Assessing in vitro dermal absorption of dry residues of agrochemical sprays using human skin within OECD TG 428.

We describe a novel experimental method that mimics exposure to dried agrochemical residues on contact surfaces during re-entry into crops. It includes the creation of dry dislodgeable residues and subsequent transfer to human skin for in vitro measurement of dermal absorption within a standard Organisation for Economic Co-operation and Development test guideline (OECD TG) 428 study. A pre-determined volume of spray containing 14C-labelled active substance is transferred onto a polytetrafluorethylene-coated septum and air-dried. The septum is then gently placed onto the pre-wetted skin mounted in a flow-through Franz diffusion chamber. The septum is gently rotated thrice to transfer the dose. Preliminary tests determined transfer efficiency to ensure the appropriate test concentration on the skin. Then, a standard dermal absorption study is performed according to OECD TG 428. Results from 10 compounds indicate that the methodology can be robustly incorporated into a standard TG study. These data show that the dermal absorption from a dry dislodgeable residue is lower than that from the equivalent dose of the aqueous spray, regardless of formulation type or active substance. Studies following the scenario described above can be a suitable tool to better estimate dermal absorption from dry residues in re-entry worker and resident exposure assessment for agrochemicals.

Assessment of an extended dataset of in vitro human dermal absorption studies on pesticides to determine default values, opportunities for read-across and influence of dilution on absorption.

Dermal absorption is a key parameter in non-dietary human safety assessments for agrochemicals. Conservative default values and other criteria in the EFSA guidance have substantially increased generation of product-specific in vitro data and in some cases, in vivo data. Therefore, data from 190 GLP- and OECD guideline-compliant human in vitro dermal absorption studies were published, suggesting EFSA defaults and criteria should be revised (Aggarwal et al., 2014). This follow-up article presents data from an additional 171 studies and also the combined dataset. Collectively, the data provide consistent and compelling evidence for revision of EFSA's guidance. This assessment covers 152 agrochemicals, 19 formulation types and representative ranges of spray concentrations. The analysis used EFSA's worst-case dermal absorption definition (i.e., an entire skin residue, except for surface layers of stratum corneum, is absorbed). It confirmed previously proposed default values of 6% for liquid and 2% for solid concentrates, irrespective of active substance loading, and 30% for all spray dilutions, irrespective of formulation type. For concentrates, absorption from solvent-based formulations provided reliable read-across for other formulation types, as did water-based products for solid concentrates. The combined dataset confirmed that absorption does not increase linearly beyond a 5-fold increase in dilution. Finally, despite using EFSA's worst-case definition for absorption, a rationale for routinely excluding the entire stratum corneum residue, and ideally the entire epidermal residue in in vitro studies, is presented.

Assessment of in vitro human dermal absorption studies on pesticides to determine default values, opportunities for read-across and influence of dilution on absorption.

Dermal absorption is an integral part of non-dietary human safety risk assessments for agrochemicals. Typically, dermal absorption data for agrochemical active substances are generated from the undiluted formulation concentrate and its spray dilutions. European Food Safety Authority (EFSA) guidance, which combines highly conservative default values, very limited opportunities for read-across from existing data and other overly conservative conclusions, was the driver for this assessment. To investigate the reliability of the EFSA guidance, a homogeneous data-set of 190 GLP and OECD guideline compliant in vitro human skin studies, chosen to match the test method preferred by EU data requirements, was evaluated. These studies represented a wide range of active substances, formulation types, and concentrations. In alignment with EFSA guidance on human exposure assessment, a conservative estimate of absorption (95th percentile) was chosen to define defaults, which were also based on the EFSA worst-case assumption that all material in skin, excluding the first two tape strips, is absorbed. The analysis supports dermal absorption defaults of 6% for liquid concentrates, 2% for solid concentrates, and 30% for all spray dilutions, irrespective of the active substance concentration. Relatively high dermal absorption values for organic solvent-based formulations, compared to water-based or solid concentrates, support their use as worst-case surrogate data for read-across to other formulation types. The current review also shows that dermal absorption of sprays does not increase linearly with increasing dilution, and provides a novel, science-based option for extrapolation from existing data.

