Toxicity of tissue culture media exposed to polyvinyl chloride plastic

Embryotoxicity testing of IVF disposables: how do manufacturers test?

STUDY QUESTION

How do manufacturers perform embryotoxicity testing in their quality control programs when validating IVF consumables?

SUMMARY ANSWER

The Mouse Embryo Assay (MEA) and Human Sperm Survival Assay (HSSA) used for IVF disposables differed from one manufacturer to another.

WHAT IS KNOWN ALREADY

Many components used in IVF laboratories, such as culture media and disposable consumables, may negatively impact human embryonic development.

STUDY DESIGN, SIZE, DURATION

Through a questionnaire-based survey, the main manufacturers of IVF disposable devices were contacted during the period November to December 2018 to compare the methodology of the MEA and HSSA. We focused on catheters for embryo transfer, catheters for insemination, straws, serological pipettes, culture dishes and puncture needles used in the ART procedures.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We approached the manufacturers of IVF disposables and asked for details about methodology of the MEA and HSSA performed for toxicity testing of their IVF disposable devices. All specific parameters like mouse strains, number of embryos used, culture conditions (media, temperature, atmosphere), extraction protocol, subcontracting, and thresholds were registered and compared between companies.

MAIN RESULTS AND THE ROLE OF CHANCE

Twenty-one companies were approached, of which only 11 answered the questionnaire. Significant differences existed in the methodologies and thresholds of the MEA and HSSA used for toxicity testing of IVF disposables. Importantly, some of these parameters could influence the sensitivity of the tests.

LIMITATIONS, REASONS FOR CAUTION

Although we approached the main IVF manufacturers, the response rate was relatively low.

WIDER IMPLICATIONS OF THE FINDINGS

Our study confirms the high degree of heterogeneity of the embryotoxicity tests performed by manufacturers when validating their IVF disposable devices. Currently, no regulations exist on this issue. Professionals should call for and request standardization and a future higher degree of transparency as regards embryotoxicity testing from supplying companies; moreover, companies should be urged to provide the users clear and precise information about the results of their tests and how testing was performed. Future recommendations are urgently awaited to improve the sensitivity and reproducibility of embryotoxicity assays over time.

STUDY FUNDING/COMPETING INTEREST(S)

This study did not receive any funding. L.D. declares a competing interest with Patrick Choay SAS.

TRIAL REGISTRATION NUMBER

N/A.

Toxicity of intravenous catheters tested in a human bone marrow culture system

Nine brands of i.v. catheter were tested for toxicity in a human bone marrow culture system, and content and leaching of plasticizers determined. Three catheters showed toxicity to the culture system and three others leached di-2-ethylhexyl-phthalate in appreciable amounts.

Randomized autocontrolled comparison of the embryo culture performance of Nunc and Falcon petri dishes

PURPOSE

Our purpose was to compare the embryo culture performance of two types of petri dishes (Nunc and Falcon).

METHODS

Mouse zygotes were cultured up to the expanded blastocyst stage in both types of dishes. The oocytes from 50 in vitro fertilization cycles were randomly divided between the two types of dishes. Fertilization, cleavage, and embryo quality were compared. Oocytes from another 50 cycles were all cultured at random in either type of dish. Pregnancy and implantation rates were compared between the two types.

RESULTS

Of 91 mouse zygotes, 81 cleaved to two-cell-stage embryos, and 64 became expanded blastocysts in Falcon dishes; of 99 zygotes, 81 cleaved to two-cell-stage embryos and 66 became expanded blastocysts in Nunc dishes. Of 248 oocyte-cumulus complexes (OCC), 145 fertilized in Falcon dishes, and of 269 OCC, 175 fertilized in Nunc dishes. The high quality embryo ratio was 51 out of 118 in Falcon dishes, not different from that in Nunc dishes, 58 out of 139. In Falcon dishes 72 out of 118 embryos were at least at the four-cell stage after 45 hr, versus 70 out of 139 in Nunc dishes. Twenty-three clinical pregnancies were obtained in the first 50 cycles with sibling oocytes. In the second group, with randomization of the cycles between Nunc and Falcon, 8 pregnancies were obtained in the Nunc and 10 in the Falcon dishes. The implantation rate in this second group of 50 cycles was 9 out of 61 in Falcon and 11 out of 57 in Nunc dishes.

