Bisphenol A: Exposure in the Environment as it Relates to Health

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Bisphenol A: Exposure in the

Environment as it Relates to

Health

Candace Waynick, RD LD

October 24, 2011

NUTN 507: Seminar

Objectives

 Discuss the synthetic and legal history of

Bisphenol A (BPA)

 Describe uses of BPA and BPA containing products

 Discuss harmful effects of exposure to BPA and controversial methods of testing

 Describe the role of dietitians to minimize public health risks associated with BPA

Synthetic History

 2 phenol compounds and 1 acetone

 Recognized for estrogenic properties in

1930’s by Edward Charles Dodd searching for the “mother substance” (synthetic estrogen)

 In the 1950’s, BPA is used to synthesize epoxy resins and polycarbonate plastics

 Superiority to glass and steel

Vogel 2009

Braun et al 2011

Biello 2008

Image: Wikipedia

Epoxy Resins

 BPA is a monomer in synthesis

 Products:

 Protective coatings of medical equipment, piping, steel drums, and interior of food/beverage/liquid infant formula cans

Vogel 2009

Groff 2010

US FDA Update 2010

Taylor 2011

Image: http://news.consumerreports.org/a/6a00d83451e0d569e20120a69fcb0e970c-800wi

Polycarbonate (PC) plastics

 Hard plastic formed when BPA is polymerized

 Products:

 Electronics, safety equipment, automobiles, food containers, plastics with recycling code # 7, intravenous tubing, dental sealant, reusable water and baby bottles

Vogel 2009

Groff 2010

US FDA Update 2010

Image: http://www.pacebutler.com/images/recycle/plastic-recycling-symbols-7.jpg

Thermal (Carbonless) Paper

 Also contains BPA causing transdermal exposure

 Products:

 Sales receipts, cigarette filters, lottery tickets, fax paper, children’s books, and recycled paper products

Groff 2010

US EPA DRAFT 2011

Braun 2011

Taylor 2011

Image: http://www.bikudo.com/preview/292638.jpg

Leaching BPA

 Monomers of BPA can hydrolyze and leach into foods or liquids

 Accelerated by:

 High temperatures

 Acidic or basic conditions

 Damaged surfaces

 Le et al study

 Exposure to

100

C (new and used PC water bottles) allowing 24 hrs to cool to room temperature

 Results: 15-55 fold increase in those exposed to

Groff 2010 heat versus room temperature water only

Braun et al 2011

Biello 2008

Le 2008

Federal Regulation

 1958- FDA approves BPA as indirect food additive

 Safety determined by toxicity, not carcinogenicity

 1977- National Cancer Institute (NCI) initiated 1st carcinogenesis study of BPA due to increased production

 Responsibility of program passed to the National

Toxicology Program (NTP) during 2 year study

 1988- Environmental Protection Agency (EPA) defines safe exposure levels to BPA as 50 micrograms/kg body weight

Vogel 2009

Shaw 2008

Health Implications

 Endocrine system disruption

 Cancer

 Obesity

 Cognitive and behavior impairment

 Cardiovascular Disease

(CVD)

 Type 2 Diabetes (DM2)

 Asthma

 Liver enzyme abnormalities

Shaw 2008

Ballard 2010

Image: http://bpafreewaterbottlespro.com/wp-content/uploads/2011/08/bpa-health-risks.jpg

Endocrine System Disruption

 BPA is an endocrine-disrupting compound

(EDC)

 An exogenous agent that interferes with synthesis, secretion, transport, metabolism, binding, action, or elimination of natural bloodborne hormones that are present in the body and are responsible for homeostasis, reproduction, and developmental processes.

Bourguignon et al 2010

Studies showing BPA as EDC

 Moriyama et al (2002) show BPA inhibiting thyroid hormone receptor (T

3

)-mediated transcription by acting as an antagonist

 Ramos et al (2003) exposed rats to BPA in utero indicating prenatal exposure induces transient and permanent age-dependent alterations in the male reproductive axis at different levels

Moriyama et al 2002

Ramos 2003

Image: http://electiondebates.com/images/stimulus-pix/rats.png

Studies showing BPA as EDC

 Song et al (2002) demonstrate BPA inducing

NR4A1 gene expression (responsible for activating steroidogenesis) in mouse testicular cells

 Akingbemi et al (2004) actually show the opposite with low doses of BPA showing an inhibitory effect on testicular steroidogenesis

Song et al 2002

Akingbemi et al 2004

Metabolic disturbances

 Lang et al use NHANES data to show higher BPA urine levels associated with increased prevalence of CVD, DM2, and liver-enzyme abnormalities

Lang et al 2008

US EPA DRAFT 2011

Image: http://www.online-diabetes-information.com/wp-content/uploads/2011/03/diabetes-heart-disease2.jpg

Young children, infants, and fetuses at higher risk

 Higher BPA concentrations reflective of higher food intake per pound of body mass

 Predominant sources:

 Fetus- shown to cross the placenta

 Infants- breast milk, canned infant formula, and baby bottles

 NICU infants exposed to higher levels due to intensive medical interventions

 Children- canned food and beverages and school lunches

Groff 2010

Lang et al 2008

Bourguignon et al 2010

US EPA DRAFT 2011

Image: http://www.sequoiapediatricgroup.com/images/nicu_baby.gif

Exposure outcomes during development

 Prenatal exposure associated with aggression and hyperactivity in 2 year old children

