Formaldehyde in residences: long-term indoor concentrations and influencing factors.

UNLABELLED: Chronic human exposure to formaldehyde is significantly increased by indoor sources. However, information is lacking on why these exposures appear to persist in older homes with aging sources. We use data from the Relationships of Indoor, Outdoor, and Personal Air study to evaluate 179 residences, most of which were older than 5 years. We assess the dependence of indoor formaldehyde concentrations (C(in)) on building type and age, whole-house air exchange rate, indoor temperature, and seasonal changes. Indoor formaldehyde had mean and median concentrations of 17 ppb, and primarily originated from indoor sources. The factors we analyzed did not explain much of the variance in C(in), probably because of their limited influence on mechanisms that control the long-term release of formaldehyde from aging pressed-wood products bound with urea-formaldehyde (UF) resins. We confirmed that the mitigating effects of ventilation on C(in) decrease with time through the analysis of data for new homes available in the literature, and through models. We also explored source control strategies and conclude that source removal is the most effective way to decrease chronic exposures to formaldehyde in existing homes. For new homes, reducing indoor sources and using pressed-wood with lower UF content are likely the best solutions. PRACTICAL IMPLICATIONS: Formaldehyde concentrations in homes due to indoor sources appear to persist throughout the lifetime of residences. Increases in ventilation rates are most effective in decreasing indoor concentrations in new homes where formaldehyde levels are high or when homes are tight. Consequently, other alternatives need to be promoted such as decreasing the amount of pressed-wood products with urea-formaldehyde (UF) resins in homes or reducing the UF content in these materials.

Treatment of anal canal carcinoma with high dose radiation therapy and concomitant fluorouracil-cisplatinum. Long-term results in 95 patients.

PURPOSE: To evaluate the long-term results of the treatment of anal canal carcinoma (ACC) with a combined concomitant radiochemotherapy (CCRT) treatment using fluorouracil (5 FU) and cisplatinum (CDDP) with a high dose of radiation therapy. PATIENTS AND METHODS: Between 1982 and 1993 a series of 95 patients were treated. Staging showed a majority of advanced squamous ACC, i.e. 6 T1, 47 T2, 28 T3, 14 T4, 53 NO, 32 N1, 6 N2 and 4 N3. Irradiation was done with high dose external beam radiation therapy (EBRT) followed by a boost with 192 Iridium implant. During EBRT all patients received one course of 5 FU continuous infusion (1 g/m2/day, days 1-4) and CDDP (25 mg/m2/day, bolus days 1-4). RESULTS: The median follow-up time was 64 months. At 5 and 8 years the overall survival was 84 and 77%, the cancer specific survival was 90 and 86% and the colostomy-free survival was 71 and 67%, respectively. The stage and the response of the tumor after EBRT were of prognostic significance. Patients with pararectal lymph nodes had an overall 5-year survival of 76% (versus 88% for non-N1). Among 78 patients who preserved their anus, the anal sphincter function was excellent or good in 72 (92%). CONCLUSION: According to these results and recent randomized trials, CCRT appears as the standard treatment of ACC. Radical surgery should be reserved for local recurrence or persisting disease after irradiation. High dose irradiation in a small volume with concomitant 5 FU-CDDP appears to give a high rate of long-term local control and survival. Careful evaluation of pararectal nodes is essential for a good staging of the disease.