Differential growth in estuarine and freshwater habitats indicated by plasma IGF1 concentrations and otolith chemistry in Dolly Varden Salvelinus malma.

This study employed a combination of otolith microchemistry to indicate the recent habitat use, and plasma concentrations of the hormone insulin-like growth factor 1 (IGF1) as an index of recent growth rate, to demonstrate differences in growth and habitat use by Dolly Varden Salvelinus malma occupying both freshwater and estuarine habitats in south-west Alaska. Extensive sampling in all habitats revealed that fish had higher IGF1 levels in estuarine compared to lake habitats throughout the summer, and that the growth rates in different habitats within the estuary varied seasonally. In addition, otolith microchemistry indicated differentiation in estuarine habitat use among individual S. malma throughout summer months. Although growth in the estuary was higher than in fresh water in nearly all sites and months, the benefits and use of the estuarine habitats varied on finer spatial scales. Therefore, this study further illustrates the diverse life histories of S. malma and indicates an evaluation of the benefits of marine waters needs to include sub-estuary scale habitat use.

Evidence-based practice in school substance use prevention: fidelity of implementation under real-world conditions.

Fidelity of program implementation under real-world conditions is a critical issue in the dissemination of evidence-based school substance use prevention curricula. Program effects are diminished when programs are implemented with poor fidelity. We assessed five domains of fidelity--adherence, exposure (dosage), quality of delivery, participant responsiveness and program differentiation (lack of contamination from other programs)--in a subset of respondents (N = 342) from a national random sample of public schools with middle school grades (N = 1721). Respondents taught 1 of 10 evidence-based universal substance use prevention programs as their primary program during the 2004-05 school year. Their responses to survey questions about their recent implementation practices indicated that fidelity was high for quality of delivery and participant responsiveness, low for program differentiation and modest for adherence and exposure--the two core domains of fidelity. Results suggest the need for continued emphasis on fidelity in program materials, trainings and on-going technical support. Particular attention should be paid to supporting use of interactive delivery strategies.

Are adolescents attempting to buy cigarettes on the internet?

OBJECTIVE: To assess the prevalence of, and demographic and smoking behaviour correlates of, attempting to purchase cigarettes via the internet among adolescent current smokers. METHODS: A representative sample of 17 181 10th and 12th grade California students completed a written questionnaire on tobacco related attitudes and behaviour during the 1999-2000 school year. Logistic regression analyses were used to determine the variables associated with attempting to purchase cigarettes on the internet. RESULTS: Among youth under 18 years of age who were current smokers (n = 1689), 2.2% (95% confidence interval 1.5% to 2.9%) reported attempting to purchase cigarettes on the internet. Attempted internet purchases were more likely among younger respondents, males, frequent smokers, and respondents reporting lower perceived availability of tobacco products from retail and social sources. CONCLUSIONS: Few adolescent smokers in California surveyed during the 1999-2000 school year had attempted to obtain cigarettes from the internet. As internet access increases, future studies should examine whether internet cigarette vendors sell to minors and whether adolescents are purchasing cigarettes on the internet.

What factors are associated with local enforcement of laws banning illegal tobacco sales to minors? A study of 182 law enforcement agencies in California.

OBJECTIVES: The aims of this study were to understand the attitudes of local law enforcement staff regarding policies to reduce youth access to tobacco, to determine what proportion of these agencies have conducted unannounced compliance checks in the past year, and to examine factors associated with conducting compliance checks. METHODS: A written questionnaire was completed by 182 law enforcement officials representing 200 cities and counties in California (some officials represented multiple jurisdictions). Logistic regression analyses were conducted to identify factors associated with conducting compliance checks. RESULTS: Only 36% of local enforcement agencies reported conducting one or more compliance checks in the previous year. Agencies were more likely to conduct compliance checks if they perceived fewer barriers to enforcement, reported more frequent collaboration with other community agencies to enforce youth access laws, and believed that youth access to tobacco is a problem in their community. CONCLUSIONS: Because active enforcement of youth access laws using unannounced compliance checks has been shown to reduce the rate of illegal tobacco sales to minors and may reduce youth smoking, efforts to increase the level of enforcement should be promoted. These study results may be used to inform efforts to encourage local agencies to enforce existing youth access laws.

Peer influences and susceptibility to smoking among California adolescents.

