Flawed MIREC fluoride and intelligence quotient publications: A failed attempt to undermine community water fluoridation.

OBJECTIVE: To assess the evidence presented in a set of articles that use the Canadian Maternal-Infant Research on Environmental Chemicals (MIREC) study database to claim that community water fluoridation (CWF) is associated with harm to foetal and infant cognitive development. METHODS: Critical appraisal of measurements and processes in the MIREC database, and articles derived therefrom. MIREC's cohort is approximately 2000 pregnant women recruited in 10 centres across Canada, 2008-2011, leading to measuring 512 children aged 3-6 years in six cities. Fluoride exposure was measured by city fluoridation status, self-reports and maternal spot urine samples. Intelligence Quotient (IQ) was measured using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) by different assessors in each city. RESULTS: MIREC's fluoride and IQ measurements are invalid and therefore cannot support the claim that CWF is associated with IQ decline in children. CONCLUSIONS: The MIREC fluoride-IQ articles' results should be considered unacceptable for legal and policy purposes; other water fluoridation studies and systematic reviews show no effect of fluoridation on cognition.

Comments on recent community water fluoridation studies.

Water fluoridation is a public health measure to reduce levels of dental caries in populations. A report of the recently completed CATFISH study has been published. This was the first UK evaluation of fluoridation introduction for many years; it was carefully designed and executed and is welcomed. The purpose of this article is to highlight the 180-page report of the study and comment on some aspects to aid interpretation of the findings. Significant features were that two cohorts, from birth and from five years, were followed for six years in a fluoridated and a non-fluoridated area, and clinical and cost analyses were reported. Areas of the report which deserve comment are: a) interruption of fluoridation for a year for half the children in the intervention area and its effect; b) clinical results were reported as absolute reduction in caries prevalence, with the preventive fraction for caries severity downplayed; c) the power of the study was diminished by an unexpected lower caries increment; and d) control for differences in diet was not possible. Nevertheless, this major UK study showed clinical and cost benefits of water fluoridation. The risk of cessation of water fluoridation is highlighted in examples of three recently published studies.

Chapter 8: Milk, Yoghurts and Dental Caries.

Milk is an important part of the human diet; after weaning, cow's milk (bovine milk) predominates and this chapter considers the effect of bovine milk on dental caries. Yoghurt, which is a milk product, is also considered here. Several published reviews have concluded that milk is of very low cariogenicity and may have some caries protective potential. For example, WHO reviewed the strength of the evidence in 2003 and concluded that a "decreased risk" of dental caries from milk was "possible." The evidence comes from several types of study: epidemiological studies (interventional and observational), animal experiments, plaque pH studies, and in vivo and in vitro enamel and dentine slab experiments. More recent observational epidemiological studies have adjusted for potential confounders and have reported that milk consumption is associated with lower caries experience or incidence. Other types of study generally support this conclusion. Reasons for these favourable caries-related properties include the lower acidogenicity of lactose compared with other dietary sugars and the protective effects of calcium, phosphate, proteins, and fats. There is less research concerning yoghurts but it is likely that the cariogenic potential of plain yoghurt is similar to that of milk. The addition of sucrose to milk increases caries risk.

WHO Global Consultation on Public Health Intervention against Early Childhood Caries.

Early Childhood Caries (ECC) is prevalent around the world, but in particular the disease is growing rapidly in low- and middle-income countries in parallel with changing diet and lifestyles. In many countries, ECC is often left untreated, a condition which leads to pain and adversely affects general health, growth and development, and quality of life of children, their families and their communities. Importantly, ECC is also a global public health burden, medically, socially and economically. In many countries, a substantial number of children require general anaesthesia for the treatment of caries in their primary teeth (usually extractions), and this has considerable cost and social implications. A WHO Global Consultation with oral health experts on "Public Health Intervention against Early Childhood Caries" was held on 26-28 January 2016 in Bangkok (Thailand) to identify public health solutions and to highlight their applicability to low- and middle-income countries. After a 3-day consultation, participants agreed on specific recommendations for further action. National health authorities should develop strategies and implement interventions aimed at preventing and controlling ECC. These should align with existing international initiatives such as the Sixtieth World Health Assembly Resolution WHA 60.17 Oral health: action plan for promotion and integrated disease prevention, WHO Guideline on Sugars and WHO breastfeeding recommendation. ECC prevention and control interventions should be integrated into existing primary healthcare systems. WHO public health principles must be considered when tackling the effect of social determinants in ECC. Initiatives aimed at modifying behaviour should focus on families and communities. The involvement of communities in health promotion, and population-directed and individual fluoride administration for the prevention and control of ECC is essential. Surveillance and research, including cost-effectiveness studies, should be conducted to evaluate interventions aimed at preventing ECC in different population groups.

