Women in toxicology in the United States

Abstract

Since the toxicology field was established, women have played a critical role in it. This article is written to celebrate the 20-year anniversary of the Special Interest Group for Women in Toxicology, affiliated with the Society of Toxicology. Six female pioneers in modern Toxicology from different social classes and education backgrounds are featured. Despite these differences, they overcame similar obstacles in gender, politics, and scientific barriers to disseminate their research. This discussion will start with Ellen Swallow Richards, who, besides being the pioneer in sanitary engineering, founded the home economics movement that applied science to the home. The discussion will continue with Alice Hamilton, a contributor to occupational health, a pioneer in the field of industrial toxicology, and an example of generosity to social movements and those in need. Subsequently, the most famous woman we discuss in this paper is Rachel Carson, whose fundamental work in environmental Toxicology is evidenced in her important book Silent Spring. This article also features Elizabeth Miller, a biochemist known for her fundamental research in cancer carcinogenesis, followed by Mary Amdur. Nowadays much of what we know about air pollution comes due to Mary, who paid from her own pocket for her experimental animals to investigate Donora smog pollutants and their health damages. And last but not least Elizabeth Weisburger, a chemist who made significant contributions in carcinogenesis and chemotherapy drugs who worked for 40 years at the National Cancer Institute. Here, we discuss the aforementioned women’s careers and personal struggles that transformed toxicology into the field we know now.

Introduction

Toxicology is at the same time an ancient field and a new field. The earliest record (4000 b.c.e.) of poisons involves a goddess named Gula or Ninisina, known as the “Goddess of Healing” and “Controller of Noxious Poisons” [1]. Toxicology, in its earliest practice, had a high female representation and many of those who studied poisons in the Renaissance and Age of Enlightenment periods were women [1]. For women in the late 1880s, the female prevalence was not a reality anymore, not only in toxicology itself, but all scientific areas [2–8]. As this paper will show, women that adventured in toxicology had to overcome gender, political, and scientific barriers to disseminate their research, and their careers were blocked by a countless number of obstacles. Some of these contemporary female scientists are highlighted in this paper.

To remember Dr Ellen Henrietta Swallow Richards, Dr Alice Hamilton, Dr Rachel Carson, Dr Elizabeth Miller, Dr Mary Amdur, and Dr Elizabeth Weisburger simply as pioneers in toxicology would be an injustice. Their persistence was admirable. From the beginning of their careers until they became well-known scientists, they were banned and prohibited from obtaining suitable paid positions, publishing, being part of professional societies, having grant proposals funded, or receiving or being nominated for awards and honors (Fig. 1).

Figure 1.

Timeline of women featured in this paper in chronological order of their year of birth.

To this day, because of the still-prevalent belief that women and science are somehow incompatible, women working in science in general face a “glass ceiling” that prevents them from reaching higher positions [3, 4, 9]. However, in toxicology the “glass ceiling” is, at minimum, “cracked”. This milestone was accomplished due to the efforts of several women in the past and currently, some which we celebrate in this paper, and the Special Interest Group Women of Toxicology (WIT) from the Society of Toxicology (SOT).

Headquartered in the USA, the SOT includes a Special Interest Group called “Women of Toxicology” [10] that focuses on empowering women in toxicology. The group was established in July of 1999 as an ad hoc working group. After 2 years, with the efforts of Dr Gina Pastino, Dr Michelle Hooth, and others, the first “official” meeting took place at Philadelphia in March of 2000. By July 2001, the group had become a Special Interest Group [11].

To celebrate the Special Interest Group of the Women in Toxicology’s 20th anniversary, we feature some pioneering female toxicologists’ career highlights. Numerous other women all over the world are undoubtedly worthy of inclusion; however, in this paper we focus on women who were not only pioneers in toxicology, but also founders of official organizations in the USA that allowed other women to make progress. They are presented chronologically as Dr Ellen Henrietta Swallow Richards, Dr Alice Hamilton, Dr Elizabeth Miller, Dr Elizabeth Weisburger, Dr Rachel Carson, and Dr Mary Amdur.

Dr Ellen Henrietta Swallow Richards

Born in 1842 in Massachusetts, Ellen was the only child of middle class parents that valued education [12] and homeschooled her until she was 15 years old [13]. Because of her proficiency in Latin, she was allowed to study French and German, which made her a valuable tutor [14]. She was a teacher/instructor for a short period but was always interrupted by setbacks—once measles, then being required to help in the family store or take care of her ill mother [13].

