Miljø- og Fødevareudvalget 2015-16
MOF Alm.del Bilag 108
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PESTICIDES UNIT
EFSA explains the carcinogenicity assessment of
glyphosate
12 November 2015
Background
During the EFSA peer-review process for the renewal of the approval of the pesticide
active substance glyphosate, EFSA received a complementary mandate from the
European Commission to consider the findings by the International Agency for Research
on Cancer (IARC) regarding the potential carcinogenicity of glyphosate or glyphosate
containing plant protection products. Following the request, EFSA has incorporated its
scientific assessment in the on-going peer review of the active substance (EFSA, 2015a).
The EFSA Conclusions on Pesticides have a complex structure, designed for supporting
the European Commission and Member States in the approval process, the subsequent
assessments of the Plant Protection Products (PPPs) by the Member States (MSs), and
the revision of the Maximum Residue Levels (MRLs) of pesticides.
The EFSA Conclusions summarise the main outputs of the scientific assessments
(Sections 1 to 6), and then focus on the identification of data gaps and studies to be
generated (Section 7), recommendations to manage the identified risks (Section 8) and
concerns to be considered by risk managers (Section 9). An appendix presents the List
of Endpoints recommended by EFSA for the hazard and the risk assessment of the active
substance.EFSA also publish supporting background documents providing the scientific
justifications.
EFSA’s assessment on pesticide active substances is based on original studies
(mandatory regulatory Good Laboratory Practice (GLP) studies, other relevant studies
and the outcome of the search of peer-reviewed scientific studies published within the
last 10 years before the submission of the dossier), that are summarised by the
rapporteur Member State (RMS) in the draft renewal assessment report (RAR). The
peer-review includes a public consultation of the draft RAR and several commenting
phases by EFSA scientists and MSs experts, the possibility for requiring additional
information from the applicants, and a set of experts’ meetings covering different
scientific areas; this is reflected in a further development of the RMS RAR during the
EFSA peer review.
Due to the length and complexity of the peer review report supporting the EFSA
Conclusion (EFSA, 2015b) and the RAR (Germany, 2015) EFSA has considered
important to clarify some key elements of its scientific evaluation in this complementary
document, in particular, regarding the assessment of the carcinogenicity of the active
substance glyphosate.
Assessment of the carcinogenic potential of the active substance
glyphosate
EFSA has assessed the carcinogenicity and genotoxicity potential of the active substance
glyphosate according to the principles and criteria applicable for the classification and
labelling of chemical substances in the EU under Regulation (EC) No 1272/2008 (CLP
European Food Safety Authority • Via Carlo Magno 1A • 43126 Parma • ITALY
Tel. +39 0521 036 111 • Fax +39 0521 036 110 • www.efsa.europa.eu
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Regulation)
1
. This regulation implements in the EU the Globally Harmonized System
developed by the United Nations for the classification and labelling of hazardous
chemical substances. The European Chemicals Agency (ECHA) has developed guidance
on the application of these criteria (available in the ECHA web page) and submitted
specific comments regarding the Rapporteur Member State (RMS) assessment (EFSA,
2015b) that were considered by EFSA and the MSs during the peer review. Glyphosate
carcinogenicity was discussed in two experts’ meetings, first during the overall
assessment of the mammalian toxicity and second during a dedicated experts’
teleconference, involving a large number of experts.
Genotoxicity
The genotoxicity data package available for the peer review is comprehensive. A large
number of studies provided in the draft RAR (over 100 studies all together; Germany,
2013) was complemented by additional studies identified during the commenting period
and public consultation that took place in 2014, and which were included in the revised
RAR (Germany, 2015).
a) glyphosate
EFSA assessed the genotoxic potential of the active substance, glyphosate, and focused
on the studies performed on well characterized test substances as manufactured.
Glyphosate is produced by many different companies, each manufacturing a technical
material presenting different impurity profiles than the others. Where considered
necessary, data gaps have been set for each individual company to complete the
toxicological information on the impurities, which are present in their own technical
material (EFSA, 2015a).
All required genotoxicity endpoints that consist of gene mutation in bacterial and
mammalian cells, structural and numerical chromosome aberrations
in vitro
and
in vivo
have been investigated in validated OECD guideline-compliant studies following the
principles of GLP, as well as published studies often following non-GLP protocols
designed by the study authors.
In vitro
tests
Bacterial and mammalian cells mutagenicity studies gave consistently negative results;
even studies that were considered less reliable and of lower quality did not reveal any
indication of genotoxicity. With regards to
in vitro
mammalian chromosome aberration
(CA), all tests that were performed under GLP conditions, as well as a number of
published studies gave negative results at concentrations up to 1250 µg/L. In contrast
positive results were obtained in some published studies on CA at lower dose levels, and
on other endpoints considered as indicator tests, such as sister chromatid exchange
(SCE) and induction of DNA strand breaks
in vitro.
