IJE Advance Access originally published online on September 6, 2005
International Journal of Epidemiology 2005 34(6):1417-1424; doi:10.1093/ije/dyi187
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Article |
Work and behavioural problems in children and adolescents
1 University of Ijui–UNIJUI, RS, Brazil.
2 Department of Social Medicine, Federal University of Pelotas, RS, Brazil.
3 Dean School of Health and Environment, University of Massachusetts Lowell, MA, USA.
4 Health Department of Pelotas, RS, Brazil.
* Corresponding author. Rua Doralino Leusin 126, Santa Rosa, RS, CEP 98.900-000, Brazil. E-mail: labenvegnu{at}brturbo.com.br
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Methods We conducted a cross-sectional study of 3139 children and adolescents from poor areas of the city of Pelotas, southern Brazil. We employed the child behaviour checklist for estimating BP. We performed multivariable analysis using Poisson's regression for confounder control.
Results The proportion of workers was 13.8% (7.3% among children and 20.7% among adolescents). Prevalence of BP among workers and prevalence ratios (PRs) were 21.4% (PR = 1.3; CI 0.9–1.9) among children and 9.5% (PR = 0.6; CI 0.4–1.0) among adolescents. Considering workers only, the risk of BP was 2.7 times greater (CI 1.4–5.1) among children when compared with adolescents. Working in domestic services among children and beginning to work at an early age among adolescents were associated with BP.
Conclusions Our results reinforce the need for respecting the minimum age for admission to employment established by the ILO Convention 138 and by the Brazilian legislation and contribute to the discussion about the occupations that should be considered as hazardous child labour.
Keywords Child labour, behavioural problems, Poisson regression, prevalence
Accepted 10 August 2005
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Worldwide, there are 352 million economically active children. Eighteen percent of children aged 5–14 years work, and this rate is as high as 42% in the 15–17 years age group.1 In Brazil, working children represent 1.8% of children in the 5–9 years age group, 11.6% in the 10–14 years group, and 31.5% in the 15–17 years group, totalling 5.4 million children.2 These children are placed mainly in the agriculture and service industries, half of them do not receive payment, and >80% are informal workers.2,3
The majority of these children work in activities hazardous to their health. Most available studies on the impact of child labour on health have been carried out in developed countries and focus mainly on work accidents. Studies evaluating the impact of work on behaviour among adolescents suggest that work may contribute to the development of discipline, responsibility, and self-confidence and to the development of money managing abilities, as well as provide role models through contact with adult workers, thus preparing for adult jobs.4–6
On the other hand, there is evidence that work may be associated with behavioural and psychological problems.7–13 These negative consequences are associated with work of a more permanent character, with longer, more alienating work shifts, lacking formal engagement, with insufficient schooling and/or training, or requiring responsibility, abilities, or experience inadequate for the child's age. The problems identified may manifest themselves immediately or may become latent, surfacing in adult life.14 Among American high school students, satisfaction with one's life was greater among students who worked between 6 and 10 h a week than among those who did not work, or who worked >10 h a week.7,8,15 The psychological problems associated with adolescent work most frequently reported in the literature include drug and alcohol abuse, insomnia, fatigue, anxiety, and depression, whereas major behavioural problems include poor school performance, delinquency, antisocial behaviour, and low self-esteem.8,10,11
In developing countries, work has specific characteristics such as earlier insertion into working activities.16 It is thus important to evaluate the impact of child work on mental health in this scenario. Pelotas, a medium-sized city in southern Brazil, is passing through a period of profound economic stagnation, with marked deindustrialization and an increase in unemployment and informal work. Although located in one of the country's most developed states—in which scandalous cases of child exploitation are not expected—the problem of child labour is still relevant. A large population-based research of low-income youth in Pelotas was carried out to study work and health among young people aged between 5 and 17 years.17–19 Details about the method can be found in Fassa (2005).17 The present study evaluates the association between child work and behavioural problems in the city of Pelotas.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
We carried out a cross-sectional study in the low-income areas of the city of Pelotas, Brazil. We considered as low-income the 70 census tracts in which <1.5% of heads of families earned more than 20 monthly minimum wages.20 We randomly selected 22 of these 70 sectors and interviewed all children living in households in these sectors who were within the age group defined. Institutionalized or homeless (quite uncommon) children and adolescents were not included.