Biological effects of di-(2-ethylhexyl) phthalate and other phthalic acid esters

Esters of o-phthalic acid are widely distributed in the ecosystem. The phthalate acid esters (PAE's) are used as plasticizers in the manufacture of polyvinylchlorides. They are also used as solvents in certain industrial processes and as vehicles for pesticides. The PAE's are used in enormous quantities for a variety of industrial uses in the formulation of plastics. While there are a number of important PAE's, di-ethylhexyl phthalate has perhaps been used the most extensively in the formulation of plastics used in medical devices and blood bag assemblies. The metabolism, biodistribution and excretion varies to some extent among the various PAE's. There are species differences with respect to the metabolism of the PAE's. The route of administration, and the level and length of exposure, are known to affect the toxicological profile of the various PAE's. There is little evidence of bioaccumulation of the various PAE's, and only at very large doses have there been reports of overt toxicity. Evidence for the carcinogenicity of certain PAE's apparently is related to prolonged exposure to high levels.

Epidemiological study of respiratory disease in workers exposed to polyvinylchloride dust

The respiratory health of workers exposed to polyvinylchloride (PVC) dust has been investigated in 818 men sampled from the work force of a factory manufacturing PVC. In a cross-sectional survey, the lung function and prevalences of respiratory symptoms and chest radiographic abnormalities were compared with estimates of individual PVC dust exposures based on detailed occupational histories and current measurements of respirable PVC dust. Complaints of slight exertional dyspnoea were associated with PVC dust exposure, though age and smoking effects were much stronger. The forced expired volume in one second (FEV1) and forced vital capacity (FVC) were inversely related to dust exposure after age, height, and smoking effects had been taken into account. This effect was seen principally in cigarette smokers, and there was suggestive evidence that PVC dust exposure and cigarette smoking interacted in the reduction of FEV1 and FVC. Gas transfer factor was not related to dust exposure. The chest radiographs were read according to the ILO U/C classification by three experienced readers. One reader recorded a low prevalence of small rounded opacities, and these were not related to age or dust exposure. Another reader recorded a higher prevalence of small rounded opacities category 0/1 or more, and these were related to age but not to dust exposure. The third reader recorded the highest prevalence of small rounded opacities (though none greater than category 1/1), and these were independently related both to age and to PVC dust exposure, indicating an effect of PVC dust on the appearance of the chest radiography. These appearances were so slight that only the higher sensitivity of this reader in the interpretation of profusion of small rounded opacities on the ILO U/C scale enabled detection of this effect of PVC dust. In conclusion, exposure to PVC dust is associated with some deterioration of lung function, slight abnormalities of the chest radiograph, and complaints of slight dyspnoea. The mean decline in FEV1 associated with the average dust exposure experienced in the study was small, though some of the men with higher dust exposures may have suffered clinically important loss of lung function as a result of their occupation.

Toxic effect of the glycoalkaloids solanine and tomatine on cultured neonatal rat heart cells

The toxic effects of the glycoalkaloids, alpha-solanine and tomatine, were studied in beating heart cell cultures from 1--2-day-old rats. After addition of alpha-solanine (80 microgram/ml) and tomatine (40 microgram/ml) to the culture medium, the cells ceased beating within a few minutes. At a concentration of 40 microgram/ml alpha-solanine and 20 microgram/ml tomatine, both compounds caused a pronounced increase of the contraction frequency, lasting for at least 2h. K-strophantin, a reference heart glycoside, caused arrhythmic beating at 20 microgram/ml and complete cessation of contractions at 160 microgram/ml.

Diethylhexyl phthalate as a factor in blood transfusion and haemodialysis

Di-2-ethylhexyl phthalate (DEHP), the most frequently occurring plasticiser in medical equipment manufactured from polymers of vinyl chloride, forms about 40% w/w of tubes and containers used for storing blood and for haemodialysis. The plasticiser leaches out into liquids with lipid contents, although it is very sparingly soluble in purely aqueous solutions. On infusion of 2-3 1 of stored blood, up to 200 mg DEHP may be transferred to the patient, while much higher quantities may be given during dialysis, which is moreover often repeated frequently over long periods. The acute toxicity of DEHP is very low (greater than 20 g/kg as LD50 in rats), and the ester is rapidly metabolised to products which are excreted in the urine and bile; chronic toxicity from the levels of dosage obtaining is thus very improbable. Carcenogenicity has never been demonstrable in animals, while teratological effects are of a very low order. Serious acute results observed after transfusion of neonates have not been proved to be caused by DEHP, and might be ascribable to accompanying foreign substances. Atheroma in chronic dialysis subjects is still unexplained, but hepatitis probably caused by diethylphthalate from plastic was resolved when apparatus plasticised by DEHP alone was substituted. The benefits of DEHP appear vastly to outweigh any risks. The status of DEHP as environmental contaminant is noted.