Factors Influencing Early Feeding of Foods and Drinks Containing Free Sugars-A Birth Cohort Study.

Early feeding of free sugars to young children can increase the preference for sweetness and the risk of consuming a cariogenic diet high in free sugars later in life. This study aimed to investigate early life factors influencing early introduction of foods/drinks containing free sugars. Data from an ongoing population-based birth cohort study in Australia were used. Mothers of newborn children completed questionnaires at birth and subsequently at ages 3, 6, 12, and 24 months. The outcome was reported feeding (Yes/No) at age 6-9 months of common foods/drinks sources of free sugars (hereafter referred as foods/drinks with free sugars). Household income quartiles, mother's sugar-sweetened beverage (SSB) consumption, and other maternal factors were exposure variables. Analysis was conducted progressively from bivariate to multivariable log-binomial regression with robust standard error estimation to calculate prevalence ratios (PR) of being fed foods/drinks with free sugars at an early age (by 6-9 months). Models for both complete cases and with multiple imputations (MI) for missing data were generated. Of 1479 mother/child dyads, 21% of children had been fed foods/drinks with free sugars. There was a strong income gradient and a significant positive association with maternal SSB consumption. In the complete-case model, income Q1 and Q2 had PRs of 1.9 (1.2-3.1) and 1.8 (1.2-2.6) against Q4, respectively. The PR for mothers ingesting SSB everyday was 1.6 (1.2-2.3). The PR for children who had been breastfed to at least three months was 0.6 (0.5-0.8). Similar findings were observed in the MI model. Household income at birth and maternal behaviours were significant determinants of early feeding of foods/drinks with free sugars.

Common risk factor approach to address socioeconomic inequality in the oral health of preschool children--a prospective cohort study.

BACKGROUND: Dental caries remains the most prevalent chronic condition in children and a major contributor to poor general health. There is ample evidence of a skewed distribution of oral health, with a small proportion of children in the population bearing the majority of the burden of the disease. This minority group is comprised disproportionately of socioeconomically disadvantaged children. An in-depth longitudinal study is needed to better understand the determinants of child oral health, in order to support effective evidence-based policies and interventions in improving child oral health. The aim of the Study of Mothers' and Infants' Life Events Affecting Oral Health (SMILE) project is to identify and evaluate the relative importance and timing of critical factors that shape the oral health of young children and then to seek to evaluate those factors in their inter-relationship with socioeconomic influences. METHODS/DESIGN: This investigation will apply an observational prospective study design to a cohort of socioeconomically-diverse South Australian newborns and their mothers, intensively following these dyads as the children grow to toddler age. Mothers of newborn children will be invited to participate in the study in the early post-partum period. At enrolment, data will be collected on parental socioeconomic status, mothers' general and dental health conditions, details of the pregnancy, infant feeding practice and parental health behaviours and practices. Data on diet and feeding practices, oral health behaviours and practices, and dental visiting patterns will be collected at 3, 6, 12 and 24 months of age. When children turn 24-30 months, the children and their mothers/primary care givers will be invited to an oral examination to record oral health status. Anthropometric assessment will also be conducted. DISCUSSION: This prospective cohort study will examine a wide range of determinants influencing child oral health and related general conditions such as overweight. It will lead to the evaluation of the inter-relationship among main influences and their relative effect on child oral health. The study findings will provide high level evidence of pathways through which socio-environmental factors impact child oral health. It will also provide an opportunity to examine the relationship between oral health and childhood overweight.

