Prioritization of chemicals according to the degree of hazard in the aquatic environment

Chemicals designated as "priority pollutants" or "toxics" have received special attention recently because the discharge of these compounds into public water is to be restricted to the maximum possible with little regard to water quality or economics. The selection of many of the 129 priority cemicals was not based on an objective scientific assessment of the exposure and effect data. In fact, for some compounds, including acenaphthene and 4-chlorophenyl-phenyl ether, the necessary data for listing were non-existent. As an alternative to arbitrarily listing or delisting chemicals for the purpose of prioity control, this paper suggests a promising scientific approach to selecting priority chemicals based on the principles of hazard assessment for chemicals in the aquatic environment. According o the hypothesis, the highest priority chemicals are those with the least margin of safety, defined as the gap between the no-observable-effect concentrations and the ambient exposure concentrations. The no-observable-effect concenrations are based on the results of chronic or sensitive life stage tests with aquatic organisms and the acceptable daily intake rate for fish eates. The ambient exposure concentrations are levels either measured in fish and water, or roughly estimated from a simple nomogram that requires only two of the following three factors: environmental release rate, ratio of dissipation to bioconcentration potential, or ambient residues in fish. THE CHEMICALS STUDIED TO ILLUSTRATE THIS APPROACH TO PRIORITIZING CHEMICALS BASED ON HAZARD ASSESSMENT ARE: polychlorinated biphenyls, di-2-ethylhexyl phthalate, linear alkylbenzene sulfonate, and pentachlorophenol.

Excretion and storage of [14C]toxaphene and two isolated [14C]toxaphene fractions

The 7-d urinary and fecal excretions of [14C]toxaphene and two isolated [14C]toxaphene fractions (polar fraction 7 and nonpolar fraction 2) were determined in orally dosed rats. The urinary, fecal, and total excretions of toxaphene were, respectively, 22.5, 35.7, and 58.2% of the administered dose. The total excretions of fractions 2 and 7 were, respectively, 69.4 and 65.0%, and the overall order of excretion was fraction 2 greater than toxaphene greater than fraction 7. All three groups had low toxaphene levels (below 0.2 ppm) in all tissues analyzed except for fat, where significant levels were detected. Hexane and chloroform extracts of the urine revealed that the activity was more polar than the parent material for all three groups. Apparently, toxaphene must be metabolized before it can be excreted in the urine. When fat extracts were analyzed by thin-layer chromatography and autoradiography, differences were found between the parent material and the extracted activity. There was an increase in polar activity in the residue obtained from toxaphene-treated rats. The fat from the fraction 2 group contained fraction 2 and two additional more polar spots, which represented about 11% of the total activity. The fat from the fraction 7 group also contained two additional spots, but they were less polar than fraction 7. Apparently, the metabolism of fraction 7 results in some products that are less polar and, perhaps, more persistent.

Organochlorine residues in young herons from the upper Mississippi River-1976

Chicks of great blue herons (Ardea herodias) from four heronaries located near South St. Paul, Royalton, and Wabasha, Minnesota, and La Crosse, Wisconsin, were analyzed for organochlorines, Highest mean wet-weight concentrations, 6.43 ppm PCBs. 1.31 ppm DDE, and 1.90 ppm sigma DDT, were found in the South St. Paul chicks. Among chicks from the other three heronries, most levels were similar, but were significantly lower than levels in South St. Paul chicks. Lowest mean organochlorine levels, 0.37 ppm DDE, 0.38 ppm sigma DDT, and 0.22 ppm PCBs, were found in chicks from Royalton. All birds from South St. Paul and La Crosse contained residues of DDT and TDE whereas only one of the 10 birds from Royalton contained DDT and one contained TDE residues. Five of the 12 birds from Wabasha contained DDT; eight contained TDE. Except for PCB residues in La Crosse heron chicks, the rate of organochlorine residue accumulation in the birds was generally less than the rate of dilution caused by growth.

Residue studies with [14C]fosamine ammonium in channel catfish

The active ingredient in du Pont Krenite brush control agent is ammonium ethyl carbamoylphosphonate (fosamine ammonium salt, formerly known as DPX-1108). Residues in channel catfish exposed to 1.1 ppm 14C-carbonyl-labeled fosamine ammonium in water for 4 wk were found to plateau in 2-3 wk with an accumulation factor (ratio of residue in fish to residue in water) of less than 1. In a separate experiment channel catfish were placed for 4 wk in a tank containing [14C]fosamine ammonium-treated soil (15 ppm) that had been aged for 30 d prior to flooding and initiation of fish exposure. The residue levels in this latter group of catfish also plateaued in 2-3 wk with an accumulation factor of less than 1. In both experiments, after the 4-wk exposures, the fish were transferred to fresh water for 2-wk depuration periods, during which residue levels dropped 50--90%. No effects on the fish were observed during these experiments.

