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BMJ Clin Evid. 2008; 2008: 1305.
Published online 2008 July 17.
PMCID: PMC2907968

Halitosis

Crispian Scully, CBE, Dean and Director of Studies# and Stephen Porter, Head of Unit and Honorary Consultant#

Abstract

Introduction

Halitosis can be caused by oral disease, or by respiratory tract conditions such as sinusitis, tonsillitis, and bronchiectasis, but an estimated 40% of affected individuals have no underlying organic disease.

Methods and outcomes

We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments in people with physiological halitosis? We searched: Medline, Embase, The Cochrane Library, and other important databases up to July 2008 (Clinical evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

Results

We found five systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

Conclusions

In this systematic review we present information relating to the effectiveness and safety of the following interventions: artificial saliva; cleaning, brushing, or scraping the tongue; diet modification; regular or single use of mouthwash; sugar-free chewing gums; and zinc toothpastes.

Key Points

Halitosis can be caused by oral disease, or by respiratory tract conditions such as sinusitis, tonsillitis, and bronchiectasis, but an estimated 40% of affected people have no underlying organic disease.

  • The main chemicals causing the odour seem to be volatile sulphur compounds, but little is known about the cause of physiological halitosis.

Regular use of a mouthwash may reduce breath odour compared with placebo, but single-use mouthwash may have only a short-term benefit.

We don't know whether tongue cleaning, sugar-free chewing gums, zinc toothpastes, artificial saliva, or dietary modification reduce halitosis, as no studies of adequate quality have been found.

About this condition

Definition

Halitosis is an unpleasant odour emitted from the mouth. It may be caused by oral conditions, including poor oral hygiene, and periodontal disease, or by respiratory tract conditions, such as chronic sinusitis, tonsillitis, and bronchiectasis. In this review, we deal only with physiological halitosis (i.e. confirmed persistent bad breath in the absence of systemic, oral, or periodontal disease). We have excluded halitosis caused by underlying systemic disease that would require disease-specific treatment, pseudo-halitosis (in people who believe they have bad breath but whose breath is not considered malodourous by others), and artificially induced halitosis (e.g. in studies requiring people to stop brushing their teeth). This review is only applicable, therefore, to people in whom such underlying causes have been ruled out, and in whom pseudo-halitosis has been excluded. There is no consensus regarding duration of bad breath for the diagnosis of halitosis, although the standard organoleptic test for bad breath involves smelling the breath on at least two or three different days.

Incidence/ Prevalence

We found no reliable estimate of prevalence, although several studies report the population prevalence of halitosis (physiological or because of underlying disease) to be about 50%. One cross-sectional study of 491 people found that about 5% of people with halitosis have pseudo-halitosis and about 40% have physiological bad breath not caused by underlying disease. We found no reliable data about age or sex distribution of physiological halitosis.

Aetiology/ Risk factors

We found no reliable data about risk factors for physiological bad breath. Mass spectrometric and gas chromatographic analysis of expelled air from the mouths of people with any type of halitosis have shown that the principal malodorants are volatile sulphur compounds, including hydrogen sulphide, methyl mercaptan, and dimethyl sulphide.

Prognosis

We found no evidence on the prognosis of halitosis.

Aims of intervention

To improve social functioning; to reduce embarrassment; to reduce odour, with minimum adverse effects.

Outcomes

Breath odor, measured by organoleptic test scores or other odour scales; quality of life including embarrassment and social functioning; adverse effects. We excluded non-clinical outcomes such as gas chromatography and spectroscopy results, and concentrations of compounds in exhaled air.