Influence of magnetocrystalline anisotropy on the magnetization dynamics of magnetic microstructures.

The study of magnetodynamics using stroboscopic time-resolved x-ray photoemission electron microscopy (TR-XPEEM) involves an intrinsic timescale provided by the pulse structure of the synchrotron radiation. In the usual multi-bunch operation mode, the time span between two subsequent light pulses is too short to allow a relaxation of the system into the ground state before the next pump-probe cycle starts. Using a deflection gating mechanism described in this paper we are able to pick the photoemission signal resulting from selected light pulses. Thus, PEEM measurements can be carried out in a flexible timing scheme with longer delays between two light pulses. Using this technique, the magnetodynamics of both Permalloy and iron structures have been investigated. The differences in the dynamic response on a short magnetic field pulse are discussed with respect to the magnetocrystalline anisotropy.

Molecular genetic analyses of a 376-kilodalton Golgi complex membrane protein (giantin)

Molecular genetic analyses of a 376-kDa Golgi complex (GC) membrane protein (giantin) are described. The immunoglobulin G fraction of a human serum containing antibodies against GC antigens as revealed by indirect immunofluorescence microscopy with Hep-2 cells was used to screen a HeLa cDNA expression library, yielding four overlapping cross-hybridizing clones. Additional cDNA clones were retrieved from a lambda gt11 human thyroid cDNA library or generated by reverse transcriptase-mediated PCR from HeLa cell mRNA. Alignment of the clones resulted in a consensus cDNA of 10,300 bp encoding a protein of 376 kDa. The corresponding mRNA with a size of about 10 kb was detected by Northern (RNA) blotting of HeLa, Hep-G2, and Jurkat cell RNA. Sequence analyses of the protein revealed an extraordinarily high content of heptad repeats with the probability of forming coiled coils similar to the proteins of the myosin family. Five overlapping recombinant proteins covering the entire sequence were synthesized and used for antibody production in rabbits and for affinity purification of human and rabbit antibodies. Indirect immunofluorescence experiments also done with brefeldin A-treated Hep-2 and Pt K1 cells revealed an identical GC staining of both the affinity-purified human and rabbit antibodies. Double labeling experiments with antibodies against the GC marker mannosidase II as well as immunoelectron microscopic studies confirmed the localization of the protein within the GC. A corresponding endogenous large-molecular-mass protein of about 390 kDa was found in [35S]methionine-labeled Hep-2 cell lysates as well as in GC-enriched subcellular fractions from rat liver. The protein as well as the recently described proteins golgin-95 and golgin-160 (M. J. Fritzler, J. C. Hamel, R. L. Ochs, and E. K. L. Chan, J. Exp. Med. 178:49-62, 1993) may belong to a new group of Golgi proteins with a high content of heptad repeats which may exert functions in scaffold formation or vesicle transport. As far as can be concluded from immunological and personally communicated partial cDNA sequence data, the protein seems to be identical with a 400-kDa Golgi protein (giantin) recently described (A. D. Linstedt and H. P. Hauri, Mol. Biol. Cell 4:679-693, 1993). Therefore, we agreed to adopt the name giantin.

A comparative study of the sensitivity of the 3-induction and 9-induction Buehler test procedures for assessing skin sensitisation potential.

Assessment of skin sensitization potential is a mandatory requirement for the registration or notification of most types of chemicals and products. Until recently, two methods using the guinea pig as test model were the most widely accepted; the guinea pig maximisation test and the Buehler test. In the case of agrochemical formulations, which constitute the final end use product in contact with operators, industry and also some regulatory authorities consider the Buehler method more appropriate as the methodology is more relevant to likely exposure in the field. However, certain European regulatory authorities have become concerned about the sensitivity of the Buehler test for this purpose and have requested that a modified method is used in which additional applications of test materials are used during the induction phase of the protocol (a total of 9 rather than the normal 3). This study was designed to assess whether this modification was justified. Six reference substances (formaldehyde, alpha-hexylcinnamaldehyde, fragrance mix, thimerosal, mercaptobenzothiazole and phthalic anhydride); all mild to moderate skin sensitizing chemicals, were assessed in a study, which compared the use of 3 and 9 induction applications. The results of this study demonstrated that, although most of these sensitisers were detected by both protocols, the modified method (9 induction applications) was no more sensitive than the standard method (3 induction applications). As the modified protocol is also potentially more stressful to the animals, it is concluded that the use of additional induction applications in the Buehler test cannot be justified from either a scientific or an animal welfare perspective.