World PCBs map: storage and effects in man and his biologic environment in the 1970s

PCB residues are found in biota all over the world. A biologic magnification of PCBs has been demonstrated in the food chain: plankton-fish-fish eating birds. A world map of the PCBs residues in biota and some of their biologic effects are given in this study. The biologic effects of PCBs are varied and may generally be explained by the induction or inhibition of the activity of a large number of enzymes, which upsets quantitatively, normal biochemical processes. Harm to reproduction, growth, development, defense systems, tissues, and organs appeared in susceptible organisms as a result of such changes or as a chain reaction to heterostases. The adverse health effects, observed in persons occupationally exposed and in those accidentally poisoned, point to the risk for the general population of an ever-increasing environmental pollution by PCBs. There is need for an integrated approach, consisting of epidemiologic studies on high risk groups in the general population and in persons occupationally exposed, as well as periodic assessment of PCB residues in man, his food, and feed supplies.

Organochlorine residues and reproduction in the little brown bat, Laurel, Maryland--June 1976

Twelve of 43 pregnant little brown bats (Myotis lucifugus) collected at Montpelier Barn, Laurel, Maryland, gave birth to dead young. Eleven of these 12 dead neonates were abnormally small. Most of the stillbirths were attributable to unknown reproductive difficulties associated with first pregnancies, but four may have been due to high concentrations of polychlorinated biphenyls (PCB) in the newborn. Residues of the PCB, DDE, and oxychlordane crossed the placenta at similar rates.

Interaction of endosulfan and metepa in rats

Repeated administration of endosulfan or metepa or their mixture did not induce any significant histological changes in the organs examined in male rats. Similarly, the activity of different enzymes assayed here showed no significant alterations. The level of endosulfan did not differ significantly in presence or absence of metepa in the samples of blood, brain, fatty tissue, kidney, liver and testis. The observations do not suggest any kind of additive or antagonistic effects or potentiation of each compound in presence of the other, at the doses and duration studied in male rats.

Hexachlorobenzene I. Uptake, distribution and excretion of hexachlorobenzene (HCB) in growing lambs

The uptake, distribution, and excretion of hexachlorobenzene (HCB) was studied in young male (castrated) lambs. Lambs were exposed for 90 days at a dietary concentration of 0, 0.01, 0.1 and 1.0 ppm. Tissue concentration of HCB were monitored by periodic omental biopsy and by post-slaughter collection of tissues at 90 and at 300 days. Blood samples were collected by venipuncture each time that biopsies or sacrifice occurred. Findings of the 300 days duration study were: (1) the growth rate of the exposed lambs was unaffected by the exposure to the dietary HCB, (2) adipose tissue concentrations reached a level approximately ten times that in the diet at the end of the 90-day exposure period, (3) HCB concentration was higher in the omental fat than in the perirenal fat at 90 days but not at 300 days, (4) a good portion of the apparent decresae in HCB in the fat following cessation of exposure is due to dilution (by increasing carcass fat), (5) the apparent half-life of HCB was approximately 90 days and was not dose-dependent at the exposure rates studied, and (6) the highest HCB concentrations in other tissues were in the brain and liver. The study demonstrated that the omental biopsy provides an excellent means of estimating body fat burden of this lipid soluble pesticide, although it tends to provide an overestimate during actual dietary exposure. The finding that the bioconcentration of and the depletion from the adipose tissues were independent of dose enables prediction of the degree to which food animals might become contaminated if allowed to feed on HCB-contaminated pastures or feed stuffs, and of the time which will be required for such residues to decrease to negligible levels. This predictive ability is of obvious benefit to both the food animal producer and the consumer. Since the HCB is apparently much more stable in the body than is indicated by the depletion half-life of 90 days in these growing lambs, it follows that environmental contamination of grazing lands or animal feeds is of far greater consequence for adult animals which would not be likely to experience the growth dilution of carcass residues.