We characterized children's work in the year preceding the interview by means of a standardized pre-coded questionnaire. The work of children and teenagers was defined as activities performed that contribute to the production of market products, goods, or services, including activities done without pay.21 Also included was household work performed in the parents' home, when it could be associated with an economic activity as, for example, when a child must devote his or her entire time to that work so that his or her parents can be employed outside home and is, therefore, deprived of the possibility of going to school. However, since household work performed at parents' home is rather specific, it was not analysed further in this paper. Occupations were grouped by work activity into non-domestic services, domestic services, retail, and others. We also evaluated the age at which the child began to work.
In order to diagnose behavioural problems, we used the child behaviour checklist (CBCL),22 which has been validated for Brazil, and is used in a number of countries for the evaluation of children and adolescents aged 4–18 years.22,23 The CBCL has been widely used and is validated in a variety of languages, validation for Brazil was done in São Paulo, obtaining 80.4% sensitivity, 66.7% specificity, and 20.4% total misclassification rate.23 During the interview, parents or caretakers answered 118 questions, stating whether the given behaviour was absent, sometimes present, or always present (corresponding to scores 0, 1, and 2). These results were converted to a normalized T-score by a specific CBCL software, based on the frequency of the items in the standard population.22 (T-scores are derived scores with a mean of 50 and a standard deviation of 10.) A total score and 8 syndrome scales are generated (withdrawn, somatic, anxiety/depression, social problems, thought problems, attention problems, delinquent behaviour and aggressive behaviour). In this study we used the Total Behaviour Scale with a cut-off point at score 64. The children with a score equal to or above the cut-off point were classified as having a clinical behavioural profile and, for analytical purposes, were considered as having behavioural problems. This score, alone, is not diagnostic of a major psychological abnormality.
We also collected socioeconomic variables family income, child's schooling—children with age greater than expected for the grade were classified as having inadequate schooling—and parents' schooling and demographic variables sex, age, marital status, and skin colour. Age groups were defined as 10–13 years and 14–17 years owing to federal regulations that, at the time, determined 14 years as the minimum age for legal work.24
We evaluated individual behavioural factors, smoking and alcohol consumption and family behavioural factors family trauma and mother's reactions. Smoking was considered regardless of the number of cigarettes smoked and former smokers were classified as non-smokers. Subjects who enjoyed drinking any alcoholic beverage were classified as drinkers. The presence of family trauma was recorded when at least one of the following situations was present in the family: separation/divorce, alcoholism/drug addiction, imprisoned relative, disabling disease, or the recent occurrence in the family of: death, serious accident, job loss, bankruptcy/large debts, or childbirth to a single mother. We classified as inadequate maternal reactions excessive yelling, beating, or severely punishing the child in case of misbehaviour. Trained interviewers under the supervision of the study coordinator administered the questionnaires.
To characterize the study population, we used univariate analysis to estimate the central tendency and distribution of each variable. We performed Poisson's regression stratified for age, since age modified the effect of work on behavioural problems. This was done using Stata software.25 In multivariable analysis, we followed a conceptual model that placed demographic and socioeconomic variables in the first group and individual and family behavioural variables in the second. The main exposure, work activity, was included in the third group. For the 14–17 years group the latter grouping was repeated for workers alone, replacing work activity with age at which work began. We did not include these two variables simultaneously in the model so as to be able to measure the independent effect of the type of work performed. We evaluated prevalence ratios (PRs) and their respective 95% confidence intervals (95% CIs), both crude and adjusted, for the remaining variables in the same level and in the grouping above. Variables showing P-values <0.2 in the likelihood ratio test were kept in the model.
As a large number of subjects were studied, the study was powerful enough to carry out analyses stratified by age. However, power differs between strata in the light of the prevalence of the studied factor and of the number of workers. Thus we were able to identify, with 95% confidence level and 80% statistical power, risks of 1.5 among adolescents, 1.7 among children, and 1.7 among adolescent workers.26
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
The census indicated that 3474 children aged between 10 and 17 years were in the study sample of whom we studied 3139 (90% participation). Of those surveyed, 434 (13.8%) were workers.