Using data from a diverse statewide sample of 10th-grade adolescents in California, in 1996-97, this study investigated the associations between peer influence variables and susceptibility to smoking. Peer influence variables included attitudes about the social consequences of smoking and subjective norms, as described by the Theory of Reasoned Action. Among never-smokers (N=2681) and ever-smokers (N=4248), attitudes about social consequences of smoking and subjective norms each were associated with an increased risk of susceptibility to smoking. The model explained a larger proportion of the variance in susceptibility among ever-smokers than among never-smokers. Results indicate that peer influences, including perceptions of the social consequences of smoking and perceived social norms, may make adolescents susceptible to smoking.

Ethnic variation in peer influences on adolescent smoking.

Previous research has indicated that the influence of peers on adolescent smoking may differ across ethnic groups. Although many studies have focused on African Americans, Hispanics, and Whites, few studies have included Asian Americans, Pacific Islanders, and multi-ethnic adolescents as distinct groups. Using data from a statewide sample of 5870 eighth-grade adolescents in California, this study examined ethnic differences in the association between peer influence variables and smoking behavior and susceptibility. Informational peer influence (best friends' smoking behavior) and normative peer influence (prevalence estimates of peer smoking) were investigated. We hypothesized that informational peer influences would be stronger among Whites (whose families originate primarily from the individualistic cultures of the USA and Western Europe) than among Asian Americans, Pacific Islanders, Hispanics, and African Americans (whose families originate primarily from collectivist cultures). Conversely, we hypothesized that normative peer influences would be stronger among ethnic minority adolescents from collectivist cultural backgrounds than among Whites. Consistent with previous studies, friends' smoking and prevalence estimates of peer smoking were risk factors for past 30-day smoking and susceptibility to smoking across ethnic groups. The influence of friends' smoking behavior was stronger among Whites than among several other groups: Pacific Islanders, African Americans, and Hispanic/Latinos. The influence of prevalence estimates of peer smoking was stronger among Whites than among multiethnic adolescents. Results indicate that cultural factors may play a role in peer influences on smoking initiation. Smoking prevention interventions for adolescents should address the differences in peer influences across ethnic groups.

Novel cyclic adenosine 3',5'-monophosphate (cAMP) response element modulator theta isoforms expressed by two newly identified cAMP-responsive promoters active in the testis.

cAMP signaling contributes to the control of the developmental progression of germ cells during the spermatogenic cycle. Genes regulated by cAMP include those encoding transcription factors such as the cAMP-responsive element modulator (CREM). The disruption of CREM gene expression in crem null mice results in arrest of spermatogenesis and infertility. The transcriptional control of the CREM gene is attributed to two promoters, P1 and P2. The P1 promoter constitutively activates the synthesis of messenger RNAs encoding activator (tau) and repressor (alpha) forms of CREM, whereas the cAMP-responsive P2 promoter activates the formation of messenger RNAs encoding the inducible cAMP early repressor. Here we report the identification of two additional promoters in the CREM gene, P3 and P4, that in the rat testis encode two novel transcriptional activator CREM isoforms, termed CREM theta1 and CREM theta2, respectively. Notably, the P3 and P4 promoters are activated by cAMP-dependent protein kinase, thereby providing cAMP-regulated transcription of CREM activators in addition to the established cAMP-regulated inducible cAMP early repressor. Analysis ex vivo of CREM gene expression in temporally staged segments of the seminiferous tubule during the spermatogenic cycle shows that the activities of the P1, P3, and P4 promoters are independently regulated. Our identification of the cAMP-activated P3 and P4 promoters that direct expression of the novel theta1 and theta2 activator isoforms of CREM brings further insight into the complex expression of the CREM gene during germ cell development and may have implications in understanding the control of fertility.

Exposure to, and perceived usefulness of, school-based tobacco prevention programs: associations with susceptibility to smoking among adolescents.

PURPOSE: To examine the relationships of exposure to school-based tobacco prevention programs and perceived usefulness of such programs to smoking susceptibility. METHODS: An ethnically representative sample of 6929 Grade 10 students participated in a cross-sectional survey of tobacco-related activities and behaviors. Perceived usefulness of prevention programs was investigated according to two dimensions: perceived helpfulness of information received at school with regard to making decisions about tobacco use and perceived availability of social resources that might help students cope with tobacco-related issues. RESULTS: The extent of exposure to school prevention programs and both dimensions of perceived usefulness of these programs were inversely associated with susceptibility to smoking. In addition, perceived information helpfulness mediated the effect of program exposure on susceptibility status, whereas perceived availability of social resources moderated that effect. The study also presented evidence suggesting ethnic/cultural variability in the status of susceptibility to smoking at this age. CONCLUSIONS: The study indicates a need to examine the perceptions of students receiving school prevention programs. Perceived usefulness of school prevention programs may be used to identify youth at high risk for smoking susceptibility. Future studies, however, should investigate other dimensions of perceived usefulness as well as intrapersonal, interpersonal, and environmental correlates of this construct.

