Paraffin waxes and Hydrocarbon waxes

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

In accordance with Section 1.2 of REACH Annex XI, testing does not appear to be scientifically necessary as the weight of evidence indicates no concern for reproductive (fertility and sexual function) effects from paraffin wax. This is based on the lack of activity observed in several similar substances, an assessment made by another regulatory authority (EFSA), and an assessment by recognised experts (American College of Toxicology).

 

A repeat dose dietary study, conducted according to OECD TG 408 (reported in IUCLID Section 7.5) with up to 2 % Paraffin wax 64, microparaffin wax mixture and low melting point wax (equivalent to ~2000 mg/kg/day in males and 1500 mg/kg/day in females) found no treatment-related effects following histopathological evaluation of the reproductive organs: there were changes in the liver, lymph nodes and heart.    This clearly demonstrates that after systemic exposure, (confirmed by histopathological effects in other organs), there were no averse pathological effects on the reproductive organs.

 

We have two oral studies, an OECD 421 and an OECD 415 that provide some information on sexual function and neonatal development.

 

The first study was conducted with a Lubricating Base Oil (CAS no. 64742-54-7) – this is upstream of paraffin wax, is less refined and can be considered a worst case. A single dose level of 1000 mg/kg/day was administered to groups of 12 male and 12 female rats by oral gavage for 14 days prior to mating and until Day 4 of lactation for the females (39 days) or for 30 days for males. There were no clinical findings and growth rates and food consumption values were normal. Fertility indices and mating indices for males and females were both 100%. At necropsy, there were no consistent findings, and the animals were considered to be normal. Organ weights and histopathology were considered normal. The NOAEL for this study was ≥1000 mg/kg/day.

 

The second study is a Highly Refined base oil (CAS no.  8042-47-5, white mineral oil) and comprises 60 % paraffinics and 40% naphthenes.  This is an earlier study from 1987 and the design is similar to an OECD 415.  The test substance was applied dermally for 5/7 days, except gestation when treatment was daily, from 10 weeks prior to mating, during mating and to gestation day 20 for females and for a further 9 weeks for males.  The design is not exactly like the OECD 421, but it covers many of the same endpoints and the doses used were 0, 125, 500 and 2000 mg/kg/day, exceeding the usual limit dose of 1000 mg/kg/day.  There were 20 females and 10 males per group. No mortality was observed in any treatment groups. No treatment-related changes in body weight gain or food consumption were observed in the females of the parental generation. No adverse effects were noted in the number of implantation sites per dam, litter size, or length of gestation in treated animals. Treatment-related clinical signs included erythema, scabs, and flaking at application site at all dose levels. No signs of gross toxicity were observed at necropsy. The parental NOAEL is greater than or equal to 2000 mg/kg bw/day for females. Data on males were not provided in this study report. The offspring exhibited no significant differences in body weight gain, eyelid disjunction, righting reflex, or viability in treated groups versus control.  No treatment-related signs of gross pathology were noted at necropsy. The offspring NOAEL is greater than or equal to 2000 mg/kg bw/day.

 

These two studies demonstrate that a less refined substance (LBO) and a similar refined substance (HRBO) following oral or dermal exposure have no effect on male or female fertility and, together with the dietary study with paraffin wax, we can confirm that the reproductive organs are not target organs for toxicity.  In the absence of any triggers with this substance, and similar (even less refined) substances further testing on vertebrate animals for this property can be omitted.

 

There are also two robust 2-generation reproductive studies (OECD 416) conducted with gas-to liquid products, a gas oil and a base oil (Boogaard et al, 2017). In both studies the test material was administered by oral gavage and in both studies, there was no effect on reproductive performance or gestation length and parturition of both the F0 and F1 parental generations. The reproductive toxicity NOEL for the gas oil was 750 mg/kg/day and for the base oil 1000 mg/kg/day; in both substances this was the highest dose tested. The gas oil contains branched and linear C8-C25 distillates and the base oil C18-C50 branched cyclic and linear distillates; these results indicate that the long chain hydrocarbons also present in paraffin wax are not associated with reproductive toxicity as there were no effects on fertility or reproductive function.

 

In addition, EFSA reviewed the use of microcrystalline wax (E 905, CAS no 63231-60-7) as a food additive in 2013. Microcrystalline wax (E 905) is authorised quantum satis as a surface treatment agent on non-chocolate confectionery, chewing gum and decorations, coatings and fillings, except fruit-based fillings. It is also permitted as a surface treatment of melons, papaya, mango and avocado.  As part of the review the panel stated that;

No study on treatment related and developmental toxicity on microcrystalline were available. However, chronic toxicity studies on various oils did not show histopathological changes on male and female reproductive organs. In addition, several reproductive and developmental toxicity studies using low viscosity mineral oils as a solvent control are available. In 2009, EFSA reviewed these studies and concluded that they were useful in providing evidence of the lack of reproductive or developmental effects of white mineral oils.