Methods

Clinical Evidence search and appraisal July 2008. The following databases were used to identify studies for this systematic review: Medline 1966 to July 2008, Embase 1980 to July 2008, and The Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Clinical Trials 2008, Issue 2 (1966 to date of issue). An additional search was carried out of the NHS Centre for Reviews and Dissemination (CRD) — for Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment (HTA). We also searched for retractions of studies included in the review. Abstracts of the studies retrieved from the initial search were assessed by an information specialist. Selected studies were then sent to the contributor for additional assessment, using predetermined criteria to identify relevant studies. Study design criteria for inclusion in this review were: published systematic reviews of RCTs and RCTs in any language, and containing more than 20 individuals of whom more than 80% were followed up. There was no minimum length of follow-up required to include studies. We excluded all studies described as "open", "open label", or not blinded unless blinding was impossible. We included systematic reviews of RCTs and RCTs where harms of an included intervention were studied, applying the same study design criteria for inclusion as we did for benefits. In addition, we use a regular surveillance protocol to capture harms alerts from organisations such as the FDA and the MHRA, which are added to the reviews as required. We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table). The categorisation of the quality of the evidence (high, moderate, low, or very low) reflects the quality of evidence available for our chosen outcomes in our defined populations of interest. These categorisations are not necessarily a reflection of the overall methodological quality of any individual study, because the Clinical Evidence population and outcome of choice may represent only a small subset of the total outcomes reported, and population included, in any individual trial. For further details of how we perform the GRADE evaluation and the scoring system we use, please see our website (www.clinicalevidence.com).

Table
GRADE Evaluation of interventions for Halitosis.

Glossary

Low-quality evidence
Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Organoleptic test scores
These are assigned by one or more examiners who sniff the person's exhaled breath on two or three different days. People having this examination should not have had antibiotics in the previous 3 weeks, and should have refrained from eating garlic, onions, and spicy foods for 48 hours, and should have refrained from usual oral hygiene and smoking for the previous 12 hours. Scoring systems vary among studies.
Very low-quality evidence
Any estimate of effect is very uncertain.

Notes

Disclaimer

The information contained in this publication is intended for medical professionals. Categories presented in Clinical Evidence indicate a judgement about the strength of the evidence available to our contributors prior to publication and the relevant importance of benefit and harms. We rely on our contributors to confirm the accuracy of the information presented and to adhere to describe accepted practices. Readers should be aware that professionals in the field may have different opinions. Because of this and regular advances in medical research we strongly recommend that readers' independently verify specified treatments and drugs including manufacturers' guidance. Also, the categories do not indicate whether a particular treatment is generally appropriate or whether it is suitable for a particular individual. Ultimately it is the readers' responsibility to make their own professional judgements, so to appropriately advise and treat their patients.To the fullest extent permitted by law, BMJ Publishing Group Limited and its editors are not responsible for any losses, injury or damage caused to any person or property (including under contract, by negligence, products liability or otherwise) whether they be direct or indirect, special, incidental or consequential, resulting from the application of the information in this publication.

Contributor Information

Crispian Scully, UCL - Eastman Dental Institute, London, UK.

Stephen Porter, UCL - Eastman Dental Institute, London, UK.

References

1. Yaegaki K, Coil JM. Examination, classification, and treatment of halitosis; clinical perspectives. J Can Dent Assoc 2000;66:257–261. [PubMed]
2. Frascella J, Gilbert RD, Fernandez P, et al. Efficacy of a chlorine dioxide-containing mouthrinse in oral malodor. Compend Contin Educ Dent 2000;21:241–254. [PubMed]
3. Meningaud JP, Bado F, Favre E, et al. Halitosis in 1999. Rev Stomatol Chir Maxillofac 1999;100:240–244. [In French] [PubMed]
4. Bollen CM, Rompen EH, Demanez JP. Halitosis: a multidisciplinary problem. Rev Med Liege 1999;54:32–36. [In French] [PubMed]
5. Tomas Carmona I, Limeres Posse J, Diz Dios P, et al. Extraoral etiology of halitosis. Med Oral 2001;6:40–47. [PubMed]
6. Delanghe G, Bollen C, van Steenberghe D, et al. Halitosis, foetor ex ore. Ned Tijdschr Tandheelkd 1998;105:314–317 [In Dutch] [PubMed]
7. Tonzetich J. Direct gas chromatographic analysis of sulphur compounds in mouth air in man. Arch Oral Biol 1971;16:587–597. [PubMed]
8. Kleinberg I, Westbay G. Oral malodor. Crit Rev Oral Biol Med 1990;1:247–259. [PubMed]
9. Winkel EG, Roldan S, Van Winkelhoff AJ, et al. Clinical effects of a new mouthrinse containing chlorhexidine, cetylpyridinium chloride and zinc-lactate on oral halitosis. A dual-center, double-blind placebo-controlled study. J Clin Periodontol 2003;30:300–306. [PubMed]
10. Borden LC, Chaves ES, Bowman JP, et al. The effect of four mouthrinses on oral malodor. Compend Contin Educ Dent 2002;23:531–546. [PubMed]
11. Codipilly DP, Kaufman HW, Kleinberg I. Use of a novel group of oral malodor measurements to evaluate an anti-oral malodor mouthrinse (TriOralTM ) in humans. J Clin Dent 2004;15:98−104. [PubMed]
12. Frascella J, Gilbert R, Fernandez P. Odor reduction potential of a chlorine dioxide mouthrinse. J Clin Dent 1998;9:39–42. [PubMed]
2008; 2008: 1305.
Published online 2008 July 17.