Even though women were not allowed to enroll in college at that time, her extraordinary talent was hard to ignore and she was accepted as a student at Vassar College, where in 1870 she graduated with a bachelor’s degree, and then earned a Master of Arts degree with a thesis on the chemical analysis of iron ore [13].

Wanting to continue pursuing her education, she applied to MIT, and in 1870 Ellen became the first woman admitted to MIT [13, 15]. In 1873, she received her Bachelor of Science degree with her thesis Notes on Some Sulpharsenites and Sulphantimonites from Colorado [16], and continued to study at MIT where she would have been awarded the first advanced degree ever given to a woman at this institution (a Master of Science degree). However, MIT hesitated at granting it to a female and did not award her the degree until 1886. Long after that, Richards was granted an honorary Doctor of Science degree in 1910 by Smith College [13].

From 1873 to 1878, she taught chemistry at MIT as an unpaid lecturer [17] while consulting as a chemist for the Massachusetts State Board of Health and US Department of Agriculture [18]. Because of her work for these organizations, in the 1880s, her interests shifted toward sanitation—in particular, air and water quality [17]. She performed a sequence of tests in 40 000 samples of drinking water and for that developed the “Richards’ Normal Chlorine Map” that mapped the chloride concentrations in Massachusetts’ waters. Her plots showed that the chloride concentrations were high near the coast. Since the amount of chlorine in the samples was an indicator of the extent of water pollution from human activity and industry, as a result, Massachusetts established the first water quality standards in America and the first modern treatment plan for sewage [19].

Ellen was married to Robert H. Richards, also from MIT, with whom she collaborated in the mineralogy laboratory. With her husband’s support she remained associated with MIT, and in 1875 she appealed to the Women’s Education Association of Boston to help her establish the Women’s Laboratory at MIT (opened in 1876) [6, 15] to which she volunteered her services and contributed $1000 of her own money annually [13]. After her marriage, she developed a method to determine the amount of nickel in metals and became an authority in the chemical analysis of minerals. She discovered a rare metal, samarskite, and was the first to isolate the element vanadium [20]. Richards was the first woman to be a member of the American Institute of Mining and Metallurgical Engineers [17].

Additionally, Richards applied her scientific knowledge to the home. She wanted all women to be educated in science, whether in a laboratory or at home taking care of the family. She was more than just an educator of women; she in fact developed home sanitation as she tested air, water and food quality at homes, and tested textiles and wallpapers for arsenic. She tested all her hypotheses in her own home. She shifted from using coal heating and cooking oil to using gas, installed fans to pull air from the home to the outside, and determined her house’s water quality [21]. Richards wrote books about home science, such as The Cost of Cleanness; Sanitation in Daily Life (1907) [22], The Chemistry of Cooking and Cleaning (1881) [23] and Food Materials and Their Adulterations (1885) [24], which led to the first Pure Food and Drug Act in Massachusetts [19].

In 1884, Richards was finally appointed as a paid instructor in sanitary chemistry in MIT at the newly formed MIT Laboratory of Sanitation [5], a position she held until her death. In addition to her faculty and administrative duties, she was also (not officially titled) Dean of Women [13].

In 1876, Richards associated herself with the first American correspondence school, the Society to Encourage Studies at Home, as an instructor and developer of its science department [13]. Along with Marion Talbot, in 1882, she also founded what was to become the American Association of University Women (AAUW) [25]. The group envisioned an organization in which women college graduates would find better opportunities to apply their training.

Richards also collaborated with Mary Hinman Abel to found the New England Kitchen of Boston, which experimented with ways to prepare inexpensive, tasty, and nutritious food [13]. This association started in some Boston high schools in 1894 to provide nutritious meals at low prices to children who would not normally have them. They ran the New England Kitchen as a private enterprise that paid for itself, and this became an inspiration for similar lunch programs in other cities [26].

Richards died at her home from heart disease in 1911, at the age of 69 [13]. Even though she is most known today as the founder of home economics, she was a pioneer in the fields of toxicology, sanitary engineering [20], public health, minerology, and she was also the founder of euthenics. Richards was the first to use the word “euthenics” in her books The Cost of Shelter (1905) [27] and Euthenics: the Science of Controllable Environment (1910) [28]. She defined the term as the improvement of living conditions. She also introduced the word ecology (coined by German biologist Ernst Haeckel) into English around 1892 [29].

