DDT exposure induces tremor-like behavior and neurotoxicity in developmental stages of embryonic zebrafish.

Dichlorodiphenyltrichloroethane (DDT) is a broad-spectrum insecticide, widely detected in environments due to its high stability characteristic and long natural half-life period. The adverse impact of DDT exposure on organisms and humans has attracted great concern worldwide. The current study explored the developmental and neurobehavioral toxicity response of DDT in embryonic zebrafish. The embryos were treated with DDT (0, 0.1, 1, 2.5 and 5 µM) during 6 h post fertilization (hpf) to 144 hpf. Our result indicated that DDT exposures increased the embryo hatching rate at 48 and 60 hpf, the larval malformation rate at 120 hpf and mortality rate at 144 hpf. The manifested malformations included uninflated swim bladder, bent spine and tail, deformed liver, and pericardial edema. The 120 hpf larval organs size of the gut and swim bladder was decreased in higher exposed concentration groups. Besides, DDT exposure resulted in hyperactivity for the embryo spontaneous movement at 24 hpf and tremor like movement measured by the free larval activity at 72 hpf, as well as the larval activity at 96 hpf under light-dark transition stimulus. Mechanistic examinations at 120 hpf revealed DDT exposure elevated oxidative stress through MDA formation increase, ATP level decrease as well as antioxidant enzyme genes (sod1 and gpx1a) expression decrease. DDT exposure induced abnormal neurotransmitters expression with DA level increase, 5-HT and NOS level decrease. DDT exposure suppressed the gene expressions involved in axon development (rab33a and nrxn2a) and potassium channel (kcnq2 and kcnq3). Our results suggest that the hyperactivity and tremor like movement in DDT-exposed embryos/larvae may result from oxidative stress involved with neuronal damage.

The effect of farming techniques on degradation of DDT in historical cotton farms.

DDT was used in the mid 20th century for crop and livestock production. After use, DDT and its degradates DDE and DDD (collectively DDX) remain in the environment for decades. A few studies have reported that the rate of degradation of DDT into its metabolites is affected by various farming techniques like tillage, irrigation, and use of fertilizers. However, most of these studies did not evaluate active farms, and none of them focused on the Southeast US or historical cotton farms. Therefore, in this study, we aimed to determine if different farming techniques affect the decomposition of DDT in Walton County, Georgia, where farms historically grew cotton. Five Walton County farms were sampled for soil, and churches were sampled as control sites. The extensive land history of the farms was recorded, and the soil levels of p,p'-DDT, p,p'-DDE, p,p'-DDD, o,p'-DDT, and o,p'-DDE were measured using gas chromatography-tandem mass spectrometry. All farm sites had detectable levels of p,p'-DDT, p,p'-DDE, and p,p'-DDD, while few sites had detectable levels of o,p'-DDT and o,p'-DDE. Tillage was found to speed up p,p'-DDE degradation, but there was no effect on p,p'-DDT degradation. Plowing was associated with an increase in decomposition of p,p'-DDT, but p,p'-DDE and p,p'-DDD were not significantly increased. The largest difference in the degradation of DDT was based on the fertilizer type. Natural fertilizer sped up degradation of p,p'-DDT and p,p'-DDE; synthetic fertilizer increased p,p'-DDE degradation, but not p,p'-DDT degradation.

Níveis de DDT no soro sanguíneo de mulheres e risco de câncer de mama na regiäo de Ribeiräo Preto, Brasil / DDT levels in the blood serum of womwn and risk for reast cancer in the Ribeiräo Preto Region, Brazil

Durante a década de 1990, mais atenção tem sido dada à contaminação ambiental como possível fator de riscos para o câncer de mama. Um total de 198 amostras de soro sanguíneo foram coletadas entre 1994 e 1997 de mulheres com câncer de mama (n=46) e mulheres do grupo controle (n=52), moradoras na região de Ribeirão Preto. A análise estatística dos fatores considerado como de risco para o câncer de mama indicou que a média de DDT total foi significativamente maior em mulheres com câncer de mama nulíparas, ou seja, aquelas que não tinham tido nenhum filho e que eram as mesmas que não haviam amamentado anteriormente. Quanto aos fatores sócio-econômicos, os níveis de DDT total foram significativamente mais elevados naquelas sem nenhuma escolaridade. Considerando a análise global dos casos e controles, a média de DDT total e os desvios padrão foram de 13,6+_ 15,7 para o grupo controle. Desta forma no presente estudo não existe evidência estatística de que uma maior concentração de DDT possa ter efeito sobre o câncer de mama

Organochlorine contaminants in Morelet's crocodile (Crocodylus moreletii) eggs from Belize

Non-viable eggs of Morelet's crocodile (Crocodylus moreletti) were collected from Gold Botton (GBL) and New River lagoons (NRL) in northern Belize and screened for organochlorine (OC) compounds using gas chromatography (GC) with electron capture detection (ECD). All egg samples from both lagoons (n=24) tested positive for one or more OCs. Primary contaminants were p,p-DDE and methoxychlor, detected in 100 percent and 29 percent of the eggs examined, respectively. Concentrations of individual OC contaminants ranged from 1 ppb (ng chemical/g egg). Total concentrations of OCs (sum of all OCs) for one egg collected from a nest at GBL reached as high as 0.7 ppm. Sediment samples from both lagoons also tested positive for OCs (lindane, aldrin, methoxychlor, heptachlor epoxide, p, p-DDT, among others). Nest media (soil and plant material) collected from crocodile nests at GBL were positive for p, p-DDT, methoxychlor, aldrin, endosulfan II, and endrin aldehyde. Based on the 24 egg samples analyzed to date, crocodiles from both lagoons are being exposed to OCs. Such exposure may present a health threat to populations of crocodiles in Central America. (AU)

Estudo dos efeitos do fenobarbital, clordano e oxitetraciclina sobre a eliminaçäo do DDT pela via biliar em ratos

Foram realizados estudos sobre efeitos do fenobarbital, clordano e oxitetraciclina sobre a eliminaçäo de DDT através da bile em ratos. Procurou-se também evidenciar a relaçäo entre um possível aumento do fluxo biliar induzido por aqueles compostos e a eliminaçäo de DDT. O fenobarbital (2,5 mg ml-1) foi colocado na água de beber e o clordano (200 mg kg-1) na raçäo, por um período de três dias consecutivos; a oxitetraciclina (200 mg kg-1/dia) foi administrada por via oral por um período de oito dias consecutivos. Após estes tratamentos, foi feita a administraçäo de 14C-DDT por via digestiva, em animais anestesiados e a seguir a bile foi coletada por canulaçäo do canal colédoco. Os resultados obtidos mostram que: -O fenobarbital e o clordano provocam uma diminuiçäo significativa no tempo de paralisis induzida pela zoxazolamina e determinam um aumento de peso do fígado, do fluxo biliar, da eliminaçäo do 14C-DDT pela bile e simultaneamente uma diminuiçäo da 14C-DDT no plasma; -A oxitetraciclina aumenta significativamente o tempo de paralisia induzido pela zoxazomina, efeito contrário ao do fenobarbital e do clordano; por outro lado, este composto näo altera o peso do fígado, o fluxo biliar, nem a eliminaçäo do 14C-DDT, mas determina uma menor concentraçäo do inseticida no sangue; -A análise dos dados das concentraçöes de 14C-DDT por ml de bile nos períodos de 2, 4, 6 e 7 horas mostrou que os mesmos näo säo significantes para o fenobarbital, clordano e oxitetraciclina, o que permite concluir que a quantidade de 14C-DDT eliminada através do canal colédoco depende da velocidade de eliminaçäo da bile