Breast Cancer and Environmental Chemicals: Why is there Concern - PowerPoint PPT Presentation

Loading...

PPT – Breast Cancer and Environmental Chemicals: Why is there Concern PowerPoint presentation | free to download - id: fe4f-NjQ0M



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Breast Cancer and Environmental Chemicals: Why is there Concern

Description:

Why is there a concern about environmental links to breast cancer risk? ... Breast cancer risk is higher in women who worked the 'grave yard' shift for many ... – PowerPoint PPT presentation

Number of Views:95
Avg rating:3.0/5.0
Slides: 35
Provided by: jeffreys89
Category:

less

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

Title: Breast Cancer and Environmental Chemicals: Why is there Concern


1
Breast Cancer and Environmental Chemicals Why
is there Concern?
  • Suzanne Snedeker, Ph.D.
  • Associate Director of Translational Research
  • Cornell University Sprecher Institute for
  • Comparative Cancer Research
  • Program on Breast Cancer and Environmental
    Factors (BCERF)
  • http//envirocancer.cornell.edu

2
Lesson Outline
  • Why is there a concern about environmental links
    to breast cancer risk?
  • Which chemicals in the workplace and home are
    associated with increased risks of breast cancer?
  • What do we know about pesticides and breast
    cancer risk?
  • What can we learn from animal cancer bioassays?
  • What is known about endocrine disrupting
    chemicals?
  • What are the challenges do we face in evaluating
    linkages between environmental chemicals and
    cancer risk?

3
How does cancer occur?
Initiated cell
Invasive Tumor
4
Risks Related to Breast Cancer
Close Relative
Advancing Age
Genetics
Gender
Age at First Birth
Early Menarche
Passive Smoke
Late Menopause
Diet
Overweight
Lack of Exercise
Chemicals -Work -Home -Garden -Recreation
Ionizing Radiation
Hormone Replacement Therapy
Benign Breast Disease
Alcohol
???
5
Exposure to Hormones
Late Menopause
Some Chemicals -Work -Home -Garden
-Recreation
Lack of Exercise
6
Breast cancer rates worldwide
7
Environmental links to breast cancer
Scandinavian Twins Study
  • Contribution of inherited vs. environmental
    factors to breast cancer risk
  • Inherited factors, 27 of risk
  • Environmental factors, 73 of risk
  • Suggests environmental factors play a
  • major role in determining breast cancer risk
  • Ref Lichtenstein et al., N. Engl. J. Med.,
    34378-85, 2000

8
How are we exposed to environmental
chemicals?
  • Routes of exposure
  • Air we breath
  • Food we eat beverages we drink
  • Contact with our skin
  • Contact with eyes
  • Some chemicals cross the placenta
  • Some can appear in breast milk

9
Exposure to environmental chemicals
  • Each chemical is unique
  • Some can be stored in body fat
  • Others quickly eliminated
  • Some need to activated by the body
  • Others are quickly detoxified
  • Some pose no cancer risk
  • Some are potent carcinogens
  • Others may be hormone mimics and support breast
    tumor growth
  • Some may act as anti-cancer agents

10
Chemicals in the workplace problems with many
studies
  • Few high quality cancer studies of women in the
    workplace
  • Many studies very small
  • Follow-up time often too short
  • Records of actual exposures often lacking
  • Methods for estimating exposures often crude
  • Frequently have exposures to multiple chemicals

11
Chemicals in the workplace what do we know?
  • Some evidence of higher breast cancer risk
  • Acid mists
  • Benzene
  • Carbon tetrachloride
  • Ethylene Oxide
  • Formaldehyde
  • Lead oxide
  • Methylene chloride
  • Styrene

Refs Blair and Kazerouni, Cancer Causes
Control, 8473-490, 1997 Cantor et al., J.
Occup. Environ. Med., 37336-348, 1995 Goldberg
and Labreche, Occup. Environ. Med., 53145-156,
1996 Hansen, Am. J. Ind. Med., 3643-47,
1999 Norman et al., Int. J. Epidemiology,
24276-284, 1995 Spiritas et al., Br. J. Ind.
Med., 48515-530, 1991
12
Chemicals in the workplace -light at night
  • Light at night
  • May disrupt the synthesis of the hormone
    melatonin
  • Changes in melatonin may affect levels of
    estrogen
  • Breast cancer risk is higher in women who worked
    the grave yard shift for many years
  • Refs Steven and Rea, Cancer Causes Control,
    12279-287, 2001
  • Davis et al., JNCI, 9315571562, 2001
  • Hansen et al., Epidemiology, 1274-77, 2001
  • Schernhammer et al, JNCI, 931563-1568, 2001