Pesticide-induced changes in hepatic microsomal enzyme systems: further studies on the effects of 1,1,-di(p-chlorophenyl)-2-chloroethylene (DDMU) in the Japanese quail

Changes in the liver resulting from the low level dietary administration of 1,1-di(p-chlorophenyl)-2-chloroethylene (DDMU),p,p'-DDT, o,p'-DDT, p,p'-DDD and p,p'-DDE to Japanese Quail have been monitored. DDMU was exceptional in causing substantial increases in relative liver wt. and hepatic glucose-6-phosphatase after feeding at 100 ppm for 28 days. The time course of liver enzyme induction by DDMU has also been studied in Japanese Quail after periods of dietary administration ranging from 1--28 days with particular reference to changes in hepatic cytochrome P-450 and relative liver wt. Structural changes in the liver have been followed by reference to protein and lipid components. The hepatic response to DDMU appears to be biphasic. Initially there are substantial increases in hepatic cytochrome P-450 and relative liver wt., but the latter is largely due to accumulation of triglycerides. After approximately 20 days the level of hepatic cytochrome P-450 remain at a high 'plateau' level. This secondary phase of liver induction probably involves cell proliferation. It is concluded that DDMU causes major changes in the avian liver and either directly or through a metabolite causes pronounced microsomal enzyme induction.

A multi-generation toxicity evaluation of P,P'-DDT and dieldrin with Japanese quail. II. Tissue residues analyses

Selected tissues and egg yolks of Japanese Quail fed diets containing DDT or dieldrin in a four-generation (parental, F1, F2 and F3) study were analyzed for residues of parent compound and/or specific metabolites. Diets containing DDT (5 and 50 ppm) or dieldrin (0.1 and 1.0 ppm) were fed to each generation for 10 wks followed by a 12-wk recovery period in order to determine generation-accumulative effects, maximum residue levels and decline of residues during recovery. Tissue-residue storage and intergeneration transmission for DDT and dieldrin were generally similar and were related to dietary levels. Tissue residues in newly hatched birds were elevated initially for each generation subsequent to the parents, but any cumulative effects between generations were transitory, as residues after 5-to-10 wks were similar in each generation. Tissue residues in all groups showed a decline during the 12-wk recovery period. Decline during recovery was greater for females than males, probably attributable to egg production. Egg yolk residues for birds fed 5.0-ppm DDT declined to near control levels during the recovery period; at 50 ppm, residues declined but remained elevated above controls. For the quail fed dieldrin, residue levels were above those in controls; as with DDT the subsequent decline was more marked in the females.

[Determination of chlorinated pesticides in food and in human adipose tissue]

Residues of chlorinated pesticides in feed for laying hens, in eggs, poultry organs, potatoes, flour, and human fat tissues were determined by means of gas chromatography using electron recording detector. Further the amount of chlorinated hydrocarbon residues in potatoes from various parts of the South Moravian Region was stated. HCH amounts in human fat tissues recorded in Czechoslovakia were higher than in some West European countries, DDT content being, however, on the same level.

Hexachlorobenzene residues and effects on esterase activities in pre-weanling rats after a reciprocal transfer between HCB-treated and control dams

Female Wistar rats were divided into two groups. One group was fed ad libitum powdered rat chow containing 80 ppm hexachlorobenzene (HCB) and the other was fed HCB-free diet 2 weeks before mating until the termination of the experiment. Immediately after parturition, the pups were randomly culled to 10 per litter and 5 pups were reciprocally transferred between HCB and control dams. All pups within same paired litters were sacrificed on the 16th to 17th day and on the 20th to 23rd day after birth. Liver esterase activity toward indophenyl, thiophenyl, and p-nitrophenyl acetates was determined. The liver to body weight ratio, liver esterase activity and HCB residues were significantly higher in pups nursed by HCB-fed dams than in those nursed by control dams. The HCB residue in the liver, kidney, spleen, heart and brain was analyzed by gas-liquid chromatography. At about the weaning time, the HCB residue levels in pups transferred after parturition from HCB fed to control dams were similar to those in pups which remained with the control dams. The results demonstrated that HCB in tissues at about weaning time was obtained largely through milk. In addition, transmission of HCB through milk had greater effects on esterase activities in suckling pups than placental transmission. The pups born to HCB-treated dams and nursed by the control dams were similar to the pups born and nursed by the same control dams.