 

Paraffin and Microcrystalline wax are also widely used in cosmetic products and have been assessed for this use (ACT 1984).  The report concluded that the waxes are safe for use as cosmetic ingredients.  Nothing was added to the conclusion following a review in 2003.

Taken together it is considered that the above provides sufficient evidence to conclude that paraffin waxes are unlikely to alter reproductive fertility or sexual function.

 

References

Peter J. Boogaard, Juan-Carlos Carrillo, Linda G. Roberts & Graham F. Whale (2017) Toxicological and ecotoxicological properties of gas-to-liquid (GTL) products. 1. Mammalian toxicology, Critical Reviews in Toxicology, 47:2, 121-144, DOI: 10.1080/10408444.2016.1214676

 

EFSA Journal 2013;11(4):3146 Scientific Opinion on the re-evaluation of microcrystalline wax (E 905) as a food additive EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2013.3146

 

JOURNAL OF THE AMERICAN COLLEGE OF TOXICOLOGY Volume 3, Number 3, 1984 Final Report on the Safety Assessment of Fossil and Synthetic Waxes https://journals.sagepub.com/doi/pdf/10.3109/10915818409010516

 

Tsitou P, Heneweer M, Boogaard PJ. Toxicogenomics in vitro as an alternative tool for safety evaluation of petroleum substances and PAHs with regard to prenatal developmental toxicity. Toxicol in vitro 2015;29:299-307

 

Kamelia L, De Haan L, Ketelslegers HB, Rietjens IMCM, Boogaard PJ. In vitro prenatal developmental toxicity induced by some petroleum substances is mediated by their 3- to 7-ring PAH constituent via activation of the aryl hydrocarbon (Ah) receptor. Toxicol Lett 2019;315:64-76

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Justification for read-across:

Parraffin wax is considered to be a UVCB substance, and is part of the continuum of petroleum substances originating from crude oil. The substances are categorised according to their chemical specification and refining history. When considering the information available for a particular petroleum category it is appropriate to consider if other categories can provide an insight into expected toxicity. Paraffin waxes are highly refined substances, they originate from a stream of Lubricating Base Oils that act as feedstocks for most of the dewaxing operations that produce finished paraffin and microcrystalline waxes. Only lubricating base oils that have been sufficiently refined i.e. they pass IP346 content ≤ 3 wt% are further refined to produce paraffin waxes. Paraffin waxes have high paraffinic content and most of the PAHs (including 3 – 7 ring) are removed.

 

Concawe hypothesises that higher tier toxicological effects such as genotoxicity, repeated dose systemic toxicity, reprotoxicity (developmental and fertility) and carcinogenicity are associated with the level and types of polycyclic aromatic hydrocarbons (PAHs). 

Polycyclic aromatic hydrocarbons (PAH) have a conjugated hydrocarbon ring structure and when they include other groups such as alkyl, nitro and amino groups and other elements such as nitrogen, sulphur or oxygen are known as poly cyclic aromatic compounds (PAC’s). PAH are of particular concern as historically certain PAH are considered to be associated with a number of health and environmental toxicities of which benzo[a]pyrene is the best-known example. PAH and PAC are essentially referring to the same molecules, although PAC is a more inclusive term as these contain hetero atoms (atoms other than carbon or hydrogen). However, heterocyclics are sufficiently low in petroleum products so that the two terms can be used inter-changeably. Toxicity is hypothesised to be attributed to interaction with the Aryl Hydrocarbon (Ah) receptor; further details on this hypothesis are available in Tsitou (2015), Kamelia (2019).

 

It is therefore predicted that paraffin and hydrocarbon waxes are unlikely to exhibit adverse effects in reproductive toxicity (fertility and developmental) endpoints.

Paraffin waxes predominantly have a typical carbon range of C12 to C85, we can gain information from the component carbon pools of paraffin waxes from the following sources:

·        Gas-to-Liquid products (GTL) which are synthetic hydrocarbons produced from natural gas using a Fisher-Tropsch process. The synthetic crude is refined to a range of products similar to those from natural crude oil but they are essentially free of unsaturated or aromatic constituents (ie PAHs) and also no sulphur-, oxygen- or nitrogen-containing constituents are present. 

·        Highly Refined Base Oils (which contain no PAHs and re predominantly C12 to C50)

·        Lubricating base oils – these are used as feedstocks for the processes that make paraffin wax but are less refined and it can be assumed they would have a worse toxicity profile. They have a typical carbon range number of C12 to C120.

