Effects of inhalative exposure to dioxins in wood preservatives on cell-mediated immunity in day-care center teachers

Skin diseases associated with Agent Orange and other organochlorine exposures

Organochlorine exposure is an important cause of cutaneous and systemic toxicity. Exposure has been associated with industrial accidents, intentional poisoning, and the use of defoliants, such as Agent Orange in the Vietnam War. Although long-term health effects are systematically reviewed by the Institute of Medicine, skin diseases are not comprehensively assessed. This represents an important practice gap as patients can present with cutaneous findings. This article provides a systematic review of the cutaneous manifestations of known mass organochlorine exposures in military and industrial settings with the goal of providing clinically useful recommendations for dermatologists seeing patients inquiring about organochlorine effects. Patients with a new diagnosis of chloracne, porphyria cutanea tarda, cutaneous lymphomas (non-Hodgkin lymphoma), and soft-tissue sarcomas including dermatofibrosarcoma protuberans and leiomyosarcomas should be screened for a history of Vietnam service or industrial exposure. Inconclusive evidence exists for an increased risk of other skin diseases in Vietnam veterans exposed to Agent Orange including benign fatty tumors, melanomas, nonmelanoma skin cancers, milia, eczema, dyschromias, disturbance of skin sensation, and rashes not otherwise specified. Affected veterans should be informed of the uncertain data in those cases. Referral to Department of Veterans Affairs for disability assessment is indicated for conditions with established associations.

A review of the role of lymphoma markers and occupational and environmental exposures

Immune deficiency and altered immunity are among the best characterized and strongest known risk factors of non-Hodgkin lymphomas (NHL). For instance, chronic inflammation or certain disturbances in the immune system are associated with an increased lymphoma risk. Occupational and environmental factors (i.e., dioxin) as well as lifestyle factors (i.e., obesity) may contribute to these risk factors. The precise role of these factors in the etiology of NHL, however, is still not entirely clear. Although the existing epidemiologic studies have not revealed consistent patterns of perturbations of the immune system by these factors, the findings might suggest an adverse impact on both the humoral and cell-mediated immune system.

A developmental approach to pediatric environmental health

Children cannot be considered "little adults" in the field of environmental medicine. There are differences in exposures, pathways of absorption, tissue distribution, ability to biotransform or eliminate chemicals from the body, and responses to chemical and radiation. The differences vary with the developmental stages of the child. Children all respond differently to environmental toxicants. Knowledge, although rapidly increasing, is still incomplete regarding the impact of the environment on children. As health care providers, prevention is an ally but must be approached differently at each stage of a child's life.

Persistent suppression of delayed-type hypersensitivity in adult F344 rats after perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin

Recently we observed a suppressed delayed-type hypersensitivity (DTH) response to bovine serum albumin (BSA) in the 4-5-month-old offspring of F344 rat dams receiving as little as 1.0 microg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)/kg on gestational day (GD) 14. This study was designed to characterize better this suppression of the DTH response. First, the persistence of the DTH suppression was determined by measuring the DTH response to BSA in the offspring of dams dosed orally with 3.0 microg TCDD/kg on GD14 as well as in age-matched controls at 4, 8, 12 and 19 months of age. TCDD significantly suppressed the males' DTH response through 19 months of age. While the females' DTH response was reduced at 8, 12 and 19 months, significant suppression was observed only at 4 months of age. Secondly, the lowest maternal dose of TCDD that produced DTH suppression was determined by measuring the DTH response to BSA in the 4- and 14-month-old offspring of dams dosed orally with 0, 0.1, 0.3 or 1.0 microg TCDD/kg on GD14. In the males, suppression was observed at a maternal dose as low as 0.1 microg TCDD/kg at 14 months of age, while a maternal dose of 0.3 microg TCDD/kg was necessary to cause suppression in the 14-month-old females. Both males and females were more sensitive to the suppression at 14 months of age than at 4 months of age. Lastly, the DTH response to a second antigen was examined by measuring the DTH response to either BSA or keyhole limpet hemocyanin (KLH) in the 5- or 4-month-old male offspring, respectively, of dams dosed orally with either 0 or 3.0 microg TCDD/kg on GD14. The DTH response to both antigens was suppressed significantly. Phenotypic analysis was performed on thymus and lymph node suspensions. Significant effects in the thymus included an increased percentage of gammadelta TCR+ cells and a decreased percentage of gammadelta TCR+/CD4- CD8- and MHCI- MHCII- cells. In the popliteal lymph node draining the BSA-injected footpad, there was a decreased percentage of gammadelta TCR+ and MHCI- MHCII- cells and an increased percentage of MHCI+ cells. In conclusion, the suppression of the DTH response associated with perinatal TCDD exposure is persistent through late adulthood, occurs at a low dose (i.e. 0.1 microg TCDD/kg) to the dam, and is more pronounced in males than females. While phenotypic analysis identified differences in subsets of thymocytes and lymph node cells between control and TCDD exposed offspring, no clear correlations were established between altered subpopulations and suppressed DTH responses.