In 1993, Richards was inducted into the National Women’s Hall of Fame, and in 2011, she was listed as eighth on MIT’s top 150 innovators and ideas list [30]. To honor her achievements, Vassar College established an interdisciplinary curriculum of euthenics studies, and MIT designated a room in their main building for female students to use and established the Ellen Swallow Richards professorship for distinguished female faculty members [31].

“We have won our standing, an acknowledged place. Now that we have influence how shall we use it? [The] Woman’s outlook will be different ten years from now. Is she still to be behind in the race? Or from her new standpoint shall she lead? The question is not woman, but ability and women,” said Richards in the same year she died [32].

Dr Alice Hamilton

Alice Hamilton was born in Manhattan into a wealthy family in 1869 and she spent her childhood on her family’s large property in Fort Wayne, Indiana [33]. Alice’s father attended Princeton University and Harvard Law School, and along with Alice’s mother, homeschooled their five children from an early age. Although Hamilton had led a privileged life in Fort Wayne and did not need to worry about money, she wished to make herself useful to the world and chose medicine as a career.

Before enrolling at the University of Michigan Medical School in 1892, she studied science with a high school teacher in Fort Wayne and anatomy at the Fort Wayne College of Medicine for a year [33–35]. She earned her medical degree in 1893 [36]. After graduating, Hamilton worked as an intern at two hospitals for women and children for 1 year, but soon realized that she was not interested in medical practice but preferred the investigative work she could do in laboratories. Thus, she returned to the University of Michigan in February 1895 to do her graduate work in bacteriology and work as a lab assistant in Frederick George Novy’s laboratory [33–35].

In the fall of 1895, Alice, along with her oldest sister, decided to study in Berlin; however, the universities did not enroll women officially. For foreign women, they were beginning to make exceptions (only two other women, one American and one English, had received their PhDs from Germany by that time), as long as a professor would take them as students [37]. Germany was not welcoming to Alice and her sister. Berlin did not accept their applications, and they both only gained permission to attend the universities of Munich and Leipzig, but at Leipzig they were allowed to attend all classes as long as they were “invisible” [37]. At Munich they had to be escorted to classes by professors to be able to pass through the crowd that formed to watch each woman enter her first class. Their seats were strategically mapped to not be placed near the male students.

In the laboratory Alice also faced repeated sexism. For example, she was not allowed to attend autopsies and work with animals, even though these were required activities for her male peers: “she was never allowed to forget she was a woman” [37]. The only place she was treated equally was in Carl Weigert’s laboratory in Frankfurt, where she worked with Ludwig Edinger, with whom she became close friends. Hamilton was resentful about her experience in Germany. She learned nothing that she had not known before, and even outside of academia, men were patronizing: she described situations in which women were pushed off the sidewalks and forced to give their seats to men in opera houses [37].

In September 1896 Alice returned to the USA and continued her postgraduate studies at Johns Hopkins University. There she worked mainly with Simon Flexner, a young pathologist [37]. At that time, she became a member and resident of Hull House, a settlement house founded by social reformers Jane Addams and Ellen Gates Starr. Hamilton was always active in social movements such as peace movements and women’s rights. Also, this association with the Hull House led her to witness the effects that exposure to carbon monoxide and lead had on workers, which fostered her growing interest in workers’ health, especially occupational illnesses. By 1916 Hamilton was America’s first authority on lead poisoning.

She examined a range of occupational toxic disorders such as those caused by mercury, benzene, aniline dyes, carbon monoxide, tetraethyl lead, radium, carbon disulfide, and hydrogen sulfide gases. Hamilton worked for a variety of state and federal health committees. In 1925, at a Public Health Service conference, she advocated against the use of lead in gasoline, warning about its dangers to people and the environment. Her claims were not heard, and in 1988 it was estimated that 68 million children had suffered toxic exposure to high lead levels from fuel [38].

