Discovery of rice as the major dietary source of inorganic arsenic
Submitting Institution
University of AberdeenUnit of Assessment
Agriculture, Veterinary and Food ScienceSummary Impact Type
PoliticalResearch Subject Area(s)
Environmental Sciences: Soil Sciences
Agricultural and Veterinary Sciences: Crop and Pasture Production
Medical and Health Sciences: Public Health and Health Services
Summary of the impact
Research by Professor Andrew Meharg at the University of Aberdeen was the
first to show that
rice constituted the major source of dietary exposure to inorganic
arsenic, a class 1, non-threshold
carcinogen, meaning that there is no dose that is risk-free. This research
directly led to the
European Food Safety Authority (EFSA) undertaking a major review of
arsenic in foods. The EU,
USA and WHO lack standards for arsenic in food, but all three are now
actively seeking to set
standards. Subsequent to the Aberdeen studies, the WHO withdrew its
standard for arsenic
Provisional Tolerable Daily Intake, considering it too high. Also, as a
direct result of this work, the
UK Food Standards Agency (FSA) has issued warnings that children under 4
should avoid rice
milks because of their inorganic arsenic content.
Therefore claimed impacts are: affected health and welfare; enhanced
awareness of health risks,
altered dietary guidelines and changes to public and international
policies and guidelines.
Underpinning research
The role of researchers at the University of Aberdeen in unravelling the
importance of arsenic in
rice began with a series of publications typified by Abedin et al. (2002)
[1]. These identified that
the irrigation of paddy rice with groundwater containing high levels of
arsenic in Bangladesh and
West Bengal, India, might be of concern, placing earlier physiological
studies on arsenic
assimilation by rice in context. This was shortly followed by the first
field survey of arsenic in rice
grain to be published anywhere, identifying that indeed there was
extensive arsenic contamination
of rice, and paddy soil, in Bangladesh [2]. Furthermore, this publication
was the first to question
the failure of international bodies to set clear arsenic standards, and,
more specifically, the failure
to account for and legislate against arsenic in foodstuffs.
These initial findings provided impetus for further study, resulting in
the first paper to consider
arsenic in rice in a global context. This study revealed that EU, USA and
Bangladeshi arsenic
levels in rice were elevated above "natural" levels, and was the first to
identify that arsenic
speciation (the identification of the chemical forms of arsenic present)
in rice varied between
different rice producing regions [3]). The findings for Bangladesh were
further clarified by detailed
rice grain surveys, culminating in the most detailed global assessment of
total and inorganic
arsenic content of rice grain to date [4]. This enabled cancer risks from
arsenic-contaminated rice
to be estimated on a regional basis, showing that there is an elevated
risk of bladder and lung
cancers from rice based on the most up to date US EPA modelling of
inorganic arsenic cancer
risks. Those risks are highest for countries such as Bangladesh that have
very high rice
consumption rates combined with highly arsenic-contaminated rice.
The realisation that rice consumption represented a major source of
inorganic arsenic exposure led
to the investigation of specific rice-based food products. This phase of
arsenic in rice studies
identified that inorganic arsenic in baby rice [5] and rice milk [6] were
of considerable concern.
These two papers led directly to the 2009 EFSA review of arsenic from
foodstuffs [c] and the UK
FSA report, also in 2009, advising that rice milk should not be given to
children under 4 years old
[a]. Highest inorganic arsenic levels were identified in stabilized
rice bran products [7]. These
products had been marketed as health supplements, and more worryingly, as
nutritional
supplements for aid programmes in developing countries. Rice bran is still
used widely in rice
products, particularly in the health-food market.
References to the research
[1] Abedin MJ, Cresser M, Meharg AA, Feldmann J & Cotter-Howells J.
(2002). Arsenic
accumulation and metabolism in rice (Oryzasativa). Environmental
Science & Technology 36, 962-968.
WoK cited 220 times.
This is the first paper to mention that arsenic in rice could be
problematic due to rice's physiology
and agronomic practice in the Bengal Delta.
[2] Meharg AA & Rahman Md M. (2003). Arsenic contamination of
Bangladesh paddy field soils:
implications for rice contribution to arsenic consumption. Environmental
Science & Technology 37,
229-234. WoK cited 307 times.
This paper represents the original body of work leading to the claimed
impact. In this the levels of
arsenic are explicitly measured in the field, and identified as
problematic.
[3] Williams PN, Price AH, Raab A, Hossain SA, Feldmann J & Meharg
AA. (2005). Variation in
arsenic speciation and concentration in paddy rice related to dietary
exposure. Environmental
Science & Technology 39, 5531-5540. WoK cited 241 times.