Dental caries: strategies to control this preventable disease.

OBJECTIVE: To provide a brief commentary review of strategies to control dental caries. Dental decay is one of man's most prevalent diseases. In many counties, severity increased in parallel with importation of sugar, reaching its zenith about 1950s and 1960s. Since then, severity has declined in many countries, due to the wide use of fluoride especially in toothpaste, but dental caries remains a disease of medical, social and economic importance. Within the EU in 2011, the cost of dental treatment was estimated to be €79 billion. The pathogenesis is well understood: bacteria in dental plaque (biofilm) metabolise dietary sugars to acids which then dissolve dental enamel and dentine. Possible approaches to control caries development, therefore, involve: removal of plaque, reducing the acidogenic potential of plaque, reduction in sugar consumption, increasing the tooth's resistance to acid attack, and coating the tooth surface to form a barrier between plaque and enamel. At the present time, only three approaches are of practical importance: sugar control, fluoride, and fissure sealing. The evidence that dietary sugars are the main cause of dental caries is extensive, and comes from six types of study. Without sugar, caries would be negligible. Fluoride acts in several ways to aid caries prevention. Ways of delivering fluoride can be classed as: 'automatic', 'home care' and 'professional care': the most important of these are discussed in detail in four articles in this issue of the Acta Medica Academica. CONCLUSION: Dental caries is preventable - individuals, communities and countries need strategies to achieve this.

Milk fluoridation for the prevention of dental caries.

UNLABELLED: The aim of this review is to give an overview of 55 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation) in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization which began in the early 1980s. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in various types of milk. Clinical trials were initiated in the 1980s - some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programmes. CONCLUSION: These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. The amount of fluoride added to milk depends on background fluoride exposure and age of the children: commonly in the range 0.5 to 1.0 mg per day. An advantage of the method is that a precise amount of fluoride can be delivered under controlled conditions. The cost of milk fluoridation programmes is low, about € 2 to 3 per child per year. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk programme.

Fluoride toothpastes and fluoride mouthrinses for home use.

OBJECTIVE: To provide a brief commentary review of fluoride-containing toothpastes and mouthrinses with emphasis on their use at home. Toothpastes and mouthrinses are just two of many ways of providing fluoride for the prevention of dental caries. The first investigations into incorporating fluoride into toothpastes and mouthrinses were reported in the middle 1940s. Unlike water fluoridation (which is 'automatic fluoridation'), fluoride-containing toothpastes and fluoridecontaining mouthrinses are, primarily, for home use and need to be purchased by the individual. By the 1960s, research indicated that fluoride could be successfully incorporated into toothpastes and clinical trials demonstrated their effectiveness. By the end of the 1970s, almost all toothpastes contained fluoride. The widespread use of fluoride- containing toothpastes is thought to be the main reason for much improved oral health in many countries. Of the many fluoride compounds investigated, sodium fluoride, with a compatible abrasive, is the most popular, although amine fluorides are used widely in Europe. The situation is similar for mouthrinses. Concentrations of fluoride (F), commonly found, are 1500 ppm (1500 µg F/g) for toothpastes and 225 ppm (225 µg F/ml) for mouthrinse. Several systematic reviews have concluded that fluoride-containing toothpastes and mouthrinses are effective, and that there is added benefit from their use with other fluoride delivery methods such as water fluoridation. Guidelines for the appropriate use of fluoride toothpastes and mouthrinses are available in many countries. CONCLUSION: Fluoride toothpastes and mouthrinses have been developed and extensive testing has demonstrated that they are effective and their use should be encouraged.

Effectiveness of water fluoridation in caries prevention.

