Biomarker reproduction

PCDDs and PCDEs, together with coplanar PCBs, can express Ah-receptor-mediated toxicity. TCDD (dioxin) is used as a reference compound in the determination of TEFs, which can be used to estimate TEQs (toxic equivalents) for residues of PHAHs found in wildlife samples. Biomarker assays for Ah-receptor-mediated toxicity have been based on the induction of P450 lAl. TEQs measured in field samples have sometimes been related to toxic effects upon individuals and associated ecological effects (e.g., reproductive success). 

Data for PCP and terrestrial wildlife are incomplete and — in view of the large interspecies variations in sensitivity — need to be collected. Research is needed on reproductive effects in animals following inhalation exposure to PCP additional acute and intermediate toxicity testing chronic duration exposure studies on cancer induction, genotoxicity, and immunotoxicity and the development of alternate biomarkers of PCP exposure and antidotes (WHO 1987 USPHS 1994). Until the results of these studies become available, it seems reasonable to apply to wildlife the same levels recommended for human health protection. 

Decreased sperm count has been observed following exposure to mirex or chlordecone in humans and/or experimental animals. Clinically, the most straightforward biomarker would be examination of sperm in the ejaculate. However, testicular biopsies may also be helpful. Both procedures have been used to assess the male reproductive toxicity of chlordecone in exposed persons (Taylor et al. 

Jonsson BA, Richthoff J, Rylander L, Giwercman A, Hagmar L (2005) Urinary phthalate metabolites and biomarkers of reproductive function in young men. Epidemiology 16 487 93... 

In the past few years the use of rotifers in ecotoxicological studies has substantially increased. The main endpoints used are mortality, reproduction, behavior, cellular biomarkers, mesocosms, and species diversity in natural populations [126]. Several workers have used Brachionus calyciflorus for various types of toxicity assessments. Thus, comprehensive evaluation of approximately 400 environmental samples for the toxicity assessment of solid waste elutriates, monitoring wells, effluents, sediment pore water, and sewage sludge was carried out by Persoone and Janssen [127]. The mortality of rotifers hatched from cysts is evaluated after 24 hours exposure. This microbiotest has been commercialized in a Rotoxkit F [128,129]. 

A Hendricks University of California Davis Test the utility of in vivo biomarkers for detecting and characterizing reproductive toxicity of 2,3,7,8-TCDD in experiments with a non-human primate model ... 

Rockett JC, Lynch CD, Buck GM (2004) Biomarkers for assessing reproductive development and health Part 1 — Pubertal development. Environ Health Perspect, 112(1) 105-112. 

In general, standard tests for effects on survival, development, reproduction, and growth are used for EQS derivation. Other endpoints should be used if they are considered relevant at the population level (e.g., behavior and avoidance). It is currently not considered appropriate to use biomarker data (e.g., molecular and biochemical endpoints) for EQS derivation unless their relevance at the population level has been clearly demonstrated. 

Substances that are carcinogenic, mutagenic, or reproductively toxic (i.e., CMRs), for example, some endocrine disrupters, may pose special problems for derivation of aquatic EQSs (e.g., lack of internationally agreed tests in some cases difficulties with prediction of safe concentrations), but use of special tests for these properties is only justified for a small subset of chemicals that meet clear criteria. Furthermore, EQSs for these substances should not be derived directly from in vitro data or from biomarkers of exposure but from in vivo tests alone. 

One of the most successful biomarker assays is the measurement of imposex in dog whelks (Nu-cella lapillus, which have brightly-colored shells). This phenomenon is caused by tributyl tins (TBTs), widely used as antifouling coatings in boats (see Section 12.3.2). TBTs impose male characteristics on females, leading to a reduction in reproductive performance and local extinction of dog whelk populations in the most contaminated sites. 

Sepulveda, M.S., Johnson, W.E., et al. (2002) An evaluation of biomarkers of reproductive function and potential contaminant effects in Florida largemouth bass (Micropterus salmoides floridanus) sampled from the St. Johns River. Science of the Total Environment, 289(1-3) 133-144. 

Relative sensitivity. It is important that the biomarker be sensitive when compared to other endpoints, such as mortality or reproductive impairment, and it is important to know the relative sensitivity of this comparison. 

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