Regular-use mouthwash (containing chlorhexidine, zinc, hydrogen peroxide, or other antimicrobial agents)

Summary

Regular use of a mouthwash may reduce breath odour compared with placebo.

Benefits and harms

Regular-use mouthwash versus placebo:

We found three RCTs. The first RCT compared an active-treatment mouthwash (containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate) versus a placebo mouthwash. The mouthwashes were used twice daily for 2 weeks. The second RCT compared four mouthwashes used twice daily for 4 weeks: one containing essential oils; one containing cetylpyridinium chloride; one containing chlorine dioxide plus zinc; and a placebo mouthwash (composition not reported). The third RCT compared three interventions over 4 weeks: mouthwash containing zinc chloride plus sodium chlorite; mouthwash containing zinc chloride alone; and placebo mouthwash. All participants were instructed to use mouthwash for 30 seconds twice daily.

Breath odour

Regular-use mouthwash compared with placebo Regular use of a mouthwash containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate or cetylpyridinium chloride alone, or zinc chloride plus sodium chlorite may be more effective than placebo at reducing breath odour at 2 to 4 weeks. However, regular use of mouthwash containing essential oil or chlorine dioxide plus zinc may be no more effective at reducing breath odour at 2 weeks (low-quality evidence).

Ref (type)PopulationOutcome, InterventionsResults and statistical analysisEffect sizeFavours
Breath odour

RCT
40 people Mean odour score change from baseline 2 weeks
–1.3 with mouthwash containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate
–0.2 with placebo mouthwash

P <0.005
Effect size not calculatedregular-use mouthwash containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate

RCT
4-armed trial
99 people Mean odour score change from baseline 4 weeks
–0.41 with mouthwash containing cetylpyridinium chloride
+0.16 with placebo mouthwash

P <0.05 for cetylpyridinium chloride mouthwash v placebo
4 people were excluded or withdrew after randomisation
Analysis not by intention to treat
Effect size not calculatedregular-use mouthwash containing cetylpyridinium chloride

RCT
4-armed trial
99 people Mean odour score change from baseline 4 weeks
+0.06 with chlorine dioxide plus zinc mouthwash
+0.16 with placebo mouthwash

P value reported as not significant for chlorine dioxide plus zinc mouthwash v placebo
4 people were excluded or withdrew after randomisation
Analysis not by intention to treat
Not significant

RCT
4-armed trial
99 people Mean odour score change from baseline 4 weeks
0 with essential oil mouthwash
+0.16 with placebo mouthwash

P value reported as not significant for essential oil mouthwash v placebo
4 people were excluded or withdrew after randomisation
Analysis not by intention to treat
Not significant

RCT
3-armed trial
48 people Organoleptic breath scores 4 weeks
with regular-use mouthwash containing zinc chloride plus sodium chlorite
with placebo mouthwash
Absolute results reported graphically

Reported as significant for zinc chloride plus sodium chlorite mouthwash v placebo mouthwash
P value not reported
Effect size not calculatedregular-use mouthwash containing zinc chloride plus sodium chlorite

Quality of life

No data from the following reference on this outcome.

