2-tert-butyl-4-methoxyphenol

Epidemiological data

Administrative data

Endpoint:

epidemiological data

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Intake of Butylated Hydroxyanisole andButylated Hydroxytoluene and StomachCancer Risk: Results from Analyses in theNetherlands Cohort Study.

Author:

.A.M. BOTTERWECK ; H. VERHAGEN; R.A. GOLDBOHM; J. KLEINJANS and P.A. van den BRANDT

Year:

2000

Bibliographic source:

Food and Chemical Toxicology 38 (2000) 599-605.

Materials and methods

Study type:

cohort study (prospective)

Endpoint addressed:

carcinogenicity

Principles of method if other than guideline:

- Principle of test: Because of the widespread use of BHA and BHT in food products and as a consequence long-term and widespread exposure of humans, it is important to investigate the potential health risks associated with their dietary intake. In this Netherlands Cohort Study (NLCS), a prospective cohort study in which various risk factors for stomach cancer has been investigated. Based on this study, the effect of usual BHA and BHT intake on stomach cancer risk has been assessed.

- Short description of test conditions: The Netherlands Cohort Study on diet and cancer (NLCS) is a prospective cohort study which started in September 1986 among the general population in the Netherlands (van den Brandtet al., 1990a). The cohort included 62,573 women and 58,279 men aged 55 to 69 year in 1986. At baseline, the cohort members completed a mailed, self-administered questionnaire on dietary habits, smoking, occupation, medical history, personal and family history of cancer, and demographic data. Follow-up for the incidence of cancer has been established by record linkage with cancer registries and a pathology register (van denBrandtet al., 1990b). For data analysis the case-cohort approach was used in which cases are derived from the entire cohort, while the person-years at risk of the entire cohort are estimated from a random sample of 3500 subjects (subcohort) (Self and Pre-ntice, 1988). This subcohort of 1812 women and 1688 men has been followed up biennially for vital status information in order to estimate the accumulated person time in the cohort. No subcohort members were lost to follow-up. The present analysis is restricted to cancer incidence in the first 6.3 year of follow-up from September 1986 until December1992. After the exclusion of subjects reporting prevalent stomach cancer at baseline (n=33), cases within situ stomach carcinoma (n=2), and cases without microscopically confiirmed stomach cancer (n=2), there were 310 incident (242 men, 68 women) stomach carcinoma cases remaining. In the sub-cohort, 1630 men and 1716 women remained after the exclusion of prevalent cancer cases other than skin cancer.

- Parameters analysed / observed: Stomach cancer risk.

GLP compliance:

not specified

Test material

Test material information

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier) and lot/batch number of test material: BHA present in food.
- Purity, including information on contaminants, isomers, etc.: No data.

Method

Type of population:

general

Ethical approval:

not specified

Details on study design:

HYPOTHESIS TESTED (if cohort or case control study): Link between BHA and BHT intake with stomach cancer risk.

METHOD OF DATA COLLECTION
- Type: Questionnaire.
- Details: At baseline, the cohort members completed a mailed, self-administered questionnaire on dietary habits, smoking, occupation, medical history, personal and family history of cancer, and demographic data. Follow-up for the incidence of cancer has been established by record linkage with cancer registries and a pathology register (van denBrandtet al., 1990b). For data analysis the case-cohort approach was used in which cases are derived from the entire cohort, while the person-years at risk of the entire cohort are estimated from a random sample of 3500 subjects (subcohort) (Self and Prentice, 1988). This subcohort of 1812 women and 1688 men has been followed up biennially for vital status information in order to estimate the accumulated person time in the cohort. Semi-quantitative food frequency questionnaire was used to assess food consumption. Information on BHA or BHT content of cooking fats, oils, mayonnaise and other creamy salad dressings and dried soups was obtained by chemical analysis, and by a Dutch database of food additives (ALBA) and the Dutch Compendium of Foods and Diet Products (Compendium of food and Diet Products, 1989/1990).


