Exposures to Environmental Agents and Preterm Delivery - PowerPoint PPT Presentation

Loading...

PPT – Exposures to Environmental Agents and Preterm Delivery PowerPoint presentation | free to view - id: 98e4f-MDg1Y



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Exposures to Environmental Agents and Preterm Delivery

Description:

... DDE, arsenic, cadmium, lead, occupation, disinfection byproducts, video, etc. ... Specific occupations/occupational exposures ... – PowerPoint PPT presentation

Number of Views:33
Avg rating:3.0/5.0
Slides: 24
Provided by: LONG85
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Exposures to Environmental Agents and Preterm Delivery


1
Exposures to Environmental Agents and Preterm
Delivery
  • Matthew P. Longnecker, MD, ScD
  • NIEHS Epidemiology Branch
  • (National Institute of Environmental Health
    Sciences)

2
Overview of presentation
  • Scope of review
  • Method of review
  • Potential Risk Factors (order nonspecific?
    specific)
  • Occupational
  • Air pollutants
  • DDE, the metabolite of DDT
  • Potential risk factors (with less supporting
    data)
  • Things that appear not to be risk factors
  • Discussion

3
Scope Environmental Agents and Preterm Delivery
  • Focused on risk factors for preterm delivery
  • Risk factors for other reproductive outcomes
    can be different than for preterm birth
    and are not covered in this review
  • Environmental agents considered are
  • Non-biologic foreign substances (or radiation)
    to which exposure was unintentional

4
Method of Identifying Reports
  • Searched MEDLINE database using PubMed
  • Key word preterm or Labor, PrematureMESH
    and ltexposuregt, where exposure was
  • environmental, air pollution, DDE, arsenic,
    cadmium, lead, occupation, disinfection
    byproducts, video, etc.
  • Reviewed reference lists
    to identify everything
    relevant
  • Re-expressed results as needed
    to increase comparability of
    results across studies

5
Potential Risk Factors1Occupational Exposures
  • Many associated with preterm birth in 1 study
  • Criteria for presentation here
  • If
    RR gt 1.5 or
    statistically significant
    and
  • reported in 2 or more studies

6
Occupations/occupational exposures that met
criteria
  • Maternal occupations
  • Metal, electrical, janitorial, food service,
    textiles
  • Maternal occupational exposures
  • Solvents
  • Paternal occupations
  • Food service, textiles
  • Paternal occupational exposures
  • Pesticides (e.g., atrazine in one study)

7
Maternal food service work and preterm
birth (an example)
8
Potential Risk Factors1Occupational Exposures,
cont.
  • Example demonstrates features of occupational
    data
  • Associations neither strong nor consistent
  • Exposure data vague or imprecise
  • e.g., job categories vary across studies
  • Associations with paternal occupation stronger
    and more numerous than those for maternal
    occupation in several studies
  • Among possible explanations is a male-mediated
    effect

9
Potential Risk Factors2Air Pollutants and
Preterm Birth
  • Two types
  • Tobacco smoke pollution (passive smoking)
  • Traditional air pollutants (e.g., particulates,
    SO2)

10
Potential Risk Factors2a Tobacco Smoke Pollution
N.B. Ahluwalia and Windham RRs gt among older
mothers
11
Potential Risk Factors2bTraditional Air
Pollutants
  • 3 studies with ecologic-time series designs
  • Limited of air monitoring stations (n2-67)
  • Little person-level data
  • ? Preterm delivery associated with ? SO2
    (Xu, 1995 Bobak, 2000)
  • Consistent ? with suspended particulates

12
Relative Risk of Preterm Birthper 50 ?g/m3
Suspended Particulates
13
Potential Risk Factors2bTraditional Air
Pollutants, cont.
  • Subtle associations with preterm birth detected
    within the range of exposure seen in the U.S.
  • U.S. data on SO2 lacking
  • Collecting better data will be a challenge
  • Individual-level measurements expensive
  • Limited data indicate air pollution also related
    to infant mortality (see Brunekreef, 1999)

14
Potential Risk Factors3DDE, the metabolite of
DDT
  • DDT used for malaria control in 25 countries
  • DDE, the metabolite of DDT, is ubiquitous
  • U.S. serum levels 5 of those in malaria areas
  • Exposures in the U.S. used to be much higher
  • Recent study of U.S. women from the 1960s, done
    using stored sera,
    showed ? risk of preterm birth with DDE

15
Odds ratios for preterm birth
Trend p lt 0.0001
Longnecker et al. Lancet 2001358110-4.
16
Potential Risk Factors3DDE, the metabolite of
DDT, cont.
  • Other published data consistent but were from
    studies in populations with lower exposure
  • If effect real, relevant only to countries using
    DDT
  • If effect real, what else might we have
    overlooked?
  • knowledge of DDE mechanism would guide

17
Potential Risk FactorsWith Less Supporting Data
  • PCBs (polychlorinated biphenyls)
  • Various other chemical exposures
  • Occupational, e.g., ethylene oxide, polyvinyl
    alcohol
  • Groundwater nitrate
  • Metals
  • Arsenic
  • Cadmium
  • Lead (both maternal and paternal)

18
Maternal lead and preterm birthbest large
studies--data summary
19
Things that appear not to be risk factors
  • chlorinated water disinfection byproducts
  • use of video display terminals

20
Discussion--1
  • None of the factors presented are established
    as related to risk of preterm delivery
  • Instead is a list of suspected agents

21
Discussion2Risk factors for preterm birth?
  • Specific occupations/occupational exposures
  • metal, electric, janitor, food, textiles,
    solvents, pesticides
  • Air pollution
  • Environmental tobacco smoke
  • Particulates
  • DDT use
  • relevant for 25 countries

22
Discussion--3
  • What might have been missed by this review?
  • Agents implicated for other reproductive
    outcomes, but not studied with respect to preterm
  • mycotoxins, dusts, mercury, ethylene glycol
    ethers
  • Agents implicated by animal studies
  • Agents with subtle effects

23
Discussion--4
  • Implications for research priorities
  • One approach study suspected agents
    with the highest
    prevalence of exposure
  • Air pollution
  • Food service work
  • Paternal pesticide exposure
  • Knowledge of toxic mechanism in humans
    could guide selection of agents to study
About PowerShow.com