Demographic characteristics of the studied population were similar to those determined by the city census for the lowest socioeconomic stratum, indicating that the sampling was representative of the studied population.27 Of every ten children (10–13 years) two showed inadequate schooling for their age. This rate was as high as 51% among adolescents (14–17 years). Prevalence of smoking was 1.4 and 13.3% and of alcohol consumption, 15.5 and 45.8% in the two age groups, respectively. The proportion of mothers with inadequate maternal reactions was greater among children (83.6%) than among adolescents (68.7%). Generally speaking, both age groups included equal numbers of boys and girls who were predominantly white, with more than half from families with incomes below four minimum wages. Roughly 40% of subjects reported family trauma (Table 1).
|
We found 117 workers among children (7.3%). Major jobs performed by this group were in retail, with 36%, and domestic services, with 29%. Among adolescents, the working contingent was larger, with 317 individuals (20.7%). In this group as well, the majority of workers (33%) worked in retail, followed by those performing non-domestic services (27%) (Table 1). Major occupations for this last group included stonemason assistant, assistant in restaurants and grocery stores, seller, yard cleaner, nanny, and maid.
The prevalence of behavioural problems was 13.5% for the whole sample studied. However, the effect of work differed between the age groups. For children, prevalence among workers was 21.4% and the PR compared with non-workers was 1.3 (CI 0.9–1.9). For adolescents, prevalence among workers was 9.5% and the PR was 0.6 (CI 0.4–1.0). Thus, the prevalence among working children was 2.7 times greater (CI 1.4–5.1) than that of working adolescents (Table 2).
|
In the children's group, after adjustment for confounders, male sex showed a PR of 1.3 (CI 1.0–1.6). Non-white children had 30% more behavioural problems than white children (CI 1.0–1.7). Family income was inversely associated with the outcome, showing a significant linear trend. Children with inadequate school grade for their age showed 60% greater risk of behavioural problems (CI 1.2–2.1). Smoking (PR = 1.9; CI 1.1–3.6), alcohol consumption (PR = 1.6; CI 1.2–2.1), presence of family trauma (PR = 2.3; CI 1.7–3.0), and suffering inadequate maternal reactions (PR = 2.0; CI 1.3–3.3), were strongly associated with greater prevalence of behavioural problems. Children performing domestic services had 60% more behavioural problems than those who did not work (CI 1.0–2.7) (Table 3).
|
Among adolescents, the adjusted model showed that boys had 30% less behavioural problems (PR = 0.7; CI 0.6–1.0). The prevalence of these problems was greater among those with family incomes below one minimum wage, and the association showed a significant linear trend. Risk of behavioural problems was greater among smokers (PR = 1.7; CI 1.2–2.3), among subjects who reported family trauma (PR = 1.7; CI 1.3–2.3), and higher yet among subjects whose mothers showed inadequate maternal reactions (PR = 3.4; CI 2.1–5.4). Adolescents who worked in non-domestic services showed a 60% lower prevalence of behavioural problems than those who did not work (CI 0.1–1.1). Age at which work began was analysed only among workers, excluding type of work activity and maintaining the remaining variables in the model. Age at which work began showed an inverse linear association with behavioural problems. Adolescents who began to work before age 10 years showed a 4.4-fold risk of behavioural problems (CI 1.7–11.0) and those who began between ages 10 and 13 years showed a 3-fold risk (CI 1.4–6.5) when compared with those who began to work after age 14 (Table 4).
|
The behavioural problems showed different associations in the two age groups. Risk of behavioural problems was greater for boys among children and for girls among adolescents. Skin colour, inadequate schooling for age, and alcohol consumption were risk factors only among children, while domestic services showed borderline significance. Among adolescents, work in non-domestic services seems to offer protection against behavioural problems, but this association was not significant. In the working adolescents' group, we observed an important inverse effect of age at which work began on behavioural problems. Low family income, smoking, family trauma, and inadequate maternal reactions showed significant associations in both groups (Tables 3 and 4).
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
The present study shows that beginning to work at an early age is an important risk factor for behavioural problems. This is supported both by the finding that working children show behavioural problems more frequently than working adolescents, and by the inverse association between age at which work began and behavioural problems among working adolescents. Furthermore, working adolescents showed fewer behavioural problems than non-working adolescents. Working in domestic services seems to be a risk factor for behavioural problems among children.