STUDY PERIOD: Septembre 1986 to December 1992.


STUDY POPULATION:
- Total population (Total no. of persons in cohort from which the subjects were drawn): The Netherlands cohort included at the beginning 62 573 women and 58 279 men. For data analysis, the case-cohort approach was used in which cases are derived from the entire cohort, while the person-years at risk of the entire cohort are estimated from a random sample of 3500 subjects (1812 women and 1688 men) (subcohort). Peaple with stomach carcinoma were also selected, 310 subjects (242 men and 68 women).
- Selection criteria: For peaple with stomach carcinomas: exclusion of subjects reporting prevalent stomach cancer at base-line (n=33), cases with in situ stomach carcinoma (n=2), and cases without microscopically confirmed stomach cancer (n=2). For subcorhort peaple: exclusion of prevalent cancer cases other than skin cancer.
- Total number of subjects participating in study: 3346 subjects (1630 men and 1716 women) + 310 subject with stomach carcinomas (242 men and 68 women) = 3656 subjects.
- Sex/age/race: Men and women aged 55 to 69 year at the beginning of the study (1986).
- Smoker/nonsmoker: Both smokers and nonsmokers sujects.
- Total number of subjects at end of study: 3656 subjects.


COMPARISON POPULATION
- Type: National registry
- Details: Follow-up for the incidence of cancer has been established by record linkage with cancer registries and a pathology register.

HEALTH EFFECTS STUDIED
- Disease(s): Stomach cancer.


Subjects and study design: The Netherlands Cohort Study on diet and cancer (NLCS) is a prospective cohort study which started in September 1986 among the general population in The Netherlands (van den Brandt et al., 1990a). The cohort included 62,573 women and 58,279 men aged 55 to 69 year in 1986. At baseline, the cohort members completed a mailed, self-administered questionnaire on dietary habits, smoking, occupation, medical history, personal and family history of cancer, and demographic data. Follow-up for the incidence of cancer has been established by record linkage with cancer registries and a pathology register (van den Brandt et al., 1990b). For data analysis the case-cohort approach was used in which cases are derived from the entire cohort, while the person-years at risk of the entire cohort are estimated from a random sample of 3500 subjects (subcohort) (Self and Prentice, 1988). This subcohort of 1812 women and 1688 men has been followed up biennially for vital status information in order to estimate the accumulated person time in the cohort. No subcohort members were lost to follow-up. The present analysis is restricted to cancer incidence in the first 6.3 year of follow-up from September 1986 until December 1992. After the exclusion of subjects reporting prevalent stomach cancer at base-line (n=33), cases with in situ stomach carcinoma (n=2), and cases without microscopically confrmed stomach cancer (n=2), there were 310 incident (242 men, 68 women) stomach carcinoma cases remaining. In the sub-cohort, 1630 men and 1716 women remained after the exclusion of prevalent cancer cases other than skin cancer.

OTHER DESCRIPTIVE INFORMATION ABOUT STUDY:
Data analysis: From an epidemiological point of view it is important to investigate the association between the consumption of mayonnaise and other creamy salad dressings per se and stomach cancer risk. All cases (282) and subcohort members (3123) could be classified as user or non-user of mayonnaise and other creamy salad dressings. Then, the association between the use of mayonnaise and creamy salad dressings with BHA or BHT and intake of BHA or BHT and stomach cancer risk was examined. These analysis were based on 192 cases (68.1%) and 2035 subcohort members (65.2%) with complete data on BHA or BHT content of mayonnaise and other creamy salad dressings. These subjects were classified by the consumption of BHA- or BHT-containing foods (yes or no) and categorized into three categories of BHA (0, >0–70, >70 μg/day) and BHT (0, >0–225, >225 μg/day).

Exposure assessment:

estimated

Remarks:

Both estimated and measured (see details in the field below)

Details on exposure:

TYPE OF EXPOSURE: Exposure by food (oral exposure).