OBJECTIVES: To review the effectiveness of adjusted fluoridation of public water supplies in the prevention of dental caries, with emphasis on results of studies published worldwide since 1990 and to discuss aspects of the design and reporting of these studies compared with those published before 1990. METHOD: Studies published worldwide, in any language, reporting the effect of water fluoridation in terms of the dmf/DMF caries index between 1990 and 2010 were examined. The literature search was by professional Internet search, back-tracking from references given in publications, hand-searching all issues of four journals and by contacting colleagues in relevant countries. For the dmf index, age 5 year was preferred, and for the DMF index, age 12 year or older was preferred. The results were compared with results obtained from worldwide literature search prior to 1990 by the same author. RESULTS: Fifty-nine studies of adjusted water fluoridation were identified, yielding 83 evaluations (30 recording dmft/s and 53 recording DMFT/S) from 10 countries. These numbers are lower than pre-1990 results of 113 studies (66 for primary and 86 for permanent teeth) from 23 countries. For the USA, for example, four studies were identified since 1990 compared with 61 studies before 1990. The most number of recent reports came from Brazil and Australia. There were fewer reports of per cent caries reductions (% CR) above 50% in the recent studies. 86% of the post-1990 investigations were concurrent control cross-sectional studies and, of these, 52% used multivariate statistical analysis to adjust for confounding factors. In the eight studies that provided dmf/DMF data before and after adjustment for confounders, the % CR were little affected by these adjustments. CONCLUSIONS: Fewer studies have been published recently. More of these have investigated effect at the multi-community, state or even national level. The dmf/DMF index remains the most widely used measure of effect. % CR were lower in recent studies, and the 'halo' effect was discussed frequently. Nevertheless, reductions were still substantial. Statistical control for confounding factors is now routine, although the effect on per cent reductions tended to be small. Further thought is needed about the purpose of evaluation and whether measures of effect and study design are appropriate for that purpose.

Contemporary biological markers of exposure to fluoride.

Contemporary biological markers assess present, or very recent, exposure to fluoride: fluoride concentrations in blood, bone surface, saliva, milk, sweat and urine have been considered. A number of studies relating fluoride concentration in plasma to fluoride dose have been published, but at present there are insufficient data on plasma fluoride concentrations across various age groups to determine the 'usual' concentrations. Although bone contains 99% of the body burden of fluoride, attention has focused on the bone surface as a potential marker of contemporary fluoride exposure. From rather limited data, the ratio surface-to-interior concentration of fluoride may be preferred to whole bone fluoride concentration. Fluoride concentrations in the parotid and submandibular/sublingual ductal saliva follow the plasma fluoride concentration, although at a lower concentration. At present, there are insufficient data to establish a normal range of fluoride concentrations in ductal saliva as a basis for recommending saliva as a marker of fluoride exposure. Sweat and human milk are unsuitable as markers of fluoride exposure. A proportion of ingested fluoride is excreted in urine. Plots of daily urinary fluoride excretion against total daily fluoride intake suggest that daily urinary fluoride excretion is suitable for predicting fluoride intake for groups of people, but not for individuals. While fluoride concentrations in plasma, saliva and urine have some ability to predict fluoride exposure, present data are insufficient to recommend utilizing fluoride concentrations in these body fluids as biomarkers of contemporary fluoride exposure for individuals. Daily fluoride excretion in urine can be considered a useful biomarker of contemporary fluoride exposure for groups of people, and normal values have been published.

Raised adolescent body mass index predicts the development of adiposity and a central distribution of body fat in adulthood: a longitudinal study.

