REcords of 36,608 Black single live births and 762 infant deaths in Washington, D.C., from 1980 to 1985 were analyzed. Bivariate and multivariate contingency table analysis were carried out to identify the groups at high risk for not obtaining adequate prenatal care. Results show that the groups of mothers which are less likely to receive adequate care also have a high risk of delivering low birthweight infants even when they receive adequate care. The paper focuses on women with high gravidity and short birth intervals for in-depth analysis of programming needs.
Quartz, the most common form of crystalline silica, was tested quantitatively for neoplastic transformation in the mouse embryo cell line, BALB/3T3/A31-1-1. Five quartz dust samples of respirable size [Min-U-Sil 5 (MQZ); hydrofluoric-acid-etched MQZ (HFMQZ); Chinese standard quartz (CSQZ); DQ12; and F600] all induced significant levels of neoplastic transformation, showing dose-dependent increases in the frequency of morphologically transformed foci at lower tested doses and a plateau level of response at higher doses. The plateau levels reached by the five tested samples did not differ substantially (maximum transformation frequencies per 10(5) cells ranging from 53.2 for MQZ to 28.3 for HFMQZ). F600 had minimal cytotoxicity but transforming activity comparable to the other samples. Cells from all tested transformed foci, when injected s.c. in nude mice, grew as sarcomas. Cytogenetic analysis showed that all tested silica-transformed cell lines had acquired one to five additional marker chromosomes, of types not seen in untreated control lines, indicative of induced chromosomal translocations and amplification. Increased expression of one or more of five genes (p53, myc, H-ras, K-ras, and abl) was observed in several quartz-transformed cell lines. No transforming activity was found for hematite and anatase (both nontoxic), and for rutile (more toxic than MQZ). Combined exposure (1:1 w/w per unit culture area) of each of these dusts with MQZ showed that hematite and anatase inhibited MQZ toxicity as well as transformation, whereas rutile markedly enhanced MQZ toxicity but not MQZ-induced transformation.
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