A common problem when dealing with observational epidemiological studies is the definition of morbidity, and this is especially true in the case of psychiatric disorders. The present study employed the CBCL, a standardized instrument that facilitates data collection when studying large samples. This instrument allows questionnaires to be administered by lay interviewers, replacing, with reasonable sensitivity and specificity, psychiatric interviews conducted by specialized professionals.23 This questionnaire has been widely used for characterizing behavioural problems in epidemiological studies.14,22,23,28,29 This instrument-based definition of outcome in a representative sample of the low-income areas of the city adds to the internal validity of the study.
The prevalence of behavioural problems found in the present study was similar to that of other studies. In a review of studies conducted in different countries, the prevalences of behavioural problems measured using the CBCL ranged from 17.6 to 39%.30 For example, using the CBCL, Jutte28 reported 12.9% prevalence among 4- to 16-year olds from low-income populations of Mexican descent in the United States. Studies using other instruments also showed similar prevalences.31,32 The World Health Organization estimates the prevalence of behavioural and emotional disorders among children and adolescents at 
20%.33 In Salvador, North-eastern Brazil, a study reported 23.2% prevalence of child psychiatric morbidities.34
Smoking and alcohol consumption were identified as independent risk factors, although direction of the association cannot be determined. Other studies6,8,35 report an association between the habit of drinking alcoholic beverages and smoking and work intensity among adolescents. These authors suggest that work stimulates behaviours characteristic of adults, and earnings facilitate the acquisition of cigarettes and alcoholic beverages. Thus, by adjusting the analysis for smoking and alcohol consumption, one can evaluate the effect of work on other behavioural problems.
The prevalence of behavioural problems was higher among boys in the 10–13 years age group and lower among adolescent girls. Jutte28 found no difference between sexes in his study of a population aged 4–16 years, while Esparo36 demonstrated a borderline positive association for girls in a population of children aged 6 years. Campbell,14 however, reports evidence of higher rates of externalization problems among boys and internalization problems among girls in a school-age population. Further analyses addressing the different types of behavioural problems may help improve our understanding of the association between sex and our outcome.
The association between low socioeconomic level and behavioural problems is consistent with the literature.14,37–39 Belonging to families from ethnic minorities has also been mentioned as a risk factor for behavioural problems,31,40 corroborating the association between skin colour and outcome. The presence of multiple risk factors in populations of low socioeconomic status may justify the associations found.31
Inadequate maternal reactions when the child or adolescent misbehaved and family trauma were strongly associated with behavioural problems. A good relationship between mother and child/adolescent plays an important role in preventing these problems, whereas inadequate maternal reactions and maternal psychiatric morbidity, such as depression, were identified as risk factors for behavioural problems in children.29,31,41 Family trauma, stressful events, problematic families, and death of relatives have also been shown to be positively associated with behavioural problems.14,31,37,42
The association between work and behavioural problems in children, evidenced in crude analysis, lost its significance after confounder control (Table 2). It is possible that the study lacks the statistical power required to demonstrate such an association, since other findings indicate the early onset of work activity as an important factor in the determination of behavioural problems. Considering workers of both age groups, children showed more behavioural problems than adolescents. Furthermore, the earlier adolescent workers had begun to work, the greater the prevalence of the outcome.
A Brazilian study identified early work activity as a risk factor for health among subjects aged 18–65 years. The risk of health-related problems was 1.6-fold among those who began to work between ages 10 and 13 years when compared to those who began to work at age 
15 years.43 Studies of the impact of work on behavioural problems usually do not evaluate children <16 years, and therefore no bibliography on this specific outcome was found.
Studies of adolescents from developed countries identify aspects of work potentially relevant to the 10–13 years age group. These studies indicate that work is associated with the reduction of the amount of time destined to educational activities, recreation, leisure, and sleep. Adolescents begin to dedicate less time to homework and extracurricular activities and spend less time socializing with friends, colleagues, and family. This effect is seen particularly in those who work long hours.5,10 Work also exposes adolescents to stressful factors, especially when they are required to assume responsibilities better fit for adults or to carry out tasks for which they lack ability, resulting in psychological problems.5,6,8,15
In addition, the quality of work has been reported as a determining factor of its impact in terms of psychological and behavioural problems. In a longitudinal study of American adolescents, depression was found to be more frequent among girls when there was a lack of integration between work and school and when they were made responsible for things beyond their control. Among boys, stressful work and work that did not promote the acquisition of useful skills were associated with depression. This study also showed that working adolescents were emotionally more independent from their parents than non-working ones.11
Similar findings were related in a study in which youths whose work offered an opportunity to develop their abilities or to acquire new ones reported greater satisfaction with their lives and greater hope concerning the future than the remainder.7 Mortimer et al. (1992)5 found benefits among American working adolescents when they identified in their work the possibility for developing skills that may prove useful in the future. In some cases, jobs with less intensity, or ones who did not disturb school activities, showed beneficial effects on the mental health of children and adolescents.6,10,35
Although the literature focuses on the association between work and behavioural problems among adolescents, it is likely that the above-mentioned factors have a still greater impact on children. This, along with the results of the present study, points towards early work as an important risk factor for behavioural problems.
