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Australian Drinking Water Guidelines: Draft fact sheet on lanthanum submission

ID: 
7
This submission reflects the views of
Organisation Name: 
Dept of Health WA
Personal Details
Consultation Questions
1. Is the information provided relevant and clear?: 
Yes, the information provided is relevant and clear.
2. Are there any issues in relation to the safety of lanthanum in drinking water that you feel have been omitted?: 
Please refer to question 3
3. Do you have any general comments on the draft fact sheet?: 
A number of editorial suggestions are proposed: ##################################################### TYPICAL VALUES IN AUSTRALIAN DRINKING WATER Re: “Australian drinking water supplies have not been routinely monitored for lanthanum. Regular monitoring of Australian drinking water reservoirs is recommended if they have been subject to the addition of a lanthanum-based water treatment product, such as PhoslockTM (NICNAS, 2014).” The fact sheet states that lanthanum “can enter water via run-off from agricultural soil where it has been used as fertiliser” … and “from leaching from the tailings of rare earth mining”, as well as from Phoslock as a source. Therefore, your advice in this section about regular monitoring being required should also apply to drinking water reservoirs subject to these other sources of lanthanum or located in or hydrologically downstream of an area rich in lanthanum bearing ores, as may occur (for example) in Western Australia. At the moment, the advice about monitoring is heavily biased towards Phoslock as being the predominant source of lanthanum. Please insert a sentence to that effect. ###################################################### Re: “There is uncertainty on the cumulative effect of lanthanum concentrations from dosing a body of water over a number of years.” In the absence of a published citation, this sentence, as currently worded, adds little to no useful information to the fact sheet, or to our understanding of the effect of lanthanum generally, and reads as speculation. Suggest deletion, or adding cited text to provide more useful information here, or rewording along the lines about what is the basis for concerns about long-term accumulation of lanthanum in surface reservoirs where products like Phoslock are used. In any event, a sentence on this aspect is out of place in a section headed “Typical Values In Australian Drinking Water”, so if you wish to retain it it is better moved to under “Health Considerations”. ##################################################### TREATMENT OF DRINKING WATER Re: "There are no published methods for the removal of lanthanum from drinking water." As an observation, similar comments are made for the fact sheets for molybdenum, bromate and antimony and their meaning is not clear. Suggest you clarify what you mean by this exactly, as it appears to imply that it can not be removed, even by reverse osmosis. As a (self-described) authoritative document, ADWG should be in a position to state specifically which treatment processes, such as RO, can or can not remove lanthanum (or molybdenum, bromate and antimony), regardless of whether there is or is not a published method, or state that "There are no published methods for the removal of lanthanum from drinking water. Water suppliers needing to remove lanthanum from drinking water are therefore advised to ..." Re: “The insoluble forms of lanthanum are not likely to persist in the water body since removal of these compounds can be achieved by sedimentation or other physical treatment processes.” In the absence of a published citation, in the absence of an explanation of what “water body” specifically means in this context, and in the absence of caveats that individual lakes or surface reservoirs may exhibit their own unique behaviours, this sentence reads as speculation or a generalisation and consequently is unsuitable for a reference document. This sentence could be mistakenly interpreted as extending to some environmental water bodies and surface catchment reservoirs where there is not necessarily a sediment removal process and the lanthanum remains available to re-solubilise. Furthermore, it appears to be irrelevant anyway. The fact sheet makes clear that lanthanum toxicity in the main derives from soluble forms of lanthanum, so stating that insoluble forms are not likely to persist is of no practical use to water suppliers. Please insert a sentence as to the persistence of the more harmful soluble forms of lanthanum, which appears to be the main area of interest here. Suggest deletion or citation with the published source of this information. As the fact sheet identifies Phoslock as a lanthanum-based water treatment product under this subsection, it is worth adding to this section a sentence explaining that water suppliers and other water body managers should refer to the NICNAS 2014 reference for detailed advice about the suitable use of products such as Phoslock for water treatment AND THAT such products are only suitable in the raw or source water part of the delivery chain. ##################################################### MEASUREMENT Re: “The concentration of lanthanum in water samples can be determined by inductively coupled plasma mass spectroscopy.” The advice we have received is that lanthanum can be analysed by both ICPAES method (reporting limit 0.005 mg/L) and ICPMS method (reporting limit 0.0001 mg/L) as part of a metal suite. Given that the proposed guideline value is 0.002 mg/L, a comment could be added explaining why the inductively coupled plasma mass spectroscopy (ICPMS) is preferred. The purpose is to remind water suppliers that, if they need to test for lanthanum, the analytical method requires an LOR at or below one tenth of the health-related guideline value, hence the ICPMS method. Suggest specifically adding that the ICPAES method, with a reporting limit of 0.005 mg/L, is not suitable as its results are likely to be indeterminate unless the lanthanum result is well over the guideline value. ##################################################### DERIVATION OF GUIDELINE The last paragraph includes the sentence: “These toxicological studies have been performed using an insoluble lanthanum salt and such insoluble forms may be in potable water sources to variable extents, and included in the total lanthanum analytical measurement.” Suggest changing “potable” to “drinking” in that sentence. The reason is that “drinking water” is the term preferentially used in ADWG to describe drinking water, not “potable water” and ADWG should really be consistent in this. The 1170 page entirety of ADWG uses the term “drinking” many thousands of times yet uses the term “potable” a mere 11 times only, so there is really no benefit in using “potable water” in this fact sheet when “drinking water” is preferred.

Page reviewed: 17 October, 2017