A substantial body of scientific evidence indicates that numerous synthetic environmental chemicals may increase the risk of some human diseases, and that for the general population food is often the main source of exposure to such compounds. Water and air pollution, personal care products, food packaging, and other consumer goods are also sources of exposure. Some types of persistent toxic substances were never intentionally released into the environment (e.g., dioxins), and the manufacture of others was halted decades ago in many countries (e.g., polychlorinated biphenyls, organochlorine pesticides). However, today many such persistent substances remain detectable in animal and human food webs, as well as in most human beings, both at low and high concentrations. Due to frequent exposure, food and human contamination by non-persistent toxic substances is also commonly observed. 1–10

While research on the potential health effects of environmental chemicals is quite strong in Spain,6,11 only some in-depth studies exist on perceptions, attitudes, and behaviours of citizens related to food safety; 12–17 and, to our knowledge, few studies have specifically addressed citizens’ views on the causes and consequences of the presence of synthetic toxic substances in food. Of course, there is a rich international scientific literature on such issues.10,12,18–24

Therefore, the main aim of the study was to explore factors influencing perceptions and views on the responsibility for the presence of toxic substances in food, on enforcement of laws and regulations that control human exposure to toxic substances in food, and on the effectiveness of such regulations.

About 23% of the participants worked with or studied toxic substances. Sixty-three percent often or sometimes consulted information about toxic substances, and 75% received this information through mass media, among another sources (Table 2). When asked about the degree of toxicity of different substances at high body concentrations, 39% of participants (significantly more men than women) identified correctly all or almost all options (Table 2). Over 71% of men and 66% of women (p value=0.008) identified the body concentration and the toxicity of the substance as the two most important factors for a substance to be toxic (Table 2).

Women held responsible a larger number of groups than men for the presence of toxic substances in food (p for trend=0.032) (Table 2). Only 16.5% of respondents (significantly more men than women) considered that laws and regulations to control human exposure to toxic substances are effective. The information about toxic substances in food provided by clinicians, technicians, scientists or associations was considered of good quality by 609 subjects (80.9% of respondents), while only 19.1% deemed the information provided by the mass media of good quality (Table 2). Over 27% of women and 35% of men considered of good quality the information provided in the workplace (p value=0.009). Of the 753 participants who answered the question about substances in food that may cause health problems, 278 (37%) identified correctly 6 to 7 such health problems (40% of women and 31% of men, p value=0.044) (Table 2). Over 68% of participants (73% of women and 58% of men, p value <0.001) considered that cans and plastic food packaging may have adverse health effects. Over 87% of subjects (with no gender difference) answered it was possible that throughout their life they could have accumulated in their body toxic substances potentially dangerous to their health in the mid- or long-term (Table 2).

Regarding occupational status, the percentage of subjects who considered that laws and regulations on exposure to toxic substances are effective ranged from 10.5% among self-employed participants to 20% among subjects employed by others (i.e., low figures, and a difference of 10 percentage points only) (see Table I in Appendix 2 online). Almost 19% of participants who worked with or studied toxic substances and 16% of participants who did not work with or study responded that laws are effective. Half of participants who never sought information about toxics responded ‘do not know’ when asked about the effectiveness of regulations, whereas 68% of participants who sought it ‘often or sometimes’ considered regulations ineffective. Regulations were also deemed ineffective by over 65% of participants who considered that foods with higher concentrations of toxic substances are available in almost all types of food stores, of participants who identified correctly 6 to 7 health problems caused by toxic substances in food, and of participants who identified 6 to 7 food groups with concentrations of toxic substances harmful to human health.

Only 38% of participants considered that laws and regulations about toxic substances in food were ‘often’ enforced in the different parts of the food production chain, whereas 17% indicated that they ‘never’ were (see Table II in Appendix 2 online). 47% of men, 46% of participants employed by others, 41% of subjects that often consulted information about toxic substances, and 48% of individuals that considered that no stores sell food with high concentrations of toxics answered that regulations about toxic substances in food are ‘often’ enforced (all p values <0.001). Over 42% of participants who worked with or studied toxic substances and 37% of subjects who did not also considered that regulations are ‘often’ enforced.

