NITRATE IN DRINKING WATER AND
CHILDHOOD-ONSET INSULIN-DEPENDENT DIABETES MELLITUS IN SCOTLAND AND
Nitrate In Drinking Water And
Childhood-Onset Insulin-Dependent Diabetes Mellitus In Scotland And
aim of the study was to determine whether geographical variation in the
incidence of childhood-onset diabetes was associated with levels of
nitrate in drinking water.
registers were the source of cases of childhood diabetes occurring
between 1990 and 1996 and nitrate sample data were supplied by the
water companies for relevant water supply zones for 1990-1996.
of the population exposure to nitrate were taken as the mean of the
monthly mean nitrate levels in 594 water supply zones. Mean nitrate
levels were ten times higher in the English study area
(22.94 mg l-1) than Scotland
with a wider range and more variability. Nitrate levels are dependent
on water source and catchment area. The EC maximum acceptable
concentration for nitrate in drinking water is 50mg l-1.
ecological analysis was conducted in the former Oxfordshire Regional
and Leicestershire District health authorities, all of Scotland and all
areas combined. Factors were examined separately followed by
multivariate modelling which accounted for the demographic factors
associated with childhood diabetes i.e. socio-economic status,
migration and ethnicity.
both the Scottish and English study areas there was no significant
geographical variation of diabetes incidence. No significant
associations were observed between diabetes incidence and nitrate in
drinking water when unadjusted by the demographic factors.
modelling of the English data, adjusting for all factors, showed no
association with childhood diabetes at the highest nitrate levels.
There was no evidence of a ‘dose response’ between
increasing levels of nitrate and childhood diabetes. However, a
significantly raised risk of childhood diabetes was restricted to areas
with medium levels of nitrate (16.7-22.2 mg/l). There is no apparent
biologically plausible explanation for this observation which may
represent a confounding effect.
adjusting for the three demographic variables in Scotland and the
larger combined study area data set no significant risks were
identified for childhood diabetes and nitrate levels in drinking water.
conclusion, the overall findings from this ecological analysis do not
provide evidence of any consistent or plausible associations between
childhood diabetes and levels of nitrate in drinking water in the
geographical areas of study.
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