Bisphenol A: Exposure in the Environment as it Relates to Health Candace Waynick, RD LD October 24, 2011 NUTN 507: Seminar.

Bisphenol A: Exposure in the Environment as it

Relates to Health

Candace Waynick, RD LDOctober 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 History2 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 2009Braun et al 2011Biello 2008Image: Wikipedia

Epoxy Resins

BPA is a monomer in synthesisProducts:

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

Vogel 2009Groff 2010US FDA Update 2010Taylor 2011Image: 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 2009Groff 2010US FDA Update 2010Image: 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 2010US EPA DRAFT 2011Braun 2011Taylor 2011Image: http://www.bikudo.com/preview/292638.jpg

Leaching BPAMonomers of BPA can hydrolyze and leach

into foods or liquidsAccelerated by:

High temperaturesAcidic or basic conditionsDamaged surfaces

Le et al studyExposure to 100

｡C (new and used PC water bottles)

allowing 24 hrs to cool to room temperatureResults: 15-55 fold increase in those exposed to heat

versus room temperature water onlyGroff 2010Braun et al 2011Biello 2008Le 2008

Federal Regulation1958- FDA approves BPA as indirect food

additiveSafety determined by toxicity, not carcinogenicity

1977- National Cancer Institute (NCI) initiated 1st carcinogenesis study of BPA due to increased productionResponsibility of program passed to the National

Toxicology Program (NTP) during 2 year study1988- Environmental Protection Agency

(EPA) defines safe exposure levels to BPA as 50 micrograms/kg body weight

Vogel 2009Shaw 2008

Health Implications

Endocrine system disruption

CancerObesityCognitive and

behavior impairment

Cardiovascular Disease (CVD)

Type 2 Diabetes (DM2)

AsthmaLiver enzyme

abnormalities

Shaw 2008Ballard 2010Image: 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 blood-borne 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 (T3)-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 2002Ramos 2003Image: 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 2002Akingbemi 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 2008US EPA DRAFT 2011Image: 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 placentaInfants- breast milk, canned infant formula,

and baby bottlesNICU infants exposed to higher levels due to

intensive medical interventionsChildren- canned food and beverages and

school lunchesGroff 2010Lang et al 2008Bourguignon et al 2010US EPA DRAFT 2011Image: 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 2010US FDA Update 2010Braun et al 2011

National Children’s StudyStarted 2009Examining fetal environment,

including BPA exposureFollowing pregnant women and

offspring until 21 years of ageGoal of 100,000 children

participantsLargest, most comprehensive study

of its kind in US

Groff 2010Image: 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 2009Lang et al 2008Image: 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 effectsIf higher doses cause no harm, lower

doses are deemed safe?Groff 2010Lang et al 2008Taylor 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 2009Taylor et al 2011Groff 2010Image: http://maxcdn.fooyoh.com/files/attach/images/3004/141/953/004/Monkey_facepalm.jpg

ExposureOver 90% of U.S. individuals have

measurable concentrations of BPA in their urineSignificantly 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 2011Lang et al 2008Groff 2010Taylor 2011Vogel 2009Image: http://3.bp.blogspot.com/_xo0o9nT5MLI/TOq_bZElPYI/AAAAAAAAAB8/nQspiA_mtwY/s1600/MP900431826.JPG

Back to Federal Regulation2007- 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 2009US FDA Update 2010Image: http://www.knowabouthealth.com/wp-content/uploads/2010/07/BPA.jpg

Current Regulation of BPAJanuary 2010- Food and Drug Administration

announces it had some concern about BPANovember 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 BPAOregon 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 2010Brown 2010USA 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 BPA-free

Eden Foods beans have been BPA free since 1999

Vogel 2009Szabo 2008USA Today 2011Image: http://www.kidsbabydesign.com/wp-content/uploads/2009/06/bpa-free-baby-bottles.jpgImage: http://www.greenbiz.com/sites/default/files/imagecache/wide_large/0410Muir.jpg

Minimizing Health RisksRudel 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 2011Image: http://3.bp.blogspot.com/_4J97xRX7uok/TG4Bj2OHSII/AAAAAAAAAAk/DOb-TqhLJh0/s1600/Fresh+foods+vs+Canned+foods.png

Role of the DietitianCounsel public to:

Avoid canned foodsReplace recycling #s 3, 6, & 7 with other

recycling #s (1, 2, 4, or 5), stainless steel, or glassware

Switch from liquid formula to powderedAvoid heating BPA plasticReplace canned foods with fresh or frozen foodsDiscard scratched baby bottles/cupsOnly use dishwasher safe and microwave safe

plastics in appliances

Braun 2011Groff 2010Bourguignon 2010US 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 usesDietitian can reduce public exposure by

suggesting replacements

Discussion

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