TYPE OF EXPOSURE MEASUREMENT: other: Personal estimation based on food type consumption and frequency (calculation). See details below in this field. A semi-quantitative food frequency questionnaire was used to assess food consumption. Information on BHA or BHT content of cooking fats, oils, mayonnaise and other creamy salad dressings and dried soups was obtained by chemical analysis, and by a Dutch database of food additives (ALBA) and the Dutch Compendium of Foods and Diet Products.

EXPOSURE LEVELS: Mean intake of BHA or BHT among subcohort members was 105 and 351 μg/day, respectively.

EXPOSURE PERIOD: during 6.3 years.


DESCRIPTION / DELINEATION OF EXPOSURE GROUPS / CATEGORIES:
Exposure assessment: For assessing BHA and BHT intake, both information on consumption of potential BHA- and/or BHT-containing foods and brand names of these foods were needed. Consumption of potential BHA-and/or BHT-containing foods was assessed using the dietary section of the baseline questionnaire of the Nertherlands Cohort Study on diet and cancer (NLCS). The dietary section was a 150-item semi-quantitative food frequency questionnaire concentrating on usual consumption of food and beverages during the year preceding the start of the study. The questionnaire was validated against a 9-day diet record (Goldbohmet al., 1994). Among other questions, participants were asked to report their frequency of consumption of potential BHA-and/or BHT-containing foods: cooking fats, oils, dried soups (from a pack), mayonnaise and other creamy salad dressings, potato products, cereals and cereal products, pastry, cakes and biscuits, sugar, sweets and sweet spreads, nuts, seeds and snacks (Verhagenet al., 1990a). They could choose one of six frequency categories, ranging from ``never or less than once per month'' to ``6±7 times per week''. Standard portion sizes were used to calculate daily intake. Participants were asked to specify type and brand for cooking fats (for preparing meat, fish and chips), oils, butter, mayonnaise and other creamy salad dressings and dried soups. Only those products with brand names could be used to obtain information on BHA and BHT content.

Collection of information on BHA and BHT content of foods: Information on BHA and/or BHT content was obtained by chemical analysis of selected potential BHA- and/or BHT-containing foods and by the use of two other information sources: a Dutch database of food additives for people with food intolerance and allergy (ALBA) and the Dutch Compendium of Foods and Diet Products (Compendium of food and Diet Products, 1989/1990).

Chemical analysis: The most frequently mentioned brand names of cooking fats, oils, mayonnaise and other creamy salad dressings and dried soups in the baseline questionnaire from a random sample of 400 cohort participants were selected in 1988. Because the fat content of dried soups is very low and as a consequence the BHA and/or BHT content, dried soups were not regarded as relevant for BHA and/or BHT intake, dried soups were therefore excluded from chemical analysis. Although oils contain naturally occurring tocopherols and do not require the addition of BHA or BHT, a number of oils were still analysed. Finally, in 1990, 55 brand-specific foods (30 mayonnaise and other creamy salad dressings, 11 oils and 14 cooking fats) were bought in local super markets and analysed by means of HPLC.

Other data sources: The ALBA database comprises data on the presence or absence of food additives in food products specified to type and brand for people with food intolerance and allergy. Regarding BHA and BHT, a list of food brand names containing BHA and/or BHT was obtained for the year 1989. Information before 1989 was not available. The Compendium of Food and Diet Products contains information about the composition of a selection of (diet) foods by type and brand and is used by general practitioners and dieticians (Compendium, 1989/1990). Since 1989, information about the presence of food additives in food and diet products was added to the Compendium. Both ALBA and the Compendium obtained their information from food manufacturers. We assumed that the BHA and/or BHT content of foods in 1989/1990 was the same as in 1986.

Based on the information of these three sources, it could be concluded that in this study only mayonnaise and other creamy salad dressings contained BHA or BHT. There were no foods that contained both BHA and BHT.