English language use as a risk factor for smoking initiation among Hispanic and Asian American adolescents: evidence for mediation by tobacco-related beliefs and social norms.

Acculturation increases the risk of smoking among Hispanic and Asian American adolescents, but the underlying mechanisms are not understood. This study examined associations between English language use and smoking among 4,167 Hispanic and 2,836 Asian American adolescents in California. Potential mediators were assessed, including access to cigarettes, perceived consequences, friends' smoking, cigarette offers, refusal self-efficacy, and prevalence estimates of peer smoking. English language use was associated with increased risk of lifetime smoking in both groups. This association became nonsignificant after access, perceived consequences, friends' smoking, and offers were controlled for. The acculturation process (as indicated by English language use) may be associated with smoking-related psychosocial variables, which may lead to an increased risk of experimentation with smoking.

Ethnic differences in adolescent smoking prevalence in California: are multi-ethnic youth at higher risk?

OBJECTIVE: Although ethnic differences in adolescent smoking have been well documented, smoking among multi-ethnic adolescents has received little research attention. This study examined smoking prevalence and tobacco related psychosocial risk factors among multi-ethnic adolescents in California, as compared with white, African American, Asian American, and Hispanic adolescents. DESIGN: This study used a cross sectional design. Data were obtained from the independent evaluation of the California Tobacco Control, Prevention, and Education Program. SETTING: Students completed a paper-and-pencil survey in their classrooms. SUBJECTS: Data were collected from a stratified random sample of 5072 eighth grade students (age 13-14 years) in California during the 1996-97 school year. The data were weighted by school enrollment in analyses to make the estimates representative of the population of California students attending public schools. MAIN OUTCOME MEASURES: Outcome variables included self reported smoking prevalence, susceptibility to smoking, access to tobacco, and related attitudes, beliefs, and behaviours. Ethnicity was assessed with a self reported, "check all that apply" question. RESULTS: Results indicated that multi-ethnic adolescents were at higher risk than single-ethnic adolescents on several variables, including 30 day cigarette smoking prevalence, lifetime smokeless tobacco use, buying cigarettes, receiving cigarette offers, and expected friends' reaction if the respondent smoked. For several other variables (lifetime cigarette smoking prevalence, susceptibility to smoking, and number of friends who smoked), Hispanic adolescents were at higher risk than all other ethnic groups including multi-ethnic adolescents. Although susceptibility to smoking was highest among Hispanics, multi-ethnic adolescents scored significantly higher on susceptibility than the three other single-ethnic groups. CONCLUSIONS: Multi-ethnic adolescents may be at increased risk for smoking and may have easier access to cigarettes. Culturally targeted smoking prevention interventions for adolescents should address the unique social challenges faced by multi-ethnic adolescents that may increase their risk for smoking.

Attitudes toward anti-tobacco policy among California youth: associations with smoking status, psychosocial variables and advocacy actions.

To prevent smoking and exposure to environmental tobacco smoke, California has implemented anti-tobacco policies, including laws restricting youth access to tobacco, and smoking bans in workplaces, schools, restaurants and bars. Although studies have examined adults' attitudes toward anti-tobacco policies, little is known about adolescents' awareness of and support for these policies. This study examined attitudes toward anti-tobacco policies in a sample of 6887 10th grade California adolescents. Awareness of anti-tobacco policies was highest among current smokers and lowest among susceptible never-smokers. Support for anti-tobacco policies was highest among non-susceptible never-smokers and lowest among current smokers. Policy awareness and support were significantly associated with psychosocial tobacco-related variables (e.g. perceived consequences of smoking, friends' smoking, perceived access to cigarettes, prevalence estimates of smoking among peers, cigarette offers and cigarette refusal self-efficacy). Policy awareness and support were associated with the probability of performing advocacy actions against tobacco use. Although these results cannot prove a causal association, they suggest that adolescents' attitudes toward anti-tobacco policies may play a role in their decisions about smoking. Tobacco control and education programs should include information about existing anti-tobacco policies, and should educate youth about the importance and benefits of anti-tobacco policies.

