Toxicity of Polybrominated Biphenyl and Its Effects on Reproduction of White Leghorn Hens HELENE C. CECIL and JOEL BITMAN U.S. Department of Agriculture, ARS, Animal Physiology and Genetics Institute, Beltsville, Maryland 20705 (Received for publication November 7, 1977)
INTRODUCTION
Polybrominated biphenyls are industrial compounds used to reduce the flammability of thermoplastics. Their use has been restricted to those applications in which the end-use product is not exposed to either feed or food, and they are not used in flame-retarding fabrics that humans would be exposed to. The only polybrominated biphenyl produced in commercial q u a n t i t y in the U.S. is Firemaster BP-6 (Michigan Chemical Corporation). 1 In the fall of 1973, 16,000 cattle and 1.5 million chickens in Michigan were fed feed contaminated with polybrominated biphenyls that had been inadvertently added to cattle feed i n s t e a d of magnesium oxide. The polybrominated biphenyl was added to some dairy feeds at rates as high as .4% (4000 ppm), and several reports have indicated severe toxic ef-
1 Trade names are used solely for the purpose of providing specific information. Mention of a trade name does not constitute a guarantee or warranty of the product by the U.S. Department Of Agriculture nor an endorsement by the Department over other products not mentioned.
1978 Poultry Sci 57:1027-1036
fects and abnormal reproduction in animals fed the contaminated feed (Jackson and Halbert, 1974; Prewitt et al, 1975). Cows had lowered feed intake, weight loss, and decreased milk production. Cows in very early stages of pregnancy returned to estrus and those in later stages of pregnancy gave birth to stillborn calves. Also during this period chicken feed in Michigan became contaminated with BP-6 at lower levels because residual feed in the mill was c o n t a m i n a t e d . Although 1.5 million chickens and 5 million eggs were destroyed because BP-6 residues exceeded regulatory limits of . 3 ppm in fat, the physiological effects in chickens were not assessed. In earlier studies, we found few toxic effects in chickens fed 20 ppm BP-6 (Cecil et al, 1974; Lillie et al, 1974, 1975). Feeding 20 ppm BP-6 to White Leghorn laying hens did not reduce hatchability but reduced egg production and depressed progeny growth (Lillie et al, 1974, 1975). We also found that BP-6 reduced pentobarbital sleeping times in quail, a result indicating that BP-6 reduced the activity of liver microsomal enzymes (Cecil et al, 1975). In the present study, we followed the food consumption, reproduction, progeny survival, and
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ABSTRACT White Leghorn hens were fed 0, 20, 64, 200, 640, and 2000 ppm of a commercial mixture of polybrominated biphenyls (BP-6). The lower levels of BP-6 (20 and 64 ppm) did not change feed intake. After 8 weeks, egg production was 59%, 51% and 39%, and hatchability was 85%, 65% and 11% for the hens fed 0, 20 and 64 ppm BP-6, respectively. During the second week of feeding 200 ppm BP-6, feed consumption was reduced to 85 g/hen/day, a 23% reduction in intake, and all hens fed 200 ppm stopped egg production within 3 weeks. Hens fed 640 and 2000 ppm refused feed immediately, and at the end of 1 week, feed consumption was 30% that of the control. During the second week of treatment, hatchability was 43%, 21%, and 43% for hens fed 200, 640, and 2000 ppm BP-6, respectively. Dead embryos had subcutaneous edema in the neck and rump areas. The day-old chicks that survived had a higher mortality and lower body weight gains during the 3-week growth test than the control progeny had. The concentration of BP-6 in the egg reached a plateau by the 4th week of feeding; the maximum concentration in the egg was 1.5 times the dietary level. When the BP-6 was replaced with uncontaminated feed, feed consumption returned to normal; and within 8 weeks, egg production of the hens fed 200, 640, and 2000 ppm BP-6 was similar to that of the control. After withdrawal of the BP-6, the concentration of BP-6 in the eggs of hens fed 20 and 64 ppm BP-6 decreased rapidly during the first 2 weeks. After the first 2 weeks, the concentration declined much less rapidly, and detectable amounts were still present 33 weeks after withdrawal of BP-6 from the diet.
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residue accumulation and depletion in eggs of White Leghorns hens fed higher levels of BP-6 which ranged between 20 ppm and the accidental contamination level of 4000 ppm. A preliminary report of this research was published previously (Cecil and Bitman, 1975). MATERIALS AND METHODS
2 Firemaster BP-6 is a mixture of brominated biphenyls with an average bromine content of 75%, equivalent to about six bromine atoms per biphenyl molecule. This product is a mixture of the following brominated biphenyls: tetrabromobiphenyl, 2.0%; pentabromobiphenyl, 10.6%; hexabromobiphenyl, 62.8%; heptabromobiphenyl, 13.8%; other bromobiphenyls. 11.4% (Kerst, 1974).