Relation between smoking and levels of DDT and dieldrin in human fat

The adipose tissue of humans with known patterns of cigarette smoking was collected during 1973-74 and analyzed for DDT components and dieldrin. Although smokers are exposed to high levels of insecticides from smoke of cigarettes and some of these compounds can be stored in adipose tissue, it could not be demonstrated that a relationship exists between smoking habit and residual levels of DDT found in fat. Smokers seem able, through induction of enzymes by substances in tobacco smoke, to metabolize these insecticides at a rate approximately equal to the rate of their intake in the smoke. Dieldrin residues in black male subjects were found to be linearly related to the number of cigarettes smoked, but the factors governing this relationship were not obvious.

Effects and residues of dietary hexachlorobenzene in growing swine

Crossbred weanling gilts were fed a standard ration containing 0, 1, 10, or 100 ppm purified hexachlorobenzene (HCB) for 13 wk. No mortalities, ill health, neurological disorders, or significant depressions in weight gain were observed. Postmortem examination revealed brightly fluorescent livers at all levels of HCB. The group receiving 100 ppm had a tendency for smaller spleens, larger livers with swollen hepatocytes, and decreased lymphocytes. HCB accumulated in the dissectable fat of growing swine to concentrations five- to sevenfold higher than the dietary concentration; residues in 11 other tissues examined were below the dietary concentration.

Pesticide residues in eggs and chicks from laying hens fed low levels of several chlorinated hydrocarbon pesticides

Eighty-four Single-Comb While Leghorn laying hens housed individually in laying cages were fed rations containing less than 0.1 p.p.m. of dieldrin, DDT, heptachlor and mirex individually or in combination for 7 days and in combination for 15 weeks. DDT residues in egg yolk reached 0.043 p.p.m. by 7 days when fed in combination with the other pesticides. None of the residues were above FDA action level at 7 days and all had declined to below trace levels by 8 weeks after termination of pesticide feeding. Residues in eggs from hens fed all four pesticides for 15 weeks increased steadily for the first few weeks and then reached a plateau or increased only slightly until pesticide feeding was terminated. By the end of the 5th week of pesticide feeding all pesticides except DDT had exceeded FDA action levels for pesticides in eggs. DDT residues reached a level of 0.139 p.p.m. by 8 weeks and did not increase thereafter. Traces of the pesticides were still present 24 weeks after termination of pesticide feeding. The pesticides tested did not affect fertility of hatchability of eggs collected during the 14th and 15th weeks of pesticide feeding. Total carcass fat of chicks hatched from these eggs had 0.024 p.p.m. dieldrin, .049 p.p.m. DDT, .001 p.p.m. heptachlor epoxide and, 0.47 mirex at 1 day of age.

Uptake of the mosquito larvicide Temefos by the salt marsh snail, New Jersey--1973-1974

Uptake of the mosquito larvicide temefos (Abate) by the salt march snail (Melampus bidentatus Say) in New Jersey was measured by gas-chromatographic analysis. Measurable quantities of temefos were found in the snails within 1 day after the first treatment with a 2% granular formulation but 3 weeks elapsed before uptake occurred following treatment with a temefos emulsion. Residues in the snails exposed to the granular formulation were generally more than 10 times higher than those in snails exposed to the emulsion although application rates of the granular formulation were only about three times higher than those of the emulsion. Residues in snails exposed to the emulsion fell below detectable levels less than 3 weeks after cessation of treatments although measurable amounts were found in snails exposed to the granular formulation for more than 5 weeks after the last treatment. The persistence of temefos in M. bidentatus suggests the potential for its movement through food webs exposed to the granular formulation.

[Study of the cumulation, desorption and mechanism of action of organochlorine pesticides on fish cestodes]

The distribution of residues of DDT and its metabolites (DDD and DDE) in tissues of Triaenophorus nodulosus and its host was studied. It has been noted that cestodes can accumulate chlororganic substances in great quantity. The ability of Bothriocephalus gowkongensis has been established to dechlorate pp-DDT and to excrete pp-, op- and mp-DDD from the organism. Pp-DDT decreases the glycogene content and causes the rise of amylolytic activity in the above cestodes in acute tests. The effect of pp-DDT on the locomotor activity of cestodes is of two-phase character. The first one is associated with the muscular influence, the second one-- with neurotrophic effect. A high toxicity of mp-DDD )0.1 mg/l) for the locomotor activity of cestodes as compared with the effect of pp- and op-DDD was revealed.

