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Semipolar polycyclic aromatic compounds (sPACs) are frequently found in association with homocyclic polycyclic aromatic hydrocarbons (PAHs) in substances of unknown or variable composition, complex reaction products, or biological materials (UVCBs) from coal or crude oil and products derived thereof. However, major information deficiencies exist with regard to their prevalence and their toxicological and ecotoxicological potential, persistency, and bioaccumulation characteristics. Therefore, in this work, the environmental concern and relevance of sPACs was addressed in a general, stepwise approach. First, a large list of sPACs was collected and subsequently refined by assessing their persistence, bioaccumulation, and toxicity (PBT) properties by quantitative structure-activity relationship (QSAR) methods and their relevance by determining their respective frequency of occurrence. In this way, 15 priority sPACs were identified. These 15 priority sPACs were further characterized in detail with respect to their ecotoxicological properties, environmental behavior, carcinogenicity, and genotoxicity attributes. All of these 15 substances were quantified in distillate or product samples. In the next step, some principles for nomination of indicator substances, indicative for the overall content of sPACs, are derived. Data gaps on ecotoxicological endpoints preclude final conclusions, but the respective necessary supplemental tests were identified. Five of the 15 sPACs were tentatively characterized as potential substances of very high concern (SVHC) for the environment. The overall results of this study also clearly show that regulatory risk management of homocyclic PAHs within the European Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) does not address the environmental concern created by sPACs within UVCBs from coal or crude oil. The study proves the need for additional regulatory steps under REACH and suggests indicator substances for their enforcement.

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It was the scope of this project to collate, compile and summarise the scientific literature on the toxicity of methyl mercury, inorganic mercury and total mercury in humans and experimental animals published since 2002 and not evaluated in former JECFA risk assessments. Epidemiological data on MeHg toxicity confirmed former findings on an association between prenatal exposure and developmental neurotoxicity. Recent findings also support an influence of methyl mercury on the cardiovascular and immune system. Existing epidemiological data reveal several shortcomings limiting their suitability for risk assessment. Developmental neurotoxicity seems to be the most critical effect of MeHg in animals. A LOAEL of 0.01 mg/kg b.w. per day has been reported in young mice for locomotor activity exposed in utero. Rats seem to be less sensitive towards this endpoint: a NOAEL of 0.04 mg/kg b.w. per day has been reported in this species for locomotor activity. Systemic effects other than neurotoxicity have been mostly observed at higher doses than those producing neurotoxicity. No qualified epidemiological data appropriate for the evaluation of the toxicity of inorganic mercury after oral intake have been identified due to several limitations of the studies, e.g. small study group, insufficient control for confounders, inadequate exposure assessment. Toxicological studies in experimental animals widely confirmed former findings with respect to the target organs (neuro-, liver-, kidney-, immune-and reproductive toxicity, oxidative stress). The animal studies indicate that there might be relevant toxicological effects (developmental toxicity, liver toxicity) of inorganic mercury at dose levels similar or below the BMDL 10 value used for the derivation of the existing PTWI. However, due to some limitations of the studies no final conclusions can be drawn from these studies and the findings need further confirmation.

1 0 9 1 -5 8 1 8 / 9 7 $ 1 2 .0 0 + .0 0 R e c ei v ed 2 0 J a n u a r y 1 9 9 7 ; a c c e p t e d 1 2 F e b r u ar y 1 9 9 7 . O u r c o n c e p t w a s d e v e l o p e d i n t h e c h a r g e o f t h e G e r m a n F e d e r a l E n v i r o n m e n t a l A g en cy ( U m w e l t b u n d e sa m t ) . T h e w o r k h a s b e e n su p p o r t e d b y t h e F e d e r a l M i n i s t r y o f t h e E n v i r o n m e n t a n d r e q u e s t e d b y t h e e n v i r o n m e n t a l a d m i n i s t r a t i o n s o f t h e 1 6 G e r m a n s t a te s i n o r d e r t o c o m e t o a u n i f o r m a n d a g r ee d u p o n t o x i c o l o g i c al d a t a b a si s. T h e a u t h o r s t h a n k t h e s e i n s t i t u t i o n s f o r t h e s u p p o r t . A d d r e ss c o r r e sp o n d e n c e t o D r. F r i t z K al b e r l a h , F o Bi G G m b H , We r d e r r i n g 1 6 , D -7 9 0 9 8 F r e i b u r g , G e r m a n y. at MOUNT ALLISON UNIV on June 15, 2015 ijt.sagepub.com Downloaded from

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