The present study presents work as a protective factor against behavioural problems among adolescents. Several studies from developed countries6–8 report that jobs of low quality and with long shifts, as in Brazil,18 have a negative impact on behaviour. However, in developed countries, the motivation behind work is usually the acquisition of superfluous goods, whereas in developing countries children are forced to work in order to ensure their own survival or that of their family.3,21 Increased schooling often does not improve the worker's perspective of social ascension or of better remuneration, leading adolescents to choose to enter the work market. For Brazilian adolescents, working signifies the onset of economic activity, and leads to the accumulation of experience and development of abilities necessary for the activities they will perform in the future.
On the other hand, a protective effect of work on behavioural problems may be overestimated owing to the ‘healthy worker effect’. Adolescents with behavioural problems, according to this form of selection bias, would be unable to enter the work market or to keep their positions once these are obtained.44 By contrast, a selection effect is unlikely to explain the findings of behavioural problems associated with work among the younger children (10–13 years).
Children who worked in domestic services showed greater prevalence of behavioural problems than those who did not work. This association showed borderline significance, possibly due to the lack of statistical power. Child domestic work has been suggested as an important risk factor for health and quality of life among children.45 There are few studies of the impact of this occupation on child health. However, factors associated with domestic work had a very important negative influence on the mental health of adult women in a poor area of Brazil.46 A prior analysis of our database indicated domestic work as a risk factor also for musculoskeletal problems, especially back pain.17 The work process in this occupation includes activities such as cooking, cleaning, exposure to chemicals, and heavy physical work, which may lead to a high risk of injuries.47 However, the possibility of reverse causality must be considered in a cross-sectional study. In that case the children with BP and consequently school difficulties were encouraged by the parents to work in activities with more simple tasks.
The study showed the association of work among children and adolescents with behavioural problems, which could be extended to low-income population in other developing and under-developed countries. Meanwhile, further studies are required, especially in developing countries, in order to better evaluate the consistency of these findings and to improve our understanding of the mechanisms behind the effect of work on behavioural problems.
By showing that work at an early age has an impact on the occurrence of behavioural problems, this study reinforces the need for respecting the minimum age established in Convention 138 of the International Labor Organization and by the Brazilian legislation.48,49 By considering domestic services as a risk factor for behavioural problems, this study also contributes to the discussion of occupations that should be regarded as hazardous child labour.
KEY MESSAGES
|
|
Acknowledgments |
|---|
This study was supported by the following Brazilian agencies: CAPES, Ministry of Education, Brazil; CNPq, Ministry of Science and Technology; Rede Unitrabalho. This study was also supported by the Fogarty Foundation, the Pan-American Health Organization (PAHO) and CAPES (BEX 0520/02-0).
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1 International Labour Organization. Every Child Counts: New Global Estimates on Child Labour. Geneva: ILO, 2002.
2 Instituto Brasileiro de Geografia e Estatística (IBGE). Pesquisa Nacional por Amostra de Domicílios: trabalho infantil 2001. Rio de Janeiro: IBGE, 2003.
3 Facchini LA, Fassa AG, Dall'agnol MM, Maia MF. Trabalho Infantil em Pelotas: perfil ocupacional e contribuição a economia. Ciênc Saúde Coletiva 2003;8:953–61.
4 Committee on the Health and Safety Implications of Child Labor. Protecting Youth at Work: Health, Safety, and Development of Working Children and Adolescents in the United States. Washington: National Academy Press, 1998.