Nature and fate of insecticide residues inhaled by rats in cigarette smoke

Radioactive carbaryl, carbofuran, parathion, leptophos, and DDT were added to cigarettes and the mainstream smoke was directed to the lungs of rats via the trachea. Total radiocarbon transfer to the lungs ranged from 9 to 15% of that in the tobacco burned during a smoking process involving eight 5-ml puffs. Exhalation of 14C residues during this time was 24 to 30% of that inhaled with all insecticides except carbofuran, of which 42% of the residues was exhaled. After 5 hr, total exhalation of the consumed radiocarbon was 35% for parathion, 65% for carbofuran, and approximately 50% for the other products. The nature of the 14C residues inhaled, their urinary and fecal excretion, and their deposition in and dissipation from various organs and tissues are presented.

[Decomposition of simazine herbicide in algal cultures]

The possibility of simazine accumulation and detoxication in the cultures of some species of green, yellow-green, and blue-green algae was investigated. It has been shown that the algae can accumulate simazine in amounts hundred times exceeding its concentration in the cultural medium. The protein fraction contained up to 28.8% of simazine accumulated by the algae. The accumulation of water-soluble products of simazine metabolism in the cultural medium is indicative of the partial transformation of the herbicide.

Effects of plant species, age and part on the disappearance of sevin, nuvacron and malathion residues

Residues as determined by bioassay using Daphnia or mosquito larvae were in agreement with each other in most cases except sevin residues at 1 h and 8 days after treatment of mallow. The mosquito larvae failed to record nuvacron, sevin and malathion on 45-day-old plants on the 8th, 12th and 24th day, respectively, whereas residues on younger plants continued to affect mosquitoes up to the 12th day and disappeared only on the 24th day. Daphnia continued to show toxicity up to the 24th day on younger and older plants. Insecticide residues of nuvacron, malathion and sevin, found on the leaves 30- and 45-day-old plants of cotton, Jew's mallow and kidney beans after 1 h, 1, 4, 8, 12 and 24 days were estimated biologically by C. pipiens larvae and D. magna. Residues of insecticides disappeared more readily on bean pods than on bean leaves. Residues of sevin, malathion and nuvacron found on the pods 12 days after treatment as indicated by Daphnia were 0.189, 0.055 and 0.059 ppm respectively. They are far less than the corresponding residues on bean leaves. The 1-hour residue was higher on younger bean leaves than on mallow and cotton with very few exceptions (nuvacron, malathion and sevin: 2.125, 11.75 and 95 ppm on cotton leaves; 2.25 and 145 ppm on Jew's mallow and 3.750, 32.500 and 250 ppm on common bean leaves, respectively). These data were obtained with C. pipiens larvae. The picture was completely reversed on 45-day-old plants. 1-h deposits of malathion were higher on mallow than on cotton or beans (nuvacron, malathion and sevin; 2.3, 200 and 140 ppm on cotton leaves, 1.90, 191.15 and 92.86 ppm on mallow leaves, 2.25, 21.5 and 137.5 ppm on common bean leaves, respectively). These data were obtained with C. pipiens larvae. Nuvacron residues on 45-day-old mallow were less on mallow than on cotton or beans. Sevin was higher in 1-h residues on cotton and beans than on mallow. Mallow did not retain insecticides as long as did cotton and beans. The initial concentration of nuvacron was little less than that of sevin and malathion. It was more toxic to mosquito larva (LC50 = 0.0016 ppm) than malathion (LC50 = 0.0034 ppm) and sevin (LC50 = 0.075 ppm). Daphnia was more affected by malathion (LC50 = 0.000098 ppm) than by nuvacron (LC50 = 0.00024 ppm). Nuvacron was nearly equitoxic to sevin (LC50 = 0.00026 ppm) against Daphnia. In spite of this all tested plants, both young or older ones, retained nuvacron in the smallest quantities in proportion to the other insecticides. The 1-h residues were less on older plants (except cotton) for only nuvacron and sevin: 2 and 94.5, 1.9 and 92.8 ppm than on younger ones 2.4 and 137.2, 2.25 and 145 ppm as indicated by Daphnia and mosquito larvae respectively. This emphasizes that the initial concentration is not the limiting factor for the determination of the 1-h residue as the initial concentration was much higher on older than on younger plants.

Bromide pharmocokinetics: a model for residue accumulation in animals

Using data obtained from pharmacokinetic experiments with bromide, illustrations are given of the application of pharmacokinetics to toxicological studies. Analog computers may be helpful, though not indispensable. The significance of ancillary pharmacokinetic investigations in the evaluation of toxicity studies is discussed.