13
Chemicals in the workplace what do we need to
know?
  • Workers that need further evaluation
  • Chemical manufacturing workers
  • Pharmaceutical industry workers
  • Laboratory and biomedical workers
  • Cosmetologists and hairdressers
  • Printers and dye workers
  • Health care workers
  • Metal plate workers
  • Airline personnel

14
Chemicals in the home what are we exposed to?
  • Cape Cod Breast Study
  • Silent Spring Institute
  • Measured household exposures to 89 hormone-like
    and cancer-causing chemicals in air and dust
    samples of 120 Cape Cod homes
  • Chemicals identified included plasticizers,
    disinfectants, certain flame retardants,
    persistent organochlorine pesticides and
    contemporary (permethrin) pesticides
  • Exposure is one step in the risk assessment
    process
  • Results will help prioritize chemicals that
    should be studied further
  • Refs Rudel et al., J. Air Waste Manage.
    Assoc. 51499-513, 2001
  • Rudel et al., Environ. Science and
    Technol., 374543-53, 2003

15
Pesticides and cancer risk exposure concerns
16
U.S. Conventional Pesticide Use historical
trends1964-1996
Ref Aspelin and Grub, Pesticide industry sales
and usage, 1996 and 1997 market estimates, Figure
10.b, US EPA, November 1999.
17
Pesticides and cancer risk why is there concern?
  • Higher cancer risk in male farmers
  • Lip
  • Skin
  • Stomach
  • Brain
  • Lymphoma
  • Prostate
  • Ref Blair and Zahm, Environ. Health Perspect.
    103 (Suppl 8)205-208, 1995

18
Pesticides and cancer risk cancer risks on the
farm
  • Environmental exposures on the farm
  • Sunlight / UV radiation
  • Nitrates
  • Pesticides
  • Solvents
  • Fuel exhaust
  • Mycotoxins (toxins formed by mold on crops some
    are cancer-causing)

19
Pesticides and cancer risk cancer risks on the
farm
  • Agricultural Health Study
  • Evaluating health effects of agricultural
    chemicals in a 10 year, prospective study
  • 55,300 men and 30,000 women
  • Cancer risks
  • Prostate cancer risk elevated 14 in male
    pesticide applicators
  • http//aghealth.org/index.html
  • Ref Alavanja et al., Am. J. Epidemiology, vol.
    157, pp. 800-814, 2003

20
Breast cancer risk of farm women
  • Few studies on cancer risks of farm women most
    studies on men
  • North Carolina Study
  • Overall, breast cancer rates lower in women
    living on or near farms
  • In farm women who applied pesticides, breast
    cancer risk 2X higher if protective clothing or
    gloves not worn
  • Reducing exposure reduces risk
  • Ref Duell et al., Epidemiology, 11523-531, 2000

21
Pesticides and breast cancer risk
-organochlorine (OC) pesticides
  • DDT and DDE
  • Early descriptive studies suggested a positive
    association between blood or adipose tissue DDE
    levels and breast cancer risk
  • Over 20 of the recent, well controlled,
    large-scale studies have not shown that levels of
    DDT or DDE predict breast cancer risk in North
    American or European white women

22
Pesticides and breast cancer risk DDT/DDE
possible explanations
  • Exposure Issues - Chemical form matters
  • Predominant exposure in western white women
  • Was not to estrogenic form that was sprayed
    (o,p-DDT)
  • But to very weak estrogenic form (p,p-DDE) in
    food
  • Heavily exposed populations less studied
  • Few studies of breast cancer risk in countries
    that currently use DDT (estrogenic form) for
    malaria control
  • Critical windows of exposure
  • Little information on whether exposure to DDT
    during early breast development affects breast
    cancer risk
  • Ref Snedeker, Environ. Health Perspect., 109
    (suppl 1) 3547, 2001

23
Chemicals and breast cancer risk laboratory
animal studies
  • Why use laboratory animal studies?
  • Human studies have the most weight when
    evaluating cancer risk
  • For most chemicals we have no information on
    human exposures and later cancer risk
  • Use controlled animal laboratory studies to
  • Identify the hazard
  • Estimate cancer risks to humans
  • National Toxicology Program Animal
    cancer bioassays
  • Of 509 chemicals tested, 42 (8) cause mammary
    (breast) tumors in laboratory animals

24
Chemicals and breast cancer risk National
Toxicology Program
  • Types of compounds that cause mammary (breast)
    tumors in laboratory animals
  • Organic solvents
  • Dyes and dye intermediates
  • Chemicals used in manufacture of rubber,
    neoprene, vinyl and polyurethane foams
  • Flame retardants
  • Food additive
  • Gasoline additives / lead scavengers
  • Metals use in microelectronics
  • Medical instrument sterilizing agent
  • Mycotoxin (toxin produced by a type of mold)
  • Pesticides and fumigants
  • Pharmaceuticals
  • Rocket fuel

