LEAD Action News Vol
1 no 3 Spring 1993 ISSN 1324-6011
Reply To Telephone Query
Risks to School Kids?
Parents and Citizens Association An Inner-Sydney
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 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:
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.
system lead poisoning |
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