ABSTRACT
Disinfection by-products are contaminants produced during drinking water disinfection. Several DBPs have been implicated in a variety of toxic effects, mainly carcinogenic and genotoxic effects. Moreover, DBPs exposure has also been associated with an increased risk of developmental effects. In this study, the developmental toxicity and genotoxicity of 10 DBPs (four trihalomethanes [THMs], five haloacetic acids [HAAs] and sodium bromate) in the zebrafish embryo model were evaluated. Embryos exposed for 72 hours were observed for different endpoints such as growth, hatching success, malformations and lethality. THMs exposure resulted in adverse developmental effects and a significant reduced tail length. Two HAAs, tribromoacetic acid and dichloroacetic acid, along with sodium bromate were found to cause a significant increase in malformation rate. Chloroform, chlorodibromomethane and sodium bromate produced a weak induction of DNA damage to whole embryos. However, developmental effects occurred at a range of concentrations (20-100 µg/mL) several orders of magnitude above the levels that can be attained in fetal blood in humans exposed to chlorinated water. In conclusion, the teratogenic and genotoxic activity observed by some DBPs in zebrafish reinforce the view that there is a weak capacity of disinfection products to cause developmental effects at environmentally relevant concentrations.
Subject(s)
Acetates/toxicity , Bromates/toxicity , Hydrocarbons, Brominated/toxicity , Hydrocarbons, Chlorinated/toxicity , Mutagens/toxicity , Sodium Compounds/toxicity , Teratogens/toxicity , Water Pollutants, Chemical/toxicity , Animals , DNA Damage , Disinfection , Drinking Water , Ear/abnormalities , Embryo, Nonmammalian/abnormalities , Embryo, Nonmammalian/drug effects , Eye Abnormalities/chemically induced , Head/abnormalities , Heart Defects, Congenital/chemically induced , Tail/abnormalities , Zebrafish/abnormalitiesABSTRACT
Two polymorphic sites of the microsomal epoxide hydrolase gene (EPHX1, 113Tyr-->113His, 139His-->139Arg) and four glutathione S-transferase genes (GSTM1, GSTM3, GSTP1, GSTT1) were genotyped in a group of patients with larynx cancer (N=204) and in a group of healthy controls (N=203), all Spanish caucasians. After adjusting for gender, age, and tobacco smoking, none of the polymorphisms alone were found to be associated with larynx cancer risk. The analysis of EPHX1/GST combinations, however, showed a significant over-representation of patients with a combination of 113Tyr/113Tyr EPHX1 and 105Ile/105Ile GSTP1 (adjusted odds ratio (OR): 1.95; 95% confidence interval (CI): 1.02-3.78). The calculation of the predicted epoxide hydrolase (EH) activity also showed an increased risk for the individuals with both predicted high activity EH and 105Ile/105Ile GSTP1 (OR: 2.90; 95% CI: 1.10-7.67). These results on larynx cancer tend to confirm a former study on lung cancer (Cancer Lett. 173 (2001) 155) suggesting the existence of an interaction between variants of EH and GSTpi, both enzymes being involved in the metabolism of aromatic hydrocarbons, that may increase susceptibility to tobacco-related cancers.