 Delayed breast development with higher BPA concentrations

 More sensitive to adverse outcomes due to exposure during development of neurological and endocrine systems

US EPA DRAFT 2011

Bourguignon et al 2010

US FDA Update 2010

Braun et al 2011

National Children’s Study

 Started 2009

 Examining fetal environment, including

BPA exposure

 Following pregnant women and offspring until 21 years of age

 Goal of 100,000 children participants

 Largest, most comprehensive study of its kind in US

Groff 2010

Image: http://www.mrothery.co.uk/images/growth.gif

Metabolism

 Oral ingestion of BPA is metabolized in the intestines and liver to yield metabolite, BPA monoglucuronide, and is excreted in the urine (in humans)

 Acute exposure studies show:

 rapid metabolism of BPA with urinary elimination to be within 24 hours of exposure based on 4-6 hour half-life

Stahlhut 2009

Lang et al 2008

Image: http://image3.examiner.com/images/blog/wysiwyg/image/water_bottle1(1).jpg

Metabolism Controversy

 BPA monoglucuronide elimination:

 humans/primates- from the blood via kidneys into urine

 Rodents- bile excretion into feces

 Current safety measured on belief that higher doses result in greater effects

 If higher doses cause no harm, lower doses are deemed safe?

Groff 2010

Lang et al 2008

Taylor et al 2011

Studies Addressing

Controversy

 Stahlhut et al suggest a longer than expected half life attributed to either environmental exposure or accumulation in adipose tissue

 Taylor et al compare bioactive BPA

(unconjugated) levels in primates and rodents reporting clearance rates are the same

Stahlhut et al 2009

Taylor et al 2011

Groff 2010

Image: http://maxcdn.fooyoh.com/files/attach/images/3004/141/953/004/Monkey_facepalm.jpg

Exposure

Over 90% of U.S. individuals have measurable concentrations of BPA in their urine

 Significantly higher levels of BPA in younger children, women, and incomes <

$45,000/year

 1997-2005- 115 studies in US, Japan, and Europe show some effects at or below the reference dose

Braun et al 2011

Lang et al 2008

Groff 2010

Taylor 2011

Vogel 2009

Image: http://3.bp.blogspot.com/_xo0o9nT5MLI/TOq_bZElPYI/AAAAAAAAAB8/nQspiA_mtwY/s1600/MP900431826.JPG

Back to Federal Regulation

 2007- Chapel Hill Consensus Statement

 BPA, at concentrations found in the human body, is associated with “organizational changes in prostate, breast, testes, mammary glands, body size, brain structure and chemistry, and behavior of laboratory animals.”

 2008- The Center for Evaluation of Risks to Human

Reproduction (CERHR) within the NTP released two statements regarding BPA at current exposure:

 “some concern for effects on the brain, behavior, and prostate gland in fetuses, infants, and children”

 “minimal concern for the effects on the mammary gland and an earlier age for puberty for females in fetuses, infants, and children”

Vogel 2009

US FDA Update 2010

Image: http://www.knowabouthealth.com/wp-content/uploads/2010/07/BPA.jpg

Current Regulation of BPA

 January 2010- Food and Drug Administration announces it had some concern about BPA

 November 2010- World Health Organization recommend holding off on regulations that limit or ban use of BPA

 Several local and state governments in US have limited or banned use of BPA

 Oregon Senate Bill: http://gov.oregonlive.com/bill/2011/SB695/

 October 2011- American Chemistry Council asks to phase out allowance of BPA in baby products

US EPA 2010

Brown 2010

USA Today 2011

BPA-free Manufacturers

 By March 2009, major baby bottle companies removed BPA from products

 Sunoco requires written confirmation of BPA plastic not sold to children ≤ 3 years

 2010- General Mills announced next tomato harvest, all Muir Glen tomatoes canned BPAfree

Vogel 2009

Szabo 2008

Eden Foods beans have been BPA free since

1999

USA Today 2011

Image: http://www.kidsbabydesign.com/wp-content/uploads/2009/06/bpa-free-baby-bottles.jpg

Image: http://www.greenbiz.com/sites/default/files/imagecache/wide_large/0410Muir.jpg

Minimizing Health Risks

 Rudel et al conducted a study following participants measuring BPA at baseline and 3 days post intervention

(eliminating canned/packaged foods)

 50-70% decrease in urinary BPA

Rudel et al 2011

Image: http://3.bp.blogspot.com/_4J97xRX7uok/TG4Bj2OHSII/AAAAAAAAAAk/DOb-TqhLJh0/s1600/Fresh+foods+vs+Canned+foods.png

Role of the Dietitian

 Counsel public to:

 Avoid canned foods

 Replace recycling #s 3, 6, & 7 with other recycling #s (1, 2, 4, or 5), stainless steel, or glassware

 Switch from liquid formula to powdered

 Avoid heating BPA plastic

 Replace canned foods with fresh or frozen foods

 Discard scratched baby bottles/cups

Braun 2011

Only use dishwasher safe and microwave safe plastics in appliances

Groff 2010

Bourguignon 2010

US DHHS

Summary

 BPA found in plastics (code # 7) and canned foods/beverages

 Health implications include endocrine system disruption, risk of CVD, neurological impairments, obesity, DM2, and liver enzyme abnormalities

 No federal limits or bans on uses

 Dietitian can reduce public exposure by suggesting replacements

Discussion

Image: http://www.sneakerfiles.com/wp-content/uploads/2011/09/Discussion-The-Discussion.jpg

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