OBJECTIVE: To test the hypothesis that adolescent body mass index (BMI) tracks into adulthood and can be used as a predictor of obesity and/or central adiposity in adulthood. METHOD: A prospective cohort study following up 111 female and 84 male subjects who participated in dietary and anthropometric surveys when aged 12 years (in 1979-1981) and 33 years (in 2000-2001). At both time points, height and weight were measured and BMI calculated. At 33 years, waist circumference (WC) and hip circumference were also measured and waist-to-hip ratio (WHR) calculated. RESULTS: In the male and female participants, BMI at 12 years was associated significantly with BMI at 33 years (R = 0.58 and 0.53, respectively, both p < 0.01) and WC at 33 years (R = 0.58 and 0.53, both p < 0.01). The probability of being an obese adult increased with rising adolescent BMI: normal weight male (BMI < 20.89 kg/m(2)) and female subjects (BMI < 21.20 kg/m(2)) at 12 years had a 20% and a 7% chance of being obese at 33 years, respectively; the probabilities for obese male (BMI > or =25.58 kg/m(2)) and female subjects (BMI > or =26.05 kg/m(2)) were 83 and 64%. The corresponding probability of becoming centrally obese (measured by WC) increased from 17 and 16% in male and female subjects of a normal weight to 58 and 59% in those being obese. CONCLUSIONS: Adolescent BMI is a good predictor of adult BMI and WC and the likelihood of becoming obese and/or centrally obese in adulthood.

Tracking of dietary intake and factors associated with dietary change from early adolescence to adulthood: the ASH30 study.

OBJECTIVE: This paper describes the tracking of food intake from adolescence to adulthood according to location as an adult (at the time of the follow-up study) and gender. Additionally this paper explores factors associated with change in food intake. METHOD: Two 3-day food diaries, demographic and socio-economic information were collected in 1980 and 2000 from the same 198 participants (81 male, 117 female). Foods consumed were assigned to the five categories in The Balance of Good Health (BGH) food model. The tracking of food intake was assessed using Pearson correlation analyses. In 2000 two questionnaires were completed. Demographic and key attributional factors, derived from closed and open-ended responses to the questionnaire, were compared with measured change using regression analysis. RESULTS: There was significant tracking of intake by food group from adolescence to adulthood according to location as an adult and gender. Eight combinations of descriptive variables and questionnaire factors were associated with change in intake of four of the five BGH food groups. CONCLUSION: Between adolescence and adulthood, dietary tracking is influenced by variables including gender and location. Attributions for change in food intake were associated with measured changes in food intake. In order to support healthier eating habits, it is important to be aware of factors contributing to changes in food intake, such as parental influences and perceived influences of time and work.

Caries prevention through the fluoridation of milk. A review.

The aim of this review is to give an overview of 50 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation) in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization from the early 1980s onwards. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in milk, and increased concentrations of fluoride in saliva, dental plaque, dental enamel and dentine, and urine, after consumption of fluoridated milk. Clinical trials were initiated in the 1980s--some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programs. These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. At present, milk fluoridation programs are running continuously in about ten countries of the world. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk program. The program should aim to provide fluoridated milk for at least 200 days per year and should commence before the children are 4 years of age.

Healthy eating: perceptions and practice (the ASH30 study).

Perceptions of healthy eating may influence food intake. Anthropometric and dietary data were collected from 197 respondents (average age 32.5 years: 2000/2001) in Northumberland (78%) and elsewhere in the UK (22%). A questionnaire and two 3-day food diaries were completed. Foods consumed were assigned to one of five food categories from The Balance of Good Health. This paper explores respondents' concepts of 'healthy eating' and responses to the statement, 'My eating patterns are healthy' and compares responses with measured intakes for each of the five food categories. Fifty-three respondents disagreed, 62 neither agreed nor disagreed and 82 agreed with the statement. Intakes of foods containing fat and/or sugar, fruit and vegetables and meat, fish and alternatives were significantly different between the three response groups. The 'agree' group had the highest intake of fruit and vegetables and the lowest intake of foods containing fat and/or sugar and meat, fish and alternatives. A significantly higher proportion of individuals from the highest socio-economic group agreed with the statement. Significantly more individuals with Body Mass Indexes in the two lower quartiles agreed with the statement. This paper shows a relationship between perceptions of eating patterns and socio-economic status, adiposity and measured food intake.

Longitudinal change in food habits between adolescence (11-12 years) and adulthood (32-33 years): the ASH30 Study.

