than those who do not smoke. Heavy drinking can lead to disorders in the
brain and liver, a heavy drinker exposed to certain organic chemicals may
therefore experience more serious liver injury than would a non-drinker.
5.7.2.5 Gender
The rate of metabolism of foreign compounds varies in animals and humans
according to gender. The response to CHCl 3 exposure by laboratory mice, for
example, shows a distinct sex variation. Male mice are highly sensitive to
CHCl 3 , and death often results following their exposure to this chemical.
15 The
higher sensitivity exhibited by male mice to certain toxicants may be due to
their inability to metabolize the chemicals as efficiently as female mice. It is
interesting that the death rate of male mice exposed to CHCl 3 is also dependent
on the strain of mouse. Studies have shown that the effect of BHC on the
weights of rats’ brains and kidneys varied with sex of the animal. The brain and
kidney weights did not differ in male rats exposed to 25 ppm BHC from those
of unexposed controls, but in female rats the weights of brain and kidney were
both increased.
5.8 NUTRITIONAL FACTORS
5.8.1 INTRODUCTION
Results obtained from human epidemiological and animal experimental
studies have clearly shown nutrition as an important factor affecting
pollutant toxicity. For example, human populations exposed to environmental fluoride may or may not exhibit characteristic fluoride poisoning,
depending on their nutritional status, such as the adequacy of protein, or
vitamins A, C, D, or E. The interaction between nutrition and environmental
pollutants is complex, and its study is a challenge to researchers in the fields
of toxicology and nutrition – a new area of study called nutritional toxicology
has emerged in recent years.
The relationship between nutrition and toxicology may include: the effect of
nutritional status on the toxicity of environmental chemicals, the additional
nutritional demands as a result of toxicant exposure, and the presence of toxic
substances in foods.
16 Generally, nutritional modulation can alter rates of
absorption of environmental chemicals, and therefore affect the circulating
levels of those chemicals. Nutrition modulation can also induce changes in
body composition, which in turn may result in altered tissue distribution of
chemicals. Dietary factors can also influence renal function and pH of body
fluids with altered toxicity. In addition, modified nutritional status of an
individual may alter the responsiveness of the target organ.
72
Environmental Toxicology
[16:54 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-005.3d]
Ref: 4365 MING-HO YU Chap-005 Page: 72 65-84
brain and liver, a heavy drinker exposed to certain organic chemicals may
therefore experience more serious liver injury than would a non-drinker.
5.7.2.5 Gender
The rate of metabolism of foreign compounds varies in animals and humans
according to gender. The response to CHCl 3 exposure by laboratory mice, for
example, shows a distinct sex variation. Male mice are highly sensitive to
CHCl 3 , and death often results following their exposure to this chemical.
15 The
higher sensitivity exhibited by male mice to certain toxicants may be due to
their inability to metabolize the chemicals as efficiently as female mice. It is
interesting that the death rate of male mice exposed to CHCl 3 is also dependent
on the strain of mouse. Studies have shown that the effect of BHC on the
weights of rats’ brains and kidneys varied with sex of the animal. The brain and
kidney weights did not differ in male rats exposed to 25 ppm BHC from those
of unexposed controls, but in female rats the weights of brain and kidney were
both increased.
5.8 NUTRITIONAL FACTORS
5.8.1 INTRODUCTION
Results obtained from human epidemiological and animal experimental
studies have clearly shown nutrition as an important factor affecting
pollutant toxicity. For example, human populations exposed to environmental fluoride may or may not exhibit characteristic fluoride poisoning,
depending on their nutritional status, such as the adequacy of protein, or
vitamins A, C, D, or E. The interaction between nutrition and environmental
pollutants is complex, and its study is a challenge to researchers in the fields
of toxicology and nutrition – a new area of study called nutritional toxicology
has emerged in recent years.
The relationship between nutrition and toxicology may include: the effect of
nutritional status on the toxicity of environmental chemicals, the additional
nutritional demands as a result of toxicant exposure, and the presence of toxic
substances in foods.
16 Generally, nutritional modulation can alter rates of
absorption of environmental chemicals, and therefore affect the circulating
levels of those chemicals. Nutrition modulation can also induce changes in
body composition, which in turn may result in altered tissue distribution of
chemicals. Dietary factors can also influence renal function and pH of body
fluids with altered toxicity. In addition, modified nutritional status of an
individual may alter the responsiveness of the target organ.
72
Environmental Toxicology
[16:54 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-005.3d]
Ref: 4365 MING-HO YU Chap-005 Page: 72 65-84