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Contact allergy is of considerable importance to the toxicologist, and regulatory authorities worldwide require testing for skin sensitization potential and appropriate hazard labeling to enable management of the risk to human health. Although traditionally the identification of skin-sensitizing chemicals has been carried out using animal models, in Europe legislative changes have promoted, and now require, the use of non-animal methods (i.e., Cosmetic Directive, REACH). Several in vitro alternatives for hazard identification have now been validated, but do not provide information on the potency of a skin sensitizer. Here, we describe an animal model, the local lymph node assay (LLNA), and an in vitro model, the RhE IL-18 potency assay, in the context of the identification and potency classification of skin sensitizers. These two assays have been chosen among the different available tests as representative of an alternative in vivo model (the LLNA) and a promising in vitro method with the potential of both hazard identification and potency classification.

To determine the prevalence of sexually transmitted diseases (STDs) and the risk for (i) the mother regarding pregnancy wastage and puerperal sepsis and (ii) the child with regard to congenital and neonatal infection, 342 routine antenatal clinic (ANC) at tenders were investigated. The prevalence of antibodies showing exposure to specific STD pathogens in pregnant women attending ANC was: syphilis (TPHA) 27%, (VDR:) 28%, gonorrhoea 43%, genital chlamydiae 54%, HBV 37%, HSV-2 35 %, H ducreyi 10%. High titre seropositivity suggestive of active infection was: gonorrhoea 10%, genital chlamydiae 31 %, HSV2 19%; with HBV SAg 5% -all of which are likely to be transmitted to the foetus in utero or during delivery. Only 10% of ANC at tenders had no serological evidence of any STD: 72% had serological evidence for two or more STDs. Among conditions requiring treatment vaginitis was the most important, 20% having a severe trichomonal infection. Despite the frequency of this condition it was noted that few women (4%) complained of vaginal discharge. Thus women attending the ANC revealed a high prevalence of STD. Consequently the foetus and neonate are put at risk because of intrauterine or intrapartum transmission of infection. The high prevalence among ANC at tenders also reflects the relative prevalence of STDs in the community. Measures such as screening at ANC and information and education regarding prevention are required to reduce STDs in pregnant women and their sexual partners. Prophylaxis for the neonate can be considered until this goal is achieved. [Ethiop. J. Health Dev. 1995;9(1):31-40]

A study of 542 women attending family planning clinics (FPC) and 1568 women attending obstetric and gynaecologic clinics in Addis Ababa showed utilisation of FPC was highest in those with a family income of 100-500 EB per month (36%), in women who were: Tigrawi (33%) or Amara (31 %), aged 20-34 years (30%), age 16 or older at first marriage/coitus (28%), parity of 2... 2 children (35%), > 5 lifetime husbands/sexual partners (39%), or were bargirls (73%) or prostitutes (43%). FPC attendance was lowest among the nulliparous (2.3%), women from rural areas (10%), the Guragie (10%) and Oromo women (19%), Moslem women 14(%), those of subsistence income ( < 10EB per month) (14%). The seroprevalence rates indicative of exposure to STD pathogens were high as was the prevalence of essentially asymptomatic pelvic inflammatory disease (PID). Only 4% of FPC at tenders had no serological evidence of STD: 64% had 3 or more different STD. Specific present or active STD infection prevalence for syphilis (VDRL) 28%, Neisseria gonorrhoea 31 %, genital chlamydia 46% and HSV-2 21% was higher in FPC at tenders than among women attending other clinics. Clinical evidence of PID was also more common in the FPC at tenders (54%), 37% having evidence of salpingitis. Thus FPCs provide a useful setting for screening women particularly at risk. Because of lack of symptoms, these women are unlikely to attend either an STDs clinic or a hospital for routine check up, and as such are not treated and represent a population from which STDs can spread into the population. Measures to screen, treat and educate FPC at tenders, their partners and their clients, are recommended in an attempt to Control STDs and ultimately HIV in the community. [Ethiop. J. Hea/th Dev. 1995;9(1):19-30]

At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it should be very important, both from ethical and economic point of view, to discriminate allergy and irritation events, and to classify sensitizers according to their potency, without the use of animals.The aim of the EU FP6 Integrated Project Sens-it-iv was to develop and optimize an integrated testing strategy consisting of in vitro, human cell based assays which will closely mimic sensitization mechanisms in vivo. These assays should be an alternative approach to the LLNA. The NCTC2544 IL-18 assay can be used to identify the sensitizing capacity of a chemical (NCTC assay, tier 1) while the Epidermal Equivalent potency assay is used to quantify the potency of the sensitizing agent (EE assay, tier 2). These assays combined, may offer an unique opportunity to provide an alternative method to the LLNA. Both assays are based on the use of human keratinocytes, which have been shown, over the last two decades, to play a key role in all phases of skin sensitization.First, 4 known chemicals were tested during a transferability study in which 6 laboratories participated. Three sensitizers (DNCB, resorcinol, PPD) and 1 non sensitizer (lactic acid) were tested in tier 1. DNCB (extreme) and resorcinol (moderate) were ranked according to their potency in tier 2. These assays were successfully transferred to laboratories that did not perform both assays previously.Second, the actual pre-validation was performed with 29 coded chemicals for tier 1 and 13 coded chemicals for tier 2. Currently, all chemicals have been tested and data is collected. After all data has been processed, evaluation of the proposed prediction model will be assessed.

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