Adverse effects

Ref (type)PopulationOutcome, InterventionsResults and statistical analysisEffect sizeFavours
Breath odour

RCT
40 people Mean change in tongue discoloration score from baseline 2 weeks
+2.8 with mouthwash containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate
+0.3 with placebo mouthwash

P <0.002
Effect size not calculatedplacebo mouthwash

RCT
40 people Tooth staining 2 weeks
with mouthwash containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate
with placebo mouthwash
Absolute results not reported

Reported as non-significant
P value not reported
Not significant

RCT
4-armed trial
99 people Adverse effects 4 weeks
with mouthwash containing cetylpyridinium chloride
with chlorine dioxide plus zinc mouthwash
with essential oil mouthwash
with placebo mouthwash
Absolute results not reported

4 people were excluded or withdrew after randomisation
Analysis not by intention to treat

No data from the following reference on this outcome.

Regular-use mouthwashes versus each other:

We found two RCTs. The first RCT compared four mouthwashes used twice daily for 4 weeks: one containing essential oils; one containing cetylpyridinium chloride; one containing chlorine dioxide plus zinc; and a placebo mouthwash (composition not reported). The second RCT compared three interventions over 4 weeks: mouthwash containing zinc chloride plus sodium chlorite; mouthwash containing zinc chloride alone; and placebo mouthwash. All participants were instructed to use mouthwash for 30 seconds twice daily.

Breath odour

Regular-use mouthwashes compared with each other We don't know how mouthwash containing cetylpyridinium chloride, chlorine dioxide plus zinc mouthwash, and essential oil mouthwash compare with each other at reducing breath odour at 4 weeks. Regular use of a mouthwash containing zinc chloride plus sodium chlorite may be more effective than mouthwash containing zinc chloride alone at reducing breath odour at 4 weeks (low-quality evidence).

Ref (type)PopulationOutcome, InterventionsResults and statistical analysisEffect sizeFavours
Breath odour

RCT
4-armed trial
99 people Mean odour score change from baseline 4 weeks
–0.41 with mouthwash containing cetylpyridinium chloride
+0.06 with chlorine dioxide plus zinc mouthwash
0 with essential oil mouthwash

P value (among the 3 treatment groups) reported as not significant
4 people were excluded or withdrew after randomisation
Analysis not by intention to treat
Not significant

RCT
3-armed trial
48 people Organoleptic breath scores 4 weeks
with regular-use mouthwash containing zinc chloride plus sodium chlorite
with regular-use mouthwash containing zinc chloride only
Absolute results reported graphically

Reported as significant for zinc chloride plus sodium chlorite mouthwash v zinc chloride alone mouthwash
P value not reported
Effect size not calculatedregular-use mouthwash containing zinc chloride plus sodium chlorite

Quality of life

No data from the following reference on this outcome.

Adverse effects

Ref (type)PopulationOutcome, InterventionsResults and statistical analysisEffect sizeFavours
Adverse effects

RCT
4-armed trial
99 people Adverse effects 4 weeks
with mouthwash containing cetylpyridinium chloride
with chlorine dioxide plus zinc mouthwash
with essential oil mouthwash
with placebo mouthwash
Absolute results not reported

4 people were excluded or withdrew after randomisation
Analysis not by intention to treat

No data from the following reference on this outcome.

Regular-use mouthwash versus single-use mouthwash, artificial saliva, diet modification, sugar-free gum, tongue cleaning, or zinc toothpastes:

We found no systematic review or RCTs.

Further information on studies

Comment

None.

Substantive changes

No new evidence

2008; 2008: 1305.
Published online 2008 July 17.

Single-use mouthwash (containing chlorhexidine, zinc, hydrogen peroxide, or other antimicrobial agents)

Summary

Single-use mouthwash may reduce breath odour compared with placebo but may have only a short-term benefit.

Benefits and harms

Single-use mouthwash versus placebo:

We found three small RCTs that compared a mouthwash after a single use versus control (distilled water or placebo). Two RCTs compared single-use chlorine dioxide 0.1% mouthwash versus distilled water in healthy adults with confirmed oral malodour. The third RCT compared regular use of three active-treatment mouthwashes versus placebo mouthwash, but also reported results for breath odour after a single use (see option on regular-use mouthwash). The RCT compared one mouthwash containing essential oils, one containing cetylpyridinium chloride, one containing chlorine dioxide plus zinc, and one placebo mouthwash (composition not reported).