Supplement to the Carcinogenic Potency Database (CPDB): results of animal bioassays published in the general literature in 1993 to 1994 and by the National Toxicology Program in 1995 to 1996.

The Carcinogenic Potency Database (CPDB) is a systematic and unifying analysis of results of chronic, long-term cancer tests. This paper presents a supplemental plot of the CPDB, including 513 experiments on 157 test compounds published in the general literature in 1993 and 1994 and in Technical Reports of the National Toxicology Program in 1995 and 1996. The plot standardizes the experimental results (whether positive or negative for carcinogenicity), including qualitative data on strain, sex, route of compound administration, target organ, histopathology, and author's opinion and reference to the published paper, as well as quantitative data on carcinogenic potency, statistical significance, tumor incidence, dose-response curve shape, length of experiment, duration of dosing, and dose rate. A numerical description of carcinogenic potency, the TD(subscript)50(/subscript), is estimated for each set of tumor incidence data reported. When added to the data published earlier, the CPDB now includes results of 5,620 experiments on 1,372 chemicals that have been reported in 1,250 published papers and 414 National Cancer Institute/National Toxicology Program Technical Reports. The plot presented here includes detailed analyses of 25 chemicals tested in monkeys for up to 32 years by the National Cancer Institute. Half the rodent carcinogens that were tested in monkeys were not carcinogenic, despite usually strong evidence of carcinogenicity in rodents and/or humans. Our analysis of possible explanatory factors indicates that this result is due in part to the fact that the monkey studies lacked power to detect an effect compared to standard rodent bioassays. Factors that contributed to the lack of power are the small number of animals on test; a stop-exposure protocol for model rodent carcinogens; in a few cases, toxic doses that resulted in stoppage of dosing or termination of the experiment; and in a few cases, low doses administered to monkeys or early termination of the experiment even though the doses were not toxic. Among chemicals carcinogenic in both monkeys and rodents, there is some support for target site concordance, but it is primarily restricted to liver tumors. Potency values are highly correlated between rodents and monkeys. The plot in this paper can be used in conjunction with the earlier results published in the CRC Handbook of Carcinogenic Potency and Genotoxicity Databases [Gold LS, Zeiger E, eds. Boca Raton FL:CRC Press, 1997] and with our web site (http://potency.berkeley.edu), which includes a guide to the plot of the database, a complete description of the numerical index of carcinogenic potency (TD50), and a discussion of the sources of data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. Two summary tables permit easy access to the literature of animal cancer tests by target organ and by chemical. For readers using the CPDB extensively, a combined plot on diskette or other format is available from the first author. It includes all results published earlier and in this paper, ordered alphabetically by chemical. A SAS database is also available.

Effects of a community-based prevention program on decreasing drug use in high-risk adolescents.

OBJECTIVES: This study investigated the secondary prevention effects of a substance abuse primary prevention program. METHODS: Logistic regression analyses were conducted on 4 waves of follow-up data from sixth- and seventh-grade baseline users of cigarettes, alcohol, and marijuana taking part in a school-based program in Indianapolis. RESULTS: The program demonstrated significant reductions in cigarette use at the initial follow-up (6 months) and alcohol use at the first 2 follow-ups (up to 1.5 years). Models considering repeated measures also showed effects on all 3 substances. CONCLUSIONS: Primary prevention programs are able to reach and influence high-risk adolescents in a nonstigmatizing manner.

Sixth plot of the carcinogenic potency database: results of animal bioassays published in the General Literature 1989 to 1990 and by the National Toxicology Program 1990 to 1993.