The positive indications observed in
some
in vitro
tests were not confirmed by
in vivo
studies covering the appropriate end-
points, such as
in vivo
micronucleus tests.
In vivo
tests
Sixteen
in vivo
studies in somatic cells were reported on rodents treated orally with dose
levels up to 5000 mg/kg bw or via intraperitoneal injections. All studies conducted
according to internationally validated guidelines and some non-GLP published studies
gave negative results, while two non-GLP studies resulted positive in mice treated
intraperitoneally with dose levels in the range of the intraperitoneal LD
50
for mice, one
study presenting major flaws. Conflicting results were obtained regarding DNA adduct
1
Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on
classification, labelling and packaging of substances and mixtures, amending and repealing Directives
67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006. OJ L 353, 31.12.2008 p.1-1355
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formation; induction of DNA strand breaks was observed in mice treated
intraperitoneally with doses close to or in excess of the LD
50
, this induction may be
caused by secondary effects of cytotoxicity. No genotoxic effects on germ cells have
been detected in rats or mice treated orally at dose levels up to 2000 mg/kg bw.
Considering a weight of evidence approach, taking into account the quality and reliability
of all available data, it is concluded that glyphosate is unlikely to be genotoxic
in vivo
and does not require hazard classification regarding mutagenicity according to the CLP
Regulation. It is noted that unpublished studies that were the core basis of the peer
review evaluation were not available to the IARC experts as reported in the IARC
monograph 112 on glyphosate (IARC, 2015).
b) glyphosate-based formulations
A number of published studies performed with glyphosate based formulations of
unknown composition gave positive results when tested
in vitro
and
in vivo.
Some of the
test systems are not validated and/or of difficult interpretation due to possible
confounding, such as cytotoxicity, specific organ toxicity or unclear relevance to human
health when tested in fish, amphibians or invertebrates according to the current
knowledge. POE-tallowamine is one of the co-formulants that is known to be used in
some glyphosate-based formulations. This co-formulant has been shown to be more
toxic than the active substance glyphosate on several toxicological endpoints, namely
acute, short term, reproductive and developmental toxicity, further to equivocal
evidence of DNA damage
in vitro
at high doses (EFSA, 2015c). Although POE
tallowamine is not present in the representative formulation, for which data have been
submitted under the European re-approval procedure and which were assessed by EFSA,
the peer review concluded that the toxicity of formulations and in particular their
genotoxic potential should be further considered and addressed.
It is noted that a number of human studies were not evaluated, since the exposure was
linked to glyphosate-based formulations of unknown composition. Therefore their
assessment would not have changed the overall conclusion.
Carcinogenicity
a) Studies in animals
Long term toxicity and carcinogenicity potential of glyphosate was assessed in five
mouse studies and nine rat studies; one further study in mice and one in rats were
considered inadequate for the evaluation of glyphosate carcinogenicity.
In the nine long term rat studies, the EU peer review concluded that no significant
increase in tumour incidence was observed in any of the treated groups of animals.
Three of these studies were not evaluated by the IARC experts. In one study, the IARC
reported a statistically significant increased incidence of pancreatic islet cell adenomas in
males treated with the low dose, which was not reproduced at higher dose levels. In
another study, the IARC reported significant increases in pancreatic islet adenomas in
males at two dose levels (not dose-related), a significant positive trend for hepatocellular
adenomas in males without progression to malignancy and a significant trend for C-cell
adenomas in females. The two evaluations differ primarily regarding the statistical
evaluation: according to a pair-wise comparison [Fisher´s exact test (one-tailed) as well
as in combination with Bonferroni inequality procedure for incidences of non-neoplastic
(at p ≤ 0.01) and neoplastic lesions (at p ≤ 0.01 and ≤0.05) and Peto Analysis for
evaluation of histopathological data as planned in the study protocol] no significant
change is observed, while a trend analysis (Cochran-Armitage trend test) performed by
the IARC experts identified significant changes. EFSA is of the opinion that the planning
of a study before the initiation of the experimentation itself as established in the
respective protocol –that includes the statistical analysis - is a key element in assessing
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the quality of a study, therefore deviations from the statistical analysis used by the study
authors should be limited and properly justified. Furthermore, clear dose-response was
not always observed and when observed, it affected only the highest dose level of 940 to
1183 mg/kg bw per day in males and females respectively, a dose eliciting other adverse
effects on body weight, liver, stomach mucosa and eyes (cataracts).
