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Health Effects of Beryllium Exposure: A Literature Review
REPRODUCTIVE AND DEVELOPMENTAL EFFECTS
Reproductive and developmental toxicity of beryllium compounds has been reviewed by EPA (1998b), the Agency for Toxic Substances and Disease Registry (ATSDR 2002), and the American Conference of Governmental Industrial Hygienists (ACGIH 2006). Animal studies have included oral and parenteral studies but no inhalation studies. Reproductive and developmental outcomes have not been examined in epidemiologic studies of beryllium workers, and only one study of reproductive and developmental outcomes in workers that included consideration of beryllium exposure was identified.
EPA’s (1998b) review focused on hazard assessment of environmentally relevant doses and concluded that “the potential of beryllium to induce developmental and/or reproductive effects has not been adequately assessed” (p. 50). It should be noted that many of the animal studies may have been conducted at doses that result in maternal toxicity.
The animal studies reviewed include a chronic dog feeding study in which beryllium sulfate was mixed in the diet at three doses (from 0.023 to 1.3 mg/kg per day) and administered to males and females from before mating through weaning of pups (Morgareidge et al. 1976) and two studies previously reviewed by EPA (1991) in which beryllium compounds were administered parenterally to rats (Clary et al. 1975; Mathur et al. 1987). No adverse reproductive or developmental effects were reported in the dog study, and mixed results were reported in the rat studies.
EPA also noted that no reproductive or developmental effects were reported after paternal occupational exposure to beryllium by Savitz et al. (1989), who examined the effect of parents’ occupational exposure on risk of stillbirth, preterm delivery, and small-for-gestational-age infants in a case-control study that used data from the 1980 national natality and fetal-mortality surveys. For stillbirths, case groups of 2,096 mothers and 3,170 fathers were examined for associations with 18 industrial or chemical categories. No maternal cases were listed for beryllium exposure, but 127 paternal cases associated with beryllium exposure were listed with an adjusted odds ratio (OR) of 1.0 (95% confidence interval [CI], 0.7-1.3). A similar analysis for preterm deliveries (363 mothers and 552 fathers) and small-for-gestational-age infants (218 mothers and 371 fathers) yielded no cases associated with maternal beryllium exposure. For paternal exposure, 23 cases of preterm delivery were associated with beryllium exposure (OR, 1.0; 95% CI, 0.5-2.0) and 16 cases of small-for-gestational-age infants were associated with beryllium exposure (OR, 0.9; 95% CI, 0.5-1.7).
ATSDR (2002) did not identify any human studies of reproductive or developmental effects of beryllium. Its review noted that concerns about the adequacy of animal studies of reproductive and developmental effects after oral beryllium exposure were said to be mitigated by the low absorption of ingested beryllium. Inhalation studies were noted as lacking.
Although neither reproductive nor developmental effects were reported in the chronic dog feeding study (Morgareidge et al. 1976), the design was noted to be nonconventional and to be a reason for low confidence in interpretation of its findings. The same group also conducted a 2-year study in which beryllium sulfate was administered to rats in drinking water (Morgareidge et al. 1975) and reported no effects in reproductive organs. Neither of those studies is reported in the peer-reviewed literature.
ATSDR (2002) also identified a limited number of parenteral studies that reported developmental effects of beryllium in rats and mice. Mathur et al. (1987) exposed pregnant rats by intravenous injection to beryllium nitrate at one-tenth the dose that was lethal to 50% of the animals (that is, the LD50). Normal pups were delivered if the dose was administered on day 1, 12, 13, 15, or 17 after coitus, but all pups died 2-3 days after delivery. If the dose was administered on day 11 after post coitus, all fetuses were resorbed. Day 11 is the day before formation of the placenta but a time when the maternal circulation is supplying nutrients to the fetuses. Thus, beryllium exposure early in pregnancy when blastocysts are supported only by uterine secretions did not interfere with implantation, and exposure later in pregnancy after formation of the placenta did not appear to affect in utero development. Developmental effects occurred in pregnant rats after intratracheal injection of beryllium oxide or beryllium chloride (Selivanova and Savinova 1986), and injecting beryllium salts into pregnant mice reached the fetus and caused developmental abnormalities in offspring (Bencko et al. 1979; Tsujii and Hashishima 1979).