5 Mortimer JT, Finch M, Shanahan M, Ryu S. Work experience, mental health, and behavioral adjustment in adolescence. J Res Adolesc 1992;2:25–57.
6 Mortimer JFS, Ryu S, Shanahan MJ, Call KT. The effect of work intensity on adolescent mental health achivemment, and behavioral adjustment: new evidence from a prospective study. Child Dev 1996;67:1234–61.
7 Bachman JG, Schulenberg J. How part-time work intensity relates to drug use, problem behavior, time use, and satisfaction among high school seniors: are these consequences or merely correlates? Dev Psychol 1993;29:220–35.[CrossRef][Web of Science]
8 Greenberger E, Steinberg L. When Teenagers Work: The Psychological and Social Costs of Adolescent Employment. New York: Basic Books, 1986.
9 Steinberg L, Cauffman E. The impact of employment on adolescent development. Ann Child Dev 1995;11:131–66.
10 Steinberg L, Dornbusch SM. Negative correlates of part-time employment during adolescence: replication and elaboration. Dev Psychol 1991;27:304–13.[CrossRef][Web of Science]
11 Shanahan MJ, Finch MD, Mortimer JT, Ryu S. Adolescent work experience and depressive affect. Soc Psychol Q 1991;54:299–317.[CrossRef][Web of Science]
12 National Research Council-Institute of Medicine. Protecting Youth at Work: Health, Safety, and Development of Working Children and Adolescents in the United States. Washington DC: National Academy Press, 1998.
13 Kinney JA. Health hazards to children in the service industries. Am J Ind Med 1993;24:291–300.[Web of Science][Medline]
14 Campbell SB. Behavior problems in preschool children: a review of recent research. J Child Psychol Psychiatry 1995;36:113–49.[Web of Science][Medline]
15 Mortimer JT, Finch M, Shanahan M, Ryu S. Adolescent work history and behavioral adjustment. J Res Adolesc 1992;2:59–80.
16 International Labour Office. A Future Without Child Labour. Geneva: ILO; 2002.
17 Fassa AG, Facchini LA, Dall'agnol MM, Christiani DC. Child Labor and Musculoskeletal Disorders: the Pelotas (Brazil) Epidemiological Survey. Public Health Rep 2005 (in press).
18 Facchini LA, Fassa AG, Dall'Agnol MM, Maia MFS, Christiani DC. Individuals at risk: the case of child labor. In: Heymann Jo (ed). Global Inequalities at Work. New York: Oxford, 2000, pp. 52–71.
19 Fassa AG, Facchini LA, Dall'Agnol MM, Christiani DC. Child labor and health: problems and perspectives. Int J Occup Environ Health 2000;6:55–62.[Medline]
20 Instituo Brasileiro de Geografia e Estatística (IBGE). Pesquisa Nacional por Amostras de Domicílios (PNAD). Rio de Janeiro: IBGE, 1998.
21 Fausto A, Cervini R. O Trabalho e a rua: crianças e adolescentes no Brasil urbano dos anos 80. São Paulo: Cortez, 1996.
22 Achenbach TM. Manual for the Child Behavior Checklist/4-18 and 1991 Profile. Burlington, VT: University of Vermont Department of Psychiatry, 1991.
23 Bordin IAS, Mari JJ, Caeiro MF. Validação da versão brasileira do "Child behavior Checklist (CBCL) (Inventário de Comportamentos da Infância e Adolescência): dados preliminares. Rev ABP–APAL 1995;17:55–66.
24 Cruz Neto O, Moreira MR. Child and adolescent labor: factors, legal aspects, and social repercussions. Cad Saude Publ 1998;14:437–41.
25 StataCorp. Stata Statistical Software version 7.0. College station, Texas: Stata Corporation, 2001.
26 Dean JA, Coulombier D, Smith DC, Brendel KA, Arner TG, Dean AG. Epi Info Program version 6.0. Atlanta: Centers for Disease Control and Prevention, 1995.
27 Instituto Brasileiro de Geografia e Estatística (IBGE). Censo Demográfico 1991: Resultados Preliminares. Rio de Janeiro: IBGE, 1991.
28 Jutte DP, Burgos A, Mendoza F, Ford CB, Huffman LC. Use of the pediatric symptom checklist in a low-income, Mexican American population. Arch Pediatr Adolesc Med 2003;157:1169–76.