This paper presents two types of information from the Carcinogenic Potency Database (CPDB): (a) the sixth chronological plot of analyses of long-term carcinogenesis bioassays, and (b) an index to chemicals in all six plots, including a summary compendium of positivity and potency for each chemical (Appendix 14). The five earlier plots of the CPDB have appeared in this journal, beginning in 1984 (1-5). Including the plot in this paper, the CPDB reports results of 5002 experiments on 1230 chemicals. This paper includes bioassay results published in the general literature between January 1989 and December 1990, and in Technical Reports of the National Toxicology Program between January 1990 and June 1993. Analyses are included on 17 chemicals tested in nonhuman primates by the Laboratory of Chemical Pharmacology, National Cancer Institute. This plot presents results of 531 long-term, chronic experiments of 182 test compounds and includes the same information about each experiment in the same plot format as the earlier papers: the species and strain of test animal, the route and duration of compound administration, dose level and other aspects of experimental protocol, histopathology and tumor incidence, TD50 (carcinogenic potency) and its statistical significance, dose response, author's opinion about carcinogenicity, and literature citation. We refer the reader to the 1984 publications (1,6,7) for a detailed guide to the plot of the database, a complete description of the numerical index of carcinogenic potency, and a discussion of the sources of data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. The six plots of the CPDB are to be used together since results of individual experiments that were published earlier are not repeated. Appendix 14 is designed to facilitate access to results on all chemicals. References to the published papers that are the source of experimental data are reported in each of the published plots. For readers using the CPDB extensively, a combined plot is available of all results from the six separate plot papers, ordered alphabetically by chemical; the combined plot in printed form or on computer tape or diskette is available from the first author. A SAS database is also available.

Recognition and liking of tobacco and alcohol advertisements among adolescents: relationships with susceptibility to substance use.

BACKGROUND: Exposure to tobacco and alcohol advertising has been associated with adolescent substance use. However, it is not clear whether favorable reactions to advertising are an antecedent to or a consequence of substance use. This study investigated relationships between adolescents' levels of susceptibility to substance use and their recognition and liking of tobacco and alcohol advertising. METHOD: Eighth-grade students viewed pictures of tobacco and alcohol advertisements with brand names and identifying information obscured, attempted to identify the brand name and type of product being advertised, and rated their liking of the advertisements. Subjects were divided into three substance use status groups: nonsusceptible nonusers (have never used and do not intend to do so), susceptible nonusers (have not used but have not made a firm commitment not to experiment in the future), and users (have tried the substance). RESULTS: Susceptible nonusers liked the tobacco advertisements at a level that was significantly greater than that of the nonsusceptible nonsmokers and comparable to that of the users. Liking of the alcohol advertisements generally increased with alcohol use status. CONCLUSIONS: These results suggest that tobacco advertisements ostensibly targeted to adult smokers may have the effect of recruiting new adolescent smokers.

The fifth plot of the Carcinogenic Potency Database: results of animal bioassays published in the general literature through 1988 and by the National Toxicology Program through 1989.

This paper is the fifth plot of the Carcinogenic Potency Database (CPDB) that first appeared in this journal in 1984 (1-5). We report here results of carcinogenesis bioassays published in the general literature between January 1987 and December 1988, and in technical reports of the National Toxicology Program between July 1987 and December 1989. This supplement includes results of 412 long-term, chronic experiments of 147 test compounds and reports the same information about each experiment in the same plot format as the earlier papers: the species and strain of test animal, the route and duration of compound administration, dose level and other aspects of experimental protocol, histopathology and tumor incidence, TD50 (carcinogenic potency) and its statistical significance, dose response, author's opinion about carcinogenicity, and literature citation. We refer the reader to the 1984 publications (1,5,6) for a guide to the plot of the database, a complete description of the numerical index of carcinogenic potency, and a discussion of the sources of data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. The five plots of the database are to be used together, as results of individual experiments that were published earlier are not repeated. In all, the five plots include results of 4487 experiments on 1136 chemicals. Several analyses based on the CPDB that were published earlier are described briefly, and updated results based on all five plots are given for the following earlier analyses: the most potent TD50 value by species, reproducibility of bioassay results, positivity rates, and prediction between species.(ABSTRACT TRUNCATED AT 250 WORDS)

Diffusion of a school-based substance abuse prevention program: predictors of program implementation.

BACKGROUND: The present study addresses diffusion of a psychosocial-based substance abuse prevention program, including: (a) teacher adoption, implementation, and maintenance; (b) teacher characteristics associated with implementation; (c) the relationship between integrity of program delivery and program outcomes; and (d) the effectiveness of teacher training and school principal involvement in increasing implementation. METHODS: Participants were teachers (n = 60), school principals (n = 25), and fifth-grade students (n = 1147) from four Los Angeles area school districts. Districts were randomly assigned to an intensive or brief teacher training condition. Schools were randomly assigned to a principal-intervention or a no-principal-intervention condition. Assessments included teacher and principal self-reports, classroom observations of program delivery, and evaluation of immediate program outcomes. RESULTS: During the first year, 78% of trained teachers implemented one or more program lessons. During the second year, only 25% maintained implementation of the program. Implementors reported fewer years of teaching experience and stronger self-efficacy, enthusiasm, preparedness, teaching methods compatibility, and principal encouragement than did nonimplementors. The principal intervention increased rates of implementation, but the intensive teacher training did not. Integrity of program delivery was positively associated with immediate program outcomes. CONCLUSIONS: Program implementation was highly variable, suggesting that widespread teacher use of psychosocial-based programs cannot be taken for granted. Strategies for increasing implementation and maintenance need to be developed.

