blood lead target of 10 µg/dL);
-
and that soil samples collected by a parent in
the school grounds found up to 1000 parts per million (ppm) lead.
The NSW Environment Protection Authority (NSW EPA)
and the Australian and New Zealand Conservation Council (ANZECC) both
advise "further investigation" wherever soil lead is found to
exceed 300 ppm, but they set no level for lead in either soil or dust,
at which any particular action should take place. Possible actions
include replacement with imported "clean" topsoil, paving or
artificial grassing, maintaining good grass cover over contaminated
areas, etc. No matter what the source of the lead contamination, ,the
owner of the property is nearly always responsible for the cost of both
assessment and remediation or abatement.
To answer the question: "Does blood lead level
correlate with period of attendance at the school, at least in the age
range of 5-7 years?", you could consider biokinetic modelling of
the school situation. The accuracy of the prediction of the mean blood
lead level, the median, the mode and the range of blood lead levels, in
the biokinetic modelling, would of course be highly dependent on the
accuracy of the estimates or actual measurements of the levels of lead
contamination in the various media which impinge on children's blood
lead levels, ie, lead in soil, dust, paint, air (both indoor and
outdoor), food, water, mother's blood. The assumptions upon which the
various estimates of these environmental levels are based, would be very
much open to criticism. Dr Bruce Markey at the NSW EPA Chatswood office,
who has much experience with mathematical modelling, is willing to run
the biokinetic model produced by the US Environmental Protection Agency.
You would need to investigate whether the model can take into account
time spent in a common environment (the school) and time spent in more
variable environments (the homes). This approach may greatly please the
children. Because of the possibility that the most significant source of
lead at your school is lead from vehicle exhausts, it would be advisable
for you to have a more accurate assessment of lead in air (both indoor
and outdoor) than is available from the data collected by the NSW EPA.
The EPA has placed 5 air monitors around Sydney in order to assess
ambient air lead as experienced by the majority of the population.
Therefore, the air lead figures obtained do not reflect air lead levels
as experienced by people who spend all or some significant proportion of
their time near a busy road. Some preliminary air lead measurements in
Sydney, have found actual roadside air lead levels up to three times
higher than the recommended air lead guideline, whilst the five EPA
monitors rarely find exceedances of the guideline. Apparently, a company
called Amdel can hire out air lead monitors (phone 9906 2311).
It is important to keep in mind that a high blood
lead level arises, logically, only when the following three conditions
occur simultaneously: firstly, significant environmental lead
contamination; secondly, individual behaviours which allow a significant
quantity of that lead to be ingested (eg unsafe renovation with children
or women present, not washing hands before eating or hand to mouth
activity); and thirdly, individual factors which allow a significant
percentage of the ingested lead to be absorbed into the blood stream (eg
iron deficiency or having an empty stomach). See 'Reducing Personal Lead
Exposures" by William Marcus, in FASE Research Report, Winter 1993,
and "Gastro-Intestinal Absorption of Lead in Children and
Adults" by Paul Mushak, in Chemical Speciation and Bioavailability,
3(314) 1991 pp 87-103 - copies available from our lead library. [The
Mushak article refers to a study in which human volunteers were fed
labelled lead at various times in relation to meals. When taken with the
meal, 5% of the labelled lead was absorbed. This figure rose to 62% when
the labelled lead was ingested 12 hours after a meal.]
It is because the second and third conditions (see
above) vary greatly between individuals, that biokinetic modelling
predicts the whole graph of blood lead level versus number of children,
and cannot be used to accurately predict an individual child's blood
lead level.
A final alternative and possibly the best for your
infants school at least, is to act as though lead were a problem (the
precautionary principle) while avoiding all the costs of ascertaining
the extent of the problem. Actions would include things like:
-
washing hands with soap and water before eating
and after outdoor play (Stickers and a poster which encourage this
and other lead-aware behaviours are available from the Public Health
Unit for Central and Sthn Sydney {ph. 95569322}); • covering the
sandpit when not in use and always replenishing it with new sand
(never tossing back what gets tossed out);
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vacuuming carpets after children have gone home
and wet-mopping (not sweeping) or wet wiping (not dusting) all hard
surfaces before children arrive in the morning;
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having carpets regularly cleaned (three
monthly) by a company which can remove the lead;
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attending to any flaking, peeling or chalking
old paint in the school which may be leaded;
-
cutting down the track-in of dust by placing
washable and effective dust collecting mats at the door and
encouraging people to wipe their feet;
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covering by paving, grassing etc, all bare
ground in the school yard;
-
paying particular attention to nutrition and
hygiene education (for both children and parents) noting that empty
stomachs absorb more lead, fingernails should be kept short, etc.;
-
teaching children about lead (they could do a
survey of how children get to school and whether car use could be
reduced for this or other purposes by their families, they could
survey car drivers to ask whether they've checked for their car on
the list of cars which can use unleaded petrol, etc.).
-
planting more evergreen trees or placing
another barrier between the cars and the children (taking into
account that lead is not the only environmental health problem
related to vehicular traffic - there is also CO, NOx,
benzene, et al emissions and noise pollution).
I trust the above information is useful to you and
your P&C. Publication of any or all of the above in the school
newsletter, if it does nothing else, will at least raise awareness of
the lead issue amongst the parents and hopefully get them asking things
like, "How do you renovate safely?", "Can my car run on
unleaded petrol?" or "Would the time and efforts of the
members of the P&C be best spent demanding an early phase-out date
for leaded petrol from the state government?". Best current
predictions are that our children, ourselves and our environment will be
subjected to 11 more years of lead from vehicle exhausts, while in NZ
the government has committed itself to a total phase-out of leaded
petrol in three years time and they haven't added lead to petrol in
Canada or Japan for at least the last three years.
Elizabeth O'Brien
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