Hamilton then began working as a special investigator for the US Bureau of Labor Statistics, investigating white lead and lead oxide, as well as pioneering the fields of occupational epidemiology, industrial hygiene, and industrial medicine in the USA [39]. Her compiling details of diagnosed poisoning cases contributed to the emerging modern toxicology and the toxicological laboratory practices [40], and were scientifically persuasive enough to influence broad health reforms that changed laws and general practice to improve workers’ health [41], which led to the current Occupational Safety and Health Administration [42].

During World War I, Hamilton assisted the US Army in uncovering a mysterious ailment striking workers in New Jersey [43]. She led a team that concluded that the workers were being exposed to trinitrotoluene (TNT), and a simple wash of clothing at the end of each shift solved the problem. Hamilton wrote the “Illinois Survey”, a report that documented her findings of industrial processes that exposed workers to lead poisoning and other diseases. Her efforts resulted in the passing of the first workers’ compensation laws in order to require employers to take safety precautions to protect workers in Illinois in 1911, in Indiana in 1915, and later in other states [36].

In 1919 Hamilton was appointed an assistant professor in what is now known as the School of Public Health at Harvard Medical School, making her the first woman to serve on Harvard’s faculty. During the 16 years she taught at Harvard, she never received a faculty promotion. She held only a series of 3-year appointments. She was excluded from social activities, the Harvard Union, the Faculty Club, and the ability to march in the university’s commencement ceremonies [36, 44].

At the age of 101, Hamilton died of a stroke at her home in Connecticut in 1970 [43]. Three months after her death, the US Congress passed the Occupational Safety and Health Act to improve safety in workplaces [45]. Until the day of her death Hamilton remained an activist in social reform in civil liberties, peace, birth control, and protective labor legislation for women.

Dr Rachael Carson

With the publication of her controversial book, The Silent Spring, in 1962, Dr Rachel Carson became an important influence in initiating the modern era of environmental toxicology. Her book emphasized stopping the widespread, indiscriminate use of pesticides and other chemicals and advocated use patterns based on sound ecology. Although sometimes inaccurate and using arguments based on frankly anecdotal evidence, her book is often credited as the catalyst leading to the establishment of the US Environmental Protection Agency, and many regard her as the mother of the environmental movement.

The daughter of an insurance salesman, Rachel Carson was born in 1907 and grew up in a farm in Pennsylvania [46]. Always interested in writing stories, often involving animals, she published her first story when she was 10 years old. Carson was known to be a loner in high school, from which she graduated at the top of her class, as well as in college. She initiated her studies in English at the Pennsylvania College for Women (today known as Chatham University) but changed her major to biology, though she continued collaborating with the student newspaper [47]. Although she was admitted to graduate standing at Johns Hopkins University in 1928, she remained at the Pennsylvania College for Women for her senior year due to financial difficulties and graduated with honors in 1929. However, she was able to find her way into Johns Hopkins after taking a summer course at the Marine Biological Laboratory and continued her studies in zoology and genetics in the fall of 1929.

As a way to earn money for tuition, Carson became a part-time student assistant in Raymond Pearl’s laboratory, where she worked with rats and drosophila. She completed her master’s degree in 1932 with the thesis “The Development of the Pronephyros During the Embryonic and Early Larval Life of the Catfish” [48]. Although she wanted to continue her graduate work and earn her doctorate, due to her father’s sudden death in addition to the Great Depression and her tight financial situation, she had to find a job and become her family’s breadwinner [46]. She spent the following years working at the US Bureau of Fisheries in Washington, DC, where she became the second woman hired by the Bureau of Fisheries, working as a junior aquatic biologist [49]. Her main responsibilities were to analyze and report field data on fish populations, as well as write brochures and other literature for the public. Using her Bureau work expertise and research, she wrote a steady stream of articles for newspapers and essays to be published [49]. At this busy time of her life, Carson was also taking care of her aging mother and raising her two nieces since her older sister died in 1937 [49].

One of her essays, “The World of Waters,” was originally written for her fisheries bureau brochure, but her supervisor considered it too good for that purpose, and she published it as “Undersea.” Impressed by her writing, the publishing house Simon & Schuster suggested she expand it into a book, and this decision became a turning point in her career [49]. By 1948, Carson decided to transition to writing full time, with a literary agent, Marie Rodell, in an arrangement that would last the rest of Carson’s career [49]. In 1952, she won the National Book Award and John Burroughs Medal, two of her books reached the best-seller list, and she received two honorary doctorate degrees, one from the Pennsylvania College for Women (now Chatham University) and another from Smith College [49].