Patient satisfaction and side effects with levonorgestrel implant (Norplant) use in adolescents 18 years of age or younger.

OBJECTIVES: Levonorgestrel implants (Norplant) have recently been approved for use in the United States. Adolescents may be especially suited for this method of contraception because of its long duration of action and lack of dependence on patient compliance for efficacy. To date, however, its use in young patients has not been investigated. This study was undertaken to compare side effects and satisfaction with this new method during the first 6 months of use among adolescents and adults. METHODS: Twenty-one adolescents 18 years of age or younger and 30 adults 19 years or older participated in this study. Information on side effects and satisfaction was obtained from clinic records and a structured interview conducted 6 months after insertion. RESULTS: The most frequent reason adolescents gave for selecting Norplant was convenience. None of the adolescents were upset by the insertion process or by its appearance in the arm, although 10 (48%) reported that it was visible. The most frequent side effect reported by both adolescents (71%) and adults (53%) was abnormal menstrual bleeding. Weight gain was reported by 8 adolescents (38%), 3 of whom attributed it to an increase in their appetite. Other side effects commonly reported by adolescents included emotional disturbances (33%) and headaches (38%), whereas adults reported acne (27%) and mastalgia (37%). Only 1 adolescent (5%) and 1 adult (3%) reported experiencing no side effects. A similar percentage of adolescents (8%) compared with adults (6%) requested removal of the implant because of side effects during the 6-month period. Overall, satisfaction was expressed by 86% (18/21) of adolescents, all of whom stated that they preferred Norplant to their previous contraceptive method. CONCLUSIONS: This investigation demonstrates that levonorgestrel implants are well tolerated by most young patients. Clinicians involved in the care of adolescents should consider Norplant as an appropriate option of birth control for this population.

An investigation into why adolescents may reject Norplant.

OBJECTIVES: To identify characteristics of patients 18 years of age and younger who would and would not consider using levonorgestrel implants (Norplant) for contraception and to isolate potential barriers to its use. STUDY DESIGN: Survey of 323 adolescents attending family planning or obstetrics clinics between April 29 and October 27, 1992. For purposes of analyses, patients were stratified by their willingness to consider using Norplant. Statements about Norplant that differentiated between groups were considered significant barriers. Additional analyses were conducted for the sample, stratified by pregnancy status, race and ethnicity, parity, and Norplant class attendance. RESULTS: Sixty-four percent of participants stated that they would be willing to consider using Norplant. These adolescents were significantly older, were more likely to already have given birth or have had abortions, planned to delay (additional) childbearing for 5 or more years, aspired to receive college educations, and reported lower annual household incomes than did adolescents unwilling to consider using the device. Identified barriers to Norplant use included misinformation, perceived advantages, physical aversions, perceived efficacy, fertility concerns, social influences, and concerns about safety and side effects. CONCLUSIONS: Misperceptions and concerns about safety and side effects will prevent many adolescents from using Norplant. Recent negative publicity surrounding its use will intensify this problem. Health care providers must work to remove these barriers so that sexually active adolescents can make informed decisions about contraceptives.

Exposure to violence and associated health-risk behaviors among adolescent girls.

