Nitrates that poison newborns come from manure dumped on soil
Chemists have pinpointed the source of nitrates that are contaminating water in the Gaza strip and could be poisoning many newborn babies in the region.
Karsten Osenbr?ck, of the Helmholtz Centre for Environmental Research in Germany, and colleagues have shown that Gazan groundwater contains levels of nitrate (NO3-) ions up to eight times higher than the World Heath Organization’s (WHO)’s safe standards.
Alarmingly, unpublished studies conducted by Basem Shomar, from the Institute of Environmental Geochemistry in Heidelberg, suggest a 50 per cent incidence rate of methemoglobinemia in the region’s newborns. The disorder - which cuts down the amount of oxygen blood can carry, and leads to blue skin, diarrhoea, vomiting, and sometimes death - is known to be triggered by nitrate-contaminated water.
’Our findings show that the majority of nitrate contamination comes from organic waste, being either human or animal manure [which is used as fertiliser],’ says Osenbr?ck. ’This result is something that previous reports on the issue of groundwater contamination have failed to conclusively prove.’
The researchers analysed water samples from 165 groundwater wells, across the central Gaza Strip, over a period of six years. They measured nitrate concentrations, and used mass spectrometry to determine the levels of nitrogen (15N) and oxygen (17O) isotopes. By comparing this field data with isotopic levels in samples of three common pollutants - synthetic fertiliser, sewage sludge and animal/human waste - the German researchers pinpointed the source of the contamination. It likely stems from the over-use of organic manure on infertile soil, and is accentuated by the soil’s high permeability, the researchers say.
In a global context, the reported levels of nitrate contamination in the groundwater of Gaza are worrying but not exceptional, says Marianne Stuart of the British Geological Survey, who is to carry out a similar survey in the region.
’In a recent study of groundwater contamination in Malta, nitrate levels as high as eight times that of the WHO’s safe standard were recorded.’ She added: ’In the case of Malta however, the comparatively healthy economy meant authorities have been able to avoid using the most heavily contaminated sources, by importing clean water supplies from abroad, or investing in desalination plants.’
As a comparison, levels of nitrate contamination in UK water supplies are at worst two times the WHO standard.
’We are planning to study the correlation between the disease and nitrate levels of the drinking water, as well as other nitrate sources in the diet,’ adds Shomar. ’Dependent on funding, the study could be done in two to three months.’
Shomar stresses that whatever the outcome of the study, simple measures such as drinking bottled water and installing home filters, should be taken wherever possible to minimise the risk of drinking contaminated water.
Palestinian authorities are yet to comment on the report, though they have previously acknowledged the problem. Since much of the groundwater in Gaza originates in Israel, tackling the issue is largely beyond Palestinian control. Any long-term solution to the problem, the researchers agree, can only come from comprehensive groundwater management schemes operated both regionally and bilaterally with Israel. And given the political instability of the region, this solution is low on politicians’ priority lists.
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et al, Sci. Total Environ.,398, 164 (DOI:10.1016/j.scitotenv.2008.02.054)