This paper was identified by Thompson Reuters Essential Science
Indicators, November 2009,
Environment & Ecology category, with Williams et al. (2005) as the
most cited paper in the Fast
Moving Front `Arsenic speciation'. http://sciencewatch.com/dr/fmf/2009/09novfmf/09novfmfMeha/.
[4] Meharg AA, Williams PN, Adamako E, Lawgali YY, Deacon C, Villada A,
Cambell RCJ, Sun
GX, Zhu YG, Feldmann J, Raab A, Zhao FJ, Islam R, Hossain S, Yanai J.
(2009). Geographical
variation in total and inorganic arsenic content of polished (white) rice.
Environmental Science &
Technology. 43, 1612-1617. WoK cited 98 times.
[5] Meharg AA, Sun G, Williams PN, Adamako E, Deacon C, Zhu YG, Feldmann
J, Raab A. (2008)
Inorganic arsenic levels in baby rice are of concern. Environmental
Pollution, 152, 746-749. WoK
cited 33 times.
This paper directly led to EFSA review of arsenic in EU diets.
[6] Meharg AA, Deacon C, Campbell RCJ, Carey A-M, Williams PN, Feldmann
J, Raab A. (2008)
Inorganic arsenic levels in rice milk exceed EU and US drinking water
standards. Journal
Environmental Monitoring, 10, 428-431. WoK cited 22 times.
This paper directly led to the UK FSA issuing advice that children
<4 should not drink rice milk.
[7] Sun, G-X, Williams PN, Carey A-M, Zhu Y-G, Deacon C, Raab A, Feldmann
J & Meharg AA
(2008). Inorganic arsenic in rice bran and its products are an order of
magnitude higher than in
bulk grain. Environmental Science & Technology. 42, 7542-7546).
Wok cited 69 times.
This paper showed that highest inorganic arsenic levels were
identified in stabilized rice bran.
Relevant grant funding:
Initial studies were funded through a Commonwealth Universities PhD
Scholarship and two
Commonwealth Universities funded Visiting Fellowships (1 year study
visits), with all recipients
being Bangladeshi. The work was then developed through a series of three
BBSRC studentships
and two further Commonwealth Universities Visiting Bangladeshi
Fellowships.
UK and EU funded grants that followed up on initial findings are as
follows:
- 2007-2010, EU Marie Curie training programme, awarded to Meharg and
Feldmann (joint PIs),
£148,000, funding an RA to look at losses from arsenic from paddy fields
through biovolatilization.
- 2007-13, various FSA awards totalling £191,000 (review of arsenic and
rice/study the effects of
cooking on removal of arsenic in rice/arsenic in meat products/ arsenic
speciation in fruit and
vegetables in geogenically arsenic elevated regions of the UK), awarded to
Meharg and
colleagues.
- 2007-2011, BBSRC-DFID, awarded to Meharg (PI), Feldmann & Price,
£650,000, to study
genetic approaches to lowering inorganic arsenic content in rice.
- 2009, NHS, awarded to Meharg and Feldmann, £12,000, to look at arsenic
and breast cancer.
- 2010, BBSRC, awarded to Meharg (PI) and Price, £29,000, capacity
building for arsenic and rice
research in Asia and Africa.
- 2012-16, BBSRC, awarded to Price (PI), Meharg and Salt, £1,100,000, to
look at genetic
dissection of traits, with arsenic being a major focus, for sustainable
water use in Bangladeshi rice.
Details of the impact
Building on scientific studies published from 2002 onwards, the direct
impact of arsenic and rice
investigations within the assessment period (2008-2013) were based on
human health impacts,
resulting in action by regulators, legislators, consumers and the food
industry.
The first assessment period impact was when focus turned to rice products
and it was
hypothesised that baby rice and rice milk might be problematic, resulting
in the first papers in this
area [5 & 6 above], which were critical of the lack of legislation
regarding arsenic in foods. As a
result of these studies, and those that the FSA had commissioned itself,
the FSA advised in May
2009 the following: `As a precaution, toddlers and young children
between 1 and 4.5 years old
should not have rice drinks as a replacement for cows' milk, breast
milk, or infant formula. This is
because they will then drink a relatively large amount of it, and their
intake of arsenic will be
greater than that of older children and adults relative to their
bodyweight. This is both on nutritional
grounds and because such substitution can increase their intake of
inorganic arsenic, which should
be kept as low as possible. A daily half pint or 280 millilitres of rice
drink could double the amount
of the more harmful form of arsenic they consume each day" [a]. Thus
the FSA directly acted on
the findings and advice of the Aberdeen University rice milk paper.