 

References

Tsitou P, Heneweer M, Boogaard PJ. Toxicogenomics in vitro as an alternative tool for safety evaluation of petroleum substances and PAHs with regard to prenatal developmental toxicity. Toxicol in vitro 2015;29:299-307

 

Kamelia L, De Haan L, Ketelslegers HB, Rietjens IMCM, Boogaard PJ. In vitro prenatal developmental toxicity induced by some petroleum substances is mediated by their 3- to 7-ring PAH constituent via activation of the aryl hydrocarbon (Ah) receptor. Toxicol Lett 2019;315:64-76

Effects on developmental toxicity

Description of key information

In accordance with Section 1.2 of REACH Annex XI, testing does not appear to be scientifically necessary as the weight of evidence indicates no concern for developmental toxicity effects from paraffin wax. This is based on the lack of activity observed in several similar substances, an assessment made by another regulatory authority (EFSA), and an assessment by recognised experts (American College of Toxicology).

 

We have the following information available which can help address concerns about developmental toxicity;

 

A rat dermal OECD 414 study with a lubricating base oil (CAS no 64741-88-4) with an IP 346 value of less than 3% (ie a non-carcinogenic stream, upstream from paraffin wax and therefore a ‘worst case’).  In this study the test material was applied by dermal application from gestation days 0 to 19 at dose levels of 0, 125, 500 or 2000 mg/kg/day.  Other than dermal irritation at all dose levels there were no signs of maternal toxicity; it should be noted that the top dose level of 2000 m/kg/day exceeds the limit dose of 1000 mg/kg/day.  The study included an additional high dose group which was administered radio labelled [1-14C]octacosane on gestation day 18, this group demonstrated the presence of metabolites in the foetuses, but no bioaccumulation was noted; this clearly supports systemic exposure to the substance. There was no evidence of teratogenicity. There were no treatment-related changes observed during the external, skeletal, or visceral evaluations. Mean foetal weight and crown-rump lengths were comparable across all dose groups. A developmental NOAEL was reported to be ≥2000 mg/kg/day.

 

A second dermal OECD 414 study with a lubricating base oil (CAS no 64742-65-0) used dose levels of 0 and 1000 mg/kg/day with application on gestation days 0 to 19.  There was no maternal or developmental toxicity at the limit dose of 1000 mg/kg/day.  This is a robust GLP guideline study conduct recently and at the limit dose.

 

These two studies show that prior to refining, the petroleum stream has no developmental toxicity; this is considered to be a worst case, after refining the petroleum stream has fewer PAH molecules.  It should be noted that although the studies are dermal, one of them uses radioactive substance to demonstrate that the foetus is exposed.

 

Other studies also confirm the lack of developmental toxicity in similar petroleum streams;

 

An oral OECD 414 study with a highly refined white mineral oil (CAS no 8042-47-5, predominantly C12 to C50), found no developmental or maternal toxicity at 5000 mg/kg/day, it should be noted that this is five times higher than the limit dose of 1000 mg/kg/day.

 

In addition, there are two Gas-to Oil oral prenatal development toxicity study, which can be used to inform us about the non-PAH components of paraffin wax, a gas oil and a base oil (Boogaard et al 2017). In both studies the test material was administered by oral gavage and in both studies, there was no effect on foetal development.  The developmental toxicity NOEL for the gas oil was 750 mg/kg/day and for the base oil 1000 mg/kg/day; in both substances this was the highest dose tested. The gas oil contains branched and linear C8-C25 distillates and the base oil C18-C50 branched cyclic and linear distillates; these results indicate that the long chain hydrocarbons also present in paraffin wax are not associated with developmental toxicity.

 

These studies demonstrate that a less refined substance (LBO), a similar refined substance (HRBO), plus GTL products with no PAH’s, have no effect on foetal development following systemic exposure. In the absence of any triggers with this substance, and similar (even less refined) substances further testing on vertebrate animals for this substance can be omitted.

 

In addition, EFSA reviewed the use of microcrystalline wax (E 905, CAS no 63231-60-7) as a food additive in 2013. Microcrystalline wax (E 905) is authorised quantum satis as a surface treatment agent on non-chocolate confectionery, chewing gum and decorations, coatings and fillings, except fruit-based fillings. It is also permitted as a surface treatment of melons, papaya, mango and avocado.  As part of the review the panel stated that;

No study on treatment related and developmental toxicity on microcrystalline were available. However, chronic toxicity studies on various oils did not show histopathological changes on male and female reproductive organs. In addition, several reproductive and developmental toxicity studies using low viscosity mineral oils as a solvent control are available. In 2009, EFSA reviewed these studies and concluded that they were useful in providing evidence of the lack of reproductive or developmental effects of white mineral oils.