OBJECTIVE: To examine the relationship between exposure to violence and health-risk behaviors. DESIGN: Cross-sectional survey. SETTING: University-based outpatient family planning clinic. PATIENTS: Sexually active adolescent girls younger than 18 years (N = 517) who presented for contraceptive care. MAIN OUTCOME MEASURES: Prevalence of witnessing or experiencing violence and the associations with health-risk behaviors, including high-risk sexual behaviors, substance use, and self-injury. RESULTS: Compared with adolescents who had not been exposed to violence, those who had only witnessed violence were 2 to 3 times more likely to report using tobacco and marijuana, drinking alcohol or using drugs before sex, and having intercourse with a partner who had multiple partners. Those who had experienced, but not witnessed violence were at increased risk of these same behaviors and were 2 to 4 times more likely than those who had neither witnessed nor experienced violence to report early initiation of intercourse, intercourse with strangers, multiple partners, or partners with multiple partners, tobacco, alcohol and drug use, or to have positive test results for a sexually transmitted disease. Individuals who had both witnessed and experienced violence demonstrated the greatest risk of adverse health behaviors. These adolescents demonstrated 3 to 6 times greater risk of suicidal ideation (odds ratio [OR], 3.1; 95% confidence interval [CI], 2.2-4.0) or suicide attempts (OR, 4.5; 95% CI, 2.2-9.4), self-injury (OR, 5.8; 95% CI, 2.6-12.9), and use of drugs before intercourse (OR, 6.2; 95% CI, 3.0-12.9) than those who had neither witnessed nor experienced violence. CONCLUSIONS: Adolescents exposed to violence are at increased risk of multiple adverse health behaviors. Programs designed to improve health outcomes should target this high-risk group.

Health risk behaviors among pregnant adolescents with older partners.

OBJECTIVE: To determine if pregnant adolescents with older (> or = 5 years) adult (> or = 20 years) vs same-age (+/- 2 years) male partners are at increased health risk. DESIGN: Medical charts of pregnant adolescents who participated in a structured interview as part of their prenatal care were reviewed. SETTING: Outpatient maternal and child health clinic at a university teaching hospital. PATIENTS: A total of 503 white, African American, and Mexican American adolescents, aged 12 to 17 years, who initiated prenatal care between January 19, 1992, and December 19, 1994, were consecutively sampled. MAIN OUTCOME MEASURE: We hypothesized that female adolescents paired with older-adult vs same-age partners would be more likely to report recent substance use, high-risk sexual behaviors, and partner-directed violence. RESULTS: Of the sample, 26% (n = 129) had an older adult partner, whereas 44% (n = 222) had a same-age partner. The remaining adolescents who did not fit either definition (n = 152) were excluded from further analysis. Logistic regression analyses demonstrated that girls with older-adult partners were more likely to have initiated sexual intercourse before 13 years (odds ratio [OR] = 2.1), have discontinued school (OR = 2.8), have used marijuana in the past 30 days (OR = 2.9), be married or living with their partner (OR = 3.2), and desire their current pregnancy (OR = 2.1). These young women also were more likely to report that their partner was employed (OR = 2.8), had other children (OR = 7.4), and used alcohol during the week (OR = 2.0). No association between tobacco use or partner-directed violence and partner age was observed. CONCLUSION: Pregnant adolescents with older-adult male partners report risk behaviors that may affect their health and that of their unborn child but are not more likely to experience partner-directed violence.

Strategies to promote breast-feeding among adolescent mothers.