Subjects who considered 6 to 8 social groups responsible for the presence of toxic substances in food answered in a lower proportion “do not know” to the question on the effectiveness of regulations (compared to subjects who considered responsible less than 6 groups). Subjects who held responsible less social groups also tended to consider that laws were effective (p value=0.009) (Table 3). Regarding the relationship between law enforcement and effectiveness, 50% of subjects who answered that laws were always or often enforced and 76% of those who considered that sometimes they were, nevertheless answered that such laws were not effective. Over 65% of subjects who answered that laws were enforced rarely or never responded “do not know” when asked about the effectiveness of the laws (p value <0.001) (Table 3).

Multivariate analyses that adjusted for age and gender showed that consulting information about toxic substances was positively associated with attributing the responsibility for toxic substances in food to 6 or more social groups (vs. <6 social groups). Working with or studying toxic substances was not (Table 4). Subjects who often or sometimes consulted information were almost twice as likely to make such attribution as subjects who sought information rarely or never or did not know (OR=1.92 for the adjusted model, p value=0.001). Three other factors were even more strongly linked with attributing responsibility to 6 or more social groups: identifying more health problems that may be caused by such substances (OR for the upper category: 2.48); identifying correctly most factors that increase the likelihood of toxic substances in food being harmful to human health (OR: 2.86); and identifying more food groups with toxic concentrations harmful to human health (OR: 2.92). All p for trend <0.001 for these three factors. Such attribution was not more frequent among respondents who worked with or studied toxic substances (Table 4). Men without college education had an OR: 2.05 (95%CI: 1.03-4.09) (adjusted for age) of attributing the responsibility for toxic substances in food to 6 or more social groups (vs. <6 social groups) than men with college education.

Women were 40% less likely than men (OR: 0.60, p value=0.001) to respond ‘often’ (vs. other answers) to the question on the frequency of law enforcement; and so were participants who identified more food groups with toxic concentrations potentially harmful to human health (see Table III in Appendix 2 online). In gender-stratified analyses, the responses of both women and men to question 22 on food groups with toxic substances were very similarly unrelated to responding ‘often’ (vs. other answers) to the question about the frequency of law enforcement (i.e., there was no effect modification by gender). By contrast, among men, an answer different to “yes” to question 24 about lifelong accumulation of toxic substances (vs. an affirmative answer) was associated (OR: 2.36; 1.08-5.14) with responding ‘often’ (vs. other answers) to the question about the frequency of law enforcement, whereas for women there was no significant relation.

Women were 65% less likely than men to answer that regulations about toxics in food are effective (OR: 0.35; p-value <0.001) (Table 5). The corresponding age- (and in these instances, sex-) adjusted OR for participants employed by others (vs. self-employed) was 2.17 (1.10-4.27); for participants informed by experience or interest (vs. little or not interested), it was 1.53 (1.03-2.29); and for subjects who answered that laws were enforced sometimes or never (vs. always/often), they were 0.19 (0.11-0.32) and 0.13 (0.06-0.28), respectively. Considering that foods with higher concentrations of toxic substances are available in more types of food stores was also inversely associated with responding that laws were effective (Table 5). Such judgements about law effectiveness were generally not associated with working or studying toxic substances. The only exception was: the attribution of responsibility to more groups was inversely related to responding that laws were effective among subjects who worked or studied toxic substances (OR: 0.27; 0.08-0.89), whereas it was positively related to responding that laws were effective among subjects who did not work or study such substances (OR: 1.59; 0.87-2.90).

We found several statistically significant and socially relevant associations; notably, attributing the responsibility for toxic substances in food to a larger number of social groups was more frequent among subjects who consulted information about the problem more often, who correctly identified factors that increase the likelihood of toxic substances in food being harmful to human health, who better knew the health problems caused by such substances, and who recognized more food groups that tend to have concentrations of toxic substances harmful to human health; such attribution was not more frequent among respondents who worked or studied toxic substances. Women were significantly less likely than men to respond that laws and regulations are often enforced; and so were participants who identified more food groups with potentially toxic concentrations. Women were also significantly less likely than men to respond that regulations about toxics in food are effective. With due caution, it seems reasonable to suggest that some of the observed associations between factors might also exist in the general population, although probably with some differences in magnitude.