Micro-determination of total phthalate esters in biological samples by gas-liquid chromatography

A method was investigated in which all of the phthalate esters in biological samples were determined as phthalic acid by gas-liquid chromatography. The method is based on the separation of phthalate esters from the sample with n-hexane, saponification of the esters with an alkaline ethanolic solution to give phthalic acid, purification of the acid by extraction with diethyl ether and column chromatography using silica gel, and conversion of the acid into bis(2,2,2-trifluoroethyl) phthalate with a 2,2,2-trifluoroethanol solution containing boron trifluoride. The derivative obtained is highly sensitive to an electron-capture detector, giving a sensitivity of 0.1 pg. Biological samples fortified with di(2-ethylhexyl) phthalate at levels of 5-100 ppb were analyzed, with recoveries of 70-100%.

Effect of dietary di-2-ethylhexyl phthalate on lipid biosynthesis in selected tissues from the rat, in vitro

Di-2-ethylhexyl phthalate (DEHP), a plasticizer commonly used in the production of polyvinyl chloride plastics, has become an environmental pollutant. At the present time, the biological significance of phthalates in the environment is unknown. In the present studies, we observed that addition of DEHP to a stock diet of rats resulted in marked effects on incorporation of 14C-acetate into lipid by liver and kidney slices; other organs, such as heart, testes, and aorta, were unaffected. Incorporation of 14C-acetate into total lipid of liver (dpm/mg wet wt) from rats fed 0.5% or 1.0% DEHP for 10 or 18 days, respectively, was decreased to ca. 50% of control values. The decreased incorporation into liver lipid is not attributable to any one lipid fraction, inasmuch as incorporation into the phospholipid, sterol + diglyceride, free fatty acid, triglyceride, and sterol ester + hydrocarbon fractions was decreased 30-70% with respect to controls. In addition, the percent distribution of 14C-acetate among the individual phospholipids was ca. 25% lower in phosphatidyl choline of the DEHP-fed rats. In rats fed 0.5% DEHP, incorporation of 14C-acetate into total lipid of kidney was similar to control values, but incorporation into the triglyceride and sterol ester + hydrocarbon fraction was decreased 30-40%, whereas incorporation into the sterol + diglyceride fraction was increased 38%. Livers from DEHP-fed rats were ca. 20% larger than livers from control rats and, at the 0.5% level of DEHP feeding, testes wts were elevated; no significant changes were noted in wts of spleen, heart, aorta, kidney, or body wt gains in rats fed DEHP. These studies emphasize a subtle toxicity of phthalate esters not previously reported and emphasize the need for further biochemical studies to evaluate the effect of phthalates on biological systems.

Di (2-ethylhexyl)phthalate content of plasma fractions prepared by low temperature ethanol (Cohn) fractionation

Plasma pools, prepared from time-expired blood stored in plastic packs, were analysed for DEHP content and levels ranging from 0.78 to 7.42 mh DEHP/100 ml plasma obtained. The DEHP content of the Cohn fractions prepared from such plasma pools was estimated. Only very low levels of DEHP were found in the four therapeutically useful fractions and high levels in the discard fractions III and IV.

Identification and measurement of plasticizer in neonatal tissues after umbilical catheters and blood products

Because of concern about tissue uptake of pasticizers used in medical equipment, di-(2-ethylhexyl) phthalate was measured by gas chromatography-mass spectrometry in neonatal heart and gastro-intestinal tissue. Seventeen infants who had umbilical catheterization alone or with administration of blood products, and 13 stillborn or older controls were studied. The mean levels of the plasticizer for heart residue and pressed extract in the study group --1.27 plus or minus 0.42 and 0.66 plus or minus 0.22 mug per gram respectively--were significantly (pgreater than 0.005) higher than the corresponding control levels (less than 0.07 plus or minus 0.03 and less than 0.07 plus or minus 0.04 mug per gram). Higher levels were associated with larger amounts of blood products, more extensive use of catheters, and early death. Levels in gastrointestinal tissue from three infants who had died of necrotizing enterocolitis were significantly (less than 0.05) higher than those in gastrointestinal tissue from infants without this disease. Thus, plasticizer from medical use of plastics does accumlate in tissues of critically ill infants.