OBJECTIVE: To identify characteristics of adolescent mothers who bottle-feed who considered breast-feeding their infants and strategies to promote breast-feeding within this special group. DESIGN: Adolescents completed an hour-long interview within 48 hours of delivery that elicited factors considered important to the mother's feeding decision and indices of mental health. SETTING: Postpartum ward of university hospital. SUBJECTS: A total of 693 adolescents 18 years old or younger (mean age, 16.7 years) from African American, Mexican American, or white race or ethnicity; 27% of Mexican American participants spoke little or no English. MAIN OUTCOME MEASURES: Factors associated with breast-feeding decision. RESULTS: Those who chose bottle-feeding (hereafter, bottle-feeders) who had considered breast-feeding were first compared with bottle-feeders who had not considered breast-feeding and then with adolescents who breast-fed. After controlling for ethnicity, bottle-feeders who had considered breast-feeding were more likely than those who had not considered breast-feeding to be impoverished (adjusted odds ratio [AOR] = 4.8), to have delayed their feeding decision until the later stages of pregnancy (AOR = 4.6), to have been encouraged to breast-feed (AOR = 4.5), to have friends who breast-fed (AOR = 2.3), and to have experienced low financial, tangible, emotional, or informational support from their families (AOR = 1.6). They were more likely to cite barriers associated with breast-feeding while returning to school or work (AOR = 2.0) and less likely to state that bottle-feeding was healthier (AOR = 0.3) as reasons for bottle-feeding. Compared with those who chose breast-feeding (hereafter, breast-feeders), this group was more likely to have made the feeding decision alone rather than relying on advice (AOR = 4.6), to have made this decision in the later stages of pregnancy (AOR = 4.4), to report fewer breast-feeding role models (AOR = 1.8) and fewer significant others who encouraged breast-feeding (AOR = 2.8), and to report at least 2 significant others who encouraged bottle-feeding (AOR= 3.2). They were also less likely to have attempted to breast-feed a previous child (AOR = 3.3). CONCLUSIONS: A subgroup of adolescent mothers who had considered breast-feeding but ultimately chose to bottle-feed may be identified in the late stages of gestation by collecting information on financial status, family support, perceived barriers to breast-feeding and attending school or working, timing of the feeding decision, prior breast-feeding experience, breast-feeding role models, and encouragement to breast-feed. We speculate that strategies to promote breast-feeding should focus on role modeling and facilitation.

The behavioral risks and life circumstances of adolescent mothers involved with older adult partners.

OBJECTIVE: To investigate behavioral risks and life circumstances of adolescent mothers with older (> or =5 years) adult (> or =20 years old) vs. similar-aged (+/-2 years) male partners at 12 months' postpartum. METHODS: Nine hundred thirty-one adolescent females were interviewed after delivery and were mailed surveys to complete at 12 months' postpartum. Analysis by chi(2) and t test was used to identify differences in behavioral risks (planned repeated pregnancy, substance use, and intimate partner violence) and life circumstances (financial status, school enrollment, and social support) for adolescent mothers with older adult vs similar-aged partners. Additional stratified analyses were conducted to evaluate the extent to which living with an adult authority figure or being with the father of her infant born 12 months previously might alter observed relationships. RESULTS: At 12 months following delivery, 184 adolescent mothers (20%) reported having an older adult partner, whereas 312 (34%) had a similar-aged partner. The remaining adolescent mothers (n = 239) were excluded from further analyses. Adolescent mothers with older adult partners were significantly less likely to be employed or enrolled in school and were more likely to report planned repeated pregnancies. These adolescent mothers also received less social support. No differences were observed in intimate partner violence or the mother's substance use. Adolescent mothers with older adult partners who did not live with an adult authority figure seemed to be at greatest risk. CONCLUSIONS: The negative educational and financial impact of coupling with an older vs. similar-aged partner seems greater for those mothers who no longer reside with an adult authority figure. These adolescent mothers are also at greater risk of planned rapid repeated pregnancy. Given their limited educational attainment and family support, a subsequent pregnancy may place these young women at considerable financial and educational disadvantage.

Contraceptive use among adolescent mothers at 6 months postpartum.

OBJECTIVE: To assess patterns and predictors of reliable and unreliable contraceptive use among adolescent mothers in the first 6 months following delivery. METHODS: We surveyed 462 women, 18 years of age or younger, at delivery and again at 6 months postpartum. Contraceptive behaviors were evaluated among the 359 adolescents who stated they were sexually active and not trying to conceive. RESULTS: Method discontinuation and switching were common during the 6-month interval. Only 100 of 189 adolescents (53%) initially prescribed oral contraceptives were still using this method 6 months after delivery; ten of these 100 stated that they had missed at least three pills in the last cycle. Twelve (10%) of the 115 adolescents who initiated depot-medroxyprogesterone acetate failed to obtain a second injection within 4 months of the initial injection or use an alternative method. In contrast nine of the ten women who received levonorgestrel implants were still using this method 6 months after delivery. Overall, 76% of the sample reported using reliable contraception at last intercourse. Multivariate analyses identified seven factors as predictive of reliable contraceptive use: school enrollment, not having failed a grade in school, adequate support, belief that pregnancy is likely without birth control, attendance at postpartum visit, prior abortion, and the adolescent's desire to wait at least 2 years before having another child. CONCLUSION: Interventions designed to reduce rapid repeat pregnancy during the adolescent years should address emotional, financial, and educational, as well as contraceptive, needs.