However, the study was not based on a representative sample of the general population due to the sampling design and, therefore, results should not be generalized to the general population of Spain; in particular, the univariate and bivariate results summarized in Table 2. Within the same theoretical framework, the study design and results complement our previous qualitative studies.12,16,17 Although we did not target for participation any specific group of people, a portion of respondents was probably comprised by citizens concerned about the study issues, and by subjects with college education. Yet, the majority of respondents were unlikely to be experts (e.g., when asked about the degree of toxicity for human health of different substances at high body concentrations, only 39% of participants answered correctly all or almost all options). Also, the educational level was not an important predictor of responses when age and gender were also considered. Associations were similar among participants who worked with or studied toxic substances than in participants who did not. The present study and project12,16,17 provide a basis for new and more complex studies, which could use representative samples of the general population or target specific subgroups through qualitative and quantitative methodologies.

Even if clearly not stemming from a representative sample, in our view results do provide ‘food for thought’: to authorities (notably, those whose policies influence public health, the safety of food and related consumer products, or chemical hazards), industries (agriculture, chemistry, food processing and packaging, distribution, marketing), social organisations, and other citizens. In the societal sectors reflected in the study, there seems to be a rather wide scepticism and distrust towards the enforcement and effectiveness of regulations that control or should control human exposure to toxic substances in food. Over 58% of participants responded that laws and regulations are not effective. And more than 87% said it was possible that throughout their life they could have accumulated substances potentially dangerous to their health; this proportion was identical in women and men.

We are not aware of the existence of survey questionnaires validated to address the specific study questions. The accuracy, reliability, reproducibility, interpretability, and other properties26 of the questionnaire used in the study were untested, and this is another study limitation. Nevertheless, no major inconsistencies were apparent; e.g., half of participants who never sought information about toxics responded ‘do not know’ when asked about the effectiveness of regulations, whereas most participants who sought it ‘often or sometimes’, but not all, considered regulations ineffective. It is also important to notice that some of the issues assessed in the survey are quite novel in Spain and other countries; thus, a sizable number of study participants (from about 0.1% to 38%) answered “do not know” to some questions. Over 45% of participants reported having little knowledge on synthetic toxic substances, their presence in food, and their possible health effects. Between 22% and 37% of participants identified correctly health problems that toxic substances in food may cause, and factors that increase the likelihood of toxic substances in food being harmful to human health.

When assessing the limitations and strengths of the present study it should be noted that it is part of a research project that has already published a synthesis of its theoretical framework and initial results from a qualitative ethnoepidemiologic study.12,16,17 Social processes of perceiving, facing, attributing meaning, and coping with risk are diverse and multifaceted; and more complex than enabled by some frameworks, as Beck's ‘risk society’.12,16,19,30–35 While the survey was conducted some three years ago, we think the results reflect long-term and profound underlying processes in Spain's society, which did not materially change in recent years.

Women were significantly less likely than men to respond that laws and regulations about toxics in food are enforced and effective. Women also tended to attribute the responsibility of the presence of toxic substances in food to more groups than men, and they more frequently considered that the responsibility belonged to groups not involved in the food production chain. Men were less likely to identify correctly health problems that may be caused by toxic substances in food, but more likely to answer correctly the degree of toxicity of certain substances. Gender differences in risk perception have been described in numerous studies, with women more often reporting higher levels of concern, higher sensitivity and lower tolerance to risk than men.18,20 The analysis of gender differences ought to take into account the sociocultural context and processes involved in this perception.20

Until a few decades ago, in the Western world most food problems were basically related to malnourishment, hunger, famine and the difficulties of achieving adequate nutrition due to food scarcity, plagues, and economic constraints.21 Modern progress in feeding populations has been immense. However, this has not happened at zero cost: adverse health, social, and environmental consequences must be acknowledged.11,36–38 Thus, our ‘risk societies’ have also long endured problems and reasonable concerns related to food and chemical risks, partly due to the vast industrialisation of food processing and the distance between food production and consumption.12 Some studies focusing on social representations of food risks have unveiled rather negative perceptions of citizens about the dangers of technological interventions in food production at an industrial scale.13 Some authors consider chemical hazards to human health as elements of risk safety.7,22 Such hazards are partly seen to stem from the presence of synthetic chemical substances (as pesticides, growth control hormones, feed conversion enhancers and feed contaminants, or antibiotics) that pollute food during the processes of production, storage, packaging and distribution.22 The literature also reflects positive views about agricultural successes, as well as social concerns about global poverty and undernutrition, or about social policies and individual behaviours to prevent obesity. Such views coexist – often, in a quite balanced and nuanced way – with the fact that for many people the presence of synthetic chemical compounds in processed food is also a problem.23 For example, some studies show how people who experience chronic illnesses express a greater concern about man-made chemicals and toxic residues in food.23