In early 1957, another family tragedy struck her when one of her nieces died, leaving her 5-year-old son, whom Carson adopted and raised. At that time, she was closely following federal proposals for pesticide spraying. Her concern about the use of synthetic pesticides began with the US government’s program for the eradication of Lymantria dispar, known as gypsy moth, that led Rachel to dedicate herself to research and her next book [49].

In 1962 Carson published Silent Spring, her best-known book, describing the harmful effects of pesticides on the environment, especially Dichlorodiphenyltrichloroethane (DDT). She collected several examples of environmental damage attributed to the use of DDT. Through her contacts with many government scientists, she had access to additional information and found a significant community of scientists who had been documenting the psychological and environmental effects of using pesticides. For Rachel, even without the support of scientists external to the pesticides and cancer area of research, the evidence for the toxicity of synthetic pesticides was unquestionable [47, 49].

Carson and her collaborators faced widespread criticism, especially from the larger pesticide companies. During that time she discovered a malignant tumor in her breast that had metastasized [49], and she decided to hide her illness so that the pesticide companies couldn’t use it against her. In the FDA hearings on the review of regulations on the use of pesticides, Carson was discouraged by the aggressive approach of the chemical industry, including expert testimonies that strongly contradicted the scientific literature she was studying, and possible financial incentives in pesticide programs [49]. Many of her critics condemned her for wanting to eliminate all pesticides [49]. However, Carson never advocated for banning pesticides and considered them helpful. She advocated instead for responsible and careful use and management. In fact, in the DDT section of her book, she advised to spray as little as possible to limit health impairments [50].

In March 1964, her doctors found out that her breast cancer had reached her liver, and in April she died of a heart attack. Carson was never married but had a romantic and long-lasting relationship with Dorothy Freeman [51, 52]. Their relationship was conducted mainly through letters and during summers spent together in Maine [49, 53]. Half of Carson’s ashes were buried beside her mother, and Dorothy received the other half, scattering them at the shores of Sheepscot Bay in Maine according to Rachel’s final wishes [49].

Dr Elizabeth Cavert Miller

Elizabeth Cavert Miller, or “Betty” as she was more affectionately known, was born in a well-educated family in Minnesota in 1920. Her parents wanted all their kids to study economics at the University of Minnesota, including the girls (which was unusual at that time). However, Elizabeth chose to study agricultural biochemistry instead. From the various universities she considered for her graduate work, she chose the University of Wisconsin in Madison, where she initiated her studies in the fall of 1941 with a Wisconsin Alumni Research Foundation (WARF) Scholarship. The Department of Biochemistry would not accept her for graduate study in biochemistry alone as she desired since she was a woman, so she was instead forced into a joint program in biochemistry and home economics [54]. At that time, she met her future husband and work colleague James A. Miller, “Jim,” when he was her teaching assistant. James was impressed by Elizabeth’s skills, and knowing she was not very satisfied with the joint program, he intervened on her behalf to encourage Professor Carl Baumann to accept her as his graduate student [54]. Hereafter, she was able to start focusing on her biochemistry interests.

In 1945, at the age of 24, Miller obtained her PhD with a thesis titled “The Effect of Pyridoxine and its Derivatives on Growth and Xanthurenic Acid Excretion,” in which she showed that high-protein diets were toxic to mice deficient in vitamin B6 [55]. Subsequently, Miller, along with her husband, began working with Professor Harold Paul Rusch at the McArdle Laboratory, where both worked for 45 years. In all those years Miller managed to serve not only in research, but as an associate director, a position she held from 1973 to her death in 1987, while simultaneously caring for their two daughters, Linda and Helen [55].

Among their countless contributions to oncology and toxicology, the greatest was demonstrating that most chemical carcinogens require metabolic activation to induce mutations and, therefore, become carcinogenic [56]. In 1948 and 1949, the Millers jointly authored papers providing the first evidence that carcinogens would bind covalently to tissue macromolecules [57–61]. They explained the pathway by which 4-dimethylaminoazobenzene, a yellow crystalline solid compound used as a dye, is metabolized to give rise to a product that can bind to proteins and become carcinogenic. They used an aminoazo dye, which developed a pink color when bound to a protein, measured by a simple bench-top spectrophotometer [62].