Calculation of BHA and BHT intake: Foods were coded to contain BHA or BHT if at least one of the three sources (chemical analysis, ALBA or Compendium) showed that BHA or BHT was present. If, in addition, the amount of BHA and/or BHT was known by chemical analysis, this information was also used. Foods for which no information was available were coded as missing. Foods of which the presence of BHA or BHT was demonstrated but no amount of BHA or BHT was known, the average content of BHA or BHT in mayonnaise or other salad dressings from which the BHA or BHT concentration was known, was substituted. Mean daily intake was calculated by multiplying BHA or BHT content of foods (in mg per gram) and consumption of mayonnaise and other creamy salad dressings (in gram per day).

These subjects were classified by the consumption of BHA- or BHT-containing foods (yes or no) and categorized into three categories of BHA (0, >0–70, >70 μg/day) and BHT (0, >0–225, >225 μg/day).

Statistical methods:

For data analysis, the GLIM statistical package was used (Baker, 1985). Case-cohort analyses were performed based on the assumption that survival times were exponentially distributed in the follow-up period (Self and Prentice, 1988). Specific macros were developed to account for the additional variance introduced by using the subcohort instead of using the entire cohort (Volovics and van den Brandt, 1997). All analyses were conducted for men and women together. Multivariate rate ratios (RRs) of stomach cancer and their 95% confidence intervals (CI) were computed for all variables. Tests for trend in the RRs were based on likelihood ratio tests. The multivariate model included age, sex, level of education, stomach disorders, family history of stomach cancer and smoking status. Other multivariate models which included also monounsaturated fat or polyunsaturated fat or fruit and vegetable consumption were tested too.

Because of potential influence of preclinical symptoms of stomach cancer on food consumption, all analyses were also conducted after excluding cases diagnosed in the first and second year of follow-up (Botterweck, Van den Brandt and Goldbohm, 1998, van den Brandt et al., 1994).

Results and discussion

Results:

EXPOSURE
- Number of measurements: Not applicable. Estimations were done based on the type of food and brand.
- Average concentrations: Mean intake of BHA and BHT: 105 µg/day for BHA and 351 µg/day for BHT.
- Arithmetic mean: No data.
- Geometric mean: No data.
- Median: No data.
- 95-Percentile: No data.
- Standard deviation: BHA: mean = 105 µg/day and standard deviation = +/- 183 / BHT : mean = 351 µg/day and standard deviation = +/- 347.
- Date(s) of measurement(s): No data.
- Other: The intake of BHA was 105 (range 2–3220) μg/day and BHT was 351 (range 19–2052) μg/day.

FINDINGS
Link between BHT and BHA intake and stomach cancer.

INCIDENCE / CASES
- Incidence/ Number of cases for each disease / parameter under consideration: No data.


STATISTICAL RESULTS
- RR (Rate ratio): Rate ratios and 95% confidence internval (95% CI) were given, see below explaination and results in table 3 in the field 'Any other information on results incl. tables'.


OTHER OBSERVATIONS AND MORE INFORMATION:
Table 1 (see table 1 in the field below 'Any other information on results incl. tables') shows the consumption of mayonnaise and creamy salad dressings in cases and subcohort members. Of the subcohort members, 65.8% consumed mayonnaise and creamy salad dressings. For the subjects with complete data on the consumption of mayonnaise and creamy salad dressings with BHA or BHT, a slightly smaller percentage of cases used foods with BHA or BHT than the subcohort members.

In Table 2 (see table 2 in the field below 'Any other information on results incl. tables'), the distribution of BHA or BHT intake in cases and subcohort members is presented. Mean intake of BHA or BHT among subcohort members was 105 and 351 μg/day, respectively. Intake of BHA or BHT was lower in cases at 89 and 330 μg/day, respectively. There were small differences in distribution of BHA or BHT intake categories between cases and subcohort members. In the highest intake category of the two variables the percentage of cases was slightly lower compared to the subcohort members.