Refs Dunnick et al., Carcinogenesis, 16173-170,
1995 Bennett and Davis, Environ. Mol. Mutagen.
39150-157, 2002
25
EnviroChem and Cancer Database
http//environcancer.cornell.edu/chemstart.cfm
  • On-line Information on 42 chemicals that cause
    mammary gland tumors in laboratory animals in NTP
    bioassays
  • Searchable by chemical name, CAS , or major use
  • http//envirocancer.cornell.edu/ECCD/chemsearch.cf
    m
  • Includes information on the chemicals
  • Major uses
  • Cancer classification
  • Whether the chemical is currently produced
  • If / when it was taken off the market
  • Use in manufacturing processes
  • Consumer products
  • Exposures of concern
  • Overview of workplace regulations and advisories
    by OSHA

26
Endocrine disrupting chemicals (Hormonally
Active Agents)
  • We know that many hormones and local growth
    factors play a role both in normal breast growth
    and in the cancer process
  • Hormones (chemical messengers)
  • Estrogen
  • Progesterone
  • Prolactin
  • Growth Hormone
  • Growth Factors (local chemical messengers)
  • Epidermal Growth Factor family
  • Insulin Growth Factor (IGFs)

27
Endocrine disrupting chemicals Whats the
evidence?
  • What we know
  • Pharmaceuticals that act like estrogen or
    estrogen / progesterone (E P) can increase
    breast cancer risk
  • Diethylstilbestrol
  • Prescribed to 5 to10 million women
  • In mothers - moderate increase in BC risk
  • In daughters - data not in yet
  • E P post-menopausal hormone therapy
  • Risk increases with duration of use
  • Small risk (8 cases per 10,000), but widely
    prescribed
  • May increase risk of more aggressive tumors

http//www.desaction.org/ http//www.cdc.gov/DES/
28
Endocrine disrupting chemicals -(hormonally
active agents)
  • Hormonally active agents
  • may affect breast cancer risk by
  • Affecting the delicate balance that controls cell
    division
  • Supporting the growth of a hormone-dependent
    breast tumor
  • The Concern
  • Do low levels of environmental chemicals that act
    like hormones or disrupt hormone pathways affect
    breast cancer risk?

29
Endocrine Disrupting Chemicals Need to know more
  • Polybrominated diphenyl ethers (PBDEs)
  • Flame retardant
  • Used in plastics, textiles, carpets, furniture
    foam
  • Detected in marine life and human breast milk
    globally
  • Can stimulate breast tumors cells to grow in the
    lab
  • Plasticizers
  • Nonyl phenol, bisphenol A - estrogenic
  • Phthalates - some may cause premature breast
    development in children (studies from Puerto
    Rico)
  • Heavy Metals
  • Cadmium and arsenite - environmental estrogens
  • Pesticides

30
Endocrine disrupting chemicals How can we
screen chemicals?
  • 1996 Food Quality Protection Act
  • Mandates testing of ALL pesticide active
    ingredients for endocrine disrupting effects
  • EPA is currently validating screening tests and
    prioritizing chemicals to be screened
  • Ref. http//www.epa.gov/scipoly/oscpendo/

31
Early exposures to chemicals can they affect
breast cancer risk?
  • Terminal end buds (TEBs)
  • Target for cancer-causing chemicals

32
Genes influence response to environmental
chemicals
  • Gene-environmental interactions
  • Many chemicals need to be activated to become
    cancer-causing agents
  • Certain genes control important enzymes involved
    in activation pathways
  • Variations in these genes can affect the
    activation pathway
  • This affects the level of cancer-causing chemical

33
Challenges
  • Complexity of the disease
  • Many risk factors involved
  • Complex biology of breast tumors
  • Takes long time for breast tumors to develop
  • Exposure issues
  • Difficult to measure low-level exposures to
    multiple chemicals from the distant past
  • Few chemicals have validated biomarkers
  • Levels of exposure to chemicals at critical
    periods of breast development (in utero through
    puberty) is lacking
  • Exposures to many chemicals in the home and
    workplace are not well characterized

34
BCERF on the web
  • http//envirocancer.cornell.edu
  • Fact Sheets and Tip Sheets
  • Critical Evaluations of chemicals
  • A Place For Women site
  • Newsletters and News You Can Use
  • Bibliographies on environmental factors
  • Cancer Maps
  • Endocrine Disrupting Chemical Information
  • Companion Animal Tumor Registry
About PowerShow.com