Ethnic differences in depressive symptomatology among young women.

OBJECTIVE: To examine racial and ethnic differences in moderate to severe depressive symptoms among young women seeking reproductive health care. METHODS: Nine hundred four white, black, or Hispanic women between 14 and 26 years of age completed an anonymous questionnaire that assessed demographic and reproductive characteristics; recent substance use, including binge drinking; sexual behaviors; occurrence of assault; and depressive symptoms. Logistic regression analysis was used to develop adjusted odds ratios (OR) and 95% confidence intervals for correlates of depressive symptomatology for each racial or ethnic group. RESULTS: Twenty-one percent (68 of 321) of whites, 28% (88 of 316) of blacks, and 29% (77 of 267) of Hispanics reported moderate to severe depressive symptoms. White females with moderate to severe depressive symptoms were more likely to report sexual assault (OR = 3.1); being a high school dropout (OR = 2.6); unemployment (OR = 2.4); two or more episodes of binge drinking (OR = 2.1); and having a mother with less than a high school education (OR = 2.4). Black females with depressive symptoms were more likely to report smoking one to nine cigarettes per day (OR = 3.5); sexual assault (OR = 3.2); and unemployment (OR = 2.1). Hispanic females with depressive symptoms were more likely to report adolescent age (OR = 3.5); physical assault (OR = 3.2); and smoking one or more cigarettes per day (OR = 2.4). CONCLUSION: Twenty to 25% of young women, regardless of race or ethnicity, have moderate to severe depressive symptoms, and behavioral markers vary according to ethnicity.

The rise and fall of levonorgestrel implants: 1992-1996.

OBJECTIVE: To assess shifts over a 4-year period in attitudes of low-income US women regarding use of levonorgestrel implants. METHODS: An anonymous questionnaire was administered at two different points in time to English-speaking women of reproductive age seeking gynecologic or obstetric care in southeast Texas. The first survey, administered to 762 women in 1992, elicited information on demographic and reproductive characteristics, as well as exposure to information on implants and attitudes regarding use of this method. This same survey was administered again in 1995-1996 to 502 women. chi2, Student t, or Kruskal-Wallis nonparametric tests were used to evaluate shifts in attitudes and perceived barriers to use across the 4-year period. RESULTS: Women portrayed less positive attitudes about levonorgestrel implants when surveyed in 1995-1996 as compared with 1992. Most notably, they appeared less appreciative of the convenience associated with implant use and more concerned with potential side effects. Nulliparous and parous women surveyed in 1995-1996 were significantly less likely than those surveyed in 1992 to state that they would consider using this method for birth control (P < .001) and were more likely to state that their partner, friends, and family would object to their use of levonorgestrel implants. CONCLUSION: This study documents the decline in popular perceptions of levonorgestrel implants among low-income English-speaking women over the 4-year period following the introduction of this contraceptive method to the US market.

Prevalence and risk factors of chorioamnionitis among adolescents.

OBJECTIVE: To identify the prevalence of chorioaminionitis and unique risk factors for this disorder among adolescents under 18 years of age. METHODS: At their first prenatal visit we interviewed 352 adolescents who received prenatal care and delivered an infant at our institution between April 20, 1992, and November 10, 1994, to elicit information on demographic characteristics and behavioral risk factors. Retrospective chart review confirmed the presence of chorioamnionitis using accepted clinical criteria. We determined reproductive history, evidence of sexually transmitted disease, duration of labor, use of oxytocin, an internal uterine pressure monitor or conduction anesthesia, timing and duration of ruptured membranes, type of delivery, and infant birth weight from review of subjects' charts. Logistic regression analysis was used to develop adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for risk factors of chorioaminionitis. RESULTS: Ten percent (34 of 352) of adolescents met the clinical definition for chorioamnionitis. Alcohol and tobacco use during pregnancy (OR 7.6; 95% CI 2.3, 25.8) and being married or living with a partner (OR 2.7; 95% CI 1.1, 6.5) were significantly associated with chorioamnionitis, as was conduction anesthesia (OR 4.1; 95% CI 1.1, 15.4), a second stage labor longer than 2 hours (OR 3.5; 95% CI 1.4, 8.5), and rupture of the membranes longer than 18 hours (OR 6.9; 95% CI 2.5, 18.9). Parity or preterm delivery did not differ significantly between those with or without chorioamnionitis. CONCLUSION: These data suggest that in addition to risk factors observed in adults, adolescents who concurrently use tobacco and alcohol during pregnancy, are married or living with a male partner, and have conduction anesthesia are at increased risk for chorioamnionitis.