The Millers were the first to demonstrate how a chemical biotransforms into a more carcinogenic metabolite [54], and characterized the molecular events that lead to the metabolic activation of 2-acetylaminofluorene [63], aflatoxin B1 [64, 65], safrole [66], estragole [67], and ethyl carbamate [68]. They also contributed to the understanding of DNA adducts caused by chemical exposure, and were one of the first to report the activation of protooncogenes in tumors induced by carcinogens. Because of their discoveries, a new research era in modern toxicology was developed. The Millers provided foundation to the development of mutagenicity, the Ames test, the use of biomarkers for exposure and metabolic activation, and others [54].

During a talk on June 6, 2014 [56], Dr Roswell “Roz” Boutwell emphasized that even though the Millers had their own studies and lab personnel, they operated most often as a team. He highlighted that they complemented each other’s work and often relied on the other’s professional expertise. Dr Boutwell emphasized that “the roles of Drs. Rusch, Potter, James Miller, Elizabeth Miller, and himself were crucial to establishing the program [McArdle Laboratory for Cancer Research] that remains in existence today, 75 years later” [56].

In October of 1987 Elizabeth Miller died of renal cancer. As Marie Curie is to radiology, Elizabeth Miller is to oncology and toxicology. Interestingly, both died at the age of 67 by the diseases to which they had dedicated their lives. Many say that the Millers did not enjoy enough recognition considering their contributions [55]. Several books and a website [2, 7, 55, 69–71] devoted to reporting on distinguished women at the University of Wisconsin- Madison do not mention Dr Elizabeth Miller. Many cancer researchers today believe that the Millers were deserving of a Nobel Prize in Medicine for their many important discoveries in chemical carcinogenesis.

Dr Mary Ochsenhirt Amdur

Born in 1921 in Pennsylvania, Dr Mary Amdur completed her bachelor’s in chemistry in 1943 from the University of Pittsburgh, and in just 3 years, she completed her PhD in biochemistry in 1946 from Cornell University with a thesis titled Role of Manganese and Choline in Bone Formation in the Rat [72]. She was known to be direct, honest, and insightful, as well as an exquisite writer and editor [73]. She soon moved to the Massachusetts Eye and Ear Infirmary in Boston to start her career and to allow her husband, Benjamin Amdur (with whom she collaborated in science and had a son), to pursue his doctoral degree [73]. After 3 years she joined the inventor of the iron lung, Philip Drinker, at Harvard School of Public Health in 1949. Her focus was to develop a test for lead in soot, matter, and air [72]. At that time, manufacturers, despite knowing lead’s dangerous properties, avoided controlling its use and exposure [73].

Intending to show that sulfuric acid and sulfur dioxide were not the primary pollutants in the 1948 worst air pollution disaster in the USA, the Donora Smog, the American Smelting and Refining Company (ASARCO) funded Drinker so he could investigate its effects. The Donora Smog occurred in 1948 in Donora, Pennsylvania, and was caused by hydrogen fluoride and sulfur dioxide emissions from steel and zinc industries that resulted in the death of 20 people and respiratory problems for thousands [74].

By 1953, Amdur and her husband researched the lung toxicity of both compounds in guinea pigs purchased with their own money. At that time, very little work had been done on the cardiopulmonary effects of inhaled pollutants, and when it was, the pollutants were found to be lethal in animals. They developed a method to spray a combination mist of sulfuric acid and sulfur dioxide into the guinea pigs’ chamber and found out that the combination mist led to dramatic effects on breathing, weight loss, and lung disease in lower concentrations than those estimated for Donora [75–77]. Dr Amdur works, along with others, ultimately resulted in the establishment of the Clean Air Act of 1963 [72, 78]. They presented their results at the annual meeting of the American Association for the Advancement of Science in 1953 but experienced many difficulties during the meeting [72, 73].