BACKGROUND: Links between diet in childhood and the prevention of disease in adulthood have been established. This longitudinal dietary survey provided quantitative evidence of dietary change from adolescence to adulthood, in Northumberland, England. OBJECTIVE: To report longitudinal dietary change in 198 respondents between the ages of 12 and 33 years, to explore dietary 'tracking' between the same time points and to describe the effects of gender, socio-economic status and location on dietary change. METHODS: A longitudinal study recorded dietary change from adolescence to adulthood. Two 3-day food diaries were collected in 1980 and 2000 from the same 198 respondents. Foods consumed were assigned to the five categories in the Balance of Good Health (BGH). Demographic and socio-economic information were obtained in 1980 and 2000. RESULTS: Intakes of foods containing fat and/ or sugar and milk and dairy foods decreased (p < 0.01 and p < 0.031, respectively), while intakes of fruits and vegetables increased (p < 0.01). Intakes of bread, other cereals and potatoes (p = 0.002, r = +0.219); fruits and vegetables (p < 0.01, r = +0.256) and meat, fish and alternatives (p = 0.026, r = +0.158) 'tracked' from adolescence to adulthood. Men had increased intake from meat, fish and alternatives and decreased milk and dairy foods more than female respondents (p = 0.003 and p = 0.019). Respondents who had moved away from Northumberland had a greater increase in intake of fruits and vegetables compared with those who remained in the local (p = 0.010). Individuals who had moved to a lower socio-economic group had increased their intake of bread, other cereals and potatoes (p = 0.040). CONCLUSION: Food intake changed considerably in a direction more in the line with current dietary recommendations. Food intake in adolescence was a significant, but not strong, predictor of intake in adulthood. Dietary change is influenced by variables including gender, location and socio-economic status.

Comparison of methods to estimate non-milk extrinsic sugars and their application to sugars in the diet of young adolescents.

Consistent information on the non-milk extrinsic sugars (NMES) content of foods and the NMES intake by the population is required in order to allow comparisons between dietary surveys. A critical appraisal of methods of NMES estimation was conducted to investigate whether the different published methods for estimating the NMES content of foods lead to significantly different values for the dietary intake of NMES by children and to consider the relative practicality of each method. NMES values of foods were calculated using three different published descriptions of methods of NMES estimation, and the values were compared within food groups. Dietary intake values for English children aged 11-12 years were calculated using each method and compared in terms of overall NMES intake and the contribution of different food groups to NMES intake. There was no significant difference in the dietary intake of NMES in children between the method used in the National Diet and Nutrition Surveys (NDNS) (81.9 g/d; 95 % CI 79.0, 84.7) and a method developed by the Human Nutrition Research Centre (84.3 g/d; 95 % CI 81.4, 87.2) at Newcastle University, UK, although the latter gave slightly higher values. An earlier method used by the Ministry of Agriculture, Food and Fisheries gave significantly higher values than the other two methods (102.5 g/d; 95 % CI 99.3, 105.6; P<0.05). The method used in the NDNS surveys and the method used by the Human Nutrition Research Centre at Newcastle University are both thorough and detailed methods that give consistent results. However, the method used in the NDNS surveys was more straightforward to apply in practice and is the best method for a single uniform approach to the estimation of NMES.

Longitudinal dietary change from adolescence to adulthood: perceptions, attributions and evidence.

Dietary patterns and change in eating habits are influenced by multiple factors from an individual's internal and external environment. A longitudinal dietary survey study provided quantitative evidence of dietary change and investigated factors influencing dietary change from adolescence to adulthood, using sociodemographic data and participants' own perceptions of, and attributions for, their dietary change. Longitudinal dietary data were obtained in 1980 and 2000 (average age 11.6 and 32.5 years, respectively). Two questionnaires (2000) and 2 x 3-day food diaries (1980 and 2000) were collected from 198 participants. Foods consumed were assigned to one of the five food groups from The Balance of Good Health (a UK food guide). Questionnaire responses were used to examine how subjects perceived their own dietary change and the factors to which they attributed such change. Six key factors were identified from the questionnaire: parents, partners, children, nutritional awareness, employment and lack of time. Demographic and key factors were associated with degree of change in intake. The complex process of change in food consumption can be linked with an individual's attributions for change.