Rate ratios (RRs) of stomach cancer according to the consumption of mayonnaise and creamy salad dressings, the use of mayonnaise and creamy salad dressings with BHA or BHT and intake of BHA or BHT are shown in Table 3. Multivariate analyses of all stomach cancer cases and multivariate analyses after exclusion of cases diagnosed in the first and second year of follow-up are shown. For consumption of mayonnaise and creamy salad dressings and BHA- or BHT-containing foods, no association with stomach cancer risk was observed. After exclusion of first and second year cases, the RRs of the consumption of mayonnaise and creamy salad dressings and BHT-containing foods did not change. However, the RR of BHA-containing foods decreased to 0.89 (95% CI 0.58–1.37) after exclusion of first and second year cases. A decreasing stomach cancer risk was observed with increasing BHA or BHT intake. The RRs of high intake vs low intake of BHA and BHT were 0.84 (95% CI 0.45–1.57) and 0.82 (95% CI 0.46–1.43), respectively. However, the RRs for stomach cancer with each consumption category of the two variables, nor the tests for trend were statistically significant. After exclusion of cases diagnosed in the first or second follow-up year, the RRs of the highest intake of BHA and BHT compared to the lowest intake category decreased to 0.57 (95% CI 0.25–1.30) and 0.74 (95% CI 0.38–1.43), respectively. Again, none of the RRs were statistically significant different from unity and none of the tests for trend were statistically significant. Inclusion of monounsaturated fat or polyunsaturated fat consumption or fruit and vegetable consumption in the model did not change the risk estimates.

Confounding factors:

However, residual confounding is possible because some unidentified risk factors may be involved in the relation between BHA or BHT and stomach cancer risk.

Strengths and weaknesses:

Strengths: One of the strengths of this study is that the food consumption was measured/estimated before stomach cancer was diagnosed, thus avoiding the problem of biased recall of dietary habits. The follow-up of person-years was 100% complete and the completeness of cancer follow-up was also very high, indicating that selection bias due to loss of follow-up is unlikely. In multivariate analysis, adjustment was made for all measured variables that were associated with stomach cancer risk in this study.

Weaknesses: A fact that could have influenced the results is misclassification of exposure. The dietary questionnaire has been designed to assess an individual's long-term food consumption and not specifically to assess the intake of BHA and BHT. We did not have information on BHA or BHT content of all foods with brand names. In the baseline questionnaire, people reported unknown or foreign brand names. The chemical analysis on BHA and BHT content were performed in a selection of foods. These were the most frequently consumed foods reported by a sample of 400 people from the cohort. Although this was a large sample we could not exclude that rather frequently consumed food products were not mentioned. Both the ALBA database and the Compendium of Food and Diet Products obtained their information from food manufacturers, but not all food manufacturers provided information on food additives. Thus, we did not have 100% complete data on BHA or BHT content of foods. However, if misclassification has occurred, this is to be expected non-differential and risk estimates are most likely biased towards the null value.

Any other information on results incl. tables

Table 1. Users of mayonnaise and creamy salad dressings and consumption of mayonnaise and creamy salad dressings with BHA or BHT in stomach cancer cases and sub-cohort members with complete consumption data: Netherlands Cohort Study 1986–1992.

	Cases n = 282	Sub-cohorts n = 3123
	n (%)	n (%)
Users of mayonnaise and creamy salad dressing	108 (63.8)	2056 (65.8)
Non-users	102 (36.2)	1067 (34.2)
Consumption of mayonnaise and creamy salad dressing*
- With BHA	43 (15.2)	497 (15.9)
- Without BHA	149 (52.8)	1538 (49.2)
- With BHT	43 (15.2)	499 (16.0)
- Without BHT	149 (52.8)	1536 (49.2)

* There was no information on BHA and/or BHT content of foods in 90 cases (31.9%) and 1088 sub-cohort members (34.8%).

Table 2. Mean intake of BHA and BHT among users of mayonnaise and creamy salad dressings (μg/day) and distribution of BHA and BHT intake in stomach cancer cases and sub-cohort members: Netherlands Cohort Study 1986–1992.

