Chlorination byproducts

1
Chlorination by-products reproductive health
effects
Nina Iszatt, Mireille Toledano, James Bennett,
Mark Nieuwenhuijsen1, Nicky Best, David Briggs ,
Paul Elliott Department of Epidemiology and
Public Health 1CREAL, Barcelona

• Imperial College is conducting a large
• research programme on disinfection by-
• products and health
• Small Area Health Statistics Unit (SAHSU) studies
  with 12 water utilities in England and Wales
  (Figure 1)
• Born-in-Bradford birth cohort
• Chemicals and pregnancy study of male infertility
  and occupational exposure to chemicals (CHAPS-UK)
• Health impacts of long-term exposure to
  disinfection by-products in drinking water
  (HiWATE)
• Integrated assessment of health risks and
  environmental stressors in Europe (INTARESE)

• Combining individual and area-level
• information
• Developing innovative Bayesian methods for
  combining multiple Individual and aggregate data
  sources in observational studies (BIAS, an ESRC
  National Centre for Research Methods project,
  based at Imperial College).
• Individual data from the Millennium Cohort Study
  and National Birth Registry are combined with
  area-level measures of THM exposure and
  socio-economic and demographic indicators
  (Molitor et al. 2008).
• Individual tap water exposure data from Born in
  Bradford cohort study will be combined with
  modelled area-level DBP concentrations to
  generate semi-individual DBP exposure estimates
  for each woman in the cohort.

• Validating exposure assessment
• Nested validation study of exposure to DBPs,
  using a 7-day water exposure diary (Figure 4) and
  a urinary biomarker (for TCAA) in a subset of the
  Born in Bradford cohort. Information will
  validate water use reported by questionnaire for
  all 10,000 cohort members. Allows improvement of
  model specification, validation of exposure
  modelling (reducing exposure misclassification),
  to reduce bias and hence improve inference.

• European research from epidemiology to public
  health
• policy
• HiWATE
• An EU funded programme with partner institutions
  in 13 countries. Imperial is
• leading on
• Water sampling programme with 4 water companies
  in the UK
• Modelling DBP precursors and concentrations to
  create predictive models of DBP formation for
  exposure assessment in epidemiological studies
• Epidemiological study using the CHAPS-UK
  case-control study to investigate the
  relationship between THMs and semen quality
• Epidemiological studies on DBPs and stillbirth
  and low birth weight (i) using the new
  prospective Born in Bradford cohort (ii)
  before and after (i.e., natural experiment)
  design to compare changes in rates over time in
  areas with and without a change of water
  treatment and corresponding THM concentrations
• Risk-benefit assessment comparing the risk of
  microbial infection with the risks of
  chlorination
• Policy recommendations for the Drinking Water
  Directive
• INTARESE
• Integrated approaches to the assessment of
  environmental health risks
• Assessing bladder cancer and selected
  reproductive health risks posed by DBPs and
  quantifying disability-adjusted life years
  (DALYs).

• Pioneering research in the UK
• Bayesian mixture modelling of routinely collected
  data on trihalomethanes (THMs) to provide water
  supply zone estimates, which are used to assign
  exposure levels to individuals, taking advantage
  of large between- relative to within-zone
  variability in concentrations of disinfection
  by-products (Whitaker et al. 2005).
• SAHSU uses geographical information systems (GIS)
  to link registry health data and THM data to
  assign exposure and health data to individuals in
  a semi-ecological design (Figure 2).
• National studies using modelled THM data and
  linked to registry data on adverse birth outcomes
  exploring the relationship between THM
  concentrations in drinking water and risk of
  stillbirth, low birth weight and congenital
  anomalies (Toledano et al. 2005, Nieuwenhuijsen
  et al. 2008).

• References
• Molitor J, Jackson C, Richardson S, Best N. Using
  Bayesian Graphical models to model biases in
  observational studies and to combine multiple
  data sources Application to low birth-weight and
  water disinfection by-products. JRSS A. In press.
• Nieuwenhuijsen MJ, Toledano MB, Bennett J, Best
  N, Hambly P, de Hoogh C, Wellesley D, Boyd PA,
  Abramsky L, Dattani N, Fawell J, Briggs D, Jarup
  L, Elliott P. Chlorination Disinfection
  By-products and Risk of Congenital Anomalies in
  England and Wales. Environ Health Perspect 2008
  116(2) 216-222.
• Toledano MB, Nieuwenhuijsen MJ, Best N, Whitaker
  H, Hambly P, de Hoogh C, Fawell J, Jarup L and
  Elliott P. Relation of Trihalomethane
  Concentrations in Public Water Supplies to
  Stillbirth and Birth Weight in Three Water
  Regions in England. Environ Health Perspect
  2005113225-32.
• Whitaker H, Best N, Nieuwenhuijsen MJ, Wakefield
  J, Fawell J, Elliott P. Modelling exposure to
  disinfection by-products in drinking water for an
  epidemiological study of adverse birth outcomes.
  J Expo Anal Environ Epidemiol.200515138-46.