Amdur faced threats and pressure from all directions. She was physically threatened in an elevator at the annual meeting and asked not to present the findings, but this did not intimidate her. On top of that, Drinker demanded that Amdur remove her name from the paper she had written about the topic and withdraw it. However, Amdur refused Drinker’s demands as the paper had already been accepted. Drinker removed her from his staff and the paper was never published [72, 73]. As she was well published and widely known, soon after this incident, she relocated to another lab and started working with James Whittenberger and Jere Mead to continue her research on air pollution. However, being a woman at a Harvard’s staff group at that time was not a pleasant experience [79, 80]. Just like other women hired by Harvard at that time, like Alice Hamilton, she knew she would never receive a faculty promotion or gain any benefits, as her male peers would [73]. Thus, she moved her research and accepted a position as lecturer at the Massachusetts Institute of Technology (MIT), changing her focus to the interaction of metals and gases in sulfuric acid inhalation and being funded by both federal and industry organizations. She wanted to combine engineering and toxicology to create appropriate aerosols for her inhalation studies [76]. In fact, she was able to determine the formation of sulfuric acid on metal oxide surfaces and how it causes toxicity in guinea pig’s lungs [72, 73, 76, 77, 81].

Despite her extremely successful research, her work was not taken seriously at MIT and did not receive much attention. She remained a non-faculty member for 12 years, and in 1989, at the age of 67, she decided to move to the Institute of Environmental Medicine at New York University as a senior research scientist, where she merged her efforts with Drs. Rich Schlesinger and Mort Lippmann; she remained there until her retirement in 1996. This position was still untenured, despite her continued success in acquiring research support funds [72, 73].

Amdur was known to have an open door policy in her laboratory, thus, even though she only supervised a few doctoral students, she mentored much more [73]. As a friend of Lou Casarett, Amdur was invited by Dr John Doull—at Dr Casarett’s recommendation prior to his death in 1972—to join them in editing the second edition of the textbook toxicology: The Basic Science of Poisons. She played a significant behind-the-scenes role to get the first edition out after Casarett died while preparing it. Dr Amdur suggested that the two first editors’ names should be added to the title, which then became Casarett and Doull’s Toxicology: The Basic Science of Poisons. The second, third, and fourth editions of the textbook were edited by Drs. Doull, Amdur, and Klaassen [82]. Amdur was also very involved in the SOT and in 1997 was the first woman to receive the Merit Award [73].

The “mother of modern toxicology” [78] died on February 16, 1998, at the age of 77, of a heart attack while returning from a holiday in Hawaii. Her students and colleagues set up a SOT Award in her name, and this award is presented by the Inhalation and Respiratory Specialty Section [72, 73].

Dr Elizabeth Amy Kreiser Weisburger

One of 10 children, Elizabeth Kreiser Weisburger was born in 1924 in Pennsylvania [83]. Since most of her family members—including her parents—were teachers, she began learning at a very young age at home. Before Weisburger began her scientific career, she worked in various services such as making men’s pajamas and women’s dresses, worked at a poultry packing facility, and perhaps most interestingly, at the Bethlehem Steel Forge Plant, where she inspected airplane cylinder barrels and bridge pins [84]. In 1944, at age 20, she completed her bachelor’s in chemistry at Lebanon Valley College, and in 1947 she received her PhD from the University of Cincinnati, where she continued to work after receiving her degree. There she worked under Francis Earl Ray and researched fluorene compounds for chemotherapeutic and carcinogenic agents. In that same year she married another graduate student, John Hans Weisburger, with whom she later had three children. Curiously, all her siblings worked in chemistry, as well as in other science fields. In fact, her sister faced discrimination in that she was not allowed to use the lab benches, since they were reserved only for men [84].

In 1949, John and Elizabeth Weisburger began their postdoctoral studies under Harold Morris’s team at the National Cancer Institute. In 1961, both Elizabeth and John started the Carcinogen Screening Section at the National Cancer Institute. Compared to her other female toxicologist colleagues at that time, some of whom are mentioned in this paper, she held higher hierarchical positions. In 1974, Weisburger became chief of the Laboratory of Carcinogen Metabolism, and then in 1981 she became assistant director for chemical carcinogenesis in the Division of Cancer Etiology. She developed significant research in the field of chemical carcinogenesis, particularly on the molecular level, that contributed to cancer prevention and treatments, making her one of the first authority in chemical carcinogenesis [85]. In 1951, Weisburger became an officer in the Commissioned Corps of the US Public Health Service, often being called upon to be an expert witness or reviewer (Weisburger, 1996).

Weisburger was always interested in the mechanism by which environmental chemicals cause mutations, and this led her to elucidate carcinogenesis using aromatic amines and aminoazo dyes. She tested a selection of environmental chemicals for possible carcinogenic activity, and she showed for the first time the carcinogenic effect of certain pesticides, textile flameproofing agents, anti-knock agents, and others [84] as can be seen in her paper “Testing of twenty-one environmental aromatic amines or derivatives for long-term toxicity or carcinogenicity” [86].