The Aberdeen studies on arsenic in rice culminating in the baby rice and
baby milk surveys also
prompted a major reassessment in 2009 of inorganic arsenic exposure of the
EU populace by the
EFSA [c]. This review by an assembled expert panel reached the same
conclusion as had the
Aberdeen studies on both rice milk and baby rice. Another major conclusion
from this EFSA
review was that the World Health Organization's inorganic arsenic
Provisional Maximum Tolerable
Daily Intake (PMTDI) was based on flawed calculations, was thus too high,
and was not
scientifically sustainable. The Aberdeen group had initiated this debate
through its series of
papers on rice, and indeed was the first and most vocal critic of this
PMTDI with respect to food
intakes. As the WHO PMTDI represented the only international benchmark of
inorganic arsenic
intake in any ingested item, it had been widely used to justify that
inorganic arsenic intakes from
rice were `safe'. This was a highly flawed argument that did not stand
scientific scrutiny, as rice is
the dominant source of inorganic arsenic globally, not water. While both
the WHO and EU have
set strict and low levels of what is the maximum allowed inorganic arsenic
in drinking water, given
that there are regions of the world that suffer from naturally elevated
arsenic in drinking waters,
they have not set food standards for inorganic arsenic. The EFSA review
and criticism of the
PMTDI led directly to rapid withdrawal of this WHO standard. The Aberdeen
group published a
critique of the current state of arsenic standards globally (Meharg AA
& Raab A (2010) Getting to
the bottom of arsenic standards and guidelines. Environmental Science
& Technology 44, 4395-4399)
which was published before the WHO withdrew their arsenic PMTDI.
A Dartmouth College PNAS study on baby rice in 2011 which followed up in
a US context the
Aberdeen group's earlier work on elevated arsenic concentrations in rice
and the need to regulate
arsenic in food, received considerable global media coverage and has led
to the US congress
asking the US FDA to consider setting arsenic standards in food,
(http://www.pnas.org/content/108/51/20656.full).
The EU, WHO and USA are all currently considering setting arsenic
standards in food as illustrated
by the EFSA (2009) review and FDAs published concerns and timelines
(http://www.fda.gov/forconsumers/consumerupdates/ucm319827.htm)
and specific calls by the US
congress to set standards for arsenic in rice
(http://www.huffingtonpost.com/2012/09/21/rice-act-
arsenic-delauro-pallone-lowey_n_1904490.html).
The BBSRC have explicitly identified Meharg's work regarding arsenic in
rice as part of their "Our
Impact": http://www.bbsrc.ac.uk/research/impact/arsenic-levels-in-food.aspx
Claimed impact as defined by REF guidance includes: evidence of
awareness of health risks and
benefits by consumers; clinical and dietary guidelines have changed;
public health, well-being has
improved and public behaviour has changed; documented changes to public
health policies;
advisory committees and guidelines; decisions by regulatory authorities
has been influenced by
research.
Sources to corroborate the impact
[a] The UK Food Standards Agency commissioned two studies, one on rice
milk and one on baby
rice, directly following publication of Aberdeen studies on this topic
(Meharg et al. 2008 a,b) [5 & 6],
with their findings corroborating those of the Aberdeen group. It issued
public advice for children
<4 not to drink rice milk.
http://www.food.gov.uk/news/newsarchive/2009/may/arsenicinriceresearch
[b] 2009 press story around this time showing the FSA was directed by UoA
study:
http://www.dailymail.co.uk/news/article-1186722/Rice-milk-arsenic-contamination-prompts-food-
watchdog-warning-children-stop-drinking-it.html
[c] EFSA commissioned a major review of arsenic in the EU diet following
the Aberdeen arsenic in
baby rice study (Meharg 2008) [5] along with the mounting evidence
produced by the group that
showed that arsenic in rice was of wide concern, starting with Williams et
al. (2005) [3]. This report
concluded that arsenic in rice was of concern to high consuming groups,
including babies, and that
action should be taken to lower inorganic arsenic in the EU diet.
http://www.efsa.europa.eu/en/efsajournal/pub/1351.htm
[d] Following the publication of the ESFA's report which criticized the
WHO's Provisional Maximum
Tolerable Daily Intake (PMTDI) as having a poor scientific grounding,
combined with Aberdeen's
own critique of the current arsenic standards globally, (Meharg AA &
Raab A (2010) Getting to the
bottom of arsenic standards and guidelines. Environmental Science
& Technology 44, 4395-4399),
this standard was removed. See page 3 of
http://www.who.int/foodsafety/chem/summary72_rev.pdf
Below is an examples of the extensive media coverage garnered (i.e. ~
80,000 hits on Google
when the string "Meharg arsenic rice" is searched):
[e] Sample newspaper coverage of Aberdeen's arsenic in baby rice research
(Meharg et al.
2008) [5]: http://www.telegraph.co.uk/health/healthnews/8440126/Arsenic-and-toxic-metals-found-in-baby-foods.html
[f] An example of industry response to the Aberdeen research findings:
http://www.lundberg.com/Info/Arsenic/Arsenic_links.aspx