RESULTS Feed Consumption and Body Weight Changes. Figure 1 shows the effects of BP-6 on feed consumption. Feeding diets containing 20 or 64 ppm BP-6 had no effect on feed con-
FOOD CONSUMPTION
|
O
O O
INTRODUCTION
Polybrominated biphenyls are industrial compounds used to reduce the flammability of thermoplastics. Their use has been restricted to those applications in which the end-use product is not exposed to either feed or food, and they are not used in flame-retarding fabrics that humans would be exposed to. The only polybrominated biphenyl produced in commercial q u a n t i t y in the U.S. is Firemaster BP-6 (Michigan Chemical Corporation). 1 In the fall of 1973, 16,000 cattle and 1.5 million chickens in Michigan were fed feed contaminated with polybrominated biphenyls that had been inadvertently added to cattle feed i n s t e a d of magnesium oxide. The polybrominated biphenyl was added to some dairy feeds at rates as high as .4% (4000 ppm), and several reports have indicated severe toxic ef-
1 Trade names are used solely for the purpose of providing specific information. Mention of a trade name does not constitute a guarantee or warranty of the product by the U.S. Department Of Agriculture nor an endorsement by the Department over other products not mentioned.
1978 Poultry Sci 57:1027-1036
fects and abnormal reproduction in animals fed the contaminated feed (Jackson and Halbert, 1974; Prewitt et al, 1975). Cows had lowered feed intake, weight loss, and decreased milk production. Cows in very early stages of pregnancy returned to estrus and those in later stages of pregnancy gave birth to stillborn calves. Also during this period chicken feed in Michigan became contaminated with BP-6 at lower levels because residual feed in the mill was c o n t a m i n a t e d . Although 1.5 million chickens and 5 million eggs were destroyed because BP-6 residues exceeded regulatory limits of . 3 ppm in fat, the physiological effects in chickens were not assessed. In earlier studies, we found few toxic effects in chickens fed 20 ppm BP-6 (Cecil et al, 1974; Lillie et al, 1974, 1975). Feeding 20 ppm BP-6 to White Leghorn laying hens did not reduce hatchability but reduced egg production and depressed progeny growth (Lillie et al, 1974, 1975). We also found that BP-6 reduced pentobarbital sleeping times in quail, a result indicating that BP-6 reduced the activity of liver microsomal enzymes (Cecil et al, 1975). In the present study, we followed the food consumption, reproduction, progeny survival, and
1027
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 15, 2015
ABSTRACT White Leghorn hens were fed 0, 20, 64, 200, 640, and 2000 ppm of a commercial mixture of polybrominated biphenyls (BP-6). The lower levels of BP-6 (20 and 64 ppm) did not change feed intake. After 8 weeks, egg production was 59%, 51% and 39%, and hatchability was 85%, 65% and 11% for the hens fed 0, 20 and 64 ppm BP-6, respectively. During the second week of feeding 200 ppm BP-6, feed consumption was reduced to 85 g/hen/day, a 23% reduction in intake, and all hens fed 200 ppm stopped egg production within 3 weeks. Hens fed 640 and 2000 ppm refused feed immediately, and at the end of 1 week, feed consumption was 30% that of the control. During the second week of treatment, hatchability was 43%, 21%, and 43% for hens fed 200, 640, and 2000 ppm BP-6, respectively. Dead embryos had subcutaneous edema in the neck and rump areas. The day-old chicks that survived had a higher mortality and lower body weight gains during the 3-week growth test than the control progeny had. The concentration of BP-6 in the egg reached a plateau by the 4th week of feeding; the maximum concentration in the egg was 1.5 times the dietary level. When the BP-6 was replaced with uncontaminated feed, feed consumption returned to normal; and within 8 weeks, egg production of the hens fed 200, 640, and 2000 ppm BP-6 was similar to that of the control. After withdrawal of the BP-6, the concentration of BP-6 in the eggs of hens fed 20 and 64 ppm BP-6 decreased rapidly during the first 2 weeks. After the first 2 weeks, the concentration declined much less rapidly, and detectable amounts were still present 33 weeks after withdrawal of BP-6 from the diet.
CECIL AND BITMAN
1028
residue accumulation and depletion in eggs of White Leghorns hens fed higher levels of BP-6 which ranged between 20 ppm and the accidental contamination level of 4000 ppm. A preliminary report of this research was published previously (Cecil and Bitman, 1975). MATERIALS AND METHODS
2 Firemaster BP-6 is a mixture of brominated biphenyls with an average bromine content of 75%, equivalent to about six bromine atoms per biphenyl molecule. This product is a mixture of the following brominated biphenyls: tetrabromobiphenyl, 2.0%; pentabromobiphenyl, 10.6%; hexabromobiphenyl, 62.8%; heptabromobiphenyl, 13.8%; other bromobiphenyls. 11.4% (Kerst, 1974).
RESULTS Feed Consumption and Body Weight Changes. Figure 1 shows the effects of BP-6 on feed consumption. Feeding diets containing 20 or 64 ppm BP-6 had no effect on feed con-
FOOD CONSUMPTION
|
O
O O