The Carcinogenic Potency Database: analyses of 4000 chronic animal cancer experiments published in the general literature and by the U.S. National Cancer Institute/National Toxicology Program.

The Carcinogenic Potency Database (CPDB) is an easily accessible, standardized resource of positive and negative long-term animal cancer tests. The CPDB has been published in four earlier papers that include results for approximately 4000 experiments on 1050 chemicals. This paper describes the CPDB: goals, inclusion criteria, fields of information, and published plot format. It also presents an overview of our published papers using the CPDB. The CPDB as published in plot format readily permits comparisons of carcinogenic potency and many other aspects of cancer tests, including for each experiment the species and strain of test animals, the route and duration of compound administration, dose level and other aspects of experimental protocol, histopathology and tumor incidence, TD50 (carcinogenic potency) and its statistical significance, dose response, author's opinion about carcinogenicity, and literature citation. A combined plot of all results from the four separate papers, which is ordered alphabetically by chemical, is available from L. S. Gold, in printed form or on computer tape or diskette. A computer readable (SAS) database is also available. The overview of papers includes descriptions of work on methods of estimating carcinogenic potency, reproducibility of results in near-replicate cancer tests, correlation in potency between species, ranking possible carcinogenic hazards, comparison of positivity and target organ in rats and mice, comparison of mutagens and nonmutagens, proportion of chemicals positive in animal tests, natural compared to synthetic chemicals, and mechanistic issues in interspecies extrapolation.

Program integrity as a moderator of prevention program effectiveness: results for fifth-grade students in the adolescent alcohol prevention trial.

This study reports the results of a test of the quality of program delivery (program integrity) as a variable that may moderate the effectiveness of alcohol prevention programs. Two theory-based programs, Resistance Training and Normative Education, were delivered to fifth-grade students who were then tested on program relevant mediating variables. Resistance Training was found to improve students' knowledge of peer pressure resistance strategies, their performance on a behavioral assessment of peer pressure resistance skills and the manifestation of their future intentions to drink alcohol. Normative Education was found to improve students' perceptions of a conservative norm regarding alcohol use, facilitated their belief that refusing unwanted offers to drink alcohol could be easily accomplished and reduced their perceptions of the prevalence of alcohol use. Program integrity was measured by program specialists who taught the programs to students and by trained observers. Ratings of program integrity were found to significantly moderate outcomes for three of seven mediating variables. Affected were knowledge of peer pressure resistance strategies, behavioral pressure resistance skills and perceived self-efficacy. These results suggest that the quality of program delivery and reception may play an important moderating function on prevention program effectiveness.

Third chronological supplement to the carcinogenic potency database: standardized results of animal bioassays published through December 1986 and by the National Toxicology Program through June 1987.

This paper is the third chronological supplement to the Carcinogenic Potency Database that first appeared in this journal in 1984. We report here results of carcinogenesis bioassays published in the general literature between January 1985 and December 1986, and in Technical Reports of the National Toxicology Program between June 1986 and June 1987. This supplement includes results of 337 long-term, chronic experiments of 121 compounds, and reports the same information about each experiment in the same plot format as the earlier papers, e.g., the species and strain of animal, the route and duration of compound administration, dose level, and other aspects of experimental protocol, histopathology, and tumor incidence, TD50 (carcinogenic potency) and its statistical significance, dose response, opinion of the author about carcinogenicity, and literature citation. The reader needs to refer to the 1984 publication for a guide to the plot of the database, a complete description of the numerical index of carcinogenic potency, and a discussion of the sources of data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. The four plots of the database are to be used together as results published earlier are not repeated. In all, the four plots include results for approximately 4000 experiments on 1050 chemicals. Appendix 14 of this paper is an alphabetical index to all chemicals in the database and indicates which plot(s) each chemical appears in. A combined plot of all results from the four separate papers, that is ordered alphabetically by chemical, is available from the first author, in printed form or on computer tape or diskette.