John and Elizabeth Weisburger continued to work together until John left the institute in 1972. Two years later, John and Elizabeth Weisburger divorced. She continued working in the Institute until her retirement in 1988, when she continued working as a consultant.

Elizabeth Weisburger was a long-time member of the SOT and an advocate for women’s space and leadership in the society. In 2007, she established a scholarship fund, the Vera W. Hudson and Elizabeth K. Weisburger Scholarship Fund, to honor the memory of her deceased friend Dr Vera Wahbé Hudson. The scholarship funds female graduate students and encourages women in the field of toxicology [87].

On February 12, 2019, Dr Weisburger died in Rockville, Maryland at age 94, with four grandchildren surviving her [83].

Women in toxicology in the SOT

The SOT was established in 1961; nevertheless, in the 59 years the SOT has existed, only 20 have had an official committee focused on the needs of women in toxicology. In 1998, Dr Gina Pastino requested that the SOT form a Women in Toxicology committee and held an informational gathering meeting in New Orleans in March 1999. The meeting was a success, with over 100 people attending, and the group was given a temporary status and 3 years to demonstrate stability. These conditions were met within the first 2 years, and the first official meeting took place at the annual SOT meeting in Philadelphia in March 2000 [11].

In July 2001, the SOT Council approved the proposal for WIT to become a Specialty Section, and the first Executive Committee was established for the 2001–2002 fiscal year, including Dr Gina Pastino as President, Dr Michelle Hooth as Vice-President, Dr Eva Oberdorster as Secretary/Treasurer, and Dr Mary Haasch, Dr Linda Birnbaum, Dr Julie Kimbell, and Dr Victoria Tu as Councilors [11].

What the organization has achieved in only 20 years as part of the SOT goes beyond words. The organization provides extensive leadership for career development opportunities for women toxicologists, promotes and recognizes the accomplishments of women toxicologists through its awards (six awards), and sponsors scientific and educational programs [10]. These measures allowed the increase of women’s representation in all hierarchical positions within the SOT. As a result, in the 2018–2019 year, most members of the executive board were also members of the SOT council or would serve on council in future years, having at least 12 WIT member representatives. Moreover, the percentage of women in Officer and Council, or Committee Chairs positions, and as Committee members increased drastically since the establishment of SOT in 1961 until 2020. Women went from zero representation in those categories to almost 70% in Officer and Council positions, almost 55% in Committee Chairs positions, and around 65% Committee members women representation [88]. In addition, there has been a sharp increase in the number of females awarded national awards, many with WIT support by offering them assistance preparing their award application materials. As a result, out of the 11 SOT national awards, eight women were awarded with national awards in 2018 and six were awarded in 2019, the highest number ever seen in the SOT national awards [89].

To support and promote even more opportunities for women in science and toxicology, the WIT will continue to serve as a resource in career development opportunities within SOT, increase women visibility and the scientific community, provide opportunities for women in leadership positions, and encourage young women to consider a career in the toxicological sciences [10].

There remain opportunities for further improvements. Women in toxicology and in science in general still face issues as juggling careers with home life and dealing with gender prejudice in the workplace. Institutions can implement strategies for advancing women and creating a better gender-neutral environment. Some of them are: implementing male parental leave, allowing flexible family care spending for grant awards so it can be used for childcare or family-related expenses to reassure that the scientist can travel for meetings or to give lectures, adopting gender-conscious peer review committee, creating the awareness by focusing on education to combat the issues facing women in science, and creating institutional data report on gender inequality to make sure the institution is not biased in its gender staff composition or pay [90].

Conclusion

This article celebrates Women in Toxicology Special Interest Group’s 20th anniversary in the SOT by sharing a summary of six women scientists that made toxicology the field we know today (Fig. 1). They were not taken seriously or accepted for being women doing science in the late 1800s and the 1900s, but they were persistent against the discrimination they suffered. They are role models for the next generation of women, a generation that now enters the profession with more opportunities and engagement, mainly due to the progress that the Women of Toxicology of the Society of Toxicology has made over time. However, further improvements are required to ensure equal opportunities for women in science and toxicology.

Declarations

Not applicable.