Skin sensitization testing in potency and risk assessment.

The purpose of this article is to review, and make recommendations for, the use of relevant skin sensitization test methods, for the purposes of determination of relative potency and the threshold dose necessary for the induction of skin sensitization, and for risk assessment. In addressing the first area, the utility of three guinea pig tests (the guinea pig maximization test, the occluded patch test, and the open epicutaneous test) of the local lymph node assay (LLNA) and of human volunteer testing for the assessment of relative potency and identification of thresholds for sensitization were considered. The following conclusions were drawn. (1) Although attempts have been made to modify the guinea pig maximization test for the purposes of deriving dose-response relationships, this method is usually unsuitable for determination of relative sensitizing potency. (2) Guinea pig methods that do not require the use of adjuvant and which employ a relevant route of exposure (the occluded patch test and the open epicutaneous test) are more appropriate for the assessment of relative skin-sensitizing potency. (3) The LLNA is suitable for the determination of relative skin sensitizing potency, and the adaptation of this method for derivation of comparative criteria such as EC3 values (the estimated concentration of test chemical required to induce a stimulation index of 3 in the LLNA) provides an effective and quantitative basis for such measurements. (4) For all the methods identified above, potency is assessed relative to other chemical allergens of known skin sensitizing potential. The estimation of likely threshold concentrations is dependent upon the availability of suitable benchmark chemicals of known potency for human sensitization. (5) Human testing (and specifically, the Human Repeat Insult Patch Test) can provide information of value in confirming the absence of skin sensitizing activity of formulations and products under specific conditions of use and exposure. Based on the above, the following recommendations are made. (1) If results are already available from suitable guinea pig tests, then judicious interpretation of the data may provide information of value in assessing relative skin sensitizing potency. This option should be explored before other analyses are conducted. (2) The LLNA is the recommended method for new assessments of relative potency, and/or for the investigation of the influence of vehicle or formulation on skin sensitizing potency. (3) Whenever available, human skin sensitization data should be incorporated into an assessment of relative potency. With respect to risk assessment, the conclusion drawn is that all the available data on skin-sensitizing activity in animals and man should be integrated into the risk-assessment process. Appropriate interpretation of existing data from suitable guinea pig studies can provide valuable information with respect to potency, as the first step in the development of a risk assessment. However, for de novo investigations, the LLNA is the method favored for providing quantitative estimations of skin-sensitizing potency that are best suited to the risk assessment process. Finally, human testing is of value in the risk assessment process, but is performed only for the purposes of confirming product safety.

Damage to mitochondrial DNA induced by the quinolone Bay y 3118 in embryonic turkey liver.