Breath odour

Compared with placebo Single-use chlorine dioxide mouthwash may reduce odour unpleasantness and odour intensity 4 to 8 hours after use, but may be no more effective after 24 to 96 hours. Single-use cetylpyridinium chloride mouthwash may be more effective after 4 hours at reducing breath odour, but essential oil mouthwash may be no more effective (very low-quality evidence).

Ref (type)PopulationOutcome, InterventionsResults and statistical analysisEffect sizeFavours
Breath odour

RCT
31 women Change in odour unpleasantness from baseline 8 hours
from –1.25 to –0.63 with single-use chlorine dioxide mouthwash
from –1.40 to –1.29 with distilled water

P <0.01
Effect size not calculatedsingle-use chlorine dioxide mouthwash

RCT
31 women Change in odour unpleasantness from baseline 24 hours
with single-use chlorine dioxide mouthwash
with distilled water
Absolute results not reported

Reported as non-significant
P value >0.05
Not significant

RCT
31 women Change in odour unpleasantness from baseline 48 hours
with single-use chlorine dioxide mouthwash
with distilled water
Absolute results not reported

Reported as non-significant
P value >0.05
Not significant

RCT
31 women Change in odour unpleasantness from baseline 72 hours
with single-use chlorine dioxide mouthwash
with distilled water
Absolute results not reported

Reported as non-significant
P value >0.05
Not significant

RCT
31 women Change in odour unpleasantness from baseline 96 hours
with single-use chlorine dioxide mouthwash
with distilled water
Absolute results not reported

Reported as non-significant
P value > 0.05
Not significant

RCT
31 women Change in odour intensity from baseline 8 hours
from 1.27 to 0.63 with single-use chlorine dioxide mouthwash
from 1.42 to 1.29 with distilled water

P <0.01
Effect size not calculatedsingle-use chlorine dioxide mouthwash

RCT
31 women Change in odour intensity from baseline 24 hours
with single-use chlorine dioxide mouthwash
with distilled water
Absolute results not reported

Reported as non-significant
P >0.05
Not significant

RCT
31 women Change in odour intensity from baseline 48 hours
with single-use chlorine dioxide mouthwash
with distilled water
Absolute results not reported

Reported as non-significant
P value >0.05
Not significant

RCT
31 women Change in odour intensity from baseline 72 hours
with single-use chlorine dioxide mouthwash
with distilled water
Absolute results not reported

Reported as non-significant
P value >0.05
Not significant

RCT
31 women Change in odour intensity from baseline 96 hours
with single-use chlorine dioxide mouthwash
with distilled water
Absolute results not reported

Reported as non-significant
P >0.05
Not significant

RCT
Crossover design
12 people Change in odour unpleasantness score from baseline 4 hours
from –1.25 to –0.61 with single-use chlorine dioxide mouthwash
from –1.06 to –1.08 with distilled water

P <0.01
Effect size not calculatedsingle-use chlorine dioxide mouthwash

RCT
Crossover design
12 people Change in odour intensity score from baseline 4 hours
from 1.14 to 0.81 with single-use chlorine dioxide mouthwash
from 1.11 to 1.19 with distilled water

P = 0.03
Effect size not calculatedsingle-use chlorine dioxide mouthwash

RCT
4-armed trial
99 people Mean odour score change from baseline 4 hours
–0.94 with single-use mouthwash containing cetylpyridinium chloride
–0.22 with placebo mouthwash

P <0.05 for single-use cetylpyridinium chloride mouthwash v placebo
Effect size not calculatedsingle-use cetylpyridinium chloride mouthwash

RCT
4-armed trial
99 people Mean odour score change from baseline 4 hours
–0.52 with single-use mouthwash containing chlorine dioxide
–0.22 with placebo mouthwash

P value reported as not significant for single-use mouthwash containing chlorine dioxide v placebo
Not significant

RCT
4-armed trial
99 people Mean odour score change from baseline 4 hours
–0.42 with essential oil mouthwash
–0.22 with placebo mouthwash

P value reported as not significant for single-use mouthwash containing essential oil v placebo
Not significant

Quality of life

No data from the following reference on this outcome.