	Cases	Sub-cohort
Mean intake (+/- SD) in µg/day of
BHA	89 (+/- 83)	105 (+/- 183)
BHT	330 (+/- 315)	351 (+/- 347)
BHA intake (µg/day)	n (%)	n (%)
0	161 (57.1)	1638 (52.4)
>0 - 70	19 (6.7)	207 (6.6)
> 70	12 (4.3)	190 (6.1)
BHT intake (µg/day)
0	161 (57.1)	1644 (52.6)
>0 - 225	16 (5.7)	182 (5.8)
> 225	15 (5.3)	209 (6.7)

 

 

 Table 3. Rate ratios (RR) and 95% confidence interval (95% CI) of stomach cancer according to use of mayonnaise and creamy salad dressings, consumption of BHA or BHT containing foods and intake of BHA or BHT (μg/day): Netherlands Cohort Study 1986–1992.

	RR (95 % CI)*	P-trend	RR (95% CI)**	P-trend
Use of mayonnaise and creamy salad dressings
No	1.00 (i)		1.00 (i)
Yes	0.9 (0.74-1.26)	-	0.93 (0.70-1.25)	-
Use of mayonnaise and creamy salad dressings:
Without BHA	1.00 (i)		1.00 (i)
With BHA	0.97 (0.67-1.40)	-	0.89 (0.53-1.37)	-
Without BHT	1.00 (i)		1.00 (i)
With BHT	0.94 (0.65-1.37)	-	0.98 (0.65-1.49)	-
BHA intake (µg/day)
0	1.00 (i)		1.00 (i)
>0 - 70	0.96 (0.57-1.61)	-	0.80 (0.43-1.48)	-
> 70	0.84 (0.45-1.57)	0.57	0.57 (0.25-1.30)	0.12
BHT intake (µg/day)
0	1.00 (i)		1.00 (i)
>0 - 225	1.00 (0.58-1.76)		0.85 (0.44-1.66)
> 225	0.82 (0.46-1.43)	0.50	0.74 (0.38-1.43)	0.30

* Adjusted for age, sex, smoking status, level of education, stomach disorders and stomach cancer in the family.

**Analyses with first and second year cases excluded and adjusted for age, sex, smoking status, level of education, stomach disorders and stomach cancer in the family.

(i) Reference category.

 

Applicant's summary and conclusion

Conclusions:

This prospective cohort study is the first epidemiologic study that evaluated the association between dietary intake of BHA and BHT and stomach cancer risk. No association between the consumption of foods containing BHA or BHT and stomach cancer risk was found. There seemed to be an indication for a decreased stomach cancer risk with increasing BHA and BHT intake.

Executive summary:

Both carcinogenic and anticarcinogenic properties have been reported for the synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The association between dietary intake of BHA and BHT and stomach cancer risk was investigated in the Netherlands Cohort Study (NLCS) that started in 1986 among 120,852 men and women aged 55 to 69 years. A semi-quantitative food frequency questionnaire was used to assess food consumption. Information on BHA or BHT content of cooking fats, oils, mayonnaise and other creamy salad dressings and dried soups was obtained by chemical analysis, a Dutch database of food additives (ALBA) and the Dutch Compendium of Foods and Diet Products. After 6.3 years of follow-up, complete data on BHA and BHT intake of 192 incident stomach cancer cases and 2035 subcohort members were available for case-cohort analysis. Mean intake of BHA or BHT among subcohort members was 105 and 351 μg/day, respectively. For consumption of mayonnaise and other creamy salad dressings with BHA or BHT, no association with stomach cancer risk was observed. A statistically non-significant decrease in stomach cancer risk was observed with increasing BHA and BHT intake [rate ratio (RR) highest/lowest intake of BHA=0.57 (95% confidence interval (CI): 0.25–1.30] and BHT=0.74 (95% CI: 0.38–1.43). In this study, no significant association with stomach cancer risk was found for usual intake of low levels of BHA and BHT.