Quinolones are a class of antibiotics that induce damage to and loss of DNA from bacteria. The structural organization of bacterial DNA is more similar to eukaryotic mitochondrial DNA (mtDNA) than to eukaryotic chromosomal or nuclear DNA (nDNA). Antibiotics affecting the bacterial genome may therefore preferentially damage mtDNA rather than nDNA. We investigated the effect of a quinolone on mtDNA in avian embryonic hepatocytes in ovo. The quinolone Bay y 3118 (1-cyclopropyl-7-(2,8-diazabicyclo[4.3.0]non-8-yl) 6-fluoro-8-chloro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid hydrochloride, chemical structure see Bremm et al. [K.D. Bremm, U. Petersen, K.G. Metzger, R. Endermann, In vitro evaluation of Bay-y 3118, a new full-spectrum fluoroquinolone, Chemotherapy 38 (1992) 376-387] was injected into fertilized turkey eggs 8 days before hatching at doses of 1, 3, 10 and 30 mg per egg. The embryos were removed from the eggs after 4 days and liver samples were shock frozen. Mitochondrial DNA was purified from samples of the embryonic liver. The integrity of mtDNA was investigated by electrophoresis on agarose gels with native mtDNA and with ribonuclease-treated mtDNA. Fluorescent staining of the electrophoresis gels allows the densitometric quantification of the mtDNA of the regular band at 16 kilobases (kb) and the amount of DNA fragments of irregular size (smear). The genotoxic nitrosamine nitrosodiethylamine (NDEA) has previously been shown to reduce the content of mtDNA of the regular size of 16 kb and to induce the occurrence of smaller fragments of mtDNA [H. Enzmann, C. Kühlem, E. Löser, P. Bannasch, Damage to mitochondrial DNA induced by the hepatocarcinogen, diethylnitrosamine in ovo, Mutation Res. 329 (1995) 113-120]. After exposure to 10 and 30 mg Bay y 3118, a dose-dependent induction of damage to the mtDNA was found, whereas exposure to 3 and 1 mg showed no effect. NDEA (25 mg) was used as positive control. Testing chemical compounds in the in ovo model is a simple and rapid approach for investigations on chemically induced alterations of mtDNA.

Factors associated with recent and discontinued alcohol use by pregnant adolescents.

PURPOSE: To determine easily identifiable risk factors that differentiate pregnant adolescents who report recent (past 30 days) alcohol use and those who discontinue use by their first prenatal visit from those who deny consuming alcohol altogether. METHODS: A structured interview was completed by 378 adolescents < or = 17 years of age as part of standard care at our institution's adolescent obstetric clinic between July 7, 1992, and December 28, 1994. Using Chi-square or Student's t-tests, unique risk factors associated with recent or discontinued alcohol use in pregnancy were separately identified by comparing demographic, reproductive, behavioral, and environmental factors among recent users (n = 43), discontinued users (n = 48), and adolescents who denied ever using alcohol (n = 108). Significant indicators were then entered into stepwise logistic regression analyses to determine the most efficient models for predicting alcohol use. RESULTS: Partner alcohol use and use of alcohol during sexual activities were important risk factors for alcohol use by pregnant adolescents. Recent alcohol users were also more likely to be Mexican-American, to have quit school, and to report recent tobacco use, while adolescents who stopped using alcohol during pregnancy were significantly more likely to have witnessed or been a victim of or known a victim of violence. CONCLUSIONS: Screening at the first prenatal visit for these unique and easily assessed factors will help clinicians identify adolescents at greatest risk for alcohol use during pregnancy.

Prevalence and correlates of psychopathology in pregnant adolescents.

PURPOSE: To investigate the prevalence and correlates of psychopathology, as measured by the Youth Self-Report Scale, in pregnant adolescents so that interventions during pregnancy may be tailored to treat the psychopathology and thereby improve maternal and child outcomes. METHODS: Scores on seven psychologic syndromes (withdrawn, delinquent, aggressive behaviors; anxiety/depression; and social, thought, and attention problems) were compared for groups of pregnant adolescents (n = 185), never pregnant teenagers (n = 126), and previously published normative samples of clinically referred (n = 518) and nonreferred (n = 518) female adolescents using chi-square, Student's t-tests, analysis of covariance, or multiple logistic regression. Correlates of psychopathology were identified for the pregnant sample using odds ratios and 95% confidence limits. RESULTS: Pregnant adolescents exhibited less serious or lower rates of psychopathology than groups against which they were compared. Correlates of psychopathology included substance use during pregnancy, prior assault, maternal childbirth before age 18 years, ethnicity, > or = 3 sexual partners, and absence of a relationship with the baby's father. CONCLUSIONS: Although the prevalence of psychopathology was lower among pregnant patients, those who exhibit psychopathology are likely to engage in risky health behaviors that contribute to poor perinatal outcome.