Adverse effects

No data from the following reference on this outcome.

Single-use mouthwashes versus each other:

We found one RCT (99 people), which compared regular use of three active-treatment mouthwashes versus placebo mouthwash, but also reported results after a single use (see option on regular-use mouthwash). The RCT compared one mouthwash containing essential oils, one containing cetylpyridinium chloride, one containing chlorine dioxide plus zinc, and one placebo mouthwash (composition not reported).

Breath odour

Single-use mouthwashes compared with each other Single-use cetylpyridinium chloride mouthwash may improve breath odour compared with chlorine dioxide plus zinc mouthwash and essential oil mouthwash after 4 hours (low-quality evidence).

Ref (type)PopulationOutcome, InterventionsResults and statistical analysisEffect sizeFavours
Breath odour

RCT
4-armed trial
99 people Mean odour score change from baseline 4 hours
–0.94 with cetylpyridinium chloride mouthwash
–0.52 with chlorine dioxide plus zinc mouthwash
–0.42 with essential oil mouthwash

P <0.05 for cetylpyridinium chloride mouthwash v other active treatments
Effect size not calculatedsingle-use cetylpyridinium chloride mouthwash

Quality of life

No data from the following reference on this outcome.

Adverse effects

No data from the following reference on this outcome.

Single-use mouthwash versus regular-use mouthwash, artificial saliva, diet modification, sugar-free gum, tongue cleaning, or zinc toothpastes:

We found no systematic review or RCTs.

Further information on studies

The two RCTs of chlorine dioxide mouthwash were conducted by the same research group.

Comment

None.

Substantive changes

No new evidence

2008; 2008: 1305.
Published online 2008 July 17.

Artificial saliva

Summary

We don't know whether artificial saliva reduces halitosis, as no trials of adequate quality have been found.

Benefits and harms

Artificial saliva:

We found no systematic review or RCTs comparing artificial saliva versus placebo or versus the other interventions covered by this review.

Further information on studies

Comment

None.

Substantive changes

No new evidence

2008; 2008: 1305.
Published online 2008 July 17.

Diet modification (drinking plenty of liquids; chewing herbs; eating fresh, fibrous vegetables such as carrots; avoiding coffee)

Summary

We don't know whether dietary modification reduces halitosis, as no trials of adequate quality have been found.

Benefits and harms

Diet modification:

We found no systematic review or RCTs comparing dietary modification versus placebo or versus the other interventions covered by this review.

Further information on studies

Comment

None.

Substantive changes

No new evidence

2008; 2008: 1305.
Published online 2008 July 17.

Sugar-free chewing gum

Summary

We don't know whether sugar-free chewing gums reduce halitosis, as no trials of adequate quality have been found.

Benefits and harms

Sugar-free chewing gum:

We found no systematic review or RCTs comparing sugar-free chewing gum versus placebo or versus the other interventions covered by this review.

Further information on studies

Comment

None.

Substantive changes

No new evidence

2008; 2008: 1305.
Published online 2008 July 17.

Tongue cleaning, brushing, or scraping

Summary

We don't know whether tongue cleaning reduces halitosis, as no trials of adequate quality have been found.

Benefits and harms

Tongue cleaning, brushing, or scraping:

We found no systematic review or RCTs comparing tongue cleaning versus placebo or versus the other interventions covered by this review.

Further information on studies

Comment

None.

Substantive changes

No new evidence

2008; 2008: 1305.
Published online 2008 July 17.

Zinc toothpastes

Summary

We don't know whether zinc toothpastes reduce halitosis, as no trials of adequate quality have been found.

Benefits and harms

Zinc toothpastes:

We found no systematic review or RCTs comparing zinc toothpastes versus placebo or versus the other interventions covered by this review.

Further information on studies

Comment

None.

Substantive changes

No new evidence


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