 

Paraffin and Microcrystalline wax are also widely used in cosmetic products and have been assessed for this use (ACT 1984).  The report concluded that the waxes are safe for use as cosmetic ingredients.  Nothing was added to the conclusion following a review in 2003.

Taken together it is considered that the above provides sufficient evidence to conclude that paraffin waxes are unlikely to alter foetal development

 

References

Peter J. Boogaard, Juan-Carlos Carrillo, Linda G. Roberts & Graham F. Whale (2017) Toxicological and ecotoxicological properties of gas-to-liquid (GTL) products. 1. Mammalian toxicology, Critical Reviews in Toxicology, 47:2, 121-144, DOI: 10.1080/10408444.2016.1214676

EFSA Journal 2013;11(4):3146 Scientific Opinion on the re-evaluation of microcrystalline wax (E 905) as a food additive EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2013.3146

JOURNAL OF THE AMERICAN COLLEGE OF TOXICOLOGY Volume 3, Number 3, 1984 Final Report on the Safety Assessment of Fossil and Synthetic Waxeshttps://journals.sagepub.com/doi/pdf/10.3109/10915818409010516

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no adverse effect observed

Study duration:

subchronic

Species:

rat

Additional information

Justification for read-across:

Parraffin wax is considered to be a UVCB substance, and is part of the continuum of petroleum substances originating from crude oil. The substances are categorised according to their chemical specification and refining history. When considering the information available for a particular petroleum category it is appropriate to consider if other categories can provide an insight into expected toxicity. Paraffin waxes are highly refined substances, they originate from a stream of Lubricating Base Oils that act as feedstocks for most of the dewaxing operations that produce finished paraffin and microcrystalline waxes. Only lubricating base oils that have been sufficiently refined i.e. they pass IP346 content ≤ 3 wt% are used to produce paraffin waxes. Paraffin waxes have high paraffinic content and most of the PAHs (including 3 – 7 ring) are removed.

 

Concawe hypothesises that higher tier toxicological effects such as genotoxicity, repeated dose systemic toxicity, reprotoxicity (developmental and fertility) and carcinogenicity are associated with the level and types of polycyclic aromatic hydrocarbons (PAHs). 

Polycyclic aromatic hydrocarbons (PAH) have a conjugated hydrocarbon ring structure and when they include other groups such as alkyl, nitro and amino groups and other elements such as nitrogen, sulphur or oxygen are known as poly cyclic aromatic compounds (PAC’s). PAH are of particular concern as historically certain PAH are considered to be associated with a number of health and environmental toxicities of which benzo[a]pyrene is the best-known example. PAH and PAC are essentially referring to the same molecules, although PAC is a more inclusive term as these contain hetero atoms (atoms other than carbon or hydrogen). However, heterocyclics are sufficiently low in petroleum products so that the two terms can be used inter-changeably. Toxicity is hypothesised to be attributed to interaction with the Aryl Hydrocarbon (Ah) receptor; further details on this hypothesis are available in Tsitou (2015), Kamelia (2019).

 

It is therefore predicted that paraffin and hydrocarbon waxes are unlikely to exhibit adverse effects in reproductive toxicity (fertility and developmental) endpoints.

Paraffin waxes predominantly have a typical carbon range of C12 to C85, we can gain information from the component carbon pools of paraffin waxes from the following sources:

·        Gas-to-Liquid products (GTL) which are synthetic hydrocarbons produced from natural gas using a Fisher-Tropsch process. The synthetic crude is refined to a range of products similar to those from natural crude oil but they are essentially free of unsaturated or aromatic constituents (ie PAHs) and also no sulphur-, oxygen- or nitrogen-containing constituents are present. 

·        Highly Refined Base Oils (which contain no PAHs and re predominantly C12 to C50)

·        Lubricating base oils – these are used as feedstocks for the processes that make paraffin wax but are less refined and it can be assumed they would have a worse toxicity profile. They have a typical carbon range number of C12 to C120.

 

References

Tsitou P, Heneweer M, Boogaard PJ. Toxicogenomics in vitro as an alternative tool for safety evaluation of petroleum substances and PAHs with regard to prenatal developmental toxicity. Toxicol in vitro 2015;29:299-307

 

Kamelia L, De Haan L, Ketelslegers HB, Rietjens IMCM, Boogaard PJ. In vitro prenatal developmental toxicity induced by some petroleum substances is mediated by their 3- to 7-ring PAH constituent via activation of the aryl hydrocarbon (Ah) receptor. Toxicol Lett 2019;315:64-76

Justification for classification or non-classification

Based on a weight of evidence and category read-across approach, there is insufficient data to classify paraffin and hydrocarbon wax as toxic for reproduction under Annex VI of EU CLP Regulation (EC No. 1272/2008).