Therefore, the scientific and social (un)certainties about the effects that some food contaminants can have on human health are part of contemporary debates on food (in)security; e.g., on the strengths and weaknesses of glocal11,38–41 food systems. Such debates are also clearly related to economically- and culturally-shaped processes of risk perception and tolerance, the industrial scale of food processing, or a dysregulated globalisation of markets.11–17 Discussions on social media and networks thus abound on highly relevant (both material and symbolic) issues as, for example, the socio-political causes of ‘mad cow disease’ (bovine spongiform encephalitis) or the effects of genetically modified organisms on human health and food sovereignty.13,21,36–38,42 The frequent distrust of citizens in the production chain and its managers, or in regulatory agencies and institutions, is also partly due to actual shortcomings (e.g., failure to regulate conflicts of interests, ‘revolving doors’ and lobbying), and to the systems of risk communication, which have all significant impacts on the perception that consumers have about food benefits and risks.14–17,22,24,36,43

Hence, there currently is a broad shift from concerns basically focused on access to food, with quite a high level of tolerance to short-term microbiological risks and little regard for long-term risks, to other views which (though still worried about access to food) are more attentive to the possible negative health consequences of eating chemically contaminated foods.11,13,24,44 In influential segments of many Western societies there is thus increasing awareness of such non-microbiological, multifactorial, cumulative, and long-term risks.11,37,44 Such realities also imply changes in the relationships of trust on food governance of citizens and societal organisations towards institutions and companies.19,24,44 Food safety and public health authorities also ought to ponder the study findings.

Among study participants there was a rather wide concern about chemical contaminants in food, and distrust towards the enforcement and effectiveness of regulations that in Spain should control exposure to toxic substances in food. Respondents had a low level of trust on the results of the work performed by the different societal actors, companies, and institutions that must protect citizens from the potential adverse health effects of synthetic chemicals that are often present in food products.

Cristina Linares Gil.

The corresponding author on behalf of the other authors guarantee the accuracy, transparency and honesty of the data and information contained in the study, that no relevant information has been omitted and that all discrepancies between authors have been adequately resolved and described.

M. Porta, C. Larrea and A. Muñoz conceived and designed the study, with assistance from J. Pumarega and M. Gasull. J. Pumarega, M. Jariod, G. Rodriguez, and N. Pallarès carried out the analyses, supervised by M. Porta, with contributions from all other authors. All authors participated in the interpretation of results. The main versions of the manuscript were written by M. Porta and J. Pumarega, with contributions from all other authors. All authors approved the final version and are jointly responsible for adequate revision and discussion of all aspects included in the manuscript.

This study is part of the interdisciplinary project “Cuerpos Tóxicos y Etnoepidemiología Sociocultural de la Contaminación Interna por Compuestos Tóxicos Persistentes (CTP) en España” (“Toxic Bodies and Sociocultural Ethnoepidemiology of the Internal Contamination by Persistent Toxic Substances in Spain”), led by C. Larrea and M. Porta, partly funded by Programa Nacional de Proyectos de Investigación Fundamental (National Programme for Fundamental Research Projects), Ministry of Science and Innovation, Spain (CSO 2010/18661). Funding was also provided by research grants from Instituto de Salud Carlos III–FEDER (FIS PI13/00020 and CIBER de Epidemiología y Salud Pública−CIBERESP), Government of Spain; the Hospital del Mar Medical Research Institute (IMIM), Barcelona; the Government of Catalonia (2009 SGR 1350 and 2014 SGR 1012); and Fundació La Marató de TV3 (20132910).

None.