29 Nix RL, Pinderhughes EE, Dodge KA, Bates JE, Pettit GS, McFadyen-Ketchum SA. The relation between mothers' hostile attribution tendencies and children's externalizing behavior problems: the mediating role of mothers' harsh discipline practices. Child Dev 1999;70:896–909.[CrossRef][Web of Science][Medline]
30 Bird HR. Epidemiology of childhood disorders in a cross-cultural context. J. Child Psychol Psychiat 1996;37:35–49.[Web of Science][Medline]
31 Halpern R, Figueiras A. Influências ambientais na saúde mental da criança. J Pediatr 2004;80:S104–S110.[CrossRef]
32 Glied S, Cuellar AE. Trends and issues in child and adolescent mental health. Health Aff (Millwood) 2003;22:39–50.
33 Organização Mundial da Saúde (OMS). Relatório sobre a saúde no mundo: saúde mental: nova concepção, nova esperança. Genebra: OMS/OPS, 2001.
34 Almeida-Filho N, Santana V, Sousa A, Jacobina R. Relações entre saúde mental das crianças em uma população urbana de Salvador-BA. Acta Psiquiatr Psicol Am Lat 1985;31:211–21.[Medline]
35 Steinberg L, Fegley S, Dornbusch S. Negative impact of part-time work on adolescent adjustment: evidence from a longitudinal study. Dev Psychol 1993;29:171–80.[CrossRef][Web of Science]
36 Esparo G, Canals J, Torrente M, Fernandez-Ballart JD. Psychological problems and associated factors at 6 years of age: differences between sexes. Span J Psychol 2004;7:53–62.[Medline]
37 Kroes M, Kalff AC, Steyaert J, et al. A longitudinal community study: do psychosocial risk factors and child behavior checklist scores at 5 years of age predict psychiatric diagnoses at a later age? J Am Acad Child Adolesc Psychiatry 2002;41:955–63.[CrossRef][Web of Science][Medline]
38 Kalff AC, Kroes M, Vles JS et al. Factors affecting the relation between parental education as well as occupation and problem behaviour in Dutch 5- to 6-year-old children. Soc Psychiatry Psychiatr Epidemiol 2001;36:324–31.[CrossRef][Web of Science][Medline]
39 Costello EJ, Compton SN, Keeler G, Angold A. Relationships between poverty and psychopathology: a natural experiment. JAMA 2003;290:2023–29.
40 Costello EJ, Angold A, Burns BJ, Erkanli A, Stangl DK, Tweed DL. The Great Smoky Mountains Study of Youth. Functional impairment and serious emotional disturbance. Arch Gen Psychiatry 1996;53:1137–43.
41 Radke-Yarrow M, Nottelmann E, Martinez P, Fox MB, Belmont B. Young children of affectively ill parents: a longitudinal study of psychosocial development. J Am Acad Child Adolesc Psychiatry 1992;31:68–77.[Web of Science][Medline]
42 Rae-Grant N, Thomas BH, Offord DR, Boyle MH. Risk, protective factors, and the prevalence of behavioral and emotional disorders in children and adolescents. J Am Acad Child Adolesc Psychiatry 1989;28:262–68.[CrossRef][Web of Science][Medline]
43 Kassouf AL, McKee M, Mossialos E. Early entrance to the job market and its effect on adult health: evidence from Brazil. Health Policy Plan 2001;16:21–28.
44 Checkoway H, Pearce NE, Kriebel D. Research Methods in Occupational Epidemiology. New York: Oxford University Press, 2004.
45 UNICEF. The State of the World's Children 1997. Oxford: Oxford University Press; 1997.
46 Santana V. Housework, paid work and psychiatric symptoms. Rev Saude Publ 2001;35:16–22.
47 UNICEF. Child domestic work. Innocenti Digest 1999;5:20.
48 International Labor Organization. C138 Minimum Age Convention. Geneve: ILO, 1973.
49 Ministério do Trabalho e Emprego. Proteção integral para crianças e adolescentes: fiscalização do trabalho saúde e aprendizagem. Florianópolis: MTE, Brasil, 2000.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. Albin, K. Broberg, and K. Jakobsson Research challenges in occupational and environmental medicine until 2030 Occup. Environ. Med., January 1, 2009; 66(1): 3 - 5. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||