In mice, the EU peer review evaluated five studies; another study was considered
inadequate for the evaluation of glyphosate carcinogenicity. From these studies, only one
study in Swiss albino mice presented a carcinogenic effect characterised by a statistically
significant increased incidence of malignant lymphomas at the top dose level of 1460
mg/kg bw per day. However, the validity of the study was questioned due to the
occurrence of viral infection that could influence survival as well as tumour incidence –
especially lymphomas. No other carcinogenic effects were observed up to the highest
dose levels of each of the other studies as tumour incidences remained within valid
historical control data from the respective performing laboratory and/or did not attain
the level of statistical significance. The IARC evaluated two of these studies and
identified positive trend in males for renal tubule adenomas and carcinomas in one study
and positive trend for haemangiosarcoma in the other study according to Cochran-
Armitage trend test. EFSA adopted a weight of evidence approach which was agreed by
the peer review taking into account all available data: the statistical significance found in
trend analysis (but not in pair-wise comparison) was balanced against the lack of
consistency in multiple animal studies, slightly increased incidences only at dose levels at
or above the limit dose of 1000 mg/kg bw per day recommended for the oral route of
exposure in chronic toxicity and carcinogenicity studies (OECD, 2012a), doses at which
confounding of concomitant toxicity is expected, incidences within valid historical control
range from the performing laboratory and lack of pre-neoplastic lesions.
Furthermore no genotoxic potential is attributed to the active substance glyphosate.
Other mechanisms of action were reported by IARC, such as inflammation,
immunosuppression, endocrine disrupting (ED) activity and oxidative stress. Although no
robust information is available to conclude on the immunomodulatory potential of
glyphosate, indications of such effects were limited to inflammatory responses of the
respiratory tract. No interaction of glyphosate with the oestrogen, androgen or thyroid
endocrine pathways were identified by the US EPA Endocrine Disruptor Screening
Program (EDSP) according to a full battery of Tier I screening assays (data gaps were
however identified in the EFSA conclusion for the submission of the respective studies for
confirmation); and no significant ED effects were identified in published studies reported
by IARC, except for a higher activity of formulations in comparison to the active
substance. Some indications of increased oxidative stress were observed in combination
with cytotoxic or degenerative effects of the target organs; however, even if these
indications are confirmed, the observation of a plausible mechanism of action
per se
is
insufficient to assume a carcinogenic potential in humans according to the current
knowledge. On this basis, EFSA concluded that glyphosate is unlikely to pose a
carcinogenic hazard to humans and no classification regarding carcinogenicity is
proposed according to CLP Regulation.
b) Epidemiological studies
Overall thirty epidemiological studies are reported in the IARC monograph, including
cohort, case-control studies and meta-analyses. A few of these studies were not
reported in the RAR (Germany, 2013), but were considered by the RMS in an addendum
on the assessment of the IARC monograph (Germany, 2015). In ten cohort studies, that
include the Agricultural Health Study (AHS) (Alavanja
et al.,
1996), the largest
prospective cohort study undertaken until today and used in many other publications,
glyphosate did not cause different types of cancer and did not increase the risk of all
cancers. Nine case-control studies did not indicate an increased risk of carcinogenicity by
glyphosate, or presented limited power. Further five case-control and one prospective
cohort studies were considered to assess the strength of evidence linking glyphosate to
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non-Hodgkin lymphoma (NHL), a statistical significant association was observed in a
small number of cases that was considered insufficient to conclude on the causality, due
to the poor consistency of the results. Epidemiological studies face several problems
linked to the small number of cancer cases and difficult identification/separation of
confounders: glyphosate is generally analysed together with several other pesticides,
exposure cannot be easily measured as it is generally based on interviews and
questionnaires that have several intrinsic recall bias, furthermore, the classification of
the type of cancer is not consistent, the adverse outcomes are not always obtained from
medical records, and finally, the contribution of co-formulants’ toxicity cannot be
assessed. Taking into consideration the weight of evidence, EFSA concluded that there is
a very limited evidence of association between glyphosate exposure and the occurrence
of NHL, which would not alter the classification proposal derived from animal studies that
glyphosate is unlikely to pose a carcinogenic hazard to humans.
Recognising the value that epidemiological studies can potentially provide to pesticide
risk assessments, EFSA has conducted a number of initiatives in this field. First, EFSA
granted an external review on epidemiological studies on pesticides which identified
some limitations (Ntzani
et al.,
2013). As a follow up, EFSA launched a project including
the preparation of two Scientific Opinions, one to facilitate the use of epidemiological
studies in the risk assessment of pesticides, and another investigating the potential link
of pesticides toxicity with Parkinson’s disease and childhood leukaemia by using criteria
within the Adverse Outcome Pathway framework. The two scientific Opinions are
expected to be launched for public consultation in November 2016 and June 2016
respectively.
Assessment of Plant Protection Products and co-Formulants
In line with Article 12 of Regulation (EC) No 1107/2009
2
the EFSA Conclusion presents
the assessment and properties of the active substance glyphosate, considering the
technical specifications provided by the applicants. The dossier includes a representative
formulated product. The information on this representative product has been considered
by EFSA during the evaluation of the active substance according to the relevant guidance
documents for the different scientific sections. Studies on the representative product or
other formulated products, either included in the dossier or made available during the
peer-review process, have been considered by EFSA when relevant for the assessment of
the active substance. The EFSA assessment would be relevant for the assessment of the
hazard properties, including classification and labelling, and risk assessment of PPPs by
the MSs, however, EFSA has not evaluated the hazard and risk of the PPPs as this is out
of the EFSA remits and would require a specific mandate and submission of additional
information, including the PPP dossiers.
EFSA has been mandated by the European Commission to assess a co-formulant, POE-
tallowamine, that although not present in the representative formulation, is reported as
co-formulant for other glyphosate containing PPPs. EFSA does not support the health-
based reference values proposed by the RMS, and considers that the genotoxicity, long
term toxicity/carcinogenicity, reproductive/developmental toxicity and endocrine
disrupting potential of this co-formulant should be clarified before setting health-based
reference values and conducting the risk assessment (EFSA, 2015c).
Consumer Risk Assessment
2
Regulation (EC) No 1107/2009 of the European Parliament and of the Council of 21 October 2009 concerning
the placing of plant protection products on the market and repealing Council Directives 79/117/EEC and
91/414/EEC. OJ No L 309, 24.11.2009, p. 1-50
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Following previous EU and JMPR assessments, the RMS in its initial assessment
(Germany, 2013) did not propose setting an Acute Reference Dose (ARfD). However,
following the re-evaluation during the EFSA peer-review, EFSA has concluded that the
toxicity of glyphosate requires setting an ARfD of 0.5 mg/kg bw. It should be noted that
this proposal has been agreed by the RMS.
This recommendation triggers the evaluation of acute exposure during the consumer risk
assessment. EFSA will consider this conclusion during the review of the MRLs for
glyphosate under Art. 12 of Regulation (EC) No 396/2005, to be conducted by EFSA in
cooperation with the MSs during 2016.
References
Alavanja et al., 1996. Alavanja, M.C.R.; Sandler, D.P.; McMaster, S.B.; Zahm,
S.H.; McDonnell, C.J.; Lynch, C.F.; Pennybacker, M.; Rothman, N.; Dosemeci,
M.; Bond, A.E.; Blair, A., The Agricultural Health Study. Environmental Health
Perspectives, Volume 104, Number 4, April 1996, 362-369
EFSA (European Food Safety Authority), 2015a. Conclusion on the peer review of
the pesticide risk assessment of the active substance glyphosate. EFSA
Journal 2015;13(issue):NNNN, 35 pp. doi:10.2903/j.efsa.2015.NNNN
EFSA (European Food Safety Authority), 2015b. Peer Review Report to the
conclusion regarding the peer review of the pesticide risk assessment of the
active substance glyphosate. Available at
www.efsa.europa.eu
EFSA (European Food Safety Authority), 2015c. Statement of EFSA on the
request for the evaluation of the toxicological assessment of the co-formulant
POE-tallowamine. Available at
www.efsa.europa.eu
Germany, 2013.
Renewal assessment report (RAR) on the active substance
glyphosate prepared by the rapporteur Member State Germany in the
framework of Regulation (EU) No 1141/2010, December 2013. Available at
www.efsa.europa.eu
Germany, 2015. Final Addendum to the renewal assessment report on
glyphosate,
compiled
by
EFSA,
October
2015.
Available
at
www.efsa.europa.eu
IARC (International Agency for Research on Cancer), 2015. Monographs, Volume
112: Some organophosphate insecticides and herbicides: tetrachlorvinphos,
parathion, malathion, diazinon and glyphosate. IARC Working Group. Lyon; 3–
10 March 2015. IARC Monogr Eval Carcinog Risk Chem Hum.
Ntzani
et al.,
2013. Ntzani EE, Chondrogiorgi M, Ntritsos G, Evangelou E,
Tzoulaki I, 2013. Literature review on epidemiological studies linking exposure
to pesticides and health effects. EFSA supporting publication 2013:EN-497,
159 pp. Available online:
www.efsa.europa.eu/publications
OECD (Organisation for Economic Co-operation and Development), 2012a.
Series on Testing and Assessment: No 116: Guidance document 116 on the
conduct and design of chronic toxicity and carcinogenicity studies, supporting
test guidelines 451, 452 and 453 2nd edition. ENV/JM/MONO(2011)47, 156
pp.
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Last date modified
Final draft version 7
DCM and JT
JT / JK / DCM / MT / BV / JS / JT
09/11/2015
7